ALBERT

Description: Colonial non-zooxanthellate corals from deep-water coral reefs, Lophelia pertusa and Madrepora oculata, produce large amounts of extracellular mucus (EMS). This mucus has various functions, e.g., an antifouling capability protecting the coral skeleton from attacks of endolithic and boring organisms. Both corals show thick epithecal and exothecal skeletal parts with a clear lamellar growth pattern. The formation of the epitheca is unclear. It is supposed that the EMS play a central role during the calcification process of the epithecal skeletal parts. Staining with the fluorochrome tetracycline has shown an enrichment of Ca2+ ions in the mucus. In order to investigate this hypothesis, the protein content of the mucus and the intracrystalline organic matter from newly formed epithecal aragonite of Madrepora oculata was determined via sodium dodecyl sulfate (SDS) gel electrophoresis. Identical band patterns within both substances could be detected, one around 45 kDa molecular weight and a cluster around 30-35 kDa molecular weight. The occurrence of identical protein patterns within the mucus and in the newly formed aragonite confirms the idea that the mucus plays an important role during the organomineralization of the coral epitheca.

Description: The incorporation of hydrogen in enstatite in a hydrous system containing various amounts of NaCl was investigated at 25 kbar. The hydrogen content in enstatite shows a clear negative correlation to the NaCl-concentration in the system. The most favourable explanation is the reduction of water fugacity due to dilution. Other reasons for the limited hydrogen incorporation at high NaCl levels, such as a significant influence of Na+ on the defect chemistry or an exchange between OH- and Cl-in enstatite, appear much less important. A partition coefficient D Na En/Fluid = 0.0013 could be determined, demonstrating that Na is less incompatible in enstatite than H. The new results support the idea that dissolved components have to be considered when the total hydrogen storage capacity in nominally anhydrous minerals is estimated, especially in geological settings with high levels of halogens, such as subduction zones.

Description: The coprecipitation of U (VI) with iron corrosion products from aqueous solutions by zero valent iron was investigated. The evidence of coprecipitation was demonstrated by conducting experiments with well characterized scrap iron,pyrite and a mixture of both materials with experimental durations of up to four months. Results indicate that under anoxic conditions only less than one tenth of the immobilized U(VI) was associated with the surface of scrap iron, whereas theremaining amount is entrapped in aging corrosion products.

Description: Five volcanic tuffs ranging from dacitic tuffs of Hungary to rhyolite, phonolite and basaltic tuffs of Germany were consolidated under laboratory conditions. Prior to consolidation an anti-hygro, a hydrous consolidant, which reduces the swelling ability of clay minerals, was applied. The three consolidants, a silicic acid ester (SAE), an elastic silicic acid ester (eSAE) and an acrylate resin (PMMA) were applied on test specimens under vacuum. Petrographic characterisation (polarizing microscopy, XRD, SEM) provided data for fabric analyses and the mineral composition of the tuffs. Changes in fabric, effective porosity, density, tensile strength, ultrasonic wave velocity were evaluated after the treatment. Weathering simulation tests such as hygric dilatation and thermal dilatation aimed to prove the effectiveness of consolidation and the durability of consolidated tuff samples. More than 500 samples were analysed. The tests showed that SAE caused the highest increase in indirect tensile strength. The water absorption and the pore size distribution of the tuffs were modified by consolidation. The PMMA reduced the water absorption the most, whereas SAE modified it the least. All the tested consolidants increased the thermal dilatation of the tuffs. The changes in hygric dilatation were not uniform: for most tuffs SAE increased and PMMA decreased the hygric dilatation, although the clay-rich Habichtswald tuff showed the opposite trend. The changes in hygric and thermal behaviour of consolidated tuff require special care when specific consolidants are chosen. These products modify the physical properties of consolidated tuffs and change the behaviour of weathering.

Description: A 782 d solubilization study using not shaken batch experiments and involving one uranium-bearing rock and three natural carbonate minerals was conducted to characterize uranium (U) leaching under oxic conditions. Results showed that aqueous U concentration increased continuously with a solubilization rate of 0.16 mgm-2h-1 for the first 564 d (1.5 y). After 1.5 y, U concentration reached a maximum value (saturation) and decreased afterwards. The saturation concentration of 54 mgL-1 (mean value) was influenced to various extent by the presence of carbonate minerals. Dissolution/precipitation, adsorption or ion exchange processes appear to control U solubilization.

Description: The veneer cladding of the Oeconomicum (OEC, Göttingen), the State Theatre of Darmstadt (STD, Darmstadt) and of the State and University Library (SUB, Göttingen) is characterised by pronounced bowing after a short time of exposure. Direct comparison of bowing data related to measurements from 2000 to 2003 at the SUB clearly show that the amplitude in bowing had significantly increased. The bowing is different in intensity and orientation (concave, convex). The cladding material (Peccia marble, Rosa Estremoz marble and Carrara marble) are different in lattice preferred orientation, grain size distribution and grain interlocking. Depending on the bowing, panels may show cracks mostly initiated at the dowels. The percentage of visible cracks and breakouts increases with the amplitude of bowing except for the STD. Repetitive heatingcooling under dry conditions leads to considerable inelastic residual strain only after the first or second thermal cycle. The residual strain continuously increases again if water is present, whereby the moisture content after a thermal cycle has a certain impact on the decay rate. The water-enhanced thermal dilatation strongly correlates with the deterioration rate obtained from the laboratory bow test. Detailed petrophysical investigations provide evidence that with increasing bowing a decrease of mechanical properties (flexural strength or breaking load at dowel hole) occur. Marble degradation is also connected with the increase in porosity and a general shift of the maximum pore radii to larger pore sizes...

Description: Recent work has shown that glaciers are a globally significant source of the micronutrient Fe to the ocean. Polar regions are particularly susceptible to climate change and have been subject to pronounced warming in the past few decades. In response to this warming, the volume of glacial meltwater runoff from Greenland has increased. This meltwater has a relatively high particulate and dissolved Fe content. Seasonal Fe limitation of marine ecosystems has been found in parts of the North Atlantic, so it has been proposed that increasing fluxes of Fe rich meltwater from Greenland to the North Atlantic could alleviate this Fe limitation and thereby increase marine primary production. However, here we use a synthesis of biogeochemical and physical oceanography studies to suggest that the physical circulation around Greenland does not favour direct export of dissolved or particulate Fe from inshore to offshore waters. The Fe budget in surface waters of the North Atlantic may therefore be insensitive to increasing meltwater fluxes from Greenland.

Description: While the geometries of diatom frustules have been investigated in detail, the processes leading to their formation—morphogenesis and biomineralization—are not well understood. The study of organic templates, which are suspected to be important for biosilicification of diatoms, have been mainly investigated on the basis of diverse demineralization techniques. In contrast to naturally occurring dissolution of diatom cell walls in natural habitats, all experiments in vitro were based on chemical reagents including HF- or alkali-based techniques with addition of some additives as presented in this chapter. Mostly, the amino acids (serine, threonine, hydrohyproline) diverse proteinaceous materials (frustulins, pleuralins, silaffins, silacidins, circulins) as well as polyamines have been proposed to regulate biosilicification in vivo in diatoms. In this chapter, we review the biochemical pathways and potential functions of these chemical compounds and their roles in the biomineralization process. In addition, we demonstrate the presence of chitin and discuss its potential as scaffolding as well as a template material in siliceous cell walls of diatoms. The current findings show that a complex network of different organic components is responsible for the biomineralization of diatoms. Since both the organic network and the precipitated silica are integrated in the material which forms the diatom frustule, the material properties must differ from that of pure silica. As the material properties are a crucial factor for the defensive performance of the frustule and thus their survival, it is likely that organic templates for silicification play a role both for the development process and for the improvement of the material properties of the finished shells.

Description: 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.

Description: 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.

