ALBERT

Description: Background: Syngnathids are a highly derived and diverse fish clade comprising the pipefishes, pipe-horses, and seahorses. They are characterized by a plethora of iconic traits that increasingly capture the attention of biologists, including geneticists, ecologists, and developmental biologists. The current understanding of the origins of their derived body plan is, however, hampered by incomplete and limited descriptions of the early syngnathid ontogeny. Results: We provide a comprehensive description of the development of Nerophis ophidion, Syngnathus typhle, and Hippocampus erectus from early cleavage stages to release from the male brooding organ and beyond, including juvenile development. We comparatively describe skeletogenesis with a particular focus on dermal bony plates, the snout-like jaw morphology, and appendages. Conclusions: This most comprehensive and detailed account of syngnathid development to date suggests that convergent phenotypes (e.g., reduction and loss of the caudal fins), likely arose by distinct ontogenetic means in pipefishes and seahorses. Comparison of the ontogenetic trajectories of S. typhle and H. erectus provides indications that characteristic features of the seahorse body plan result from developmental truncation. Altogether, this work provides a valuable resource and framework for future research to understand the evolution of the outlandish syngnathid morphology from a developmental perspective.

Description: The climactic Los Chocoyos (LCY) eruption from Atitlán caldera (Guatemala) is a key chronostratigraphic marker for the Quaternary period given the extensive distribution of its deposits that reached both the Pacific and Atlantic Oceans. Despite LCY tephra being an important marker horizon, a radioisotopic age for this eruption has remained elusive. Using zircon (U–Th)/He geochronology, we present the first radioisotopically determined eruption age for the LCY of 75 ± 2 ka. Additionally, the youngest zircon crystallization 238U–230Th rim ages in their respective samples constrain eruption age maxima for two other tephra units that erupted from Atitlán caldera, W-Fall (130 +16/−14 ka) and I-Fall eruptions (56 +8.2/−7.7 ka), which under- and overlie LCY tephra, respectively. Moreover, rim and interior zircon dating and glass chemistry suggest that before eruption silicic magma was stored for 〉80 kyr, with magma accumulation peaking within ca. 35 kyr before the LCY eruption during which the system may have developed into a vertically zoned magma chamber. Based on an updated distribution of LCY pyroclastic deposits, a new conservatively estimated volume of ~1220 ± 150 km3 is obtained (volcanic explosivity index VEI 〉 8), which confirms the LCY eruption as the first-ever recognized supereruption in Central America.

Description: A new autotrophic hydrogen‐oxidizing Chromatiaceae bacterium, namely bacterium CTD079, was enriched from a water column sample at 1500 m water depth in the southern Pacific Ocean. Based on the phylogeny of 16S rRNA genes it was closely related to a scaly snail endosymbiont (99.2% DNA sequence identity) whose host so far is only known to colonize hydrothermal vents along the Indian ridge. The average nucleotide identity between the genomes of CTD079 and the snail endosymbiont was 91%. The observed differences likely reflect adaptations to their specific habitats. For example, CTD079 encodes additional enzymes like the formate dehydrogenase increasing the organism's spectrum of energy generation pathways. Other additional physiological features of CTD079 included the increase of viral defense strategies, secretion systems and specific transporters for essential elements. These important genome characteristics suggest an adaptation to life in the open ocean.

Description: Idealized models or emulators of volcanic aerosol forcing have been widely used to reconstruct the spatiotemporal evolution of past volcanic forcing. However, existing models, including the most recently developed Easy Volcanic Aerosol (EVA; Toohey et al., doi: 10.5194/gmd‐2016‐83), (i) do not account for the height of injection of volcanic SO urn:x-wiley:jgrd:media:jgrd55987:jgrd55987-math-0001; (ii) prescribe a vertical structure for the forcing; and (iii) are often calibrated against a single eruption. We present a new idealized model, EVA_H, that addresses these limitations. Compared to EVA, EVA_H makes predictions of the global mean stratospheric aerosol optical depth that are (i) similar for the 1979–1998 period characterized by the large and high‐altitude tropical SO urn:x-wiley:jgrd:media:jgrd55987:jgrd55987-math-0002 injections of El Chichón (1982) and Mount Pinatubo (1991); (ii) significantly improved for the 1998–2015 period characterized by smaller eruptions with a large variety of injection latitudes and heights. Compared to EVA, the sensitivity of volcanic forcing to injection latitude and height in EVA_H is much more consistent with results from climate models that include interactive aerosol chemistry and microphysics, even though EVA_H remains less sensitive to eruption latitude than the latter models. We apply EVA_H to investigate potential biases and uncertainties in EVA‐based volcanic forcing data sets from phase 6 of the Coupled Model Intercomparison Project (CMIP6). EVA and EVA_H forcing reconstructions do not significantly differ for tropical high‐altitude volcanic injections. However, for high‐latitude or low‐altitude injections, our reconstructed forcing is significantly lower. This suggests that volcanic forcing in CMIP6 last millenium experiments may be overestimated for such eruptions.

