ALBERT

Beschreibung: Using a portable gas analyzer system, the geogenic gas regime below and around an ancient gate to hell at Hierapolis/Phrygia was characterized. The site was first described by Strabo and Plinius as a gate to the underworld. During centuries, it attracted even ancient tourists. In a grotto below the temple of Pluto, CO2 was found to be at deadly concentrations of up to 91%. Astonishingly, these vapors are still emitted in concentrations that nowadays kill insects, birds, and mammals. The concentrations of CO2 escaping from the mouth of the grotto to the outside atmosphere are still in the range of 4–53% CO2 depending on the height above ground level. They reach concentrations during the night that would easily kill even a human being within a minute. These emissions are thought to reflect the Hadean breath and/or the breath of the hellhound Kerberos guarding the entrance to hell. The origin of the geogenic CO2 is the still active seismic structure that crosses the old town of ancient Hierapolis as part of the Babadag fracture zone. Our measurements confirm the presence of geogenic CO2 in concentrations that explain ancient stories of killed bulls, rams, and songbirds during religious ceremonies. They also strongly corroborate that at least in the case of Hierapolis, ancient writers like Strabo or Plinius described a mystic phenomenon very exactly without much exaggeration. Two thousand years ago, only supernatural forces could explain these phenomena from Hadean depths whereas nowadays, modern techniques hint to the well-known phenomenon of geogenic CO2 degassing having mantle components with relatively higher helium and radon concentrations.

Beschreibung: Continental rifting and ocean basin formation can be observed at the present day in the Red Sea, which is used as the modern analogue for the formation of mid-ocean ridges. Competing theories for how spreading begins—either by quasi-instantaneous formation of a whole spreading segment or by initiation of spreading at multiple discrete “nodes” separated by thinned continental lithosphere—have been put forward based, until recently, on the observations that many seafloor features and geophysical anomalies (gravity, magnetics) along the axis of the Red Sea appeared anomalous compared to ancient and modern examples of ocean basins in other parts of the world. The latest research shows, however, that most of the differences between the Red Sea Rift (RSR) and other (ultra)slow-spreading mid-ocean ridges can be related to its relatively young age and the presence and movement of giant submarine salt flows that blanket large portions of the rift valley. In addition, the geophysical data that was previously used to support the presence of continental crust between the axial basins with outcropping oceanic crust (formerly named “spreading nodes”) can be equally well explained by processes related to the sedimentary blanketing and hydrothermal alteration. The observed spreading nodes are not separated from one another by tectonic boundaries but rather represent “windows” onto a continuous spreading axis which is locally inundated and masked by massive slumping of sediments or evaporites from the rift flanks. Volcanic and tectonic morphologies are comparable to those observed along slow and ultra-slow spreading ridges elsewhere and regional systematics of volcanic occurrences are related to variations in volcanic activity and mantle heat flow. Melt-salt interaction due to salt flows, that locally cover the active spreading segments, and the absence of large detachment faults as a result of the nearby Afar plume are unique features of the RSR. The differences and anomalies seen in the Red Sea still may be applicable to all young oceanic rifts, associated with plumes and/or evaporites, which makes the Red Sea a unique but highly relevant type example for the initiation of slow rifting and seafloor spreading and one of the most interesting targets for future ocean research.

Beschreibung: Coral reefs in the Red Sea belong to the most diverse and productive reef ecosystems worldwide, although they are exposed to strong seasonal variability, high temperature, and high salinity. These factors are considered stressful for coral reef biota and challenge reef growth in other oceans, but coral reefs in the Red Sea thrive despite these challenges. In the central Red Sea high temperatures, high salinities, and low dissolved oxygen on the one hand reflect conditions that are predicted for ‘future oceans’ under global warming. On the other hand, alkalinity and other carbonate chemistry parameters are considered favourable for coral growth. In coral reefs of the central Red Sea, temperature and salinity follow a seasonal cycle, while chlorophyll and inorganic nutrients mostly vary spatially, and dissolved oxygen and pH fluctuate on the scale of hours to days. Within these strong environmental gradients micro- and macroscopic reef communities are dynamic and demonstrate plasticity and acclimatisation potential. Epilithic biofilm communities of bacteria and algae, crucial for the recruitment of reef-builders, undergo seasonal community shifts that are mainly driven by changes in temperature, salinity, and dissolved oxygen. These variables are predicted to change with the progression of global environmental change and suggest an immediate effect of climate change on the microbial community composition of biofilms. Corals are so-called holobionts and associate with a variety of microbial organisms that fulfill important functions in coral health and productivity. For instance, coral-associated bacterial communities are more specific and less diverse than those of marine biofilms, and in many coral species in the central Red Sea they are dominated by bacteria from the genus Endozoicomonas. Generally, coral microbiomes align with ecological differences between reef sites. They are similar at sites where these corals are abundant and successful. Coral microbiomes reveal a measurable footprint of anthropogenic influence at polluted sites. Coral-associated communities of endosymbiotic dinoflagellates in central Red Sea corals are dominated by Symbiodinium from clade C. Some corals harbour the same specific symbiont with a high physiological plasticity throughout their distribution range, while others maintain a more flexible association with varying symbionts of high physiological specificity over depths, seasons, or reef locations. The coral-Symbiodinium endosymbiosis drives calcification of the coral skeleton, which is a key process that provides maintenance and formation of the reef framework. Calcification rates and reef growth are not higher than in other coral reef regions, despite the beneficial carbonate chemistry in the central Red Sea. This may be related to the comparatively high temperatures, as indicated by reduced summer calcification and long-term slowing of growth rates that correlate with ocean warming trends. Indeed, thermal limits of abundant coral species in the central Red Sea may have been exceeded, as evidenced by repeated mass bleaching events during previous years. Recent comprehensive baseline data from central Red Sea reefs allow for insight into coral reef functioning and for quantification of the impacts of environmental change in the region.

Beschreibung: The Laptev and Eastern Siberian shelves are the world’s broadest shallow shelf systems. Large Siberian rivers and coastal erosion of up to meters per summer deliver large volumes of terrestrial matter into the Arctic shelf seas. In this chapter we investigate the applicability of Ocean Colour Remote Sensing during the ice-free summer season in the Siberian Laptev Sea region. We show that the early summer river peak discharge may be traced using remote sensing in years characterized by early sea-ice retreat. In the summer time after the peak discharge, the spreading of the main Lena River plume east and north-east of the Lena River Delta into the shelf system becomes hardly traceable using optical remote sensing methods. Measurements of suspended particulate matter (SPM) and coloured dissolved organic matter (cDOM) are of the same magnitude in the coastal waters of Buor Khaya Bay as in the Lena River. Match-up analyses of in situ chlorophyll-a (Chl-a) show that standard Medium Resolution Imaging Spectrometer (MERIS) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-derived Chl-a is not a valid remote sensing product for the coastal waters and the inner shelf region of the Laptev Sea. All MERIS and MODIS-derived Chl-a products are overestimated by at least a factor of ten, probably due to absorption by the extraordinarily high amount of non-algal particles and cDOM in these coastal and inner-shelf waters. Instead, Ocean Colour remote sensing provides information on wide-spread resuspension over shallows and lateral advection visible in satellite-derived turbidity. Satellite Sea Surface Temperature (SST) data clearly show hydrodynamics and delineate the outflow of the Lena River for hundreds of kilometres out into the shelf seas.

Beschreibung: The size of current plankton image datasets renders manual classification virtually infeasible. The training of models for machine classification is complicated by the fact that a large number of classes consist of only a few examples. We employ the recently introduced weight imprinting technique in order to use the available training data to train accurate classifiers in absence of enough examples for some classes. The model architecture used in this work succeeds in the identification of plankton using machine learning with its unique challenges, i.e. a limited number of training examples and a severely skewed class size distribution. Weight imprinting enables a neural network to recognize small classes immediately without re-training. This permits the mining of examples for novel classes.

Beschreibung: The Alpine orogeny is well recorded onshore and offshore by tectonic inversion of the Mesozoic rift basins. Large scale linear seamounts (more than 250 km long and with up to 5 km of uplift) involving oceanic and continental lithosphere were carried on top of thrusts, such as the Gorringe seamount and the Estremadura Spur in the SouthWest and West Iberia Margin, respectively. The SouthWest Iberia Margin also recorded the westward migration of the Gibraltar Oceanic slab as the westwards propagation of the Neo-Tethys subduction. Rotation of the tectonic compression from NW-SE to WNW-ESE inPliocene times caused the development of large scale dextral wrench faults as the present day Africa-Iberia plate boundary. Neotectonics of this plate boundary caused large to mega-scale destructive earthquakes and tsunamis.

Beschreibung: Hydrothermal circulation at mid-ocean ridges and assimilation of hydrothermally altered crust or hydrothermal fluids by rising magma can be traced by measuring chlorine (Cl) excess in erupted lavas. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an ultra-slow spreading ridge (maximum 1.6 cm yr−1 full spreading rate) by Cl, due to its saline seawater (40–42‰, cf. 35‰ in open ocean water), the presence of (hot) brine pools (up to 270‰ salinity and 68 °C) and the thick evaporite sequences that flank the young rift. Absolute chlorine concentrations (up to 1300 ppm) and Cl concentrations relative to minor or trace elements of similar mantle incompatibility (e.g., K, Nb) are much higher in Red Sea basalts than in basalts from average slow spreading ridges. Mantle Cl/Nb concentrations can be used to calculate the Cl-excess, above the magmatic Cl, that is present in the samples. Homogeneous within-sample Cl concentrations, high Cl/H2O, the decoupling of Cl-excess from other trace elements and its independence of the presence of highly saline seafloor brines at the site of eruption indicate that Cl is not enriched at the seafloor. Instead we find basaltic Cl-excess to be spatially closely correlated with evidence of hydrothermal activity, suggesting that deeper assimilation of hydrothermal Cl is the dominant Cl-enrichment process. A proximity of samples to both evaporite outcrops and bathymetric signs of volcanism on the seafloor enhance Cl-excess in basalts. The basaltic Cl-excess can be used as a tracer together with new bathymetric maps as well as indications of hydrothermal venting (hot brine pools, metalliferous Hydrothermal circulation at mid-ocean ridges and assimilation of hydrothermally altered crust or hydrothermal fluids by rising magma can be traced by measuring chlorine (Cl) excess in erupted lavas. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an ultra-slow spreading ridge (maximum 1.6 cm yr−1 full spreading rate) by Cl, due to its saline seawater (40–42‰, cf. 35‰ in open ocean water), the presence of (hot) brine pools (up to 270‰ salinity and 68 °C) and the thick evaporite sequences that flank the young rift. Absolute chlorine concentrations (up to 1300 ppm) and Cl concentrations relative to minor or trace elements of similar mantle incompatibility (e.g., K, Nb) are much higher in Red Sea basalts than in basalts from average slow spreading ridges. Mantle Cl/Nb concentrations can be used to calculate the Cl-excess, above the magmatic Cl, that is present in the samples. Homogeneous within-sample Cl concentrations, high Cl/H2O, the decoupling of Cl-excess from other trace elements and its independence of the presence of highly saline seafloor brines at the site of eruption indicate that Cl is not enriched at the seafloor. Instead we find basaltic Cl-excess to be spatially closely correlated with evidence of hydrothermal activity, suggesting that deeper assimilation of hydrothermal Cl is the dominant Cl-enrichment process. A proximity of samples to both evaporite outcrops and bathymetric signs of volcanism on the seafloor enhance Cl-excess in basalts. The basaltic Cl-excess can be used as a tracer together with new bathymetric maps as well as indications of hydrothermal venting (hot brine pools, metalliferous sediments) to predict where hydrothermal venting or now inactive hydrothermal vent fields can be expected. Sites of particular interest for future hydrothermal research are the Mabahiss Deep, the Thetis-HadarbaHatiba Deeps and Shagara-Aswad-Erba Deeps (especially their large axial domes), and Poseidon Deep. Older hydrothermal vent fields may be present at the Nereus and Suakin Deeps. These sites significantly increase the potential of hydrothermal vent field prospection in the Red Sea.

Beschreibung: The deep-sea brines of the Red Sea are unusual extreme environments and form characteristically steep gradients across the brine-seawater interfaces. Due to their unusual nature and unique combination of physical-chemical conditions these interfaces provide an interesting source of new findings in the fields of geochemistry, geology, microbiology, biotechnology, virology, and general biology. The current chapter summarizes recent and new results in the study of geochemistry and life at the interfaces of brine-filled deeps of the Red Sea.

Beschreibung: This paper addresses visual navigation of autonomous underwater vehicles (AUVs) with and without a given map, where the latter is called Simultaneous Localization and Mapping (SLAM). We summarize the challenges and opportunities in underwater environments that make visual navigation different from land navigation and also briefly survey the current state-of-the-art in this area. Then as a position paper we argue why many of these challenges could be met by a proper modeling of uncertainties in the SLAM representation. This would in particular allow the SLAM algorithm to thoroughly handle the ambiguity between “I see the same feature again.”, “I see a different but similar looking feature.” and “The environment has changed and the feature moved.”.

Beschreibung: The application of acoustic techniques, such as multibeam echosounders, has permitted the identification of Maltese submarine landscapes and landforms that were progressively inundated during the postglacial sea-level rise. Remarkably, geomorphological features due to fluvial, gravity-induced and karst processes that took place under former subaerial conditions can be clearly recognised on the present seafloor around the Maltese archipelago, and they were only slightly modified by sea action during the postglacial transgression phases. The analysis of the submerged landforms described in this chapter is crucial for understanding the evolution of the Maltese Islands during the last ca. 20,000 years.

Beschreibung: The study presents the results of continuous measurements of carbon dioxide concentration in the atmospheric surface layer at Tiksi and Cape Baranov Arctic stations over the period of August 2010–May 2017 and over the whole 2016, respectively. The amplitude of diurnal variations in the CO2 concentration in Tiksi from June to September is 1.1 ± 1.3, 2.4 ± 2.0, 4.1 ± 2.3, and 2.0 ± 2.4 ppm. Diurnal variations in CO2 at Cape Baranov station are absent. The observed seasonal variations in the CO2 concentration are compared with the data of the MBL empirical model for the marine atmospheric boundary layer of the Arctic region. In 2016, the difference between the observed and model concentrations at Tiksi and Cape Baranov stations amounted to 1.7 and 0.5 ppm, respectively, in winter and −3.0 and −1.9 ppm, respectively, in summer. It is shown that wildfires in Siberia caused a long synchronous increase in the CO2 concentration by 20 ppm in Tiksi and by 15 ppm at Cape Baranov station.

Beschreibung: The water of Atlantic origin (Atlantic water) is of special importance for the formation of the hydrological regime of the Arctic Ocean and provides a “building material” for the main water masses in the surface and intermediate layers. Atlantic water are structurally included to the Arctic Transpolar System (ATS); it is a multicomponent physical object whose state defines the role of the Arctic Ocean in the planetary climate. The recent advances in the Atlantic water research are discussed, in particular, the role of Atlantic water in the Arctic sea ice reduction. Particular attention is paid to the possible activation of feedbacks in ATS that may result in an accelerated Arctic sea ice loss recorded after 2007.