Description: Pteropods are important organisms in high-latitude ecosystems, and they are expected to severely suffer from climate change in the near future. In this study, sedimentation patterns of two pteropod species, the polar Limacina helicina and the subarctic boreal L. retroversa, are presented. Time series data received by moored sediment traps at the Long-Term Ecological Research (LTER) Observatory HAUSGARTEN in eastern Fram Strait were analyzed during the years 2008 to 2012. Results were derived from four different deployment depths (~200, 1,250, 2,400, and 2,550 m) at two different sites (79°N 04°20′E; 79°43′N 04°30′E). A species-specific sedimentation pattern was present at all depths and at both sites showing maximal flux rates during September/October for L. helicina and in November/December for L. retroversa. The polar L. helicina was outnumbered by L. retroversa (55–99 %) at both positions and at all depths supporting the recently observed trend toward the dominance of the subarctic boreal species. The largest decrease in pteropod abundance occurred within the mesopelagic zone (~200–1,250 m), indicating loss via microbial degradation and grazing. Pteropod carbonate (aragonite) amounted up to ~75 % of the total carbonate flux at 200 m and 2–13 % of the aragonite found in the shallow traps arrived at the deep sediment traps (~160 m above the seafloor), revealing the significance of pteropods in carbonate export at Fram Strait. Our results emphasize the relevance and the need for continuation of long-term studies to detect and trace changes in pteropod abundances and community composition and thus in the vertical transport of aragonite.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: Coral bleaching continues to be one of the most devastating and immediate impacts of climate change on coral reef ecosystems worldwide. In 2015, a major bleaching event was declared as the “3rd global coral bleaching event” by the United States National Oceanic and Atmospheric Administration, impacting a large number of reefs in every major ocean. The Red Sea was no exception, and we present herein in situ observations of the status of coral reefs in the central Saudi Arabian Red Sea from September 2015, following extended periods of high temperatures reaching upwards of 32.5C in our study area. We examined eleven reefs using line-intercept transects at three different depths, including all reefs that were surveyed during a previous bleaching event in 2010. Bleaching was most prevalent on inshore reefs (55.6% ± 14.6% of live coral cover exhibited bleaching) and on shallower transects (41% ± 10.2% of live corals surveyed at 5m depth) within reefs. Similar taxonomic groups (e.g., Agariciidae) were affected in 2015 and in 2010. Most interestingly, Acropora and Porites had similar bleaching rates (~30% each) and similar relative coral cover (~7% each) across all reefs in 2015. Coral genera with the highest levels of bleaching (〉60%) were also among the rarest (〈1% of coral cover) in 2015. While this bodes well for the relative retention of coral cover, it may ultimately lead to decreased species richness, often considered an important component of a healthy coral reef. The resultant long-term changes in these coral reef communities remain to be seen.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: Radiolaria are unicellular holoplanktonic protozoa with siliceous or strontium sulfate skeletons. Mainly studied by micropaleontologists because of their excellent fossil record, they are also key members of planktonic communities and play important roles in various oceanic ecosystems. This chapter presents an overview of the current knowledge on living Radiolaria (orders Acantharia, Collodaria, Nassellaria, Spumellaria and Taxopodia). Besides general considerations on Radiolaria as a whole, it focuses on the taxonomy, biology, and ecology of each radiolarian order. Finally this chapter provides insights on research perspectives to improve our knowledge of living radiolarians and their ecological role in marine ecosystems.

Description: 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.

Description: 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.

Description: Ongoing acidification of the ocean through uptake of anthropogenic CO2 is known to affect marine biota and ecosystems with largely unknown consequences for marine food webs. Changes in food web structure have the potential to alter trophic transfer, partitioning, and biogeochemical cycling of elements in the ocean. Here we investigated the impact of realistic end-of-the-century CO2 concentrations on the development and partitioning of the carbon, nitrogen, phosphorus, and silica pools in a coastal pelagic ecosystem (Gullmar Fjord, Sweden). We covered the entire winter-to-summer plankton succession (100 days) in two sets of five pelagic mesocosms, with one set being CO2 enriched (~760 μatm pCO2) and the other one left at ambient CO2 concentrations. Elemental mass balances were calculated and we highlight important challenges and uncertainties we have faced in the closed mesocosm system. Our key observations under high CO2 were: (1) A significantly amplified transfer of carbon, nitrogen, and phosphorus from primary producers to higher trophic levels, during times of regenerated primary production. (2) A prolonged retention of all three elements in the pelagic food web that significantly reduced nitrogen and phosphorus sedimentation by about 11 and 9%, respectively. (3) A positive trend in carbon fixation (relative to nitrogen) that appeared in the particulate matter pool as well as the downward particle flux. This excess carbon counteracted a potential reduction in carbon sedimentation that could have been expected from patterns of nitrogen and phosphorus fluxes. Our findings highlight the potential for ocean acidification to alter partitioning and cycling of carbon and nutrients in the surface ocean but also show that impacts are temporarily variable and likely depending upon the structure of the plankton food web.

Description: 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.

Description: The surface microlayer (SML) in marine systems is often characterized by an enrichment of biogenic, gel-like particles, such as the polysaccharide-containing transparent exopolymer particles (TEP) and the protein-containing Coomassie stainable particles (CSP). This study investigated the distribution of TEP and CSP, in the SML and underlying water, as well as their bio-physical controlling factors in Daya Bay, an area impacted by warm discharge from two Nuclear power plants (Npp’s) and aquaculture during a research cruise in July 2014. The SML had higher proportions of cyanobacteria and of pico-size Chl a contrast to the underlayer water, particularly at the nearest outlet station characterized by higher temperature. Diatoms, dinoflagellates and chlorophyll a were depleted in the SML. Both CSP and TEP abundance and total area were enriched in the SML relative to the underlying water, with enrichment factors (EFs) of 1.5–3.4 for CSP numbers and 1.32–3.2 for TEP numbers. Although TEP and CSP showed highest concentration in the region where high productivity and high nutrient concertation were observed, EFs of gels and of dissolved organic carbon (DOC) and dissolved acidic polysaccharide (〉 1 kDa), exhibited higher values near the outlet of the Npp’s than in the adjacent waters. The positive relation between EF’s of gels and temperature and the enrichment of cyanobacteria in the SML may be indicative of future conditions in a warmer ocean, suggesting potential effects on adjusting phytoplankton community, biogenic element cycling and air-sea exchange processes

Description: Integrated multi-trophic aquaculture (IMTA) is being explored on both economic and environmental grounds in many traditional aquaculture regions. To test a variety of suitable macroalgae species and management scenarios, a numerical model is developed to quantify the remediation of dissolved nutrients and production of macroalgae near a nutrient source. Differences in the morphological, physiological, and economic characteristics of different macroalgae species can provide flexibility when considering the cost and benefit of farming macroalgae. Results show that of the three species studied, Macrocystis pyrifera removed 75 % of dissolved inorganic nitrogen (DIN) input from a point source, while Porphyra umbilicalis and Ulva lactuca removed 5 %. Both M. pyrifera and P. umbilicalis have reduced bioremediation capacity at increasing flow rates. U. lactuca showed increased bioremediation potential as flow rate increased from low to moderate flows. Increasing the optical depth increased the bioremediation potential of M. pyrifera for moderate values of the light attenuation coefficient, whereas bioremediation was unaffected by optical depth for both U. lactuca and P. umbilicalis. Harvesting increased bioremediation capacity of all species by up to 25-fold dependent on the establishment phase and harvesting frequency. We conclude that the choice of macroalgae species greatly affects the success of IMTA and that both harvesting and farm arrangements can be used to greatly optimize bioremediation.

Description: 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.

Description: 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.

Description: Hydrothermal vents on mid-oceanic ridges are patchily distributed and host many taxa endemic to deep-sea chemosynthetic environments, whose dispersal may be constrained by geographical barriers. The aim of this study was to investigate the connectivity of three populations of the ‘scaly-foot gastropod’ (Chrysomallon squamiferum Chen et al., 2015), a species endemic to hydrothermal vents in the Indian Ocean, amongst two vent fields on the Central Indian Ridge (CIR) and Longqi field, the first sampled vent field on the Southwest Indian Ridge (SWIR). Connectivity and population structure across the two mid-oceanic ridges were investigated using a 489-bp fragment of the cytochrome oxidase c subunit I (COI) gene. Phylogeographical approaches used include measures of genetic differentiation (FST), reconstruction of parsimony haplotype network, mismatch analyses and neutrality tests. Relative migrants per generation were estimated between the fields. Significant differentiation (FST = 0.28–0.29, P 〈 0.001) was revealed between the vent field in SWIR and the two in CIR. Signatures were detected indicating recent bottleneck events followed by demographic expansion in all populations. Estimates of relative number of migrants were relatively low between the SWIR and CIR, compared with values between the CIR vent fields. The present study is the first to investigate connectivity between hydrothermal vents across two mid-ocean ridges in the Indian Ocean. The phylogeography revealed for C. squamiferum indicates low connectivity between SWIR and CIR vent populations, with implications for the future management of environmental impacts for seafloor mining at hydrothermal vents in the region, as proposed for Longqi.

Description: 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.

Description: 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.

Description: 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.