Description: The methane oxidation potential of active layer profiles of permafrost soils from the Lena Delta, Siberia, was studied with regard to its respond to temperature, and abundance and distribution of type I and type II methanotrophs. Our results indicate vertical shifts within the optimal methane oxidation temperature and within the distribution of type I and type II methanotrophs. In the upper active layer, maximum methane oxidation potentials were detected at 21°C. Deep active layer zones that are constantly exposed to temperatures below 2°C showed a maximum potential to oxidize methane at 4°C. Our results indicate a dominance of psychrophilic methanotrophs close to the permafrost table. Type I methanotrophs dominated throughout the active layer profiles but their number strongly fluctuated with depth. In contrast, type II methanotrophs were constantly abundant through the whole active layer and displaced type I methanotrophs close to the permafrost table. No correlation between in situ temperatures and the distribution of type I and type II methanotrophs was found. However, the distribution of type I and type II methanotrophs correlated significantly with in situ methane concentrations. Beside vertical fluctuations, the abundance of methane oxidizers also fluctuated according to different geomorphic units. Similar methanotroph cell counts were detected in samples of a flood plain and a polygon rim, whereas cell counts in samples of a polygon centre were up to 100 times lower.

Description: Three volcanic arcs have been the source of New Zealand's volcanic activity since the Neogene: Northland arc, Coromandel Volcanic Zone (CVZ) and Taupō Volcanic Zone (TVZ). The eruption chronology for the Quaternary, sourced by the TVZ, is well studied and established, whereas the volcanic evolution of the precursor arc systems, like the CVZ (central activity c. 18 to 2 Ma), is poorly known due to limited accessibility to, or identification of, onshore volcanic deposits and their sources. Here, we investigate the marine tephra record of the Neogene, mostly sourced by the CVZ, of cores from IODP Exp. 375 (Sites U1520 and U1526), ODP Leg 181 (Sites 1123, 1124 and 1125), IODP Leg 329 (Site U1371) and DSDP Leg 90 (Site 594) offshore of New Zealand. In total, we identify 306 primary tephra layers in the marine sediments. Multi-approach age models (e.g. biostratigraphy, zircon ages) are used in combination with geochemical fingerprinting (major and trace element compositions) and the stratigraphic context of each marine tephra layer to establish 168 tie-lines between marine tephra layers from different holes and sites. Following this approach, we identify 208 explosive volcanic events in the Neogene between c. 17.5 and 2.6 Ma. This is the first comprehensive study of New Zealand's Neogene explosive volcanism established from tephrochronostratigraphic studies, which reveals continuous volcanic activity between c. 12 and 2.6 Ma with an abrupt compositional change at c. 4.5 Ma, potentially associated with the transition from CVZ to TVZ. Key Points New Zealand's Neogene explosive volcanism based on the marine tephra record Geochemical fingerprinting of marine tephra layers across the study area to establish volcanic events Insights into geochemical variations with time, repose times and spatiotemporal distribution