Beschreibung: Three most common Arctic foraminiferal species of the family Cassidulinidae from the Laptev Sea sediment cores were analyzed for paleoenvironmental reconstructions. This paleontological study is focused on morphological characteristics of apertural elements and the wall structure. The species Cassidulina neoteretis is considered an indicator of the Atlantic influence in contrast to the Arctic species Cassidulina reniforme and Islandiella norcrossi.

Beschreibung: The ecology and taxonomy of Islandiella norcrossi (Cushman, 1933), a typical representative of the Arctic calcareous benthic foraminifers, are analyzed based on microfossils from the Late Pleistocene-Holocene deposits of the Laptev Sea. This species is distributed on the shelf and continental slope of the Arctic seas, and indicates normal marine conditions with a seasonal ice cover and cold Arctic water masses. The species is also associated with a high seasonal productivity in sea-ice marginal zone. Tests are abundant in the Laptev Sea sediments, and show some variability in the size and shape of chambers, which was possibly caused by harsh environmental conditions of the Arctic (limited period of growth and reproduction); aberrant forms with an additional aperture being also present. The population contains tests of macrospherical and microspherical generations, as well as juveniles.

Beschreibung: Dome ports act as spherical windows in underwater housings through which a camera can observe objects in the water. As compared to flat glass interfaces, they do not limit the field of view, and they do not cause refraction of light observed by a pinhole camera positioned exactly in the center of the dome. Mechanically adjusting a real lens to this position is a challenging task, in particular for those integrated in deep sea housings. In this contribution a mechanical adjustment procedure based on straight line observations above and below water is proposed that allows for accurate alignments. Additionally, we show a chessboard-based method employing an underwater/above-water image pair to estimate potentially remaining offsets from the dome center to allow refraction correction in photogrammetric applications. Besides providing intuition about the severity of refraction in certain settings, we demonstrate the methods on real data for acrylic and glass domes in the water.

Beschreibung: We discuss the results of measurements in the region of Cape Baranov (the Severnaya Zemlya archipelago) of the set of physicochemical characteristics of atmospheric aerosol: aerosol optical depth, aerosol and black carbon concentrations, elemental and ion compositions of aerosol, organic and elemental carbon contents in aerosol, as well as the isotopic composition of carbon in the aerosol and snow samples. It is shown that the average values of most aerosol characteristics, measured in April–June 2018, are a little lower than in the Arctic settlement Barentsburg (Spitsbergen archipelago) and several-fold smaller than in the south of Western Siberia in the same period.

Beschreibung: Plastic has become indispensable for human life. When plastic debris is discarded into waterways, these items can interact with organisms. Of particular concern are microscopic plastic particles (microplastics) which are subject to ingestion by several taxa. This review summarizes the results of cutting-edge research about the interactions between a range of aquatic species and microplastics, including effects on biota physiology and secondary ingestion. Uptake pathways via digestive or ventilatory systems are discussed, including (1) the physical penetration of microplastic particles into cellular structures, (2) leaching of chemical additives or adsorbed persistent organic pollutants (POPs), and (3) consequences of bacterial or viral microbiota contamination associated with microplastic ingestion. Following uptake, a number of individual-level effects have been observed, including reduction of feeding activities, reduced growth and reproduction through cellular modifications, and oxidative stress. Microplastic-associated effects on marine biota have become increasingly investigated with growing concerns regarding human health through trophic transfer. We argue that research on the cellular interactions with microplastics provide an understanding of their impact to the organisms’ fitness and, therefore, its ability to sustain their functional role in the ecosystem. The review summarizes information from 236 scientific publications. Of those, only 4.6% extrapolate their research of microplastic intake on individual species to the impact on ecosystem functioning. We emphasize the need for risk evaluation from organismal effects to an ecosystem level to effectively evaluate the effect of microplastic pollution on marine environments. Further studies are encouraged to investigate sublethal effects in the context of environmentally relevant microplastic pollution conditions.

Beschreibung: Stable carbon isotopes of sediment organic matter (δ13COM) are widely applied in paleoenvironmental studies. Interpretations of δ13COM, however, remain challenging and factors that influence δ13COM may not apply across all lakes. Common explanations for stratigraphic shifts in δ13COM include changes in lake productivity or changes in inputs of allochthonous OM. We investigated the influence of different oxygen conditions (oxic versus anoxic) on the δ13COM values in the sediments of Lake Tiefer See. We analysed (1) a long sediment core from the deepest part of the lake, (2) two short, sediment–water interface cores from shallower water depths, and (3) OM in the water column, i.e. from sediment traps. Fresh OM throughout the entire water column showed a relatively constant δ13COM value of approximately − 30.5‰. Similar values, about − 31‰, were obtained for well-varved sediments in both the long and short, sediment–water interface cores. In contrast, δ13COM values from non-varved sediments in all cores were significantly less negative (− 29‰). The δ13COM values in the sediment–water interface cores from different water depths differ for sediments of the same age, if oxygen conditions at the time of deposition were different at these sites, as suggested by the state of varve preservation. Sediments deposited from AD 1924 to 1980 at 62 m water depth are varved and exhibit δ13COM values around − 31‰, whereas sediments of the same age in the core from 35 m water depth are not varved and show less negative δ13COM values of about − 29‰. The relation between varve occurrence and δ13COM values suggests that δ13COM is associated with oxygen conditions because varve preservation depends on hypolimnetic anoxia. A mechanism that likely influences δ13COM is selective degradation of OM under oxic conditions, such that organic components with more negative δ13COM are preferably decomposed, leading to less negative δ13COM values in the remaining, undegraded OM pool. Greater decomposition of OM in non-varved sediments is supported by lower TOC concentrations in these deposits (~ 5%) compared to well-varved sediments (~ 15%). Even in lakes that display small variations in productivity and terrestrial OM input through time, large spatial and temporal differences in hypolimnetic oxygen concentrations may be an important factor controlling sediment δ13COM.

Beschreibung: In den tropischen und subtropischen Meeren existieren in mittleren Tiefen riesige sauerstoffarme Zonen. Im Zuge des Klimawandels dehnen sie sich immer stärker aus. Auch in Küstenregionen entstehen durch Stickstoffbelastung aus der Landwirtschaft lebensfeindliche Zonen ohne Sauerstoff – mit verheerenden Folgen für das marine Ökosystem.

Beschreibung: The invasive round goby has established a viable population within 9 years of its first introduction to Lithuanian coastal waters (SE Baltic Sea). During its expansion phase, abundances increased 23-fold, which led to the near complete eradication of its main prey, the blue mussel, at 〈 20 m depth. The round goby population showed a stabilizing trend after blue mussel biomass was depleted; however, their abundance has not declined. The round goby feeds efficiently on newly settled mollusks, causing a severe constraint for blue mussel recovery. Changes in blue mussel availability and size structure induced a dietary shift in wintering long-tailed duck towards fish prey. An energetically dense food source sustains a good body condition in long-tailed ducks, however the change in trophic position (from 3.1 to 4.3 trophic level) suggests the potential for a reduction in their carrying capacity. Results from this study also show that coastal habitats with low and unpredictable population dynamics of blue mussel become less attractive wintering sites for long-tailed duck in the Baltic Sea. We also document a cascading effect of invasive species in the food web.

Beschreibung: We introduce a new parallelizable numerical multiscale method for advection-dominated problems as they often occur in engineering and geosciences. State of the art multiscale simulation methods work well in situations in which stationary and elliptic scenarios prevail but are prone to fail when the model involves dominant lower order terms which is common in applications. We suggest to overcome the associated difficulties through a reconstruction of subgrid variations into a modified basis by solving many independent (local) inverse problems that are constructed in a semi-Lagrangian step. Globally the method looks like a Eulerian method with multiscale stabilized basis. The method is extensible to other types of Galerkin methods, higher dimensions, nonlinear problems and can potentially work with real data. We provide examples inspired by tracer transport in climate systems in one and two dimensions and numerically compare our method to standard methods.

Beschreibung: Natural polysaccharides of marine origin are gaining interest in biomedical applications. Seaweeds are most abundant source of polysaccharides, as alginates, agar and agarose as well as Carrageenans. Even cellulose and amylose have been extracted from the macroalgae. Chitin and chitosan are derived from the exoskeleton of marine crustaceans. Interdisciplinary fields involving various science and technology aspects such as cell sciences, biomaterials, medical sciences and engineering are referred to as tissue engineering, which is an upcoming new field intended to replace biological functions in human body. Tissue engineered scaffolds and artificial organs developed by such technique has replace injured parts in human body. Technological advancements have made it possible to obtain active ingredient in marine organisms by controlling the growth and isolation conditions. Present review has focused on progress in discovering and producing new applications of marine polysaccharides in biomedical and tissue engineering.

Beschreibung: Differences in habitat and diet between species are often associated with morphological differences. Habitat and trophic adaptation have therefore been proposed as important drivers of speciation and adaptive radiation. Importantly, habitat and diet shifts likely impose changes in exposure to different parasites and infection risk. As strong selective agents influencing survival and mate choice, parasites might play an important role in host diversification. We explore this possibility for the adaptive radiation of Lake Tanganyika (LT) cichlids. We first compare metazoan macroparasites infection levels between cichlid tribes. We then describe the cichlids’ genetic diversity at the major histocompatibility complex (MHC), which plays a key role in vertebrate immunity. Finally, we evaluate to what extent trophic ecology and morphology explain variation in infection levels and MHC, accounting for phylogenetic relationships. We show that different cichlid tribes in LT feature partially non-overlapping parasite communities and partially non-overlapping MHC diversity. While morphology explained 15% of the variation in mean parasite abundance, trophic ecology accounted for 16% and 22% of the MHC variation at the nucleotide and at the amino acid level, respectively. Parasitism and immunogenetic adaptation may thus add additional dimensions to the LT cichlid radiation.

Beschreibung: Common problems in state-of-the-art climate models are a cold sea surface temperature (SST) bias in the equatorial Pacific and the underestimation of the two most important atmospheric feedbacks operating in the El Niño/Southern Oscillation (ENSO): the positive, i.e. amplifying wind-SST feedback and the negative, i.e. damping heat flux-SST feedback. To a large extent, the underestimation of those feedbacks can be explained by the cold equatorial SST bias, which shifts the rising branch of the Pacific Walker Circulation (PWC) too far to the west by up to 30°, resulting in an erroneous convective response during ENSO events. Based on simulations from the Kiel Climate Model (KCM) and the 5th phase of Coupled Model Intercomparison Project (CMIP5), we investigate how well ENSO dynamics are simulated in case of underestimated ENSO atmospheric feedbacks (EAF), with a special focus on ocean–atmosphere coupling over the equatorial Pacific. While models featuring realistic atmospheric feedbacks simulate ENSO dynamics close to observations, models with underestimated EAF exhibit fundamental biases in ENSO dynamics. In models with too weak feedbacks, ENSO is not predominantly wind-driven as observed; instead ENSO is driven significantly by a positive shortwave radiation feedback. Thus, although these models simulate ENSO, which in terms of simple indices is consistent with observations, it originates from very different dynamics. A too weak oceanic forcing on the SST via the positive thermocline, the Ekman and the zonal advection feedback is compensated by weaker atmospheric heat flux damping. The latter is mainly caused by a biased shortwave-SST feedback that erroneously is positive in most climate models. In the most biased models, the shortwave-SST feedback contributes to the SST anomaly growth to a similar degree as the ocean circulation. Our results suggest that a broad continuum of ENSO dynamics can exist in climate models and explain why climate models with less than a half of the observed EAF strength can still depict realistic ENSO amplitude.

Beschreibung: Diseases increasingly threaten aquaculture of kelps and other seaweeds. At the same time, protection concepts that are based upon application of biocides are usually not applicable, as such compounds would be rapidly diluted in the sea, causing ecological damage. An alternative concept could be the application of immune stimulants to prevent and control diseases in farmed seaweeds. We here present a pilot study that investigated the effects of oligoalginate elicitation on juvenile and adult sporophytes of Saccharina japonica cultivated in China and on adult sporophytes of Saccharina latissima cultivated in Germany. In two consecutive years, treatment with oligoalginate clearly reduced the detachment of S. japonica juveniles from their substrate curtains during the nursery stage in greenhouse ponds. Oligoalginate elicitation also decreased the density of endobionts and the number of bacterial cells on sporophytes of S. latissima that were cultivated on sea-based rafts. However, the treatment increased the susceptibility of kelp adults to settlement of epibionts (barnacles in Germany and filamentous algal epiphytes in China). In addition, oligoalginate elicitation accelerated the aging of S. japonica adults. Based upon these findings, oligoalginate elicitation could be a feasible way to provide “environmentally friendly” protection of kelp juveniles in nurseries. The same treatment causes not only beneficial, but also unwanted effects in adult kelp sporophytes. Therefore, it is not recommended as a treatment after the juvenile stage is completed. Future tests with other elicitors and other cultivated seaweed species may allow for the development of more feasible applications of targeted defense elicitation in seaweed aquaculture.

Beschreibung: The present study details the effects of basin-scale hydrographic characteristics of the Red Sea on the macroecology of Chaetognatha, a major plankton component in the pelagic realm. The hydrographic attributes and circulation of the Red Sea as a result of its limited connection with the northern Indian Ocean make it a unique ecohydrographic region in the world ocean. Here, we aimed to identify the prime determinants governing the community structure and vertical distribution of the Cheatognatha in this ecologically significant world ocean basin. The intrusion of Gulf of Aden Water influenced the Chaetognatha community composition in the south, whereas the overturning circulation altered their vertical distribution in the north. The existence of hypoxic waters (〈 100 µmol kg−1) at mid-depth also influenced their vertical distribution. The detailed evaluation of the responses of the different life stages of Chaetognatha revealed an increased susceptibility of adult individuals to hypoxic waters compared to immature stages. Higher oxygen demands of the adults for the egg and sperm production might have prevented them from inhabiting the oxygen-deficient mid-depth zones. The carbon and nitrogen content of the Copepoda and Chaetognatha communities and the quantification of the predation impact of Chaetognatha on Copepoda based on the feeding rate helped in corroborating the significant trophic link between these two prey–predator taxa. The observed influences of physical and chemical attributes on the distribution of Chaetognatha can be used as a model example for the role of the hydrography on the zooplankton community of the Red Sea.

Beschreibung: As coastal areas become increasingly vulnerable to climate change, the study of nearshore sediment textures along the littoral cell of the Medjerda delta in the Gulf of Tunis, southern Mediterranean coast can provide valuable information (i) on the origin (continental or marine) of the sediment, (ii) its transport direction, and (iii) constitutes an important tool in the assessment of coastal sensitivity. A total of 120 sediments samples underwent grain size analysis and statistic parameters have been calculated. These allowed the identification of five different Sedimentary Types (ST). Accordingly, using grain size indexes (i.e. Mz, SKI and Ku), Sediment Trend Analysis (STA) modeling tools were applied to define the seasonal sediment transport pathways throughout the nearshore of the Medjerda sedimentary cell. Results show that grain size distribution (GSD) and STA model pathways are determined by cross-shore geomorphology, location of the sediment-cell, seasonal incident wave and local terrestrial supply. The appearance in an atypical seabed location of the finer (Mo = 0.1 mm) and the coarser STs (Mo = 0.8 mm) can be indicative of human influence since the coarser particles are usually retained by dam structures. Moreover, the bimodality and the increased distribution of mud are also related to the seasonal incident wave winnowing of the historic deltaic plain submerged by the relative rise in sea level. The evolution of the sediment pattern towards a greater proportion of very fine grains indicates a deficit of sediment supply, particularly of the coarser grains, and demonstrates the coastal vulnerability of the Gulf of Tunis due to anthropic effects.