Description: Ocean warming and acidification (OA) may alter the fitness of species in marine pelagic ecosystems through community effects or direct physiological impacts. We used the zooplanktonic appendicularian, Oikopleura dioica, to assess temperature and pH effects at mesocosm and microcosm scales. In mesocosms, both OA and warming positively impacted O. dioica abundance over successive generations. In microcosms, the positive impact of OA, was observed to result from increased fecundity. In contrast, increased pH, observed for example during phytoplankton blooms, reduced fecundity. Oocyte fertility and juvenile development were equivalent under all pH conditions, indicating that the positive effect of lower pH on O. dioica abundance was principally due to increased egg number. This effect was influenced by food quantity and quality, supporting possible improved digestion and assimilation at lowered pH. Higher temperature resulted in more rapid growth, faster maturation and earlier reproduction. Thus, increased temperature and reduced pH had significant positive impacts on O. dioica fitness through increased fecundity and shortened generation time, suggesting that predicted future ocean conditions may favour this zooplankton species. © 2018 Bouquet et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: In the coming decades, environmental change like warming and acidification will affect life in the ocean. While data on single stressor effects on fish are accumulating rapidly, we still know relatively little about interactive effects of multiple drivers. Of particular concern in this context are the early life stages of fish, for which direct effects of increased CO2 on growth and development have been observed. Whether these effects are further modified by elevated temperature was investigated here for the larvae of Atlantic herring (Clupea harengus), a commercially important fish species. Over a period of 32 days, larval survival, growth in size and weight, and instantaneous growth rate were assessed in a crossed experimental design of two temperatures (10°C and 12°C) with two CO2 levels (400 μatm and 900 μatm CO2) at food levels mimicking natural levels using natural prey. Elevated temperature alone led to increased swimming activity, as well as decreased survival and instantaneous growth rate (Gi). The comparatively high sensitivity to elevated temperature in this study may have been influenced by low food levels offered to the larvae. Larval size, Gi and swimming activity were not affected by CO2, indicating tolerance of this species to projected "end of the century" CO2 levels. A synergistic effect of elevated temperature and CO2 was found for larval weight, where no effect of elevated CO2 concentrations was detected in the 12°C treatment, but a negative CO2 effect was found in the 10°C treatment. Contrasting CO2 effects were found for survival between the two temperatures. Under ambient CO2 conditions survival was increased at 12°C compared to 10°C. In general, CO2 effects were minor and considered negligible compared to the effect of temperature under these mimicked natural food conditions. These findings emphasize the need to include biotic factors such as energy supply via prey availability in future studies on interactive effects of multiple stressors. © 2018 Sswat et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Description: 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.

Description: 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.

Description: 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.

Description: Climate variability plays a central role in the dynamics of marine pelagic ecosystems shaping the structure and abundance changes of plankton communities, thereby affecting energy pathways and biogeochemical fluxes in the ocean. Here we have investigated complex interactions driven a climate-hydrology-plankton system in the southern East China Sea over the period 2000 to 2012. In particular, we aimed at quantifying the influence of climate phenomena playing out in tropical (El Nino 3.4) and middle-high latitudes (East Asia Winter Monsoon, EAWM, and Pacific Decadal Oscillation, PDO) on pelagic copepods. We found that the EAWM and El Nino 3.4 showed a non-stationary and non-linear relationship with local temperature variability. In the two cases, the strength of the relationship, as indexed by the wavelet coherence analysis, decreased along with the positive phase of the PDO. Likewise, the influence of EAWM and El Nino3.4 on copepods exhibited a non-stationary link that changed along with the PDO state. Indeed, copepods and EAWM were closely related during the positive phase, while the link copepods–El Nino 3.4 was stronger during the negative phase. Our results pointed out cascading effects from climate to plankton driven by the positive phase of the PDO through its effect on temperature conditions, and likely through a larger southward transport of nutrient-rich water masses to northern Taiwan and the Taiwan Strait. We suggest a chain of mechanisms whereby the PDO shapes interannual dynamics of pelagic copepods and highlight that these results have implications for integrative management measures, as pelagic copepods plays a prominent role in food web dynamics and for harvested fish in the East China Sea. © 2018 Molinero et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Description: 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

Description: The ultimate, possibly geodynamic control and potential impact of changes in circulation activity and salt discharge of Mediterranean outflow waters (MOW) on Atlantic meridional overturning circulation have formed long-standing objectives in paleoceanography. Late Pliocene changes in the distal advection of MOW were reconstructed on orbital timescales for northeast Atlantic DSDP/ODP sites 548 and 982 off Brittany and on Rockall Plateau, supplemented by a proximal record from Site U1389 west off Gibraltar, and compared to Western Mediterranean surface and deep-water records of Alboran Sea Site 978. From ~3.43 to 3.3 Ma, MOW temperatures and salinities form a prominent rise by 2–4 °C and ~3 psu, induced by a preceding and coeval rise in sea surface and deep-water salinity and increased summer aridity in the Mediterranean Sea. We speculate that these changes triggered an increased MOW flow and were ultimately induced by a persistent 2.5 °C cooling of Indonesian Through-Flow waters. The temperature drop resulted from the northward drift of Australia that crossed a threshold value near 3.6–3.3 Ma and led to a large-scale cooling of the eastern subtropical Indian Ocean and in turn, to a reduction of African monsoon rains. Vice versa, we show that the distinct rise in Mediterranean salt export after ~3.4 Ma induced a unique long-term rise in the formation of Upper North Atlantic Deep Water, that followed with a phase lag of ~100 ky. In summary, we present evidence for an interhemispheric teleconnection of processes in the Indonesian Gateways, the Mediterranean and Labrador Seas, jointly affecting Pliocene climate.

Description: Seafloor elongated depressions are indicators of gas seepage or slope instability. Here we report a sequence of slope-parallel elongated depressions that link to headwalls of sediment slides on upper slope. The depressions of about 250 m in width and several kilometers in length are areas of focused gas discharge indicated by bubble-release into the water column and methane enriched pore waters. Sparker seismic profiles running perpendicular and parallel to the coast, show gas migration pathways and trapped gas underneath these depressions with bright spots and seismic blanking. The data indicate that upward gas migration is the initial reason for fracturing sedimentary layers. In the top sediment where two young stages of landslides can be detected, the slope-parallel sediment weakening lengthens and deepens the surficial fractures, creating the elongated depressions in the seafloor supported by sediment erosion due to slope-parallel water currents.

Description: Seafloor morphology plays a key role in submarine mineral exploration as precious minerals are associated with specific geomorphological settings. Mn-nodules occur in abyssal plains, seafloor massive sulphides are strongly connected to volcanic areas and sand, gravel and other marine minable aggregates are deposited in coastal environments. For resource assessments and exploitation, a detailed knowledge of the seafloor morphology is essential to evaluate areas of terrain that cannot be mined due to technical limitations, and to estimate abundance, extent and thickness of the deposits. The most important method used is multibeam mapping, from which bathymetric and backscatter data are derived. These are often linked to side scan sonar surveys and sub-bottom profiling. Optical video and photo data provide additional information about substrate type and ecology, and help improve and adapt exploration and exploitation plans and technology. For the three most important marine mineral types—sand and gravel, Mn-nodules and seafloor massive sulphides—exploration and exploitation methods are described and the environmental impacts associated with mining these resources are discussed.

Description: Sperm storage is common in internally fertilizing animals, but is also present in several external fertilizers, such as many cephalopods. Cephalopod males attach sperm packets (spermatangia) to female conspecifics during mating. Females of eight externally fertilizing families comprising 25% of cephalopod biodiversity have sperm-storage organs (seminal receptacles) in their buccal area, which are not in direct physical contact with the deposited spermatangia. The mechanism of sperm transmission between the implantation site and the storage organ has remained a major mystery in cephalopod reproductive biology. Here, jumbo squid females covering almost the entire life cycle, from immature to a laboratory spawned female, were used to describe the internal structure of the seminal receptacles and the process of sperm storage. Seminal fluid was present between the spermatangia and seminal receptacles, but absent in regions devoid of seminal receptacles. The sperm cellular component was formed by spermatozoa and round cells. Although spermatozoa were tracked over the buccal membrane of the females to the inner chambers of the seminal receptacles, round cells were not found inside the seminal receptacles, suggesting that spermatozoa are not sucked up by the muscular action of the seminal receptacles. This finding supports the hypothesis that spermatozoa are able to actively migrate over the female skin. Although further experimental support is needed to fully confirm this hypothesis, our findings shed light on the elusive process of sperm storage in many cephalopods, a process that is fundamental for understanding sexual selection in the sea.

Description: Mature organisms often have to trade reproductive opportunities against the need to survive, especially in species with exaggerated, sexually selected traits. Life history theory predicts that old males with low residual reproductive value (RRV) would accept greater risk for current reproduction than their younger counterparts. Accordingly, we tested the prediction that, under predation risk, old males of the rock shrimp Rhynchocinetes typus pair with females faster and for a longer time than young males do. We exposed young and old dominant males (in the final ontogenetic stage, called “robustus”) to a female in the absence and presence of a predator. As predicted, older robustus males modified their mating behavior when exposed to a predator. However, in contrast to the prediction, they delayed female seizure under predation risk, possibly to carefully assess the actual threat before initiating female guarding. Once they had established the mate-guarding position, old robustus males did not interrupt it until the end of female spawning and, in the presence of predators, even guarded the female significantly longer than in predator-free treatments. In contrast, younger robustus males did not delay female seizure but abandoned the female repeatedly when a predator was present, suggesting that they perceived and responded to the predation risk. Our results suggest that older robustus males have the experience to assess threats before engaging in risky behaviors that bolster their reproductive success. Although consistent with the theory that low RRV individuals should accept greater reproductive risk, we suggest that old individuals do not recklessly engage in risky behaviors but rather cautiously evaluate the threats before investing in a potentially terminal reproductive event.