Description: Submarine groundwater discharge (SGD) is a globally important process supplying nutrients and trace elements to the coastal environment, thus playing a pivotal role in sustaining marine primary productivity. Along with nutrients, groundwater also contains allochthonous microbes that are discharged from the terrestrial subsurface into the sea. Currently, little is known about the interactions between groundwater‐borne and coastal seawater microbial populations, and groundwater microbes' role upon introduction to coastal seawater populations. Here, we investigated seawater microbial abundance, activity and diversity in a site strongly influenced by SGD. In addition, through laboratory‐controlled bottle incubations, we mimicked different mixing scenarios between groundwater and seawater. Our results demonstrate that the addition of 0.1 μm filtered groundwater stimulated heterotrophic activity and increased microbial abundance compared to control coastal seawater, whereas 0.22 μm filtration treatments induced primary productivity and Synechococcus growth. 16S rRNA gene sequencing showed a strong shift from a SAR11‐rich community in the control samples to Rhodobacteraceae dominance in the 〈0.1 μm treatment, in agreement with Rhodobacteraceae enrichment in the SGD field site. These results suggest that microbes delivered by SGD may affect the abundance, activity and diversity of intrinsic microbes in coastal seawater, highlighting the cryptic interplay between groundwater and seawater microbes in coastal environments, which has important implications for carbon cycling. Plain Language Summary Submarine groundwater discharge (SGD) is an important process where groundwater flows into the ocean along the coast. When the groundwater mixes with seawater, the microbes from both sources interact with each other, which can impact the diversity, activity, and amount of microbes in the coastal environment. Currently, little is known about how groundwater‐borne microbes affect marine microbial populations. Our research shows that when groundwater microbes are removed before mixing groundwater with seawater, the abundance and activity of certain microbes that consume organic matter significantly increase. Additionally, we noticed a significant difference in the types of microbes present between the sites where SGD occurs versus background (uninfluenced) coastal water, especially in terms of the microbes that consume organic matter. Overall, this study suggests that there is a connection between groundwater and seawater microbes, which can influence the delicate balance between organisms that produce carbon and those that consume it. This has important implications for how carbon cycles globally. Key Points Groundwater discharge into the coastal zone delivers both nutrients and allochthonous microbes Groundwater microbes interact with seawater populations, by which affecting the delicate autotroph‐heterotroph balance Subterranean microbial processes are key drivers of food webs, potentially affecting biogenic carbon fluxes in the ocean

Description: Key Points: - A new CHBr3 emission inventory based on natural and anthropogenic sources suggests that the latter account for 12%–28% of the global emissions - In the NH, new anthropogenic estimates increase known natural CHBr3 emissions by up to 70.5%, leading to higher atmospheric CHBr3 levels - At the NH extratropical tropopause, CHBr3 is enhanced by 0.9 ppt Br due to anthropogenic sources thus doubling natural CHBr3 abundances Bromoform (CHBr3) contributes to stratospheric ozone depletion but is not regulated under the Montreal Protocol due to its short lifetime and large natural sources. Here, we show that anthropogenic sources contribute significantly to the amount of CHBr3 transported into the Northern Hemisphere (NH) extratropical stratosphere. We present a new CHBr3 emission inventory comprised of natural and anthropogenic sources, with the latter estimated from ship ballast, power plant cooling and desalination plant brine water. Including anthropogenic sources in the new inventory increases CHBr3 emissions by up to 31.5% globally and 70.5% in the NH. In consequence, atmospheric CHBr3 is also significantly higher, especially over the NH extratropics during boreal winter. Here anthropogenic sources enhance bromine at the tropopause by 0.9 ppt Br, thus doubling natural CHBr3 abundances. For some latitudes, tropopause bromine increases by 2.4 ppt Br suggesting significant contributions of anthropogenic CHBr3 to the NH lowermost stratosphere.

Description: Foraging is a behavioural process and, therefore, individual behaviour and diet are theorized to covary. However, few comparisons of individual behaviour type and diet exist in the wild. We tested whether behaviour type and diet covary in a protected population of Atlantic cod, Gadus morhua. Working in a no-take marine reserve, we could collect data on natural behavioural variation and diet choice with minimal anthropogenic disturbance. We inferred behaviour using acoustic telemetry and diet from stable isotope compositions (expressed as δ13C and δ15N values). We further investigated whether behaviour and diet could have survival costs. We found cod with shorter diel vertical migration distances fed at higher trophic levels. Cod δ13C and δ15N values scaled positively with body size. Neither behaviour nor diet predicted survival, indicating phenotypic diversity is maintained without survival costs for cod in a protected ecosystem. The links between diet and diel vertical migration highlight that future work is needed to understand whether the shifts in this behaviour during environmental change (e.g. fishing or climate), could lead to trophic cascades.