Beschreibung: A broad variety of materials of biological origin have been successfully used in recent decades for the removal of pollutants from waters. These biosorbents include natural polymers that play a key role for adsorption. It is therefore critical to understand the physicochemical properties of the chemical groups of these biopolymers. The acid–base properties of biomass are affected by pH, ionic strength and medium composition. Nevertheless, these parameters are not always considered during biosorption studies. According to the literature, less than 3% of biosorption reports include studies on proton binding. Moreover, in 60% of these papers, there is key experimental information missing such as the calibration of the electrodes employed for potentiometric titrations. We consider therefore that there is an important need for reviewing the role of proton binding in biosorption studies. This review outlines the major advances on data interpretation and modelling of proton binding on biosorbents. In addition, we discuss issues concerning the acid–base properties of biosorbents.

Beschreibung: Hydrothermal fluids on the modern seafloor are important carriers of base and precious metals in a wide range of volcanic and tectonic settings. The concentrations and distribution, especially of gold and silver, in associated seafloor massive sulfide (SMS) deposits are strongly influenced by variable source rocks, fluid chemistry, and precipitation mechanisms. Compositional data of 130 SMS deposits around the world show a large range of gold and silver grades, in part reflecting strong buffering of the hydrothermal fluids by their host rocks. Geochemical reaction-path modeling shows that in most cases the investigated hydrothermal fluids are undersaturated with gold and silver, and solubilities can be orders of magnitude higher than the Au and Ag concentrations measured in the corresponding fluids. Precipitation of gold during conductive cooling of mid-ocean ridge black smoker (MOR) fluids occurs at low temperatures but can be very rapid, with 〉 90% of the gold deposited in the first 25 °C of cooling below ~ 150 °C. The result is a Zn–Au polymetallic assemblage with Au and Ag deposited at the same time together with Pb and sulfosalts. In ultramafic-dominated (UM) systems, the strongly reduced hydrothermal fluids promote the deposition of gold at higher temperatures and explain the correlation between gold and copper in these deposits. In this case, the lower stability of the AuHS° complex at low ƒO2 (buffered by fayalite, magnetite, and quartz) results in gold deposition at 〉 250 °C with early bornite and chalcopyrite and before sphalerite and silver, producing a high-temperature Cu–Au assemblage. In sediment-hosted (SED) systems, the much higher pH stabilizes Au(HS)2− and keeps gold in solution to very low temperatures, after the precipitation of chalcopyrite, sphalerite, and galena, resulting in Au-poor polymetallic sulfides and very late-stage deposition of gold, commonly with amorphous silica. In arc-related (ARC) systems, gold deposition occurs at somewhat higher temperatures than in the MOR case, in part because the fluids start with higher gold concentrations. This can be explained by probable direct magmatic contributions, and the high ƒO2 of the fluids, which promotes the solubility of gold at the source. During cooling, gold precipitates at about 160 °C with sphalerite, tennantite, silver, and galena, resulting in an Au-rich polymetallic sulfide assemblage. The mixing of hydrothermal fluids with seawater generally causes oxidation and eventually a decrease in the pH at a mixing ratio of 1:1, causing an initial increase in the solubility of gold and silver. This can delay gold deposition from aqueous species to very low temperatures. These complex systematics make prediction of Au and Ag grades difficult. However, important new data are coming to light on the actual concentrations of the precious metals in hydrothermal fluids. In particular, the input of magmatic volatiles and leaching of pre-existing gold can lead to significant increases in the Au and Ag concentrations of the venting fluids and earlier deposition. In several cases, it appears that at least part of the gold load is present as nanoparticles in suspension, allowing bulk gold concentrations that may be far in excess of liquid saturation. Boiling at the seafloor is now widely observed, even at great water depths close to the critical point of seawater. Model calculations of phase separation during boiling show the competing effects on gold solubility of H2, H2S, and CO2 partitioning into the vapor, which can result in highly variable gold-to-base metal ratios in the deposits. Flashing of the vent fluids into steam at high temperatures is also commonly observed and can lead to spectacular Au grades, with a strong Cu–Au association in the deepest and hottest vents.

Beschreibung: The ecological approach to comparative cognition emphasizes that the ecological and social environment are important predictors of cognitive performance. We used this approach to test whether differences in habitat use and social behavior in the facultative Caribbean cleaning goby Elacatinus prochilos predict differences in learning performance in two discriminatory two-choice tasks. This species has two behavioral ecotypes: one that frequently engages in cleaning interactions and inhabits corals in male–female pairs (cleaning gobies) and another that rarely engages in cleaning interactions and inhabits barrel sponges in large groups (sponge-dwellers). We predicted that cleaning gobies would outperform sponge-dwellers in a pattern-cued task, which consisted of identifying the pattern on a plate that consistently provided food, while sponge-dwellers would outperform cleaning gobies in a spatial task, which consisted of identifying the location of the plate. Contrary to our predictions, there was no difference in performance between the two ecotypes. Most of the gobies performed poorly in the pattern-cued task and well in the spatial task. A possible explanation for these results is that the association of a pattern with positive and negative reinforcement may not be a pre-requisite for engaging in cleaning interactions, while spatial skills might be equally required in both ecotypes. Alternatively, the two ecotypes can flexibly adjust to new feeding conditions, which would explain their similar performance in the spatial task. Further research should investigate which aspects of E. prochilos’ social and ecological environment might impose challenges that require spatial cognition and whether individuals can flexibly adjust to new habitats and feeding conditions.

Beschreibung: Precipitation in California is modulated by variability in the tropical Pacific associated with El Nino/Southern Oscillation (ENSO): more rainfall is expected during El Nino episodes, and reduced rainfall during La Nina. It has been suggested that besides the shape and location of the sea surface temperature ( SST) anomaly this remote connection depends on the strength and location of the atmospheric convection response in the tropical Pacific. Here we show in a perturbed physics ensemble of the Kiel Climate Model and CMIP5 models that due to a cold equatorial SST bias many climate models are in a La Nina-like mean state, resulting in a too westward position of the rising branch of the Pacific Walker Circulation. This in turn results in a convective response along the equator during ENSO events that is too far west in comparison to observations. This effect of the equatorial cold SST bias is not restricted to the tropics, moreover it leads to a too westward SLP response in the North Pacific and too westward precipitation response that does not reach California. Further we show that climate models with a reduced equatorial cold SST bias have a more realistic representation of the spatial asymmetry of the teleconnections between El Nino and La Nina.

Beschreibung: The spatial pattern of the first mode of interannual variability associated with the East Asian summer monsoon (EASM), obtained from a multivariate Empirical Orthogonal Functions (MV-EOF) analysis, corresponds to the Pacific–Japan (PJ) pattern and is referred to as the PJ-mode. The present study investigates the interannual variation of the PJ-mode from the perspective of the intraseasonal timescale. In particular, the impact of the Madden–Julian oscillation (MJO) on the interannual variation of the PJ-mode is investigated. The results show that the MJO has a significant influence on the interannual variation of the PJ-mode mainly in the lower troposphere (850 hPa) and that the former accounts for approximately 11% of the amplitude of the latter. The major part of the contribution comes from a change in frequency of the different phases of the MJO, especially that of MJO phase 6. This suggests that intraseasonal variation of the convection anomalies over the tropical eastern Indian and western Pacific Oceans plays an important role in the interannual variation of the PJ-mode. In addition, MJO phase 7 also contributes to the interannual variability of the PJ-mode, in this case induced by both the change in frequency and the change in circulation anomalies associated with MJO phase 7.

Beschreibung: This book includes invited contributions presenting the latest research on the oceanography and environment of the Red Sea. In addition to covering topics relevant to research in the region and providing insights into marine science for non-experts, it is also of interest to those involved in the management of coastal zones and encourages further research on the Red Sea

Beschreibung: The nature of the warm climates of the Cretaceous has been enigmatic since the first numerical climate models were run in the late 1970s. Quantitative simulations of the paleoclimate have consistently failed to agree with information from plant and animal fossils and climate sensitive sediments. The ‘cold continental interior paradox’ (first described by DeConto et al. in Barrera E, Johnson C (eds) Evolution of the Cretaceous Ocean/climate system, vol 332. Geological Society of America Special Paper, Boulder, pp 391–406, 1999), has been an enigma, with extensive continental interiors, especially in northeast Asia, modeled as below freezing in spite of plant and other evidence to the contrary. We reconsider the paleoelevations of specific areas, particularly along the northeastern Siberian continental margin, where paleofloras indeed indicate higher temperatures than suggested by current climate models. Evidence for significant masses of ice on land during even the otherwise warmest times of the Cretaceous is solved by reinterpretation of the δ18O record of fossil plankton. The signal interpreted as an increase in ice volume on land is the same as the signal for an increase in the volume of groundwater reservoirs on land. The problem of a warm Arctic, where fossil floras indicate that they never experienced freezing conditions in winter, could not be solved by numerical simulations using higher CO2 equivalent greenhouse gas concentrations. We propose a solution by assuming that paleoelevations were less than today and that there were much more extensive wetlands (lakes, meandering rivers, swamps, bogs) on the continents than previously assumed. Using ~ 8 × CO2 equivalent greenhouse gas concentrations and assuming 50–75% water surfaces providing water vapor as a supplementary greenhouse gas on the continents reduces the meridional temperature gradients. Under these conditions the equatorial to polar region temperature gradients produce conditions compatible with fossil and sedimentological evidence.

Beschreibung: Climate model components involve both high-dimensional input and output fields. It is desirable to efficiently generate spatio-temporal outputs of these models for applications in integrated assessment modelling or to assess the statistical relationship between such sets of inputs and outputs, for example, uncertainty analysis. However, the need for efficiency often compromises the fidelity of output through the use of low complexity models. Here, we develop a technique which combines statistical emulation with a dimensionality reduction technique to emulate a wide range of outputs from an atmospheric general circulation model, PLASIM, as functions of the boundary forcing prescribed by the ocean component of a lower complexity climate model, GENIE-1. Although accurate and detailed spatial information on atmospheric variables such as precipitation and wind speed is well beyond the capability of GENIE-1’s energy-moisture balance model of the atmosphere, this study demonstrates that the output of this model is useful in predicting PLASIM’s spatio-temporal fields through multi-level emulation. Meaningful information from the fast model, GENIE-1 was extracted by utilising the correlation between variables of the same type in the two models and between variables of different types in PLASIM. We present here the construction and validation of several PLASIM variable emulators and discuss their potential use in developing a hybrid model with statistical components.

Beschreibung: There is a controversy about the origin of the recent decadal Atlantic Meridional Overturning Circulation (AMOC) slowing observed at 26.5°N and concurrent sea surface temperature cooling in the central and eastern mid-latitude North Atlantic. We investigate decadal AMOC slowing events simulated in a multi-millennial preindustrial control integration of the Kiel Climate Model (KCM), providing an estimate of internal AMOC variability. Preindustrial control integrations of 15 models participating in the Coupled Model Intercomparison Project phase 5 also are investigated, as well as historical simulations with them providing estimates of AMOC variability during 1856–2005. It is shown that the recent decadal AMOC decline is still within the range of the models’ internal AMOC variability and thus could be of natural origin. In this case, the decline would represent an extreme realization of internal variability provided the climate models yield realistic levels of AMOC variability. The model results suggest that internal decadal AMOC variability is large, requiring multi-decadal observational records to detect an anthropogenic AMOC signal with high confidence. When analyzing the strongest decadal AMOC slowing events in the KCM, which have amplitudes similar to or larger than the recently observed decadal AMOC decline, the following composite picture emerges: a very strong decadal AMOC decline is preceded by a decadal rise in atmospheric surface pressure over large parts of the mid-latitude North Atlantic. The change in low-level atmospheric circulation drives reduced oceanic heat loss over and diminished upper-ocean salt content in the Labrador Sea. In response, oceanic deep convection and subsequently the AMOC and northward oceanic heat transport weaken, and anomalously cold sea surface temperatures develop in the central and eastern mid-latitude North Atlantic

Beschreibung: Climate engineering (CE) deployment would alter prevailing relationships between Earth system variables, making indicators and metrics used so far in the climate change assessment context less appropriate to assess CE measures. Achieving a comprehensive CE assessment requires a systematic and transparent reevaluation of the indicator selection process from Earth system variables. Here, we provide a first step towards such a systematic assessment of changes in correlations between Earth system variables following simulated deployment of different CE methods. We therefore analyze changes in the correlation structure of a broad set of Earth system variables for two conventional climate change scenarios without CE and with three idealized CE model experiments: (i) solar radiation management, (ii) large-scale afforestation, and (iii) ocean alkalinity enhancement. First, we investigate how the three CE scenarios alter prevailing correlations between Earth system variables when compared to an intermediate-high and a business-as-usual future climate change scenario. Second, we contrast the indicators identified for the non-CE climate change scenarios and the indicators identified when all five scenarios are considered. Finally, we use the identified indicator sets for an evaluation of the five climate change scenarios. We find that the additional indicators provide valuable information for the assessment of the CE measures, and their application hence allows for a more comprehensive and a comparative assessment of the mitigation and CE deployment scenarios.

Beschreibung: Reproductive systems of rare adult specimens of the deep-sea squid genera Chiroteuthis, Mastigoteuthis, Liocranchia, and Bathoteuthis were collected in 2006 and 2015 in the different research surveys in the Atlantic Ocean between 46 degrees 40'S and 17 degrees 11'N. Whole squids were preserved in 4% buffered formaldehyde solution, subsequently transferred into 70% ethanol and studied in laboratory condition providing initial observations on spawning pattern in these animals. The potential fecundity of Ch. cf. joubini was similar to 45,000-50,000, the maximum egg size was 1.6-1.7 mm, while those of M. agassizii were similar to 8000-16,000 and 1.7-1.9 mm respectively. A maturing female of B. skolops had similar to 4800 eggs of which some similar to 1200 were atretic. The ovary of a spent L. reinhardti contained similar to 116,500 post-ovulatory follicles and no residual egg. Mature females of Chiroteuthis and Mastigoteuthis had spematangia implanted externally in the mantle, whereas Liocranchia had a specialised spermatangia receptacle on the inside of the mantle. Reproductive adaptations of these genera are discussed in relation to spawning habits of other deep-sea squids. Synchronous ovulation was found to be a prevailing type of the gonad development with all eggs being spawned as a single batch, with ot without brooding. In some species, this single batch is not released at once but in several consequent portions exhibiting 'extended synchronous' spawning.