Description: Studies that focus on meiofaunal assemblages of deep-sea mud volcanoes show an unpredictable abundance and diversity in a clear response to the different environmental conditions of the seeped sediment. The mud volcanoes Abzu, Tiamat and M. Ivanov (ATI), are located along the SWIM1 fracture zone, in front of the accretionary wedge of the Gulf of Cadiz (AWGC). The geological setting and the fluid geo- chemical characteristics of the ATI mud volcanoes are differ- ent from those located within the AWGC. The main aim of this study is to describe and compare the spatial and vertical distributions of the meiofauna and nematode assemblage s from the ATI mud volcanoes, the Porto mud volcano located in the AWGC, and a non-seep site (Site 2) as reference. The pore-water on the uppermost sediment layers has composi- tions close to the near-bottom seawater. The meiofauna abun- dances were generally lower and the vertical distribution of the assemblages showed a typical pattern, gradually decreas- ing towards depth. The lack of spatial patterns of the standing stocks contrasts with the spatial variability of diversity and biomass, related to the differences in the nematode assem- blages that are distinct between ATI, Site 2 and the Porto mud volcano. The ATI and Site 2 assemblages are similar to deep-sea non-seep habitats, and are clearly coupled with the environmental conditions of the bottom seawater. No evi- dence of seep conditions favouring the development of specialised fauna were found. The lower diversity and the presence of higher dominance species could be driven by dis- tinct seepage conditions of the Porto mud volcano.

Description: Climate change resulting from increasing atmospheric CO2 is having detrimental effects on the Earth system. Societies have recognized that anthropogenic CO2 emissions must be reduced and ultimately cease to avoid potentially catastrophic impacts. However, at present timely and necessary emissions reductions appear to be very difficult to achieve. To compliment less than sufficient emissions reductions carbon dioxide removal (CDR) from the atmosphere is suggested. CDR is proposed through increasing natural carbon sinks, engineering new carbon sinks, or combing natural uptake with engineered storage. Initial studies demonstrate that removal of CO2 from the atmosphere will elicit a carbon cycle response with a “rebound” and other feedbacks generally opposing and so reducing the net-removal. We review this work into the carbon cycle response to CDR in general and for different proposed CDR methods and discuss future research needs. Understanding these dynamics and their uncertainties have important implications for quantifying the efficacy of CDR.

Description: During their spring migration, Atlantic herring (Clupea harengus) populations in the Baltic Sea rely on shallow transitional waters, such as estuaries, bays, and lagoons for spawning. Such inshore spawning grounds are ecologically important by providing suitable substrates for demersal egg deposition. These habitats are often highly impacted by multiple anthropogenic threats. Decades of eutrophication have caused a decline in depth distribution of submerged aquatic vegetation, the main herring spawning substrate in the Baltic Sea. Nowadays, spawning beds are limited to the shallow littoral zone (≤3 m depth). Accordingly, macrophytes are increasingly exposed to mechanic forcing due to storm-induced wave action. Generally, reproductive success and year class strength of the Western Baltic herring population is strongly determined by the survival of early life stages such as eggs and larvae in local nursery areas. However, explicit mechanisms by which local stressors might affect overall recruitment are currently not well understood. Hypothesizing that aquatic vegetation limited by water depth causes high herring egg mortality due to increased exposure to storm-induced hydrodynamics, we performed a combination of field studies investigating the impact of storm events on herring egg loss. Results of an egg loss experiment revealed a total egg loss of 29% in one single spawning bed during a storm event within the spawning season and the quantification of eggs attached to macrophyte litter on the shoreline emphasize the potential for regional weather extremes such as storm events to act as influential stressors for herring reproduction.

Description: Climate change research is advancing to more complex and more comprehensive studies that include long-term experiments, multiple life-history stages, multi-population, and multi-trait approaches. We used a population of the barnacle Balanus improvisus known to be sensitive to short-term acidification to determine its potential for long-term acclimation to acidification. We reared laboratory-bred individuals (as singles or pairs), and field-collected assemblages of barnacles, at pH 8.1 and 7.5 ( 400 and 1600 ?atm pCO2 respectively) for up to 16 months. Acidification caused strong mortality and reduced growth rates. Acidification suppressed respiration rates and induced a higher feeding activity of barnacles after 6 months, but this suppression of respiration rate was absent after 15 months. Laboratory-bred barnacles developed mature gonads only when they were held in pairs, but nonetheless failed to produce fertilized embryos. Field-collected barnacles reared in the laboratory for 8 months at the same pH’s developed mature gonads, but only those in pH 8.1 produced viable embryos and larvae. Because survivors of long-term acidification were not capable of reproducing, this demonstrates that B. improvisus can only partially acclimate to long-term acidification. This represents a clear and significant bottleneck in the ontogeny of this barnacle population that may limit its potential to persist in a future ocean.

Description: Marine top predators forage in environments that show potentially extreme temporal and spatial variation in prey availability, with reproductive success being crucially linked to food supply. Multiple factors of interannual and sexual variation, as well as variation across breeding stages, can shape patterns of spatial use in foraging seabirds, yet studies that address all of these variables simultaneously are rare. We present spatial assessment of foraging patterns by µGPS tracking of a sexually size monomorphic, long-lived species, the Australasian gannet (Morus serrator). The study spanned the incubation and chick-rearing stages in three consecutive breeding seasons. Our findings revealed high interannual variability in foraging distances and trip durations, but no consistent differences between birds across different breeding stages or the sexes. The exception was that core foraging areas were different for female and male Australasian gannets, although trip durations or distances were similar for both sexes. Our results also indicate bimodality in foraging distance and trip duration in this species, while highlighting interannual variability in the extent of bimodality. These findings contribute to a scarcely documented type of foraging behaviour in the seabird family of the Sulidae. Overall, these spatial use patterns provide a baseline for understanding the evolution of sex-specific foraging differences in biparental seabirds, and the extent to which these differences might help in securing breeding success across years of variable food availability.

Description: We introduced the results of investigations conducted in Japan (Yamagata, Fukui, Hiroshima and Oita Prefectures) and discussed the contribution of SGD to the production of fishery resources and their prey (meiobenthic communities). Our recent surveys provided evidence of the contribution of SGD to the production of fishes and their prey. These results strongly support the hypothesis that the contribution of nutrients from SGD to the coastal fishery resources production is much higher than previously suggested. The negative ecological impacts of SGD on meiofaunal abundance were confirmed at the high seepage areas of Kamaiso where the small spatial scale presented strong heterogeneity in SGD environmental conditions. However, the meiofaunal abundance was not low at the low seepage area located slightly apart from the high seepage area. Therefore, the effect of SGD on meiofaunal communities could be limited. However, the environmental heterogeneity significantly enhanced the conservation of the meiofaunal diversity. Thus, SGD determined the property of benthic communities.

Description: We present a solution of using adaptive nodal finite-element (FE) method to solve the marine controlled-source electromagnetic (CSEM) problem for 3-D earth models in the frequency domain. The forward problem is solved based on the secondary Coulomb-gauged electromagnetic (EM) potentials. We implement an adaptive mesh refinement algorithm according to an a posteriori error estimator based on a gradient-recovery operator of the secondary EM potentials. To increase the quality of the mesh at the receiver locations, the elements containing the receiver locations are constrained by assigning them a maximum volume for the initial mesh. An unstructured tetrahedral mesh used in our approach can provide an accurate description of complex structures such as dipping layers and rough topography that are not accurately fitted using structured meshes. We first validate the adaptive FE approach and demonstrate the convergence of the adaptive grid refinement procedure using a 1-D layered model. The canonical disc model example illustrates the capability of the adaptive FE approach for 3-D CSEM modeling. The bathymetry model shows that the algorithm is well suited to deal with complex seafloor topography, which needs to be simulated exactly to avoid the misinterpretation of marine CSEM data sets.

Description: The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) is involved in a broad range of cellular processes including cell proliferation, apoptosis and inflammation. It is now also increasingly acknowledged as having a role to play in cognitive-related processes such as neurogenesis, synaptic plasticity and neural cell survival. Cognitive impairment represents a major debilitating feature of many neurodegenerative and psychiatric disorders, including Alzheimer's disease, mood disorders, schizophrenia and fragile X syndrome, as well as being a result of traumatic brain injury or cranial irradiation. Accordingly, GSK-3 has been identified as an important therapeutic target for cognitive impairment, and recent preclinical studies have yielded important evidence demonstrating that GSK-3 inhibitors may be useful therapeutic interventions for restoring cognitive function in some of these brain disorders. The current review summarises the role of GSK-3 as a regulator of cognitive-dependent functions, examines current preclinical and clinical evidence of the potential of GSK-3 inhibitors as therapeutic agents for cognitive impairments in neuropsychiatric disorders, and offers some insight into the current obstacles that are impeding the clinical use of selective GSK-3 inhibitors in the treatment of cognitive impairment.

Description: The European water framework directive and the marine strategy framework directive have the objective to establish at least ‘good’ ecological status in all European waters by 2015. Therefore a classification system has to be established in each European country, in order to assess their water bodies. For the German coastal waters of the Baltic Sea, a classification system for phytoplankton based on the abundance of Cyanophyceae and Chlorophyceae was already presented. This system has been successfully adapted in regions with low salinity levels (〈10 PSU). With this study, we present the results trying to develop a classification system for our German region of the Baltic Sea characterized by higher salinity (〉15 PSU). All present taxonomic groups, most common species and functional groups were tested. It could be shown that all tested correlations to nitrogen concentration as eutrophication descriptor are relatively week. Nevertheless, the biovolume of Cryptophyceae was found to be the most reliable phytoplankton composition indicator, which could serve as future assessment criterion. Furthermore, as proposed by some experts, the use of maximal dissolved winter nitrogen concentration as eutrophication descriptor might be an advantage over using the total nitrogen concentrations in summer.