Description: A site at the gas hydrate stability limit was investigated offshore northwestern Svalbard to study methane transport in sediment. The site was characterized by chemosynthetic communities (sulfur bacteria mats, tubeworms) and gas venting. Sediments were sampled with in‐situ porewater collectors and by gravity coring followed by analyses of porewater constituents, sediment and carbonate geochemistry, and microbial activity, taxonomy, and lipid biomarkers. Sulfide and alkalinity concentrations showed concentration maxima in near‐surface sediments at the bacterial mat and deeper maxima at the gas vent site. Sediments at the periphery of the chemosynthetic field were characterized by two sulfate‐methane transition zones (SMTZ) at ~204 and 45 cm depth, where activity maxima of microbial anaerobic oxidation of methane (AOM) with sulfate were found. Amplicon sequencing and lipid biomarker indicate that AOM at the SMTZs was mediated by ANME‐1 archaea. A 1D numerical transport reaction model suggests that the deeper SMTZ‐1 formed on centennial scale by vertical advection of methane, while the shallower SMTZ‐2 could only be reproduced by non‐vertical methane injections starting on decadal scale. Model results were supported by age distribution of authigenic carbonates, showing youngest carbonates within SMTZ‐2. We propose that non‐vertical methane injection was induced by increasing blockage of vertical transport or formation of sediment fractures. Our study further suggests that the methanotrophic response to the non‐vertical methane injection was commensurate with new methane supply. This finding provides new information about for the response time and efficiency of the benthic methane filter in environments with fluctuating methane transport.

Description: In recent decades, the increase in terrestrial inputs to freshwater and coastal ecosystems, especially occurring at northern latitudes, has led to a process of water color darkening known as “brownification.” To assess how brownification affects plankton community composition and functioning in northern coastal areas, an in situ mesocosm experiment using a highly colored humic substance to simulate a brownification event was performed in a North Atlantic bay (Hopavågen, Norway) in August 2019. Manual sampling for analyses of nutrient concentrations, phytoplankton pigments and zooplankton abundances was combined with high-frequency (every 15 min) monitoring of key environmental variables to investigate the response of the plankton community in terms of oxygen metabolism and community composition. In response to brownification, the oxygen gross primary production (GPP) and community respiration (R) slowed down significantly, by almost one-third. However, GPP and R both decreased to the same extent; thus, the oxygen metabolic balance was not affected. Moreover, the chlorophyll-a concentration significantly decreased under brownification, by 9% on average, and the chemotaxonomic pigment composition of the phytoplankton changed, indicating their acclimation to the reduced light availability. In addition, brownification seemed to favor appendicularians, the dominant mesozooplankton group in the mesocosms, which potentially contributed to lowering the phytoplankton biomass. In conclusion, the results of this in situ mesocosm experiment suggest that brownification could induce significant changes in phytoplankton and zooplankton community composition and significantly alter the overall oxygen metabolism of plankton communities in a northern Atlantic bay.

Description: Direct dimethyl sulfide (DMS) flux measurements using eddy covariance have shown a suppression of gas transfer at medium to high wind speed. However, not all eddy covariance measurements show evidence of this suppression. Processes, such as wave-wind interaction and surfactants, have been postulated to cause this suppression. We measured DMS and carbon dioxide eddy covariance fluxes during the Asian summer monsoon in the western tropical Indian Ocean (July and August 2014). Both fluxes and their respective gas transfer velocities show signs of a gas transfer suppression above 10 m/s. Using a wind-wave interaction, we describe a flow separation process that could be responsible for a suppression of gas transfer. As a result we provide a Reynolds number-based parameterization, which states the likelihood of a gas transfer suppression for this cruise and previously published gas transfer data. Additionally, we compute the difference in the gas transfer velocities of DMS and CO2 to estimate the bubble-mediated gas transfer using a hybrid model with three whitecap parameterizations.

Description: Oceanic dimethyl sulfide (DMS) is of interest due to its critical influence on atmospheric sulfur compounds in the marine atmosphere and its hypothesized significant role in global climate. High-resolution shipboard underway measurements of surface seawater DMS and the partial pressure of carbon dioxide (pCO2) were conducted in the Atlantic Ocean and Indian Ocean sectors of the Southern Ocean (SO), the southeast Indian Ocean, and the northwest Pacific Ocean from February to April 2014 during the 30th Chinese Antarctic Research Expedition. The SO, particularly in the region south of 58°S, had the highest mean surface seawater DMS concentration of 4.1 ± 8.3 nM (ranged from 0.1 to 73.2 nM) and lowest mean seawater pCO2 level of 337 ± 50 μatm (ranged from 221 to 411 μatm) over the entire cruise. Significant variations of surface seawater DMS and pCO2 in the seasonal ice zone (SIZ) of SO were observed, which are mainly controlled by biological process and sea ice activity. We found a significant negative relationship between DMS and pCO2 in the SO SIZ using 0.1° resolution, [DMS] seawater = -0.160 [pCO2] seawater + 61.3 (r2 = 0.594, n = 924, p 〈 0.001). We anticipate that the relationship may possibly be utilized to reconstruct the surface seawater DMS climatology in the SO SIZ. Further studies are necessary to improve the universality of this approach. Key Points: • The characteristics of surface water DMS and pCO2 distributions from the Southern Ocean to northwest Pacific Ocean are investigated • The correlations between DMS, pCO2, and environmental parameters are analyzed • Anticorrelation between DMS and pCO2 is found in the seasonal ice zone of the Southern Ocean