Beschreibung: Easter Island is an isolated volcanic island in the Pacific Ocean. Despite the extended knowledge about its origin, flora, and fauna, little is known about the bacterial diversity inhabiting this territory. Due to its isolation, Easter Island can be considered as a suitable place to evaluate microbial diversity in a geographically isolated context, what could shed light on actinobacterial occurrence, distribution, and potential novelty. In the present study, we performed a comprehensive analysis of marine Actinobacteria diversity of Easter Island by studying a large number of coastal sampling sites, which were inoculated into a broad spectrum of different culture media, where most important variations in composition included carbon and nitrogen substrates, in addition to salinity. The isolates were characterized on the basis of 16S ribosomal RNA gene sequencing and phylogenetic analysis. High actinobacterial diversity was recovered with a total of 163 pure cultures of Actinobacteria representing 72 phylotypes and 20 genera, which were unevenly distributed in different locations of the island and sample sources. The phylogenetic evaluation indicated a high degree of novelty showing that 45% of the isolates might represent new taxa. The most abundant genera in the different samples were Micromonospora, Streptomyces, Salinispora, and Dietzia. Two aspects appear of primary importance in regard to the high degree of novelty and diversity of Actinobacteria found. First, the application of various culture media significantly increased the number of species and genera obtained. Second, the geographical isolation is considered to be of importance regarding the actinobacterial novelty found.

Beschreibung: Dramatic changes from a cold and dry last glacial to a warm and wet Holocene period intensified the Indian summer monsoon (ISM), resulting in vigorous hydrology and increased terrestrial erosion. Here we present seawater neodymium (Nd) data (expressed in εNd) from Andaman Sea sediments to assess past changes in the ISM and the related impact of Irrawaddy–Salween and Sittoung (ISS) river discharge into the Andaman Sea in the northeastern Indian Ocean. Four major isotopic changes were identified: (1) a gradual increase in εNd toward a more radiogenic signature during the Last Glacial Maximum (22–18 ka), suggesting a gradual decrease in the ISS discharge; (2) a relatively stable radiogenic seawater εNd between 17.2 and 8.8 ka, perhaps related to a stable reduced outflow; (3) a rapid transition to less radiogenic εNd signature after 8.8 ka, reflecting a very wet early–mid-Holocene with the highest discharge; and (4) a decrease in εNd signal stability in the mid–late Holocene. Taking into account the contribution of the ISS rivers to the Andaman Sea εNd signature that changes proportionally with the strengthening (less radiogenic εNd) or weakening (more radiogenic εNd) of the ISM, we propose a binary model mixing between the Salween and Irrawaddy rivers to explain the εNd variability in Andaman Sea sediments. We hypothesize that the Irrawaddy river mainly contributed detrital sediment to the northeastern Andaman Sea for the past 24 ka. Our εNd data shed new light on the regional changes in Indo-Asian monsoon systems when compared with the existing Indian and Chinese paleo-proxy records.

Beschreibung: The genus Tabrizicola with its type species and strain Tabrizicola aquatica RCRI19T was previously described as a purely chemotrophic genus of Gram-negative, aerobic, non-motile and rod-shaped bacteria. With the present study, we expand the description of the metabolic capabilities of this genus and the T. aquatica type strain to include chlorophyll-dependent phototrophy. Our results confirmed that T. aquatica, does not grow under anaerobic photoautotrophic or photoheterotrophic conditions. However, the presence of the photosynthesis-related genes pufL and pufM could be demonstrated in the genomes of several Tabrizicola strains. Additionally, photosynthetic pigments (bacteriochlorophyll a) were formed under aerobic, heterotrophic and low light conditions in T. aquatica strain RCRI19T. Furthermore, all the genes necessary for a fully operational photosynthetic apparatus and bacteriochlorophyll a are present in the T. aquatica type strain genome. Therefore, we suggest categorising T. aquatica RCRI19T, isolated from freshwater environment of Qurugöl Lake, as an aerobic anoxygenic phototrophic (AAP) bacterium.

Beschreibung: Warming is one of the most dramatic aspects of climate change and threatens future ecosystem functioning. It may alter primary productivity and thus jeopardize carbon sequestration, a crucial ecosystem service provided by coastal environments. Fucus vesiculosus is an important canopy-forming macroalga in the Baltic Sea, and its main consumer is Idotea balthica. The objective of this study is to understand how temperature impacts a simplified food web composed of macroalgae and herbivores to quantify the effect on organic carbon storage. The organisms were exposed to a temperature gradient from 5 to 25 °C. We measured and modeled primary production, respiration, growth and epiphytic load on the surface of Fucus and respiration, growth and egestion of Idotea. The results show that temperature affects physiological responses of Fucus and Idotea separately. However, Idotea proved more sensitive to increasing temperatures than the primary producers. The lag between the collapse of the grazer and the decline of Fucus and epiphytes above 20 °C allows an increase of carbon storage of the primary productivity at higher temperatures. Therefore, along the temperature gradient, the simplified food web stores carbon in a non-monotonic way (reaching minimum at 20 °C). Our work stresses the need of considering the combined metabolic performance of all organisms for sound predictions on carbon circulation in food webs.

Beschreibung: This study applied the Systems Approach Framework (SAF) to address the issue of declining Atlantic cod fishery in coastal areas. Interviews of 58 fishers from 26 harbours and meetings with national fisheries organisations and managers revealed the perception of an offshore movement of coastal cod. Numerical modelling based on fishing survey data did not substantiate these perceptions in the data-poor coastal waters. However, Data Storage Tag (DST) information combined with bottom sea water temperature data from the spatio-temporal hydrodynamic Baltic Sea Ice-Ocean Model showed changes in potential cod habitat distribution in the Skagerrak-Kattegat and western Baltic from 1979 to 2016. Subsequently, cod habitats were defined in three categories: (i) potentially suitable (T 〈= 12 degrees C); (ii) episodic (12 〈 T 〈= 16 degrees C); and (iii) unsuitable (T 〉 16 degrees C). The environmental changes were linked to the socio-economic component of cod fishery. Cod catches (weight and monetary value) were retrieved using logbook information and data from the Vessel Monitoring System (VMS, 2005-2016) and the Automatic Identification System (AIS, 2006-2016). General additive modelling significantly showed the largest proportion of catches took place in the potentially suitable habitat whereas catches were lower in the episodic habitat and rare in the unsuitable habitat. The results of this first large-scale SAF application are highly valuable for adapting existing fisheries management by: (i) providing information on habitat shrinkage for Maximum Sustainable Yield (MSY) based stock assessments; (ii) adding a spatio-temporal dimension for coastal productivity relative to the vessel-based Individual Transferable Quota (ITQ) system; and (iii) providing a predictive scenario simulation tool for sustainable management under changing environmental conditions.

Beschreibung: The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions against reference (or nonimpaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise. Another important aspect is to ensure that water quality assessment is comparable among the different Member States. In this context, the present paper offers a constructive critique of the practices followed during the WFD implementation in Greece by pinpointing methodological weaknesses and knowledge gaps that undermine our ability to classify the ecological quality of Greek lakes. One of the pillars of WDF is a valid lake typology that sets ecological standards transcending geographic regions and national boundaries. The national typology of Greek lakes has failed to take into account essential components. WFD compliance assessments based on the descriptions of phytoplankton communities are oversimplified and as such should be revisited. Exclusion of most chroococcal species from the analysis of cyanobacteria biovolume in Greek lakes/reservoirs and most reservoirs in Spain, Portugal, and Cyprus is not consistent with the distribution of those taxa in lakes. Similarly, the total biovolume reference values and the indices used in classification schemes reflect misunderstandings of WFD core principles. This hampers the comparability of ecological status across Europe and leads to quality standards that are too relaxed to provide an efficient target for the protection of Greek/transboundary lakes such as the ancient Lake Megali Prespa.

Beschreibung: The order Botryosphaeriales includes many latent fungal pathogens with a wide range of woody hosts. The taxonomy of these pathogens has been difficult due to the use of poorly informing markers in phylogenetic analyses and the lack of good morphological characters. Many genera and families in this order have not yet been systematically studied in different hosts and from different regions. In this study, a total of 29 fungal strains from the Aplosporellaceae and Botryosphaeriaceae were isolated from branches or twigs with symptoms of canker and dieback disease in Mount Yudu of China. Morphology and multigene analyses (ITS, LSU and TEF1-α) indicated five distinct lineages, including Aplosporella javeedii, Botryosphaeria dothidea, Diplodia quercicola sp. nov., Phaeobotryon aplospora sp. nov. and Phaeobotryon rhois. Diplodia quercicola is characterized by multiloculate conidiomata, producing oblong to cylindrical, thick-walled, hyaline, aseptate conidia. Phaeobotryon aplospora is characterized by pulvinate, multiloculate conidiomata, producing ellipsoid to oblong, brown, aseptate conidia. The new species differ from related species phylogenetically and ecologically and in morphological features.

Beschreibung: We have studied iron (Fe)-isotope signals in particles (〉 0.22 µm) and the dissolved phase (〈 0.22 µm) in two subarctic, boreal rivers, their estuaries and the adjacent sea in northern Sweden. Both rivers, the Råne and the Kalix, are enriched in Fe and organic carbon (up to 29 µmol/L and up to 730 µmol/L, respectively). Observed changes in the particulate and dissolved phase during spring flood in May suggest different sources of Fe to the rivers during different seasons. While particles show a positive Fe-isotope signal during winter, during spring flood, the values are negative. Increased discharge due to snowmelt in the boreal region is most times accompanied by flushing of the organic-rich sub-surface layers. These upper podzol soil layers have been shown to be a source for Fe-organic carbon aggregates with a negative Fe-isotope signal. During winter, the rivers are mostly fed by deep groundwater, where Fe occurs as Fe(oxy)hydroxides, with a positive Fe-isotope signal. Flocculation during initial estuarine mixing does not change the Fe-isotope compositions of the two phases. Data indicate that the two groups of Fe aggregates flocculate diversely in the estuaries due to differences in their surface structure. Within the open sea, the particulate phase showed heavier δ56Fe values than in the estuaries. Our data indicate the flocculation of the negative Fe-isotope signal in a low salinity environment, due to changes in the ionic strength and further the increase of pH.

Beschreibung: The climate system can potentially switch from one stable state to another. The closer a system is to a bifurcation point (i.e., ‘tipping point’), the more likely it is that even small perturbations can force the system to experience a state shift, e.g., a collapsing Atlantic meridional overturning circulation (AMOC) and associated cooling in parts of the North Atlantic. Here, we present an abrupt state transition from a warm to a cold North Atlantic climate state with expanded sea ice during an orbitally forced transient Holocene simulation performed with the Community Climate System Model version 3. The state transition is associated with a weakening of the AMOC by about 33% in this simulation. The changing background climate induced by slow external orbital forcing plays an important role for the abrupt climate shift. The model allows the identification of regions and variables that play a key role for a potential climate transition and show early-warning signals. Increase in autocorrelation and standard deviation as well as trends in skewness especially for sea-surface salinity in the northern North Atlantic are identified as robust early-warning signals, whereas no early-warning signals are found in the time series of the AMOC stream function.

Beschreibung: Beside its global effects, climate change is manifested in many regionally pronounced features mainly resulting from changes in the oceanic and atmospheric circulation. Here we investigate the influence of the North Atlantic SST on shaping the winter-time response to global warming. Our results are based on a long-term climate projection with the Max Planck Institute Earth System Model (MPI-ESM) to investigate the influence of North Atlantic sea surface temperature pattern changes on shaping the atmospheric climate change signal. In sensitivity experiments with the model’s atmospheric component we decompose the response into components controlled by the local SST structure and components controlled by global/remote changes. MPI-ESM simulates a global warming response in SST similar to other climate models: there is a warming minimum—or ”warming hole”—in the subpolar North Atlantic, and the sharp SST gradients associated with the Gulf Stream and the North Atlantic Current shift northward by a few a degrees. Over the warming hole, global warming causes a relatively weak increase in rainfall. Beyond this, our experiments show more localized effects, likely resulting from future SST gradient changes in the North Atlantic. This includes a significant precipitation decrease to the south of the Gulf Stream despite increased underlying SSTs. Since this region is characterised by a strong band of precipitation in the current climate, this is contrary to the usual case that wet regions become wetter and dry regions become drier in a warmer climate. A moisture budget analysis identifies a complex interplay of various processes in the region of modified SST gradients: reduced surface winds cause a decrease in evaporation; and thermodynamic, modified atmospheric eddy transports, and coastal processes cause a change in the moisture convergence. The changes in the the North Atlantic storm track are mainly controlled by the non-regional changes in the forcing. The impact of the local SST pattern changes on regions outside the North Atlantic is small in our setup.

Beschreibung: Solar signals in the atmosphere and the ocean, especially in tropopause temperatures and lower stratospheric water vapour are investigated using recent observational and reanalyses data sets for the period from 1958 through 2013. Previous observational and modeling studies demonstrated solar influences in the lower stratosphere resembling a positive Northern Annular Mode due to the top-down mechanism involving enhanced solar UV radiation in the stratosphere during solar maxima and dynamical amplification mechanisms in the atmosphere. We found that these stratospheric changes might propagate down to the troposphere and become zonally asymmetric with characteristic pressure and wind pattern over the North Atlantic and North Pacific. Such changes in tropospheric circulation are related to anomalous positive SST anomalies in the central Pacific which resemble an El Niño Modoki event. We show for the first time with ocean reanalysis data that these SST anomalies are amplified by a positive feedback through oceanic subsurface currents and heat transport in the equatorial Pacific. Anomalous warm SSTs in the equatorial central Pacific change the zonal SST gradient and lead to anomalous westerly winds and currents in the western Pacific and easterly winds and currents in the eastern Pacific. This indicates a convergence and less upwelling and therefore enhances the positive SST anomalies in the equatorial central Pacific. Such a positive feedback results in a peak of El Niño Modoki events about 2 years after the solar maximum. These solar-induced signals in the ocean in turn modify the circulation and convection in the troposphere, resulting in lagged solar signals of anomalous high tropopause heights and negative anomalies in tropopause temperatures as well as in lower stratospheric water vapour over the equatorial Pacific which are in agreement with a time evolving solar-induced El Niño Modoki-like SST pattern. We demonstrate a solar modulation of intrinsic decadal climate variability over the Pacific which is amplified by positive feedbacks between the ocean and the atmosphere.

Beschreibung: Dosidicus gigas (the Humboldt squid) is a widely distributed and ecologically important predator in the eastern Pacific Ocean, but its mating behaviour is poorly understood. Individuals of this species have undergone a drastic change in size at maturity in the last years. We investigated mating activity of Humboldt squid in the Gulf of California in 2013, 2014, and 2015 by quantifying spermatangia deposited in the tissue of the buccal area. In 2015, we encountered the smallest mean mantle length of mature specimens recorded to date in the Gulf of California. In all years, numerous males were encountered that had been mated by other males. Spermatangia in males were deposited on the tissue in similar numbers and in the same location as normally occurs in females (the buccal area), suggesting that male-to-male mating behaviour is similar to male-to-female. This behaviour is referred to as same-sex sexual behaviour and has been described for various taxa, including other cephalopods. Overall similarity in mating frequency between males and females and in body size of mated individuals (in 2015) suggests non-discriminative and brief encounters with body size being a cue for mating. This mating strategy may be beneficial for males, as Humboldt squid live in groups where competition for mates is likely high. The energetic costs of male-to-male mating events may be counterbalanced by the fitness profits of indiscriminate mating behaviour.