Description: A comparison of micropaleontological data on the distribution of the Cycladophora davisiana radiolarian species in the surface sediment layer and the Late Quaternary sediments from the Subarctic Pacific and Far East marginal seas allowed conclusions concerning the possible conditions and occurrence of intermediate waters during the last glacial maximum. We used the modern data on the C. davisiana species, which is a micropaleontological indicator of the cold oxygen-rich upper intermediate water mass, which is now forming only in the Sea of Okhotsk. The high amount of C. davisiana in sediments of the last glacial maximum may point to the possible formation and expansion of the ventilated intermediate water in the most part of the Subarctic paleo-Pacific: the Bering Sea, the Sea of Okhotsk, within the NW Gyre, and in the Gulf of Alaska.

Description: Coral reefs are the most abundant shallow water ecosystems in the Red Sea, harboring a high species diversity and habitat complexity over large environmental gradients. At the same time the semi-enclosed ocean basin and its partly extreme environmental conditions may promote species evolution being distinct from Indo-Pacific coral reefs. Extreme conditions are found in the southern Red Sea, where temperatures reach up to 33 °C in summer and where nutrient input is high. Mechanisms of organism adjustment to these conditions are of particular interest in the light of climate change research. Towards the north, conditions become more ‘coral-promoting’ finally reaching temperatures between 21–27 °C (winter-summer) and clear waters at the northern end of the Red Sea (Gulf of Aqaba). In this chapter, we summarize the current knowledge about the biology of shallow water, symbiotic, reef-building corals of the Red Sea. We start with an overview on the environmental conditions of the Red Sea, the history of coral reef research in this region and a general introduction into coral biology, before we describe the ecophysiology of Red Sea corals. Coral ecophysiology is presented in the context of varying environmental conditions over depth (e.g., light), between seasons, and over latitudes (e.g., light, temperature, nutrients). Mechanisms and patterns of coral reproduction are discussed in the context of seasonal and latitudinal environmental changes. Finally, we briefly describe anthropogenic influences on Red Sea coral reefs. Acclimatization mechanisms of corals to changing conditions over a depth gradient (mainly light reduction) have been well studied in the Gulf of Aqaba and include the following metabolic adjustments with depth: (i) an upregulation of light-harvesting pigments (chlorophyll a) and a downregulation of photo-protective pigments (xanthophyll), (ii) an increase of heterotrophy, and (iii) a decrease of metabolic activity (e.g., calcification and growth). In addition, a change in the symbiont composition (Symbiodinium clade and/or type) over depth was observed in some coral species. Seasonal environmental changes (mainly light availability, temperature, nutrients) lead to various metabolic responses of the corals, including (i) changes in zooxanthellae pigmentation and density and (ii) changes in the metabolic activity. In particular, changes in calcification and growth rates can be observed with lowest rates during low temperatures in winter. Interestingly, however, this reverses in the southern Red Sea, where calcification rates are higher in winter than in summer. This kind of latitudinal shift is also evident in the timing of reproduction, which occurs earlier in the year (January–March) in the south compared to the north (March–August). This indicates that growth and reproduction are strongly linked to temperature, following a single temperature optimum, which occurs at different times throughout the year from north to south. Furthermore, this hints towards a high phenotypic plasticity (acclimatization) rather than local genetic adaptation of the investigated coral species. A clear shift in the genetic population structure from north to south in another coral species, however, indicates local adaption. Adjusting mechanisms need to be further understood in order to provide indication for predicted climate change effects.

Description: Sub-micron marine aerosol particles (PM1) were collected over the period 22 June–21 July 2011 during the RV MARIA S. MERIAN cruise MSM 18/3, which travelled from the Cape Verdean island of São Vicente to Gabon, in the process crossing the tropical Atlantic Ocean with its equatorial upwelling regime. According to air mass origin and the chemical composition of the sampled aerosol particles, three main regimes could be established. Aerosol particles in the first part of the cruise were mainly of marine origin (Region I). In the second part of the cruise, marine influences mixed with increasing influence from biomass burning (Region II). In the final part of the cruise, which approached the African mainland, the biomass burning influence became dominant (Region III). Generally, aerosol particles were dominated by sulfate (caverage = 2.0 μg m−3) and ammonium ions (caverage = 0.7 μg m−3), which were well-correlated and increased slightly over the duration of the cruise. High concentrations of water-insoluble organic carbon (WISOC; caverage = 0.4 μg m−3) were found, most likely as a result of the high oceanic productivity in this region. Water-soluble organic carbon (WSOC) concentrations increased from 0.26 μg m−3 in Region I to 2.3 μg m−3 in Region III, most likely as a result of biomass burning influences. The major organic aerosol constituents were oxalic acid, methanesulfonic acid (MSA), and aliphatic amines. MSA concentrations were quite constant during the cruise (caverage = 42 ng m−3). Aliphatic amines were most abundant in Region I, with concentrations of ~ 20 ng m−3. Oxalic acid showed the opposite trend, with average concentrations of 12 ng m−3 in Region I and 158 ng m−3 in Region III. The α-dicarbonyl compounds glyoxal and methylglyoxal were detected in the aerosol particles in the low ng m−3 range and were closely correlated with oxalic acid. MSA and aliphatic amines arise from biogenic marine sources, whereas oxalic acid and the α-dicarbonyl compounds were attributed to biomass burning. Concentrations of n-alkanes increased from 0.8 to 4.7 ng m−3 over the duration of the cruise. PAHs and hopanes were abundant only in Region III (caverage of PAHs = 0.13 ng m−3; caverage of hopanes = 0.19 ng m−3). Levoglucosan was identified in several samples obtained in Region III, with caverage = 1.9 ng m−3, which points to (aged) biomass burning influences. The organic compounds quantified in this study could explain 8.3 % of WSOC in Regions I, where aliphatic amines and MSA dominated, 3.7 % of WSOC in Region II and 2.5 % of WSOC in Region III, where oxalic acid dominated.

Description: An ocean circulation model is run using two different idealized equatorial basin configurations under steady wind forcing. Both model versions produce bands of vertically alternating zonal flow at depth, similar to observed Equatorial Deep Jets (EDJs) and with a time scale corresponding to that of the gravest equatorial basin mode for the dominant baroclinic vertical normal mode. Both model runs show evidence for enhanced variability in the surface signature of the North Equatorial Counter Current (NECC) with the same time scale. We also find the same link between the observed NECC and the EDJs in the Atlantic by comparing the signature of the EDJ in moored zonal velocity data at 23° W on the equator with the signature of the NECC in geostrophic velocities from altimeter data. We argue that the presence of a peak in variability in the NECC associated with the EDJ basin mode period is evidence that the influenceatthis time scale is upward, from the EDJ to the NECC

Description: Ocean acidification studies in the past decade have greatly improved our knowledge of how calcifying organisms respond to increased surface ocean CO2 levels. It has become evident that, for many organisms, nutrient availability is an important factor that influences their physiological responses and competitive interactions with other species. Therefore, we tested how simulated ocean acidification and eutrophication (nitrate and phosphate enrichment) interact to affect the physiology and ecology of a calcifying chlorophyte macroalga (Halimeda opuntia (L.) J.V. Lamouroux) and its common noncalcifying epiphyte (Dictyota sp.) in a 4-week fully crossed multifactorial experiment. Inorganic nutrient enrichment (+NP) had a strong influence on all responses measured with the exception of net calcification. Elevated CO2 alone significantly decreased electron transport rates of the photosynthetic apparatus and resulted in phosphorus limitation in both species, but had no effect on oxygen production or respiration. The combination of CO2 and +NP significantly increased electron transport rates in both species. While +NP alone stimulated H. opuntia growth rates, Dictyota growth was significantly stimulated by nutrient enrichment only at elevated CO2, which led to the highest biomass ratios of Dictyota to Halimeda. Our results suggest that inorganic nutrient enrichment alone stimulates several aspects of H. opuntia physiology, but nutrient enrichment at a CO2 concentration predicted for the end of the century benefits Dictyota sp. and hinders its calcifying basibiont H. opuntia.