Description: [1]  Monthly zonal mean climatologies of atmospheric measurements from satellite instruments can have biases due to the non-uniform sampling of the atmosphere by the instruments. We characterize potential sampling biases in stratospheric trace gas climatologies of the Stratospheric Processes and their Role in Climate (SPARC) Data Initiative using chemical fields from a chemistry climate model simulation and sampling patterns from 16 satellite-borne instruments. The exercise is performed for the long-lived stratospheric trace gases O 3 and H 2 O. Monthly sample biases for O 3 exceed 10% for many instruments in the high latitude stratosphere and in the upper troposphere/lower stratosphere, while annual mean sampling biases reach values of up to 20% in the same regions for some instruments. Sampling biases for H 2 O are generally smaller than for O 3 , although still notable in the upper troposphere/lower stratosphere and Southern Hemisphere high latitudes. The most important mechanism leading to monthly sampling bias is the non-uniform temporal sampling of many instruments, i.e., the fact that for many instruments, monthly means are produced from measurements which span less than the full month in question. Similarly, annual mean sampling biases are well explained by non-uniformity in the month-to-month sampling by different instruments. Non-uniform sampling in latitude and longitude are shown to also lead to non-negligible sampling biases, which are most relevant for climatologies which are otherwise free of sampling biases due to non-uniform temporal sampling.

Description: Monthly zonal mean climatologies of atmospheric measurements from satellite instruments can have biases due to the non-uniform sampling of the atmosphere by the instruments. We characterize potential sampling biases in stratospheric trace gas climatologies of the Stratospheric Processes and their Role in Climate (SPARC) Data Initiative using chemical fields from a chemistry climate model simulation and sampling patterns from 16 satellite-borne instruments. The exercise is performed for the long-lived stratospheric trace gases O3 and H2O. Monthly sample biases for O3 exceed 10% for many instruments in the high latitude stratosphere and in the upper troposphere/lower stratosphere, while annual mean sampling biases reach values of up to 20% in the same regions for some instruments. Sampling biases for H2O are generally smaller than for O3, although still notable in the upper troposphere/lower stratosphere and Southern Hemisphere high latitudes. The most important mechanism leading to monthly sampling bias is the non-uniform temporal sampling of many instruments, i.e., the fact that for many instruments, monthly means are produced from measurements which span less than the full month in question. Similarly, annual mean sampling biases are well explained by non-uniformity in the month-to-month sampling by different instruments. Non-uniform sampling in latitude and longitude are shown to also lead to non-negligible sampling biases, which are most relevant for climatologies which are otherwise free of sampling biases due to non-uniform temporal sampling.

Description: Rapid evolution of non-native species can facilitate invasion success, but recent reviews indicate that such microevolution rarely yields expansion of the climatic niche in the introduced habitats. However, because some invasions originate from a geographically restricted portion of the native species range and its climatic niche, it is possible that the frequency, direction and magnitude of phenotypic evolution during invasion has been underestimated. We explored the utility of niche-shift analyses in the red seaweed Gracilaria vermiculophylla, which expanded its range from the northeastern coastline of Japan to North America, Europe and northwestern Africa within the last 100 years. A genetically-informed climatic niche shift analysis indicates that native source populations occur in colder and highly seasonal habitats, while most non-native populations typically occur in warmer, less seasonal habitats. This climatic niche expansion predicts that non-native populations evolved greater tolerance for elevated heat conditions relative to native source populations. We assayed 935 field-collected and 325 common-garden thalli from 40 locations and as predicted, non-native populations had greater tolerance for ecologically-relevant extreme heat (40°C) than did Japanese source populations. Non-native populations also had greater tolerance for cold and low-salinity stresses relative to source populations. The importance of local adaptation to warm temperatures during invasion was reinforced by evolution of parallel clines: populations from warmer, lower-latitude estuaries had greater heat tolerance than did populations from colder, higher-latitude estuaries in both Japan and eastern North America. We conclude that rapid evolution plays an important role in facilitating the invasion success of this and perhaps other non-native marine species. Genetically-informed ecological niche analyses readily generate clear predictions of phenotypic shifts during invasions, and may help to resolve debate over the frequency of niche conservatism versus rapid adaptation during invasion.