Beschreibung: Gelatinous zooplankton (GZ) such as medusae, ctenophores, siphonophores, pyrosomes and salps are important components of oceanic pelagic communities and small calycophoran siphonophores (CS) are typically abundant at shallow depths. The Sargasso Sea spawning area of the Atlantic catadromous freshwater eels has a regular pattern of shallow autumn to spring temperature fronts. There is limited information about the southern Sargasso Sea GZ fauna, and it is not known which species are distributed across these frontal zones. Plankton samples from a survey of larval European eel (Anguilla anguilla) abundance in March and April 2017 using an Isaacs-Kidd Midwater Trawl (0–300 m, 35 stations, three transects) were used to examine the distribution and abundance of net-captured CS and other GZ species in relation to oceanographic characteristics. More than 2200 specimens of 15 taxa were sub-sampled, with five CS (Abylopsis tetragona, A. eschscholtzii, Chelophyes appendiculata, Eudoxoides spiralis and E. mitra) dominating catches at every station. GZ were most abundant around the 22 and 24 °C isotherms, and higher abundances of CS in the north were correlated with lower water temperature. The widespread presence of CS across the European eel spawning area is consistent with a recent study detecting their DNA sequences in the gut contents of young eel larvae collected in the Sargasso Sea, suggesting CS material was either eaten directly or as part of ingested marine snow particles. The present study shows that both types of organisms occupy the southern Sargasso Sea during the European eel spawning season.

Beschreibung: Climate change has been altering the ocean environment, affecting as a consequence the biological communities including microorganisms. We performed a mesocosm experiment to test whether biodiversity loss caused by one stressor would influence plankton community sensitivity to a subsequent stressor, as envisioned in Vinebrooke's multiple stressor concept. A natural Baltic Sea diatom-dominated phytoplankton assemblage was used as a model system where we examined whether a preceding heat shock would affect the community's response to changing salinity. Initially, the community was treated by a short-term temperature increase of 6 °C, which resulted in a loss of species compared to the control. Thereafter, the control and the heat-shocked communities were subject to a salinity change (- 5 psu, control, + 5 psu). The species Skeletonema dohrnii, Thalassiosira anguste-lineata, Thalassiosira nordenskioeldii, Chaetoceros socialis and Ditylum brightwellii were major components of the control and heat-shocked assemblages (〉 80% of the total biomass). We examined the effect on species composition and biodiversity (morphospecies and operational taxonomic units (OTUs) related to phytoplankton) and on phytoplankton biomass. In addition, we explored the single species response of five dominant diatoms on these environmental perturbations. Our results showed that increased salinity significantly reduced the OTUs richness both in the control and the less diverse heated community as well as the phytoplankton biomass in the heated community. On the other hand, decreased salinity significantly increased species richness and phytoplankton biomass in both communities and OTUs richness in the control community. The five dominant diatoms reached their highest biomass under decreased salinity and responded negatively to increased salinity (lower biomass than ambient salinity). Contrary to Vinebrooke's multiple stressor concept, there was no indication that the heat treatment had altered the community's sensitivity to the salinity stress in our study system.

Beschreibung: This manuscript reports the first sightings and collection of the swimming crab Cronius ruber (Lamarck, 1818) on the coast of Madeira Island, Portugal. After the recent record in the Canary Islands, this represents a further step northward on this species’ expansion in distribution in the eastern Atlantic. The crab was first spotted during underwater visual census surveys done by scuba diving in July 2018 and was repeatedly observed during the following months, in different locations on the south coast of Madeira. Analysis of temperature data from several geographic locations where C. ruber is present was performed to assess how thermal regimes and ongoing changes may influence this recent distribution shift. Current temperature trends in Madeira suggest that the arrival and establishment of C. ruber to Madeira might have been facilitated this thermophilic species, adding evidence for the ongoing tropicalization of this area. Finally, the current spread of C. ruber in both Canaries and Madeira island systems highlights the need for a long-term monitoring program targeting this and other non-indigenous species (NIS).

Beschreibung: Clonal behavior has been hypothesized to provide an escape from allometric metabolic scaling that limits the maximum mass achieved by a single individual. Here, we demonstrate the capacity of a wide-spread, non-native sea anemone to buffer its colony biomass accumulation rate across environments by modulating ramet body size through environmentally dependent growth, fission, and catabolism. In 2015, thermal reaction norms for growth and fission behavior were constructed using clonal lines of the sea anemone Diadumene lineata. In 2018, variation in growth patterns under a factorial cross of temperature level and oxygen availability was examined to test the hypothesis that individual ramet size is regulated by oxygen limitation in accordance with optimal size theory. Across a wide range of temperatures, colonies accumulated a similar amount of biomass despite a radical shift from unitary to clonal growth, supporting fission as a mechanism to buffer growth rates over a range of conditions. Individual body size appears to be regulated by the environment with increased temperature and reduced oxygen modifying fission and mass-specific growth patterns, leading to the production of smaller-bodied ramets in warm conditions. However, whether anemones in common garden conditions reduce individual body size through catabolism or fission depends on the region of origin and may relate to differences in seasonal temperature patterns among coastlines, which influence the energetic benefits of fission rate plasticity.

Beschreibung: The Osborn Plateau is a large intraplate rise in the eastern part of the Indian Ocean, which has been poorly studied by the geological and geophysical methods. In cruise SO258/1 on the R/V Sonne, new data were collected using Parasound seismic profiling and a multibeam echo-sounder survey. Faults in the sedimentary cover, which extend to the bottom surface, indicate high neotectonic activity in the Osborn Plateau area. It may continue up to the present, as well as in the adjacent segment of the Ninetyeast Ridge, where strong earthquakes have been recorded. Two reflectors in the upper part of the sedimentary cover mark the global lowering of the World Ocean level at the Miocene/Pliocene and Pliocene/Pleistocene boundaries. The reflector in the sediments at the Lower/Upper Pliocene boundary is associated with a change in the regional hydrodynamic regime that occurred at that time in the eastern Indian Ocean. The rocks dredged on Osborn Plateau are identical to some volcanic rocks of the Ninetyeast Ridge, confirming their assumed genetic link, but they are more similar to the basalts of the Kerguelen Plateau. Extremely altered vitroclastic tuffs appear to have been formed as a result of explosive volcanic eruptions of alkali basalts or foidites under subaeral or relatively shallow water conditions and represent the most recent eruptions in the region.

Beschreibung: Biodiversity is critical for maintaining and stabilizing ecosystem processes. There is a need for high-resolution biodiversity maps that cover large sea areas in order to address ecological questions related to biodiversity-ecosystem functioning relationships and to provide data for marine environmental protection and management decisions. However, traditional sampling-point-wise field work is not suitable for covering extensive areas in high detail. Spatial predictive modeling using biodiversity data from sampling points and georeferenced environmental data layers covering the whole study area is a potential way to create biodiversity maps for large spatial extents. Random forest (RF), generalized additive models (GAM), and boosted regression trees (BRT) were used in this study to produce benthic (macroinvertebrates, macrophytes) biodiversity maps in the northern Baltic Sea. Environmental raster layers (wave exposure, salinity, temperature, etc.) were used as independent variables in the models to predict the spatial distribution of species richness. A validation dataset containing data that was not included in model calibration was used to compare the prediction accuracy of the models. Each model was also evaluated visually to check for possible modeling artifacts that are not revealed by mathematical validation. All three models proved to have high predictive ability. RF and BRT predictions had higher correlations with validation data and lower mean absolute error than those of GAM. Both mathematically and visually, the predictions by RF and BRT were very similar. Depth and seabed sediments were the most influential abiotic variables in predicting the spatial patterns of biodiversity.

Beschreibung: A long-standing difficulty of climate models is to capture the annual cycle (AC) of eastern equatorial Pacific (EEP) sea surface temperature (SST). In this study, we first examine the EEP SST AC in a set of integrations of the coupled Kiel Climate Model, in which only atmosphere model resolution differs. When employing coarse horizontal and vertical atmospheric resolution, significant biases in the EEP SST AC are observed. These are reflected in an erroneous timing of the cold tongue’s onset and termination as well as in an underestimation of the boreal spring warming amplitude. A large portion of these biases are linked to a wrong simulation of zonal surface winds, which can be traced back to precipitation biases on both sides of the equator and an erroneous low-level atmospheric circulation over land. Part of the SST biases also is related to shortwave radiation biases related to cloud cover biases. Both wind and cloud cover biases are inherent to the atmospheric component, as shown by companion uncoupled atmosphere model integrations forced by observed SSTs. Enhancing atmosphere model resolution, horizontal and vertical, markedly reduces zonal wind and cloud cover biases in coupled as well as uncoupled mode and generally improves simulation of the EEP SST AC. Enhanced atmospheric resolution reduces convection biases and improves simulation of surface winds over land. Analysis of a subset of models from the Coupled Model Intercomparison Project phase 5 (CMIP5) reveals that in these models, very similar mechanisms are at work in driving EEP SST AC biases.

Beschreibung: Methane gas hydrates have increasingly become a topic of interest because of their potential as a future energy resource. There are significant economical and environmental risks associated with extraction from hydrate reservoirs, so a variety of multiphysics models have been developed to analyze prospective risks and benefits. These models generally have a large number of empirical parameters which are not known a priori. Traditional optimization-based parameter estimation frameworks may be ill-posed or computationally prohibitive. Bayesian inference methods have increasingly been found effective for estimating parameters in complex geophysical systems. These methods often are not viable in cases of computationally expensive models and high-dimensional parameter spaces. Recently, methods have been developed to effectively reduce the dimension of Bayesian inverse problems by identifying low-dimensional structures that are most informed by data. Active subspaces is one of the most generally applicable methods of performing this dimension reduction. In this paper, Bayesian inference of the parameters of a state-of-the-art mathematical model for methane hydrates based on experimental data from a triaxial compression test with gas hydrate-bearing sand is performed in an efficient way by utilizing active subspaces. Active subspaces are used to identify low-dimensional structure in the parameter space which is exploited by generating a cheap regression-based surrogate model and implementing a modified Markov chain Monte Carlo algorithm. Posterior densities having means that match the experimental data are approximated in a computationally efficient way.

Beschreibung: A strong warm event occurred in the southeastern tropical Atlantic Ocean off Angola and Namibia in January and February 2016 with sea surface temperature anomalies reaching 3 °C. In contrast to classical Benguela Niño events, the analysis of various direct observations indicates that the warming was not predominantly forced by an equatorial Kelvin wave exciting a coastally trapped wave but instead resulted from a combination of local processes that are related to (1) a weakening of the alongshore, i.e. mainly southerly, winds and (2) enhanced freshwater input through local precipitation and river discharge. Consistent with the weakened winds, we find a reduction in latent heat loss from the ocean and a poleward surface current anomaly. The surface freshening, which is detected in satellite observations of sea surface salinity, caused a very shallow mixed layer and enhanced upper ocean stratification. This is supported by the analysis of the velocity structure of the Angola Current at 11°S, which shows that at the time of the event subsurface velocities were directed northward while surface velocities were directed southward. The shallow layer of warm and fresh surface water was thus advected poleward by the surface current. In addition, a reduction of the local upwelling and the formation of a barrier layer that inhibits the entrainment of cool subsurface waters into the surface mixed layer might have contributed to the warm surface anomaly. The sudden termination of the warm event was accompanied by a re-intensification of southerly winds in March

Beschreibung: An interactive (multi-access) global identification key (OncIdent) has been developed for the pelagic marine microcopepod family Oncaeidae and made accessible online. Details of the general approach and development of the key are given in Bottger-Schnack and Schnack (J Nat Hist 49:2727-2741, 2015). After beta-testing, new additions include illustrations for all species and feature attributes considered, plus a textual summary of each species' feature states in the key. Additional taxonomic notes are given where required, highlighting morphological or molecular genetic peculiarities or problems, with links to large data bases leading directly to more comprehensive information about each species. The present paper briefly reviews the taxonomic background for key construction, summarizes the opportunities and limitations of the current online version OncIdent2.0, and provides guidance for its practical use.

Beschreibung: Almost all the inorganic carbon on Earth is converted into biomass via the Calvin–Benson–Bassham (CBB) cycle. Here, the central carboxylation reaction is catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), which can be found in numerous primary producers including plants, algae, cyanobacteria, and many autotrophic bacteria. Although RubisCO possesses a crucial role in global biomass production, it is not a perfect catalyst. Therefore, research interest persists on accessing the full potential of yet unexplored RubisCOs. We recently developed an activity-based screen suited to seek active recombinant RubisCOs from the environment—independent of the native host’s culturability. Here, we applied this screen to twenty pre-selected genomic fosmid clones from six cultured proteobacteria to demonstrate that a broad range of phylogenetically distinct RubisCOs can be targeted. We then screened 12,500 metagenomic fosmid clones from six distinct hydrothermal vents and identified forty active RubisCOs. Additional sequence-based screening uncovered eight further RubisCOs, which could then also be detected by a modified version of the screen. Seven were active form III RubisCOs from yet uncultured Archaea. This indicates the potential of the activity-based screen to detect RubisCO enzymes even from organisms that would not be expected to be targeted.