Description: Metals constitute an important group of abiotic stressors that elicit stress responses in marine algae that include the production of reactive oxygen species (ROS). Silver (Ag) is a highly toxic metal to organisms but despite this there are relatively few studies on how it affects marine macroalgae (seaweeds). In a landmark study published in 1977 the first information was provided on the accumulation of Ag in Fucus spp. (Phaeophyceae) from the Looe estuary, located in south-west England, an area with a long history of mining activity. In the present study, the estuary has been re-visited and the patterns of Ag accumulation in two Fucus spp. and sediment re-examined after 35 years. We conclude that Ag concentrations in sediment and macroalgae from specific sites within the catchment remain high, but more generally sediment concentrations have declined by approximately 65 % and the dissolved, bioavailable fraction by 24 % over this period. In addition, from laboratory studies we provide data on the speciation and toxic effects of Ag under different salinity regimes in the euryhaline brown seaweed, Fucus ceranoides. From these exposure experiments, it was found that with increasing Ag concentrations growth was inhibited and lipid peroxidation associated with ROS production increased. The magnitude of the toxic effects was greater at a salinity of 10 than 28 psu which reflects the greater bioavailability of the toxic species of Ag (Ag+ and AgCl0) at reduced salinities. These findings emphasise the importance of investigating the effects of metal pollution in conjunction with other, natural, environmental stressors such as salinity.

Description: Aurelia spp. is a cosmopolite scyphozoan species and likely the most studied jellyfish in the world. Its pelagic–benthic life cycle is complex, and the benthic asexual reproducing stage (polyp) is acknowledged fundamentally in bloom onset. Despite this, field investigations remain scarce and are mainly restrained to the western Pacific Ocean. Thau lagoon (43°23′59.10″ N 3°36′37.15″ E), a semi-enclosed system that harbours a resident population of Aurelia sp., is in essence a natural laboratory that offers an ideal framework to investigate the life cycle of the species. We here used a non-destructive approach consisting on a field survey over the entire lagoon (ca. 7 ha) and several substrate types by free diving to examine the distribution and habitat use of Aurelia sp. benthic population. We show that polyps were largely distributed over the entire lagoon, settled mainly on artificial hard substrates, thereby stressing the promoting role of anthropogenic perturbations in coastal areas, i.e. habitat modification, for jellyfish proliferations. Therefore, our study suggest a potential increase in Aurelia sp. benthic populations as an outcome of mounting coastal constructions in the near future; the consequences of which ultimately might promote an increase in jellyfish outbreaks.

Description: Estuarine systems play a critical role as nursery areas for some fish species. Nursery function, nevertheless, is likely to vary among estuaries, mostly due to differences in habitat quality. High quality nursery habitats are those in which growth and survival of early stages of fish are enhanced. The nutritional condition of larval fishes has vital implications for their mortality and growth, and thereby their recruitment. This study aimed to compare the nutritional condition of Gichristella aestuaria larvae, using individual RNA-DNA ratios and growth rates in the upper reaches of six estuaries in South Africa to find the environmental factors that better determine the nutritional condition of fish larvae. Physico-chemical factors as well as calorific value of zooplankton were used to correlate to fish body condition. Results showed that the larvae of G. aestuaria from the freshwater rich Gamtoos and the Sundays estuaries were in better nutritional condition than the larvae from other estuaries, while larvae from the Swartkops Estuary, a highly eutrophic system, presented the worst nutritional condition of all studied larvae. Salinity and the abundance of zooplankton were the major factors determining the nutritional condition of G. aestuaria larvae in these warm temperate estuaries. In addition, our results suggest that the match-mismatch hypothesis might also be important in estuarine systems. This study represents one of the few studies worldwide that applied a multispecies growth model for fish larvae in warm temperate estuaries

Description: Many exploited fish species are threatened with collapse and the European eel is no exception. Its abundance has declined dramatically and various reasons account for this, among them the introduction of the invasive swim bladder nematode Anguillicola crassus. For developing an adequate immune response against this parasite, variation at the genes of the major histocompatibility complex (MHC), a key component of the adaptive immune system, might be essential and assessing their diversity might provide critical information for improving conservation strategies. Here, we characterized the MHC class II of the European eel. We provide evidence for relatively high diversity at both MHC IIA and MHC IIB, which contrasts with findings for other endangered species. Furthermore, both genes show signs of site-specific positive selection. The absence of overall positive selection at MHC IIB might, however, suggests that demographic shifts have negatively impacted that gene, thereby possibly reducing the adaptive potential of the European eel.

Description: Stable carbon isotopes of dissolved inorganic carbon (δ13CDIC) in the ocean are generally not well understood as they are governed by a complex interplay of biological processes and air–sea exchange. In the Arctic Ocean, δ13CDIC values are prone to change in the near future with rapidly changing climate conditions. This study provides a baseline to assess the δ13CDIC of the Arctic Ocean with a focus on upper to intermediate waters (to ~500 m). Measured δ13CDIC values in the Arctic Ocean range from ~−0.6 to +2.2 ‰. In the Eurasian Basin, the δ13CDIC values lie between ~1 and 1.5 ‰ and exhibit little variation within the upper layers. In the Canada Basin, δ13CDIC values reach 2 ‰ in the surface layer, with lowest values of ~−0.6 ‰ found at ~200 m water depth. At greater depth, δ13CDIC values range from ~1 to 1.5 ‰ within both basins. In the Canada Basin, nutrient levels are higher than in the Eurasian Basin and associated variations in δ13CDIC are clearly related to biological processes. However, low δ13CDIC values in the Canada Basin are also strongly influenced by non-equilibrium air–sea exchange processes. The different δ13CDIC patterns between the Canada Basin and the Eurasian Basin appear to be linked to differences in transport processes within the Arctic Ocean halocline. The upper layers in the Canada basins have direct contributions of waters from the Laptev, East Siberian and Chukchi shelves, which contain elevated fractions of river waters and sea-ice related brines, whereas their counterparts, in the Eurasian Basin, are mostly formed by halocline waters from the Barents and Kara seas. River waters have low δ13CDIC of ~−8 ‰ on average, but in the Arctic basins this signal is mostly lost and δ13CDIC values show only a weak correlation to river water fractions contained in the water mass. No relation between δ13CDIC and sea-ice related brine contribution is apparent.

Description: Definition Ocean acidification refers to the process of increasing seawater acidity by dissolving additional carbon dioxide (CO2) from the atmosphere. As CO2 dissolves in seawater, it forms carbonic acid (H2CO3), which readily dissociates into bicarbonate (HCO3−) and hydrogen (H+) ions. The hydrogen ion concentration determines the acidity of seawater, expressed by the pH scale. Part of the hydrogen ions released in this process is buffered by the seawater carbonate system by consuming carbonate ions (CO32−) and forming additional bicarbonate. As pH is defined as the negative logarithm of the hydrogen ion concentration, pH decreases as the acidity increases (Fig. 1). Fig. 1 The process of ocean acidification: (1) atmospheric carbon dioxide (CO2) dissolving in seawater; (2) dissolved CO2 reacting with water to form carbonic acid (H2CO3); (3) carbonic acid dissociating to bicarbonate (HCO3−) and hydrogen ion (H+); and (4) hydrogen ion reacting with carbonate (CO3 ... This is an excerpt from the content

Description: The ~16-ka-long record of explosive eruptions from Shiveluch volcano (Kamchatka, NW Pacific) is refined using geochemical fingerprinting of tephra and radiocarbon ages. Volcanic glass from 77 prominent Holocene tephras and four Late Glacial tephra packages was analyzed by electron microprobe. Eruption ages were estimated using 113 radiocarbon dates for proximal tephra sequence. These radiocarbon dates were combined with 76 dates for regional Kamchatka marker tephra layers into a single Bayesian framework taking into account the stratigraphic ordering within and between the sites. As a result, we report ~1,700 high-quality glass analyses from Late Glacial–Holocene Shiveluch eruptions of known ages. These define the magmatic evolution of the volcano and provide a reference for correlations with distal fall deposits. Shiveluch tephras represent two major types of magmas, which have been feeding the volcano during the Late Glacial–Holocene time: Baidarny basaltic andesites and Young Shiveluch andesites. Baidarny tephras erupted mostly during the Late Glacial time (~16–12.8 ka BP) but persisted into the Holocene as subordinate admixture to the prevailing Young Shiveluch andesitic tephras (~12.7 ka BP–present). Baidarny basaltic andesite tephras have trachyandesite and trachydacite (SiO2 〈 71.5 wt%) glasses. The Young Shiveluch andesite tephras have rhyolitic glasses (SiO2 〉 71.5 wt%). Strongly calc-alkaline medium-K characteristics of Shiveluch volcanic glasses along with moderate Cl, CaO and low P2O5 contents permit reliable discrimination of Shiveluch tephras from the majority of other large Holocene tephras of Kamchatka. The Young Shiveluch glasses exhibit wave-like variations in SiO2 contents through time that may reflect alternating periods of high and low frequency/volume of magma supply to deep magma reservoirs beneath the volcano. The compositional variability of Shiveluch glass allows geochemical fingerprinting of individual Shiveluch tephra layers which along with age estimates facilitates their use as a dating tool in paleovolcanological, paleoseismological, paleoenvironmental and archeological studies. Electronic tables accompanying this work offer a tool for statistical correlation of unknown tephras with proximal Shiveluch units taking into account sectors of actual tephra dispersal, eruption size and expected age. Several examples illustrate the effectiveness of the new database. The data are used to assign a few previously enigmatic wide-spread tephras to particular Shiveluch eruptions. Our finding of Shiveluch tephras in sediment cores in the Bering Sea at a distance of ~600 km from the source permits re-assessment of the maximum dispersal distances for Shiveluch tephras and provides links between terrestrial and marine paleoenvironmental records.