Description: Submarine groundwater discharge (SGD) into coastal areas is a common global phenomenon and is rapidly gaining scientific interest due to its influence on marine ecology, the coastal sedimentary environment and its potential as a future freshwater resource. We conducted an integrated study of hydroacoustic surveys combined with geochemical porewater and water column investigations at a well‐known groundwater seep site in Eckernförde Bay (Germany). We aim to better constrain the effects of shallow gas and SGD on high frequency multibeam backscatter data and to present acoustic indications for submarine groundwater discharge. Our high‐quality hydroacoustic data reveal hitherto unknown internal structures within the pockmarks in Eckernförde Bay. Using precisely positioned sediment core samples, our hydroacoustic‐geochemical approach can differentiate intra‐pockmark regimes that were formerly assigned to pockmarks of a different nature. We demonstrate that high‐frequency multibeam data, in particular the backscatter signals, can be used to detect shallow free gas in areas of enhanced groundwater advection in muddy sediments. Intriguingly, our data reveal relatively small (typically 〈15 m across) pockmarks within the much larger, previously mapped, pockmarks. The small pockmarks, which we refer to as “intra‐pockmarks”, have formed due to the localized ascent of gas and groundwater; they manifest themselves as a new type of ‘eyed’ pockmarks, revealed by their acoustic backscatter pattern. Our data suggest that, in organic‐rich muddy sediments, morphological lows combined with a strong multibeam backscatter signal can be indicative of free shallow gas and subsequent advective groundwater flow.

Description: Males and females follow distinct life-history strategies that have co-evolved with several sex-specific traits. Higher investment into parental investment (PI) demands an increased lifespan. Thus, resource allocation toward an efficient immune system is mandatory. In contrast, resources allocated toward secondary sexual signals (ornamentation) may negatively correlate with investment into immunity and ultimately result in a shorter lifespan. Previous studies have addressed how resource allocation toward single sex-specific traits impacts lifetime reproductive success (LRS). However, the trade-offs between diverse sex-specific characteristics and their impact on LRS remain largely unassessed impeding our understanding of life-history evolution. We have designed a theoretical framework (informed by experimental data and evolutionary genetics) that explores the effects of multiple sex-specific traits and assessed how they influence LRS. From the individual sex-specific traits, we inferred the consequences at the population level by evaluating adult sex ratios (ASR). Our theory implies that sex-specific resource allocation toward the assessed traits resulted in a biased ASR. Our model focuses on the impact of PI, ornamentation, and immunity as causal to biased ASR. The framework developed herein can be employed to understand the combined impact of diverse sex-specific traits on the LRS and the eventual population dynamics of particular model systems.

Description: The Los Chocoyos (14.6°N, 91.2°W) supereruption happened ∼75,000 years ago in Guatemala and was one of the largest eruptions of the past 100,000 years. It emitted enormous amounts of sulfur, chlorine, and bromine, with multi‐decadal consequences for the global climate and environment. Here, we simulate the impact of a Los Chocoyos‐like eruption on the quasi‐biennial oscillation (QBO), an oscillation of zonal winds in the tropical stratosphere, with a comprehensive aerosol chemistry Earth System Model. We find a ∼10‐year disruption of the QBO starting 4 months post eruption, with anomalous easterly winds lasting ∼5 years, followed by westerlies, before returning to QBO conditions with a slightly prolonged periodicity. Volcanic aerosol heating and ozone depletion cooling leads to the QBO disruption and anomalous wind regimes through radiative changes and wave‐mean flow interactions. Different model ensembles, volcanic forcing scenarios and results of a second model back up the robustness of our results.