Beschreibung: Fluctuations in abundance of dominant species can cause competitive release of resources with consequences on community structure and functioning. In the present study, changes in the intertidal macroinfauna community of an exposed sandy beach were evaluated during two contrasting periods characterized by low and high densities of the yellow clam Amarilladesma mactroides. The increase in clam abundance and biomass was associated with a significant decrease in abundance of the rest of the community. In particular, a decline was observed for the pea crab Austinixa patagoniensis, a commensal species that lives in the burrows of the shrimp Sergio mirim. Our study demonstrates that fluctuations in clam abundance lead to long-term changes in community structure, suggesting the presence of competitive interactions. The environmental stability over the two periods strengthens the hypothesis that the competition between species is crucial for shaping the ecological community. Stable isotope analysis allows discarding trophic competition as mechanism of exclusion. Image maps reveal complementary distribution of species, showing the relevance of the spatial competition, which is mediated by changes in abundance of a third species. Indeed, high densities of A. mactroides reduce the available area for the establishment of the S. mirim burrows, limiting the foraging behavior of its commensal, the pea crab. Such an interaction drives density-dependent exclusion of the pea crab from the intertidal zone following the establishment of the yellow clam population. This study illustrates that spatial competition triggered by the increase of a bed-forming species can have community-wide consequences in exposed sandy beaches

Beschreibung: The NW-SE striking volcanic front in Nicaragua is dissected into a western and an eastern segment separated by 20 km of N-S offset. The Chiltepe volcanic complex lies at the eastern end of the western segment and at the northern tip of the Nejapa-Miraflores tectonic and volcanic lineament that traces the arc offset. The Chiltepe peninsula attained its present shape and composition during highly explosive and effusive volcanic activity through the Late Pleistocene and Holocene, which formed the Chiltepe Formation (CF) and culminated in the 1.9 ka plinian eruption of the Chiltepe tephra. The previous evolution of this volcanic system is recorded in the volcaniclastic Mateare Formation (MF) exposed west (downwind) of the peninsula and separated from the CF by a large regional erosional unconformity. We divide the MF into the lower MF-1 member (22 volcaniclastic units) and the upper MF-2 member (17 volcaniclastic units), which are separated by a major erosional unconformity. The MF-1 was formed by variably evolved (basalt to dacite) magmas from a mantle source that was moderately metasomatized by fluids derived from subducted sediments. These high-Al moderately hydrous magmas fractionated in a tholeiitic fashion, with early plagioclase but delayed magnetite fractionation (initial Fe-Ti enrichments). Apart from the variable degree of differentiation, magmatic conditions during MF-1 remained fairly constant. While MF-1 contains several erosional unconformities suggesting tectonic activity, MF-2 is conformably stratified and the tholeiitic magmas persisted during this time. However, during MF-2, Al-poor tholeiitic compositions gradually replaced the Al-rich of MF-1 without significant changes in metasomatism or degree of melting at their mantle sources. At the same time, a different mantle source was tapped that was richer in the sediment components, and which produced more hydrous magmas that differentiated in a calc-alkaline fashion with early fractionation of both plagioclase and magnetite. Hence, two mantle source compositions were active during MF-2. The erosional interval between MF and CF, associated with strike-slip motion at the Mateare Fault, correlates with initiation of Nejapa-Miraflores volcanism. We postulate that extension along the Najapa-Miraflores fault system facilitated rapid ascent of mafic magmas from a mantle source laterally away from the arc axis that was less metasomatized than sources directly below the arc. On the Chiltepe peninsula, the Nejapa-Miraflores and Chiltepe magma systems interacted to form tholeiitic, less hydrous types of magmas (andesite to dacite) that erupted intermittently with the dominant calc-alkaline hydrous dacites. While associations of tholeiitic and calc-alkaline magmas at other subduction zones have often been attributed to variable intracrustal processes, we here argue for changes in the mantle source, particularly hydration by slab-derived fluids, as the main control on subsequent differentiation behavior. We further attribute the long-term changes in mantle source conditions through MF and CF, possibly over about 1 My, to result from temporal heterogeneity caused by mantle wedge solid flow and possibly variable fluid flow from the slab.

Beschreibung: The increasing use of rare earth elements (REEs) in diverse technological applications has augmented the demand and exploitation of these worldwide, leading to a higher input of REEs + Yttrium (Y) in the marine environment. The present study investigated the ecotoxicity of Lanthanum (La) and Y to Mytilus galloprovincialis developing embryos and juveniles. This was achieved by quantifying the embryogenesis success after 48 h, and survival of juveniles after 96 h of exposure to different concentrations of La and Y. Results show that both La and Y are more toxic to developing embryos and larvae than to juveniles of M. galloprovincialis. Predicted no-effect concentration (PNEC) values were also derived for the embryo development as a preliminary approach to assess the environmental risk for these compounds to marine organisms. Results revealed that La is more toxic than Y. The high sensitivity of the early developmental stages to these compounds highlight the relevance of including these stages when evaluating the toxicity of chemicals where little information is available. Although older life stages may be more tolerant to toxicants, the population survival will be compromised if new recruits are not viable, with implications to the whole ecosystem health and functioning of the impacted area. Information on the ecotoxicity of chemicals with expanded technological use and that may be released during deep-sea mining activities is urgent in order to help estimate environmental impacts.

Beschreibung: Abyssal plains of the Clarion Clipperton Fracture Zone (CCZ) in the NE Pacific Ocean probably harbour one of the world’s most diverse ecosystems. Gaining a basic understanding of the mechanisms underlying the evolution and persistence of CCZ biodiversity in terms of biogeography and connectivity has both scientific merit and informs the development of policy related to potential future deep-sea mining of mineral resources at an early stage in the process. Existing archives of polychaetes and isopods were sorted using a combined molecular and morphological approach, which uses nucleotide sequences (cytochrome c oxidase subunit I (COI)) and morphological information to identify appropriate sample sets for further investigations. Basic patterns of genetic diversity, divergence and demographic history of five polychaete and five isopod species were investigated. Polychaete populations were found to be genetically diverse. Pronounced long- and short-distance dispersal produces large populations that are continuously distributed over large geographic scales. Although analyses of isopod species suggest the same, spatial genetic structuring of populations do imply weak barriers to gene flow. Mining-related, large-scale habitat destruction has the potential to impact the continuity of both isopod and polychaete populations as well as their long-term dispersal patterns, as ecosystem recovery after major impacts is predicted to occur slowly at evolutionary time scales.

Beschreibung: The Earth will exhibit continued global surface warming in response to a sustained increase of atmospheric carbon dioxide (CO2) levels. Massive meltwater input from the Antarctic ice sheet into the Southern Ocean could be one consequence of this warming. Here we investigate the impacts which this meltwater input may have on Earth’s surface climate and ocean circulation in a warming world. To this end a set of ensemble experiments has been conducted with a global climate model forced by increasing atmospheric CO2-concentration and an idealized Antarctic meltwater input to the Southern Ocean with varying amplitude and spatial pattern. As long as the atmospheric CO2-concentration stays moderate, i.e. below approximately twice the preindustrial concentration, and if a strong meltwater forcing of either 0.05 or 0.1 Sv is applied, enhanced Antarctic sea–ice cover and surface air temperature cooling over most parts of the Southern Ocean is observed. When the atmospheric CO2-concentration becomes larger than twice the preindustrial concentration, the meltwater only plays a minor role. The Antarctic meltwater drives significant slowing of the Southern Ocean meridional overturning circulation (MOC). Again, the meltwater influence only is detectable as long as the CO2-forcing is moderate. Much larger MOC changes develop in response to highly elevated atmospheric CO2-levels independent of whether or not a meltwater forcing is applied. The response of the Antarctic circumpolar current (ACC) is nonlinear. Substantial and persistent ACC slowing is simulated when solely the meltwater forcing of 0.1 Sv is applied, which is due to the halt of Weddell Sea deep convection and subsequent collapse of the Southern Ocean MOC. When the increasing atmospheric CO2-concentration additionally drives the model the ACC partly recovers in the long run. The partial recovery is due to strengthening westerly wind stress over the Southern Ocean, which intensifies the Ekman Cell. This study suggests that Southern Hemisphere climate projections for the twenty-first century could benefit from incorporating interactive Antarctic ice sheet.

Beschreibung: Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR’s CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.

Beschreibung: Numerical models of magmatic hydrothermal systems have become powerful tools for linking surface and seafloor observations to chemical and fluid-dynamic processes at depth. This task requires resolving multi-phase flow over large distances of several kilometers, a wide range of pressure (p) and temperature (T) conditions, and over timescales of several thousands of years. The key numerical challenge is that realistic simulations have to consider the high nonlinearity and strong coupling of the governing conservation equations for mass and energy, while also being numerically efficient so that the required spatial and temporal scales can be resolved. Here we outline possible solutions to this problem by evaluating different implementation strategies and presenting a numerical scheme for fully coupled accurate and efficient flow solutions. The general scheme, based on the Newton–Raphson (NR) method, is presented for the simplified case of 2-D pure water convection and uses a control volume discretization on unstructured meshes. We find that the presented techniques significantly reduce the computational effort with respect to sequential/decoupled schemes. Key to this is a theta-time-differencing method for better accuracy, stability and convergence behavior of the NR-iterations, as well as improvements regarding upwinding. These features make the presented methods useful for coupled simulations of magmatic hydrothermal systems and a potential basis for future 3-D multi-phase codes.

Beschreibung: A novel actinobacterium, strain DB165T, was isolated from cold waters of Llullaillaco Volcano Lake (6170 m asl) in Chile. Phylogenetic analysis based on 16S rRNA gene sequences identified strain DB165T as belonging to the genus Subtercola in the family Microbacteriaceae, sharing 97.4% of sequence similarity with Subtercola frigoramans DSM 13057T, 96.7% with Subtercola lobariae DSM 103962T, and 96.1% with Subtercola boreus DSM 13056T. The cells were observed to be Gram-positive, form rods with irregular morphology, and to grow best at 10–15 °C, pH 7 and in the absence of NaCl. The cross-linkage between the amino acids in its peptidoglycan is type B2γ; 2,4-diaminobutyric acid is the diagnostic diamino acid; the major respiratory quinones are MK-9 and MK-10; and the polar lipids consist of phosphatidylglycerol, diphosphatidylglycerol, 5 glycolipids, 2 phospholipids and 5 additional polar lipids. The fatty acid profile of DB165T (5% 〉) contains iso-C14:0, iso-C16:0, anteiso-C15:0, anteiso-C17:0, and the dimethylacetal iso-C16:0 DMA. The genomic DNA G+C content of strain DB165T was determined to be 65 mol%. Based on the phylogenetic, phenotypic, and chemotaxonomic analyses presented in this study, strain DB165T (= DSM 105013T = JCM 32044T) represents a new species in the genus Subtercola, for which the name Subtercola vilae sp. nov. is proposed.

Beschreibung: Pockmarks are variably sized crater-like structures that occur in young continental margin sediments. They are formed by gas eruptions and/or long-term release of fluid or gas. So far no pockmarks were known from the Pacific coast of South America between 51°S and 55°S. This article documents an extensive and previously unknown pockmark field in the Seno Otway (Otway Sound, 52°S) with multibeam bathymetry and parametric echosounding as well as sediment drill cores. Up to 31 pockmarks per square kilometer occur in water depths of 50 to 〉100 m in late glacial and Holocene sediments. They are up to 150 m wide and 10 m deep. Below and near the pockmarks, echosounder profiles image acoustic blanking as well as gas chimneys often crosscutting the 20 to 〉30 m thick glacial sediments above the acoustic basement, in particular along fault zones. Upward-migrating gas is trapped within the sediment strata, forming dome-like features. Two 5 m long piston cores from inside and outside a typical pockmark give no evidence for gas storage within the uppermost sediments. The inside core recovered poorly sorted glacial sediment, indicating reworking and re-deposition after several explosive events. The outside core documents an undisturbed stratigraphic sequence since ~15 ka. Many buried paleo-pockmarks occur directly below a prominent seismic reflector marking the mega-outflow event of the Seno Otway at 14.3 ka, lowering the proglacial lake level by about 80 m. This decompression would have led to frequent eruptions of gas trapped in reservoirs below the glacial sediments. However, the sediment fill of pockmarks formed after this event suggests recurrent events throughout the Holocene until today. Most pockmarks occur above folded hydrocarbon-bearing Upper Cretaceous and Paleogene rocks near the western margin of the Magallanes Basin, constraining them as likely source rocks for thermogenic gas.

Beschreibung: Shallow shore zones are generally considered to provide juvenile habitats for many invertebrate and fish species and additionally serve as spawning grounds for important components of oceanic food webs and fishery resources such as herring (Clupea spp.). Herring attach their demersal eggs to benthic substrates, rendering reproduction success vulnerable to environmental changes and local habitat alterations. However, little information is available on the effects of different substrates on the survival of demersal eggs. Hypothesizing that the structural complexity of spawning substrates generally affects herring egg survival and that the effect magnitude depends on the suitability of ambient environment, field experiments were conducted on a major spawning ground of C. harengus in the Southwestern Baltic Sea. Herring eggs were artificially spawned on substrates of different structural complexities and incubated in situ under differing temperature regimes, at the beginning and the end of the natural herring spawning season, to include the full suite of stressors occurring on littoral spawning beds. Results of this study indicate a positive relation between high structural complexity of spawning substrates and herring egg survival. Mean egg mortality was three times higher on substrates of lowest complexity than on highly complex substrates. These differences became even more prominent under unfavorable conditions that appeared with rising water temperatures later in the spawning season. Although the mechanisms are still unclear, we conclude that structural complexity, particularly formed by submerged aquatic vegetation, provides a crucial prerequisite for the successful reproduction of substrate spawning marine fishes such as herring in the Baltic Sea.

Beschreibung: Insight into a species’ native and introduced range is essential in understanding the invasion process. Genetic diversity, propagule pressure and environmental conditions all have been recognised as playing a determinant role in invasion success. Here, we aimed to investigate the genetic diversity and population genetic structure (using the COI mtDNA gene region and 22 nDNA microsatellite markers) of the Asian green mussel Perna viridis within its potential native range in Asia and at introduced locations in the USA and the Caribbean. We also analyse genetic data from vessel intercepts and an incursion. By doing so, we aimed to identify genetic signatures that could allow to track vessel samples to their source and provide further insight into potential high-risk invasive populations or areas. Three top hierarchical clusters were identified using the individual-based Bayesian clustering method in STRUCTURE, corresponding to populations in three world regions: (1) USA and Caribbean, (2) India and (3) Southeast Asia. Within Southeast Asia, additional analysis indicate a shallow genetic differentiation of three subgroups consisting of (3a) Thailand, (3b) Taiwan and Hong-Kong, and (3c) a cluster of Singapore–Indonesia samples. Overall, the population structure found in this study suggests that the markers used could be useful in identifying source populations, particularly between the three mains world regions. Most surprisingly however, this study shows that the genetic diversity of samples collected from vessel intercepts and incursions did not differ significantly from established populations in Southeast Asia. In this region, in addition to the high vessel connectivity and number of P. viridis transported, all sampled populations are likely to pose a comparable risk in terms of genetic diversity. The present work represents the most comprehensive population genetic study of P. viridis, and the first to address the potential genetic introduction risk posed by populations of this species. The information and genetic markers in this study constitute a valuable addition to the tools already used to infer on potential high-risk source populations of P. viridis. They should therefore prove useful for biosecurity surveillance and management actions directed at this species.

Beschreibung: The Azores archipelago is geochemically distinct amongst the oceanic intraplate volcanoes in that it has trace element and radiogenic Sr–Nd–Pb–Hf isotope signatures that cover much of the global variation observed in Ocean Island Basalts. Thus, it is the prime example of an intraplate melting anomaly preserving the compositional heterogeneity of the Earth’s mantle. Here, we review the trace element and radiogenic isotope geochemistry of the Azores islands and few submarine samples analysed and published over the past decades and summarise these findings and conclusions. The volcanoes of all islands erupted lavas of the alkaline series and their compositions broadly range from basalts to trachytes (see also Chapter “ Petrology of the Azores Islands” by Larrea et al.). Temperatures and pressures of melting imply that melting in the Azores occurs as a result of both slightly increased temperatures in the mantle (~35 °C) and addition of volatile elements into the mantle source. Basalts from the island of São Miguel show a stronger enrichment in highly incompatible elements like K and the Light Rare Earth Elements than the other islands further to the west. The older and easternmost island Santa Maria has lavas that are more silica-undersaturated than the rocks occurring on the younger islands. Each of the eastern islands shows a different and distinct radiogenic isotope composition and much of this variability can be explained by variably enriched recycled components of different age in their source regions. Amongst the global array, the lavas from eastern São Miguel are uniquely enriched in that they display radiogenic 206Pb/204Pb, 208Pb/204Pb and 87Sr/86Sr isotope ratios best explained by a distinct source in the mantle. The implication of the preservation of such unique, enriched sources in the mantle may indicate that stirring processes in the Azores mantle are not efficiently homogenising heterogeneities over the timescales of recycling of 0.1–1 Ga and possibly even up to 2.5 Ga. One possible explanation is the low buoyancy flux of the Azores mantle when compared to other intraplate settings. The preservation of these source signatures in the lavas on the easternmost Azores islands are the result of smaller degrees of partial melting due to a thicker lithosphere. This likely prevents a homogenisation during magma ascent compared to the western islands, preferentially sampling deep, low degree partial melts from the more fertile mantle sources. The geochemical signatures of the two islands west of the Mid-Atlantic Ridge (Corvo and Flores) imply a source enrichment and degrees of partial melting similar to those east of the ridge. Melting underneath the western islands is the result of a source that must be related to the Azores melting anomaly but has been modified by shallow level processes such as assimilation of oceanic crustal material.