Description: Increasing anthropogenic CO2 concentration in the atmosphere is altering sea water carbonate chemistry with unknown biological and ecological consequences. Whereas some reports are beginning to emerge on the effects of ocean acidification (OA) on fish, very little is known about the impact of OA on jellyfish. In particular, the benthic stages of metagenetic species are virtually unstudied in this context despite their obvious importance for bloom dynamics. Hence, we conducted tri-trophic food chain experiments using the algae Rhodomonas salina as the primary producer, the copepod Acartia tonsa as the primary consumer and the benthic life stage of the scyphozoans Cyanea capillata and Chrysaora hysoscella as secondary consumers. Two experiments were conducted examining the effects of different levels of CO2 and food quality (experiment 1) and the effect of food quality and quantity (experiment 2) on the growth and respiration of scyphozoan polyps. Polyp growth and carbon content (µg polyp−1) were not affected by the CO2 treatments, but were significantly negatively affected by P limitation of the food in C. capillata but not in Ch. hysoscella. Growth and carbon content were reduced in low-food treatments, but increased with decreasing P limitation in high- and low-food treatments in C. capillata. Respiration was not significantly influenced by food quality and quantity in C. capillata. We conclude that phosphorus can be a limiting factor affecting the fitness of scyphopolyps and that P-limited food is of poor nutritional quality. Furthermore, OA, at least using realistic end-of-century scenarios, will have no direct effect on the growth of scyphistomae

Description: We estimated the relative contribution of atmosphere (ic Nitrogen (N) input (wet and dry deposition and N fixation) to the epipelagic food web by measuring N isotopes of different functional groups of epipelagic zooplankton along 23°W (17°N-4°S) and 18°N (20-24°W) in the Eastern Tropical Atlantic. Results were related to water column observations of nutrient distribution and vertical diffusive flux as well as colony abundance of Trichodesmium obtained with an Underwater Vision Profiler (UVP5). The thickness and depth of the nitracline and phosphocline proved to be significant predictors of zooplankton stable N isotope values. Atmospheric N input was highest (61% of total N) in the strongly stratified and oligotrophic region between 3 and 7°N, which featured very high depth-integrated Trichodesmium abundance (up to 9.4×104 colonies m-2), strong thermohaline stratification and low zooplankton δ15N (~2‰). Relative atmospheric N input was lowest south of the equatorial upwelling between 3 and 5°S (27%). Values in the Guinea Dome region and north of Cape Verde ranged between 45 and 50%, respectively. The microstructure-derived estimate of the vertical diffusive N flux in the equatorial region was about one order of magnitude higher than in any other area (approximately 8 mmol m-2 d 1). At the same time, this region received considerable atmospheric N input (35% of total). In general, zooplankton δ15N and Trichodesmium abundance were closely correlated, indicating that N fixation is the major source of atmospheric N input. Although Trichodesmium is not the only N fixing organism, its abundance can be used with high confidence to estimate the relative atmospheric N input in the tropical Atlantic (r2 = 0.95). Estimates of absolute N fixation rates are two- to tenfold higher than incubation-derived rates reported for the same regions. Our approach integrates over large spatial and temporal scales and also quantifies fixed N released as dissolved inorganic and organic N. In a global analysis, it may thus help to close the gap in oceanic N budgets.

Description: Microfluidics, or lab-on-a-chip (LOC) is a promising technology that allows the development of miniaturized chemical sensors. In contrast to the surging interest in biomedical sciences, the utilization of LOC sensors in aquatic sciences is still in infancy but a wider use of such sensors could mitigate the undersampling problem of ocean biogeochemical processes. Here we describe the first underwater test of a novel LOC sensor to obtain in situ calibrated time-series (up to 40 h) of nitrate+nitrite (ΣNOx) and nitrite on the seafloor of the Mauritanian oxygen minimum zone, offshore Western Africa. Initial tests showed that the sensor successfully reproduced water column (160 m) nutrient profiles. Lander deployments at 50, 100 and 170 m depth indicated that the biogeochemical variability was high over the Mauritanian shelf: The 50 m site had the lowest ΣNOx concentration, with 15.2 to 23.4 μM (median=18.3 μM); while at the 100 site ΣNOx varied between 21.0 and 30.1 μM over 40 hours (median = 25.1μM). The 170 m site had the highest median ΣNOx level (25.8 μM) with less variability (22.8 to 27.7 μM). At the 50 m site, nitrite concentration decreased fivefold from 1 to 0.2 μM in just 30 hours accompanied by decreasing oxygen and increasing nitrate concentrations. Taken together with the time series of oxygen, temperature, pressure and current velocities, we propose that the episodic intrusion of deeper waters via cross-shelf transport leads to intrusion of nitrate-rich, but oxygen-poor waters to shallower locations, with consequences for benthic nitrogen cycling. This first validation of an LOC sensor at elevated water depths revealed that when deployed for longer periods and as a part of a sensor network, LOC technology has the potential to contribute to the understanding of the benthic biogeochemical dynamics.

Description: Current pressures to mine polymetallic sulfide deposits pose threats to the animal communities found at deep-sea hydrothermal vents. Management plans aimed at preserving these unusual communities require knowledge of historical and contemporary forces that shaped the distributions and connectivity of associated species. As most vent research has focused on the eastern Pacific and mid-Atlantic ridge systems less is known about Indo-Pacific vents, where mineral extraction activities are imminent. Deep-sea mussels (Bivalvia: Mytilidae) of the genus Bathymodiolus include the morphotypic species B. septemdierum, B. brevior, B. marisindicus, and B. elongatus which are among the dominant vent taxa in western Pacific back-arc basins and the Central Indian Ridge. To assess their interpopulational relationships, we examined multilocus genotypes based on DNA sequences from four nuclear and four mitochondrial genes, and allozyme variation encoded by eleven genes. Bayesian assignment methods grouped mussels from seven widespread western Pacific localities into a single cluster, whereas the Indian Ocean mussels were clearly divergent. Thus, we designate two regional metapopulations. Notably, contemporary migration rates among all sites appeared to be low despite limited population differentiation, which highlights the necessity of obtaining realistic data on recovery times and fine-scale population structure to develop and manage conservation units effectively. Future studies using population genomic methods to address these issues in a range of species will help to inform management plans aimed at mitigating potential impacts of deep-sea mining in the Indo-Pacific region.

Description: The Atlantic meridional overturning circulation (AMOC) and the subpolar gyre (SPG) are important elements in mechanisms for multidecadal variability in models in the North Atlantic Ocean. In this study, a 2000-year long global ocean model integration forced with the atmospheric patterns associated with a white noise North Atlantic Oscillation (NAO) index is shown to have three distinct timescales of North Atlantic Ocean variability. First, an interannual timescale with variability shorter than 15 years, that can be related to Ekman dynamics. Second, a multidecadal timescale, on the 15- to 65-year range, that is mainly concentrated in the SPG region and is controlled by constructive interference between density anomalies around the gyre and the changing NAO forcing. Finally, the centennial timescales, with variability longer than 65 years, that can be attributed to the ocean being in a series of quasi-equilibrium states. The relationship between the ocean’s response and the NAO index differs for each timescale; the 15-year and shorter timescales are directly related to the NAO of the same year, 15- to 65-year timescales are dependent on the NAO index in the last 25–30 years in a sinusoidal sense while the 65-year and longer timescales relate to a sum of the last 50–80 years of the NAO index.

Description: Extraordinarily strong El Niño events, such as those of 1982/1983 and 1997/1998, cause havoc with weather around the world, adversely influence terrestrial and marine ecosystems in a number of regions and have major socio-economic impacts. Here we show by means of climate model integrations that El Niño events may be boosted by global warming. An important factor causing El Niño intensification is warming of the western Pacific warm pool, which strongly enhances surface zonal wind sensitivity to eastern equatorial Pacific sea surface temperature anomalies. This in conjunction with larger and more zonally asymmetric equatorial Pacific upper ocean heat content supports stronger and longer lasting El Niños. The most intense events, termed Super El Niños, drive extraordinary global teleconnections which are associated with exceptional surface air temperature and rainfall anomalies over many land areas.