Description: We show that inflows of oxygenated waters into sulfidic layers have a strong impact on biogeochemical transformation at oxic/anoxic transition zones. Taking the pelagic methane dynamics in the Gotland Basin as an example, we performed our studies when one of the largest inflows ever recorded entered the Baltic Sea in March 2015. An inflowing gravity current transported oxic waters into the sulfidic deep layers and freshly generated a near-bottom secondary redox interface. At the upper slope, where the inflowing water masses were vigorously turbulent and the main and secondary redox interfaces in close contact to each other, methane oxidation rates inside the transition zone were found to be higher compared to the weakly turbulent basin interior. At the main redox interface in the basin center, lateral intrusions of oxygenated waters into intermediate water depth may have stimulated the growth of the methanotrophic community and their activity.

Description: Clonal reproduction, the formation of nearly identical individuals via mitosis in the absence of genetic recombination, is a very common reproductive mode across plants, fungi and animals. To detect clonal genetic structure, genetic similarity indices based on shared alleles are widely used, such as the Jaccard index, or identity by state. Here we propose a new pairwise genetic similarity index, the SH index, based on segregating genetic marker loci (typically single nucleotide polymorphisms) that are identically heterozygous for pairs of samples (NSH). To test our method, we analyse two old seagrass clones (Posidonia australis, estimated to be around 8500 years old; Zostera marina, 〉750 years old) along with two young Z. marina clones of known age (17 years old). We show that focusing on shared heterozygosity amplifies the power to distinguish sample pairs belonging to different clones compared to methods focusing on all shared alleles. Our proposed workflow can successfully detect clonemates at a location dominated by a single clone. When the collected samples involve two or more clones, the SH index shows a clear gap between clonemate pairs and interclone sample pairs. Ideally NSH should be on the order of approximately ≥3000, a number easily achievable via restriction-site associated DNA (RAD) sequencing or whole-genome resequencing. Another potential application of the SH index is to detect possible parent–descendant pairs under selfing. Our proposed workflow takes advantage of the availability of the larger number of genetic markers in the genomic era, and improves the ability to distinguish clonemates from nonclonemates in multicellular diploid clonal species.

Description: Dinoflagellates are a diverse group of eukaryotic microbes that are ubiquitous in aquatic environments. Largely photosynthetic, they encompass symbiotic, parasitic, and free-living lineages with a broad spectrum of trophism. Many free-living taxa can produce bioactive secondary metabolites such as biotox- ins, some of which cause harmful algal blooms. In contrast, most symbiotic species are crucial for sustaining coral reef health. The year 2023 marked a decade since the first genome data of dinoflagellates became available. The growing genome-scale resources for these taxa are highlighting their remarkable evolutionary and genomic complexities. Here, we discuss the prospect of developing dinoflagellate models using the criteria of accessibil- ity, tractability, resources, research support, and promise. Moving forward in the post-genomic era, we argue for the development of fit-to-purpose models that tailor to specific biological contexts, and that a one-size-fits-all model is inadequate for encapsulating the complex biology, ecology, and evolutionary history of dinoflagellates.

Description: NOAA 20th century and ERA-20C reanalysis datasets are evaluated regarding the representation of extra-tropical cyclones and windstorms over the Northern and Southern Hemisphere during the respective 6-month winter seasons. The results indicate substantial differences in low-frequency variability between the two datasets – especially in the first half of the 20th century – expressed in different signs and/or magnitudes of long-term trends. This is hampering a reliable analysis of real long-term trends of cyclone and windstorm activity. However, higher-frequency variability is in good agreement between both datasets especially for the Northern Hemisphere.

Description: Genetic divergence among populations arises through natural selection or drift and is counteracted by connectivity and gene flow. In sympatric populations, isolating mechanisms are thus needed to limit the homogenizing effects of gene flow to allow for adaptation and speciation. Chromosomal inversions act as an important mechanism maintaining isolating barriers, yet their role in sympatric populations and divergence with gene flow is not entirely understood. Here, we revisit the question of whether inversions play a role in the divergence of connected populations of the marine fish Atlantic cod (Gadus morhua), by exploring a unique data set combining whole-genome sequencing data and behavioural data obtained with acoustic telemetry. Within a confined fjord environment, we find three genetically differentiated Atlantic cod types belonging to the oceanic North Sea population, the western Baltic population and a local fjord-type cod. Continuous behavioural tracking over 4 year revealed temporally stable sympatry of these types within the fjord. Despite overall weak genetic differentiation consistent with high levels of gene flow, we detected significant frequency shifts of three previously identified inversions, indicating an adaptive barrier to gene flow. In addition, behavioural data indicated that North Sea cod and individuals homozygous for the LG12 inversion had lower fitness in the fjord environment. However, North Sea and fjord-type cod also occupy different depths, possibly contributing to prezygotic reproductive isolation and representing a behavioural barrier to gene flow. Our results provide the first insights into a complex interplay of genomic and behavioural isolating barriers in Atlantic cod and establish a new model system towards an understanding of the role of genomic structural variants in adaptation and diversification.