Beschreibung: Recruitment patterns of sessile species often do not reflect the composition of the local propagule pool. This is, among other processes, attributed to the stimulation or inhibition of settlement by resident species. In an experimental study, we evaluated the effects of different densities of the ascidian Diplosoma listerianum on the settlement of the hydrozoan Obelia sp. For this, we monitored the cover of the dominant fouler Obelia sp. on vertically orientated PVC tiles, which were either bare or pre-seeded with two different densities (sparse or dense) of Diplosoma colonies, over the course of 8 weeks. The settlement tiles were deployed at two study sites in La Herradura Bay, Chile. The presence of D. listerianum enhanced the settlement or the growth or both of the colonial hydrozoan, but this effect disappeared within 4–8 weeks. Furthermore, we tested whether the initial enhancement of Obelia sp. by Diplosoma colonies goes back to the fact that larvae, which reject the ascidian tunic as a settlement substratum after a first contact, colonize nearby surfaces because of their limited mobility. However, we found no support for this assumption. We rather suggest that D. listerianum facilitated colonization indirectly by the accumulation of organic material in its vicinity and/or by its pumping activity. Initial resident-mediated enhancement of the hydrozoan was overridden by processes such as competition between later colonizers within the course of weeks and we could not detect any lasting effects of D. listerianum on the structure of the developing communities.

Beschreibung: We present the development and validation of a numerical modeling suite for bubble and droplet dynamics of multiphase plumes in the environment. This modeling suite includes real-fluid equations of state, Lagrangian particle tracking, and two different integral plume models: an Eulerian model for a double-plume integral model in quiescent stratification and a Lagrangian integral model for multiphase plumes in stratified crossflows. Here, we report a particle tracking algorithm for dispersed-phase particles within the Lagrangian integral plume model and a comprehensive validation of the Lagrangian plume model for single- and multiphase buoyant jets. The model utilizes literature values for all entrainment and spreading coefficients and has one remaining calibration parameter (Formula presented.), which reduces the buoyant force of dispersed phase particles as they approach the edge of a Lagrangian plume element, eventually separating from the plume as it bends over in a crossflow. We report the calibrated form (Formula presented.), where b is the plume half-width, and r is the distance of a particle from the plume centerline. We apply the validated modeling suite to simulate two test cases of a subsea oil well blowout in a stratification-dominated crossflow. These tests confirm that errors from overlapping plume elements in the Lagrangian integral model during intrusion formation for a weak crossflow are negligible for predicting intrusion depth and the fate of oil droplets in the plume. The Lagrangian integral model has the added advantages of being able to account for entrainment from an arbitrary crossflow, predict the intrusion of small gas bubbles and oil droplets when appropriate, and track the pathways of individual bubbles and droplets after they separate from the main plume or intrusion layer.

Beschreibung: Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 is described. At the National Research Council Canada (NRC), column separation was performed to remove the seawater matrix prior to the determination of Cd, Cr, Cu, Fe, Pb, Mn, Mo, Ni, U, V, and Zn, whereas As was directly measured in 10-fold diluted seawater samples, and B was directly measured in 200-fold diluted seawater samples. High-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) was used for elemental analyses, with double isotope dilution for the accurate determination of B, Cd, Cr, Cu, Fe, Pb, Mo, Ni, U, and Zn in seawater NASS-7 and CASS-6, and standard addition calibration for As, Co, Mn, and V. In addition, all analytes were measured using standard addition calibration with triple quadrupole (QQQ)-ICPMS to provide a second set of data at NRC. Expert laboratories worldwide were invited to contribute data to the certification of trace metals in NASS-7 and CASS-6. Various analytical methods were employed by participants including column separation, co-precipitation, and simple dilution coupled to ICPMS detection or flow injection analysis coupled to chemiluminescence detection, with use of double isotope dilution calibration, matrix matching external calibration, and standard addition calibration. Results presented in this study show that majority of laboratories have demonstrated their measurement capabilities for the accurate determination of trace metals in seawater. As a result of this comparison, certified/reference values and associated uncertainties were assigned for 14 elements in seawater CRMs NASS-7 and CASS-6, suitable for the validation of methods used for seawater analysis.

Beschreibung: Marine macroalgae in temperate regions are constantly exposed to colonization by fouling organisms, but the intensity of fouling fluctuates in time. We, therefore, hypothesized that a macroalgal species from these latitudes should be able to adjust its antifouling defense to the prevailing colonization pressure. To test this assumption, fouling pressure in the Western Baltic Sea as well as the activity of surface extracts gained from the non-native Gracilaria vermiculophylla against the diatom Stauroneis constricta and the filamentous alga Ceramium tenuicorne were assessed over one vegetation period on a monthly basis. We used two solvents with different polarities to extract chemical compounds from the alga. Both, hexane and dichloromethane (DCM) surface extracts, inhibited settlement of C. tenuicorne, while only hexane surface extracts deterred S. constricta. Furthermore, the activities of both extracts fluctuated on the scale of months and the fluctuations in the activity against C. tenuicorne, which were observed in DCM extracts, correlated with the intensity of fouling pressure that C. tenuicorne inflicted on G. vermiculophylla in the field. Thus, G. vermiculophylla appears to be able to adjust its antifouling defenses—at least partly—to fouling pressure.

Beschreibung: Estuaries are among the most valuable aquatic systems in terms of their services to human welfare. They offer an ideal framework to assess multiscale processes linking climate and food web dynamics through the hydrological cycle. Resolving food web responses to climate change is fundamental to resilience management of these threatened ecosystems under global change scenarios. Here, we examined the temporal variability of the plankton food web in the Mondego Estuary, central Iberian Peninsula, over the period 2003 to 2012. The results pointed out a cascading effect from climate to plankton communities that follow a non-stationary behavior shaped by the climate variance envelope. Concurrent changes in hydrographic processes at the regional, that is, upwelling intensity, and local, that is, estuarine hydrology, scales were driven by climatic forcing promoted by the North Atlantic Oscillation; the influence of which permeated the physical environment in the estuary affecting both autotrophic and heterotrophic communities. The most conspicuous change arose around 2008 and consisted of an obvious decrease in freshwater taxa along with a noticeable increase in marine organisms, mainly driven by gelatinous zooplankton. The observed increase in small-sized cosmopolitan copepods, that is, Clausocalanus arcuicornis, Oithona plumifera, thermophilic species, that is, Penilia avirostris, and gelatinous zooplankton suggests a structural change in the Mondego plankton community. These results provide empirical support to the expectation that expanding climate variance changes plankton structure and functioning, likely fostering trophic interactions in pelagic food webs.

Beschreibung: Marine biofouling is a paramount phenomenon in the marine environment and causes serious problems to maritime industries worldwide. Marine algae are known to produce a wide variety of chemical compounds with antibacterial, antifungal, antialgal, and anti-macrofouling properties, inhibiting the settlement and growth of other marine fouling organisms. Significant investigations and progress have been made in this field in the last two decades and several antifouling extracts and compounds have been isolated from micro- and macroalgae. In this minireview, we have summarized and evaluated antifouling compounds isolated and identified from macroalgae and microalgae between January 2010 and June 2016. Future directions for their commercialization through metabolic engineering and industrial scale up have been discussed. Upon comparing biogeographical regions, investigations from Southeast Asian waters were found to be rather scarce. Thus, we have also discussed the need to conduct more chemical ecology based research in relatively less explored areas with high algal biodiversity like Southeast Asia.

Beschreibung: The height, volume, and alongshore extent of the foredune are primary controls on the response of barrier islands to the elevated storm surge that accompanies hurricanes and extra-tropical storms. In this respect, the ability of the foredune to recover following a storm determines whether a barrier island can maintain elevation as sea level rises and the island migrates landward through the redistribution of sediment to the back of the island through washover and breaching. This chapter provides a review of a body of recent fieldwork on the role of the foredune in controlling island transgression. It is argued that the role of the foredune to control washover and island transgression is analogous to that of a variable resistor in an electrical circuit, with the strength of the resistor dependent on the ability of the dune to recover in height and extent following each storm. Recovery of the foredune requires that sediment removed to the nearshore during a storm be returned to the beachface through the landward migration and welding of the innermost bars where it is eventually transported to the backshore and trapped by vegetation. Field observations from Padre Island in Texas, Santa Rosa Island in Florida, and Assateague Island in Virginia suggest that the recovery of dune height can be modeled using a sigmoidal growth curve, and that recovery can take up to a decade. The slow rate of dune recovery suggests that the resiliency of barrier islands to sea level rise is dependent on whether there is a change in the frequency and magnitude of storm events or an interruption to the exchange of sediment among the nearshore, beach, and dune. Ultimately, the height and volume of the foredune can be controlled by the framework geology (to varying degrees), which determines beach and nearshore state through the availability and texture of sediment and structural controls. In this respect, the response of barrier islands to sea level rise can be expected to vary regionally and alongshore as a reflection of diverse framework geology. The local response to sea level rise depends on the ability of the dune to recover following storms. Assuming no new sediment from alongshore or offshore sources, an increase in the frequency of washover will limit the ability of the dune to recover, and recent field evidence suggests that a change in dune height and volume is self-reinforcing, which suggests a lack of island resiliency. Further testing is required to determine how the field observations and modeling described in this chapter from a select group of barrier islands around the United States are applicable to other islands and consistent throughout the evolution of a barrier island.

Beschreibung: A thorough literature review in combination with an analysis of fossil material from collections enables a detailed reconstruction of the ecosystem of the lower Gatun Formation (Serravallian to Tortonian; late middle to early late Miocene) of Central Panama. The fossil record is highly diverse and includes foraminifers, sponges, corals, mollusks, polychaetes, crustaceans, bryozoans, echinoderms, and vertebrates. The fauna indicates fully marine conditions in a shallow basin with a soft, stable substrate and mostly low water energy. The benthic life is dominated by suspension-feeding bivalves and carnivores including mainly gastropods and crustaceans. Herbivores are strikingly rare. Predator-prey relationships can be directly inferred from abundant drill holes in mollusk shells caused by naticid and muricid gastropods showing strong prey selectivity. Additionally, deep and narrow incisions at the outer lip of the apertures of gastropod shells are reported for the first time and proposed to be caused by crustaceans. Investigating the life habits of the benthic organisms revealed a moderate tiering of the fauna and the importance of empty shells as habitats for a variety of taxa. The nektonic life is highly diverse including nautilids, fishes, rays, sharks, sea turtles, crocodiles, and toothed whales. An analysis of the food preferences of the fossil fauna enables the reconstruction of a trophic web for the ecosystem of the lower Gatun Formation.

Beschreibung: It is unclear whether transport by human vectors can increase the robustness of translocated populations and thereby enhance their invasiveness. To test this concept, we investigated the effect of heat stress on the tolerance of mussel populations towards a second stress event of the same kind. The heat challenges we mimicked can be faced by marine invertebrates that are transported through regions with high sea surface temperatures on ship hulls or in ballast water tanks. The study included 5 mussel species that were collected at sites in Brazil, Chile, Finland, Germany (Baltic Sea) and Portugal. In parallel laboratory experiments, monospecific groups of individuals were exposed to heat challenges that caused 60–83% mortality in the experimental groups within 15–28 days. The surviving individuals were exposed to a second stress event of the same kind, while their survival was then compared to the robustness of conspecifics that had not been exposed to elevated temperatures before. We observed that thermal tolerance was significantly enhanced by previous heat stress experience in case of Semimytilus algosus from Chile and in case of Mytilus edulis from Germany. Our results suggest that heat challenges, which marine invertebrates experience during transport, can enhance stress tolerance in founder populations of these species in their non-native range by potentially increasing the frequency of genetically adapted genotypes. This points at the necessity to learn more about selection acting on organisms during human-mediated transport—in the aquatic but also in the terrestrial environment.

Beschreibung: The geological, hydrological and microbiological features of the Salar de Atacama, the most extensive evaporitic sedimentary basin in the Atacama Desert of northern Chile, have been extensively studied. In contrast, relatively little attention has been paid to the composition and roles of microbial communities in hypersaline lakes which are a unique feature in the Salar. In the present study biochemical, chemical and molecular biological tools were used to determine the composition and roles of microbial communities in water, microbial mats and sediments along a marked salinity gradient in Laguna Puilar which is located in the “Los Flamencos” National Reserve. The bacterial communities at the sampling sites were dominated by members of the phyla Bacteroidetes, Chloroflexi, Cyanobacteria and Proteobacteria. Stable isotope and fatty acid analyses revealed marked variability in the composition of microbial mats at different sampling sites both horizontally (at different sites) and vertically (in the different layers). The Laguna Puilar was shown to be a microbially dominated ecosystem in which more than 60% of the fatty acids at particular sites are of bacterial origin. Our pioneering studies also suggest that the energy budgets of avian consumers (three flamingo species) and dominant invertebrates (amphipods and gastropods) use minerals as a source of energy and nutrients. Overall, the results of this study support the view that the Salar de Atacama is a heterogeneous and fragile ecosystem where small changes in environmental conditions may alter the balance of microbial communities with possible consequences at different trophic levels.

Beschreibung: We investigate the quality of simulating tropical Atlantic (TA) sector climatology and interannual variability in integrations of the Kiel climate model (KCM) with varying atmosphere model resolution. The ocean model resolution is kept fixed. A reasonable simulation of TA sector annual-mean climate, seasonal cycle and interannual variability can only be achieved at sufficiently high horizontal and vertical atmospheric resolution. Two major reasons for the improvements are identified. First, the western equatorial Atlantic westerly surface wind bias in spring can be largely eliminated, which is explained by a better representation of meridional and especially vertical zonal momentum transport. The enhanced atmospheric circulation along the equator in turn greatly improves the thermal structure of the upper equatorial Atlantic with much reduced warm sea surface temperature (SST) biases. Second, the coastline in the southeastern TA and steep orography are better resolved at high resolution, which improves wind structure and in turn reduces warm SST biases in the Benguela upwelling region. The strongly diminished wind and SST biases at high atmosphere model resolution allow for a more realistic latitudinal position of the intertropical convergence zone. Resulting stronger cross-equatorial winds, in conjunction with a shallower thermocline, enable a rapid cold tongue development in the eastern TA in boreal spring. This enables simulation of realistic interannual SST variability and its seasonal phase locking in the KCM, which primarily is the result of a stronger thermocline feedback. Our findings suggest that enhanced atmospheric resolution, both vertical and horizontal, could be a key to achieving more realistic simulation of TA climatology and interannual variability in climate models.