Description: Molecular diversity surveys have demonstrated that aquatic fungi are highly diverse, and that they play fundamental ecological roles in aquatic systems. Unfortunately, comparative studies of aquatic fungal communities are few and far between, due to the scarcity of adequate datasets. We combined all publicly available fungal 18S ribosomal RNA (rRNA) gene sequences with new sequence data from a marine fungi culture collection. We further enriched this dataset by adding validated contextual data. Specifically, we included data on the habitat type of the samples assigning fungal taxa to ten different habitat categories. This dataset has been created with the intention to serve as a valuable reference dataset for aquatic fungi including a phylogenetic reference tree. The combined data enabled us to infer fungal community patterns in aquatic systems. Pairwise habitat comparisons showed significant phylogenetic differences, indicating that habitat strongly affects fungal community structure. Fungal taxonomic composition differed considerably even on phylum and class level. Freshwater fungal assemblage was most different from all other habitat types and was dominated by basal fungal lineages. For most communities, phylogenetic signals indicated clustering of sequences suggesting that environmental factors were the main drivers of fungal community structure, rather than species competition. Thus, the diversification process of aquatic fungi must be highly clade specific in some cases.The combined data enabled us to infer fungal community patterns in aquatic systems. Pairwise habitat comparisons showed significant phylogenetic differences, indicating that habitat strongly affects fungal community structure. Fungal taxonomic composition differed considerably even on phylum and class level. Freshwater fungal assemblage was most different from all other habitat types and was dominated by basal fungal lineages. For most communities, phylogenetic signals indicated clustering of sequences suggesting that environmental factors were the main drivers of fungal community structure, rather than species competition. Thus, the diversification process of aquatic fungi must be highly clade specific in some cases.

Description: Benthic suspension feeding mussels are an important functional guild in coastal and estua-rine ecosystems. To date we lack information on how various environmental gradients and biotic interactions separately and interactively shape the distribution patterns of mussels in non-tidal environments. Opposing to tidal environments, mussels inhabit solely subtidal zone in non-tidal waterbodies and, thereby, driving factors for mussel populations are expected to differ from the tidal areas. In the present study, we used the boosted regression tree modelling (BRT), an ensemble method for statistical techniques and machine learning, in order to explain the distribution and biomass of the suspension feeding mussel Mytilus trossulus in the non-tidal Baltic Sea. BRT models suggested that (1) distribution patterns of M. trossulus are largely driven by separate effects of direct environmental gradients and partly by interactive effects of resource gradients with direct environmental gradients. (2) Within its suitable habitat range, however, resource gradients had an important role in shaping the biomass distribution of M. trossulus. (3) Contrary to tidal areas, mussels were not competitively superior over macrophytes with patterns indicating either facilitative interactions between mussels and macrophytes or co-variance due to common stressor. To conclude, direct environmental gradients seem to define the distribution pattern of M. trossulus, and within the favourable distribution range, resource gradients in interaction with direct environmental gradients are expected to set the biomass level of mussels.

Description: Marine sponge–associated actinomycetes are considered as promising sources for the discovery of novel biologically active compounds. In the present study, a total of 64 actinomycetes were isolated from 12 different marine sponge species that had been collected offshore the islands of Milos and Crete, Greece, eastern Mediterranean. The isolates were affiliated to 23 genera representing 8 different suborders based on nearly full length 16S rRNA gene sequencing. Four putatively novel species belonging to genera Geodermatophilus, Microlunatus, Rhodococcus and Actinomycetospora were identified based on a 16S rRNA gene sequence similarity of 〈 98.5% to currently described strains. Eight actinomycete isolates showed bioactivities against Trypanosma brucei brucei TC221 with half maximal inhibitory concentration (IC50) values 〈20 μg/mL. Thirty four isolates from the Milos collection and 12 isolates from the Crete collection were subjected to metabolomic analysis using high resolution LC-MS and NMR for dereplication purposes. Two isolates belonging to the genera Streptomyces (SBT348) and Micromonospora (SBT687) were prioritized based on their distinct chemistry profiles as well as their anti-trypanosomal activities. These findings demonstrated the feasibility and efficacy of utilizing metabolomics tools to prioritize chemically unique strains from microorganism collections and further highlight sponges as rich source for novel and bioactive actinomycetes.

Description: The hypothesis that the tropical oceans lead the global warming at the Termination I and II by ~2,000 to ~3,000 years (Visser et al. 2003) whereas melting of the northern continental ice masses is lacking behind challenges the Milankovitch theory of climate change and emphasizes the role of the tropics for global climate change. Although the simultaneous multi-proxy approach of planktonic foraminiferal Mg/Ca, δ18O and δ44/40Ca from tropical sediment core SO-164-03-4 (16° 32.37′ N; 72° 12.31′ W; 2,744 m) from the Caribbean tend to confirm the observation by Visser et al. (2003) we interpret the shift between Mg/Ca and δ18O in core SO-164-03-4 to be due to local changes in sea-surface salinity (SSS) variations triggered by glacial/interglacial related shifts of the Inter-tropical Convergence Zone (ITCZ).

Description: Biologists studying animals in their natural environment are increasingly using sensors such as accelerometers in animal-attached ‘smart’ tags because it is widely acknowledged that this approach can enhance the understanding of ecological and behavioural processes. The potential of such tags is tempered by the difficulty of extracting animal behaviour from the sensors which is currently primarily dependent on the manual inspection of multiple time series graphs. This is time consuming and error-prone for the domain expert and is now the limiting factor for realising the value of tags in this area. We introduce TimeClassifier, a visual analytic system for the classification of time series data for movement ecologists. We deploy our system with biologists and report two real-world case studies of its use

Description: A seasonal forecast system is presented, based on the global coupled climate model MPI-ESM as used for CMIP5 simulations. We describe the initialisation of the system and analyse its predictive skill for surface temperature. The presented system is initialised in the atmospheric, oceanic, and sea ice component of the model from reanalysis/observations with full field nudging in all three components. For the initialisation of the ensemble, bred vectors with a vertically varying norm are implemented in the ocean component to generate initial perturbations. In a set of ensemble hindcast simulations, starting each May and November between 1982 and 2010, we analyse the predictive skill. Bias-corrected ensemble forecasts for each start date reproduce the observed surface temperature anomalies at 2–4 months lead time, particularly in the tropics. Niño3.4 sea surface temperature anomalies show a small root-mean-square error and predictive skill up to 6 months. Away from the tropics, predictive skill is mostly limited to the ocean, and to regions which are strongly influenced by ENSO teleconnections. In summary, the presented seasonal prediction system based on a coupled climate model shows predictive skill for surface temperature at seasonal time scales comparable to other seasonal prediction systems using different underlying models and initialisation strategies. As the same model underlying our seasonal prediction system—with a different initialisation—is presently also used for decadal predictions, this is an important step towards seamless seasonal-to-decadal climate predictions.

Description: Keilhack reported his impressions from his participation at the International Geological Congress in Russia in 1897 in several consecutive articles. In the more than 100 years since that time, a lot has changed. Apart from the totally different style of scientific presentations, with almost no illustrations, except maps, being shown during a talk, field trips were also a very special event, involving huge amounts of logistics. More than 200 people were transported to very remote areas of the European part of Russia. As well as organizing transportation by coaches and horses, places to stay overnight had to be found in large numbers and special regulations had to be issued by the government to allow access to various outcrops. Keilhacks visit of the oil-producing sites around Baku are of special interest, since they belonged obviously to the most productive ones on the globe at that time.

Description: Different genetic types of marine sediments that were deposited on the continental slope of the Kronotskii Peninsula with the rate of several tens of centimeters per thousand years during the last 20 ka have been investigated. It is established that their lithological, mineral, and chemical compositions were determined by climate changes.

Description: After two companies were awarded a 30-year license for the exploration and exploitation of metalliferous sediments in the Atlantis II Deep (Red Sea) in 2011, we herewith present conclusions and recommendations derived from an environmental risk assessment, the Metalliferous Sediment Atlantis II Deep (MESEDA) study, conducted in the period 1977–1981. For economic reasons, this program was discontinued before final report delivery and fell dormant for 30 years. The effects of environmental disturbances of the benthic and the near-bottom water layer habitats in and around the mining site deserve further and more modern risk assessments. We examine the relevance of our 1981 recommendations and of subsequent publications to the extended period of resource extraction planned for this century and recommend more up-to-date risk assessment investigations and evaluations.

Description: The squat lobster Pleuroncodes monodon is a key species of the highly productive, but oxygen-poor upwelling system of the Eastern Tropical South Pacific. Observations of P. monodon in the water column off Peru have led to the hypothesis that anoxic conditions force this otherwise primarily benthic species to adopt a pelagic lifestyle. Here we show that off Peru, P. monodon can be found in the oxygenated surface water, but also on the anoxic seafloor. Our physiological experiments demonstrate that juvenile and adult specimens have a very low critical respiratory pO2 of 0.5 kPa and that adults survive anoxia for 30.5–70.5 h. Anoxic conditions at the seafloor should therefore force P. monodon to regularly migrate to the oxic surface layer in order to restore energy reserves and recycle metabolic end products of anaerobic metabolism. It was recently estimated that the ammonium supply mediated by diel vertical migrations (DVMs) of zooplankton and nekton considerably fuels bacterial anaerobic ammonium oxidation—a major loss process for fixed nitrogen in the ocean. These estimates were based on the implicit assumption that anoxia does not result in a down-regulation of ammonium excretion. We here show that exposure to anoxia elicits a fourfold reduction in ammonium excretion from 2.1 ± 0.6 µmol h−1 g dry weight−1 under normoxic to 0.5 ± 0.6 µmol h−1 g DW−1 under anoxic conditions in P. monodon. Estimates of ammonium supply to the anoxic core of oxygen minimum zones via DVM therefore are likely too high.