Beschreibung: Gas hydrate dissociation is often considered as a precursor or triggering factor for submarine slope failures occurring in relatively deep waters where the bulk of the gas hydrate is found in fine-grained sediments. However, there are actually relatively few studies that focus on the effect of gas hydrate dissociation on the behavior of clays, and very few on what physically happens to clay during and after the dissociation process and how gas hydrate dissociation affects the geotechnical properties of clays. In this paper, we illustrate the effects of hydrate dissociation in clays from laboratory strength tests (direct simple shear) combined with visualization including very-high-resolution 3D imaging (computed tomography), using R11 as the hydrate forming fluid in both laponite and Onsøy clay. The test results reveal that the hydrate dissociation creates bubbles in the surrounding clay matrix and around pipe/well models. In addition, we use CO2-saturated water as the pore fluid in soft clay, and test results show that cracks may develop, allowing gas migration to take place after reducing back pressure in an oedometer cell. Direct simple shear tests show that the undrained shear strength decreases by up to ∼15% due to this process. The test results were then implemented in a 2D finite element model to assess the influence of hydrate dissociation on submarine slope stability. We chose a slope segment west of Svalvard—an area where methane gas bubbles escape from the seabed. The gas bubbling in this area is likely due to climate-controlled hydrate-dissociation (warming of bottom water masses). In the finite-element model, we include the change of methane hydrate stability zone (MHSZ) with time as well as the hydrate-dissociation-induced failure zone, which may be a potential leakage pathway. The numerical study indicates that the hydrate dissociation caused by bottom water warming is unlikely to be the main cause generating a leakage pathway or failure plane. However, the hydrate dissociation causing the reduction in shear strength facilitates a potentially unstable condition. The results imply that the hydrate dissociation may contribute to slope failure as a secondary driver, but are unlikely the main driving force. The aim of this study was to improve our understanding of the physical processes of gas expansion, migration and effect of hydrate dissociation through visualization and a finite element model. In addition, this study discussed methods to detect gas hydrate through a case study, and it was found possible to predict average gas hydrate saturation at sites where the sulfate-methane transition depth is known.

Beschreibung: The Atlantic Niño is the dominant mode of interannual sea surface temperature (SST) variability in the eastern equatorial Atlantic. Current coupled global climate models struggle to reproduce its variability. This is thought to be partly related to an equatorial SST bias that inhibits summer cold tongue growth. Here, we address the question whether the equatorial SST bias affects the ability of a coupled global climate model to produce realistic dynamical SST variability. We assess this by decomposing SST variability into dynamical and stochastic components. To compare our model results with observations, we employ empirical linear models of dynamical SST that, based on the Bjerknes feedback, use the two predictors sea surface height and zonal surface wind. We find that observed dynamical SST variance shows a pronounced seasonal cycle. It peaks during the active phase of the Atlantic Niño and is then roughly 4–7 times larger than stochastic SST variance. This indicates that the Atlantic Niño is a dynamical phenomenon that is related to the Bjerknes feedback. In the coupled model, the SST bias suppresses the summer peak in dynamical SST variance. Bias reduction, however, improves the representation of the seasonal cold tongue and enhances dynamical SST variability by supplying a background state that allows key feedbacks of the tropical ocean–atmosphere system to operate in the model. Due to the small zonal extent of the equatorial Atlantic, the observed Bjerknes feedback acts quasi-instantaneously during the dynamically active periods of boreal summer and early boreal winter. Then, all elements of the observed Bjerknes feedback operate simultaneously. The model cannot reproduce this, although it hints at a better performance when using bias reduction.

Beschreibung: Gas hydrate dissociation is often considered as a precursor or triggering factor for submarine slope failures occurring in relatively deep waters where the bulk of the gas hydrate is found in fine-grained sediments. However, there are actually relatively few studies that focus on the effect of gas hydrate dissociation on the behavior of clays, and very few on what physically happens to clay during and after the dissociation process and how gas hydrate dissociation affects the geotechnical properties of clays. In this paper, we illustrate the effects of hydrate dissociation in clays from laboratory strength tests (direct simple shear) combined with visualization including very-high-resolution 3D imaging (computed tomography), using R11 as the hydrate forming fluid in both laponite and Onsøy clay. The test results reveal that the hydrate dissociation creates bubbles in the surrounding clay matrix and around pipe/well models. In addition, we use CO2- saturated water as the pore fluid in soft clay, and test results show that cracks may develop, allowing gas migration to take place after reducing back pressure in an oedometer cell. Direct simple shear tests show that the undrained shear strength decreases by up to ∼15% due to this process. The test results were then implemented in a 2D finite element model to assess the influence of hydrate dissociation on submarine slope stability. We chose a slope segment west of Svalvard—an area where methane gas bubbles escape from the seabed. The gas bubbling in this area is likely due to climate-controlled hydrate-dissociation (warming of bottom water masses). In the finite-element model, we include the change of methane hydrate stability zone (MHSZ) with time as well as the hydrate-dissociation-induced failure zone, which may be a potential leakage pathway. The numerical study indicates that the hydrate dissociation caused by bottom water warming is unlikely to be the main cause generating a leakage pathway or failure plane. However, the hydrate dissociation causing the reduction in shear strength facilitates a potentially unstable condition. The results imply that the hydrate dissociation may contribute to slope failure as a secondary driver, but are unlikely the main driving force. The aim of this study was to improve our understanding of the physical processes of gas expansion, migration and effect of hydrate dissociation through visualization and a finite element model. In addition, this study discussed methods to detect gas hydrate through a case study, and it was found possible to predict average gas hydrate saturation at sites where the sulfate-methane transition depth is known.

Beschreibung: Marine copepods provide the major food-web link between primary producers and higher trophic levels, and their feeding ecology is of acute interest in light of global change impacts on food-web functioning. Recently, quantitative polymerase chain reaction (qPCR) protocols have been developed, which can complement classic diet quantification methods, such as stable isotope or fatty acid analyses tools. Here, we present first results of feeding experiments assessing sex- and stage-specific food intake by the ubiquitous calanoid copepod Acartia tonsa by 18S targeted qPCR and microscopic grazing assessment. In triplicated mixed-diet feeding treatments, three suitable A. tonsa diets, the cryptophyte Rhodomonas balthica, the haptophyte Isochrysis galbana, and the diatom Thalassiosira weissflogii, were offered in equal biomass proportions under constant conditions. Prey uptake substantially varied between different algal species, as did the extent of sex- and stage-specificity of prey uptake. Male adult copepods had higher R. balthica gut contents than females, and nauplii contained more of this prey source than copepodites or adult copepods in mixed treatments. A trend towards higher amounts of ingested T. weissflogii in adult females than in males and in nauplii than in other stages was detected. Genetic gut content quantifications indicated low feeding on I. galbana, and no consistent sex- or stage-specific differences of I. galbana content in A. tonsa. Our results highlight diet-specific feeding differences between Acartia life stages and sexes, which can have implications on food-web dynamics and specific nutrient transfer to higher trophic levels in copepod populations of varying age composition under changing environmental parameters, such as rising temperatures and increasing ocean acidification.

Beschreibung: Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.

Beschreibung: Study of the microstructure and isotopic composition of authigenic tubule-shaped carbonate concretions from sediment core PS51/154-11 on the western Laptev Sea continental slope (present water depth 270 m) has allowed for reconstruction of the conditions prevailing during their formation and identification of the mechanisms controlling their genesis. Concretions were collected from the basal sediment unit with an extrapolated age estimate of 16.3–17.6 cal.ka. Crystallization of carbonate tubules occurred at the beginning of the last deglaciation when the site was located in the proximity to the former coastline and the mouths of the Olenek and Anabar-Khatanga rivers in water depths of about 150–170 m. Microprobe analysis showed that the studied carbonate tubules consist of the minerals belonging to the siderite–rhodochrosite isomorphic series. The measured isotopic composition of δ13С and δ18O in the carbonates varies between − 21.0 and − 17.0‰ and between − 9.86 and 1.72‰ VPDB, respectively. The δ18O values in the authigenic carbonates give evidence for the gradual transition from a freshwater affected to modern-like marine sedimentation environment during carbonate crystallization. Water freshening is confirmed by the co-occurrence of authigenic Fe–Mn carbonates and Fe-phosphate vivianite that is a typical mineral of freshwater environments. The dominant source of dissolved inorganic carbon in the pore water was the isotopically light carbon derived from the diagenetic decomposition of organic matter. Two possible scenarios of authigenic carbonates formation are proposed: penetration of freshened ground waters and/or enhanced freshwater influence during short seasonal floods in combination with geochemical processes in a narrow marginal filter zone that was located extremely close to the Laptev Sea continental slope and the studied core site.

Beschreibung: Rhodopila globiformis: is the most acidophilic anaerobic anoxygenic phototrophic purple bacterium and was isolated from a warm acidic sulfur spring in Yellowstone Park. Its genome is larger than genomes of other phototrophic purple bacteria, containing 7248 Mb with a G + C content of 67.1% and 6749 protein coding and 53 RNA genes. The genome revealed some previously unknown properties such as the presence of two sets of structural genes pufLMC for the photosynthetic reaction center genes and two types of nitrogenases (Mo-Fe and V-Fe nitrogenase), capabilities of autotrophic carbon dioxide fixation and denitrification using nitrite. Rhodopila globiformis assimilates sulfate and utilizes the C1 carbon substrates CO and methanol and a number of organic compounds, in particular, sugars and aromatic compounds. It is among the few purple bacteria containing a large number of pyrroloquinoline quinone-dependent dehydrogenases. It has extended capacities to resist stress by heavy metals, demonstrates different resistance mechanisms to antibiotics, and employs several toxin/antitoxin systems.

Beschreibung: Estuaries are highly dynamic systems that serve as nursery areas to fishes and are likely to vary in nursery function, mostly due to habitat quality and food availability. Mangroves are thought to be good nurseries as they enhance food availability and protection, improving growth and survival of juvenile fishes. Food quantity and quality may be reflected in nutritional condition, which may in turn be a useful proxy for growth and survival of larval fishes. This study compared the nutritional condition and growth rate of 793 late stage larvae of estuarine roundherring, Gilchristella aestuaria, by using RNA:DNA indices to indirectly compare the feeding environment among similar warm-temperate mangrove and non-mangrove estuaries in South Africa during January 2015 and 2016. Results indicated that G. aestuaria larvae had differing nutritional conditions within the sampling years and within the estuaries. The standardised RNA:DNA (sRD) as well as the RNA residual index values were higher within mangrove estuaries only in 2016. The instantaneous growth rates (Gi) of larvae in mangrove and non-mangrove estuaries were similar; however, post-flexion larvae were found to have a higher Gi and sRD in mangrove estuaries. Turbidity was the major factor influencing the nutritional condition of G. aestuaria larvae. Mangroves have been found to act as sediment sinks and thus may provide advantages that increase feeding success for post-flexion larvae; however, more is yet to be understood in terms of feeding environment dynamics and how habitat quality influences the survival of larval fishes.

Beschreibung: This observational study compares seasonal variations of surface fluxes (turbulent, radiative, and soil heat) and other ancillary atmospheric/surface/permafrost data based on in-situ measurements made at terrestrial research observatories located near the coast of the Arctic Ocean. Hourly-averaged multiyear data sets collected at Eureka (Nunavut, Canada) and Tiksi (East Siberia, Russia) are analyzed in more detail to elucidate similarities and differences in the seasonal cycles at these two Arctic stations, which are situated at significantly different latitudes (80.0°N and 71.6°N, respectively). While significant gross similarities exist in the annual cycles of various meteorological parameters and fluxes, the differences in latitude, local topography, cloud cover, snowfall, and soil characteristics produce noticeable differences in fluxes and in the structures of the atmospheric boundary layer and upper soil temperature profiles. An important factor is that even though higher latitude sites (in this case Eureka) generally receive less annual incoming solar radiation but more total daily incoming solar radiation throughout the summer months than lower latitude sites (in this case Tiksi). This leads to a counter-intuitive state where the average active layer (or thaw line) is deeper and the topsoil temperature in midsummer are higher in Eureka which is located almost 10° north of Tiksi. The study further highlights the differences in the seasonal and latitudinal variations of the incoming shortwave and net radiation as well as the moderating cloudiness effects that lead to temporal and spatial differences in the structure of the atmospheric boundary layer and the uppermost ground layer. Specifically the warm season (Arctic summer) is shorter and mid-summer amplitude of the surface fluxes near solar noon is generally less in Eureka than in Tiksi. During the dark Polar night and cold seasons (Arctic winter) when the ground is covered with snow and air temperatures are sufficiently below freezing, the near-surface environment is generally stably stratified and the hourly averaged turbulent fluxes are quite small and irregular with on average small downward sensible heat fluxes and upward latent heat and carbon dioxide fluxes. The magnitude of the turbulent fluxes increases rapidly when surface snow disappears and the air temperatures rise above freezing during spring melt and eventually reaches a summer maximum. Throughout the summer months strong upward sensible and latent heat fluxes and downward carbon dioxide (uptake by the surface) are typically observed indicating persistent unstable (convective) stratification. Due to the combined effects of day length and solar zenith angle, the convective boundary layer forms in the High Arctic (e.g., in Eureka) and can reach long-lived quasi-stationary states in summer. During late summer and early autumn all turbulent fluxes rapidly decrease in magnitude when the air temperature decreases and falls below freezing. Unlike Eureka, a pronounced zero-curtain effect consisting of a sustained surface temperature hiatus at the freezing point is observed in Tiksi during fall due to wetter and/or water saturated soils.

Beschreibung: According to historical oceanographic data, anomalies in the dynamic topography during the winter period were calculated and two climatic stages of dynamic condition of the Arctic Ocean were defined: 1949–1993 and 2007–2013. The associativity of opposition of anomalies in the dynamic topography of the Eurasian and Amerasian basins with fluctuations in the thermal condition of the Northern Atlantic and Pacific oceans, the indexes of atmospheric circulation, river runoff, and change in the area of ice in August of the Laptev, East Siberian, and Chukchi seas is established.

Beschreibung: The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps–Apennines–Carpathians–Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth.

Beschreibung: Parasitic and commensal species can impact the structure and function of ecological communities and are typically highly specialized to overcome host defences. Here, we report multiple instances of a normally free-living species, the blue mussel Mytilus edulis Linnaeus, 1758, inhabiting the branchial chamber of the shore crab Carcinus maenas (Linnaeus, 1758) collected from widely separated geographical locations. A total of 127 C. maenas were examined from four locations in the English Channel, one location in the Irish Sea and two locations at the entrance of the Baltic Sea. The branchial chambers of three crabs (one from the English Channel and two from Gullmar Fjord, Sweden) were infested with mussels resembling the genus Mytilus. Sequencing at the Me15/16 locus on the polyphenolic adhesive protein gene confirmed the identity as M. edulis. Bivalve infestation always occurred in larger red male individuals. Up to 16 mussels, ranging from 2 to 11 mm in shell length, were found in each individual, either wedged between gill lamellae or attached to the branchial chamber inner wall. This is one of the first reports of a bivalve inhabiting crustacean gills and is an intriguing case of a normally free-living prey species infesting its predator