Description: Mesoscale eddies are frequently observed in the Eastern Tropical North Atlantic (ETNA), yet their effects on the transport and distribution of biogeochemical solutes, and specifically on the production and remineralization of dissolved organic matter (DOM) remain difficult to elucidate. Here, we investigated the submesoscale variability of chromophoric DOM (CDOM) and fluorescent DOM (FDOM) together with microbial production and remineralization processes in two cyclonic eddies (CEs) in the ETNA during summer and winter 2019. One CE, formed near the coast off Mauritania during the post-upwelling season, was sampled along a ∼900 km zonal corridor between Mauritania and the Cape Verde Islands. The other CE, formed nearby Brava Island, was out of coastal influence. Four fluorescent components were identified with parallel factor analysis, two humic-like, and two protein-like components. Humic-like FDOM components correlated to optode-based community respiration and were also good indicators of upwelling associated with the Brava Island CE as they correlated to physical parameters (e.g., temperature) and to dissolved inorganic nitrogen. The tryptophan-like FDOM components correlated with the carbon and nitrogen content of semi-labile DOM, phytoplankton biomass, community respiration, and bacterial production. Overall, our study revealed that DOM optical properties are suitable for tracing freshly produced organic matter and the transport of remineralized DOM within offshore eddies. Key Points: - Four fluorescent dissolved organic matter (FDOM) components were studied in two cyclonic eddies (CEs) in the Eastern Tropical North Atlantic - Tryptophan-like FDOM was an indicator of the CEs' productivity as it correlated with semi-labile dissolved organic matter and microbial metabolic activities - Humic-like FDOM was a by-product of microbial respiration; its distribution within an offshore CE covaried with nutrient upwelling

Description: The phase and mixing state of atmospheric aerosols is a central determinant of their properties and, thus, their role in atmospheric cycling and climate. Particularly, the hygroscopic response of aerosol particles to relative humidity (RH) variation is a key aspect of their atmospheric life cycle and impacts. Here, we applied X-ray microspectroscopy under variable RH conditions to internally mixed aerosol particles from the Amazonian rainforest collected during periods with anthropogenic pollution. Upon hydration, we observed substantial and reproducible changes in particle microstructure, which appear as mainly driven by efflorescence and recrystallization of sulfate salts. Multiple solid and liquid phases were found to coexist, especially in intermediate humidity regimes. We show that X-ray microspectroscopy under variable RH is a valuable technique to analyze the hygroscopic response of individual ambient aerosol particles. Our initial results underline that RH changes can trigger strong particle restructuring, in agreement with previous studies on artificial aerosols.

Description: Physical removal (e.g., harvest via traps or nets) of mature individuals may be a cost-effective or socially-acceptable alternative to chemical control strategies for invasive species, but requires knowledge of the spatial distribution of a population over time. We used acoustic telemetry to determine the current and possible future role of traps to control and assess invasive sea lampreys, Petromyzon marinus , in the St. Marys River, the connecting channel between Lake Superior and Lake Huron. Exploitation rates (i.e., fractions of an adult sea lamprey population removed by traps) at two upstream locations were compared among three years and two points of entry to the system. Telemetry receivers throughout the drainage allowed trap performance (exploitation rate) to be partitioned into two components: proportion of migrating sea lampreys that visited trap sites (availability) and proportion of available sea lampreys that were caught by traps (local trap efficiency). Estimated exploitation rates were well below those needed to provide population control in the absence of lampricides and were limited by availability and local trap efficiency. Local trap efficiency estimates for acoustic-tagged sea lampreys were lower than analogous estimates regularly obtained using traditional mark-recapture methods, suggesting that abundance had been previously under-estimated. Results suggested major changes would be required to substantially increase catch, including: improvements to existing traps, installation of new traps, or other modifications to attract and retain more sea lampreys. This case study also shows how bias associated with telemetry tags can be estimated and incorporated in models to improve inferences about parameters that are directly relevant to fishery management. This article is protected by copyright. All rights reserved.

Description: Air masses in the convective outflows of four large convective systems near Borneo Island in Malaysia were sampled in the height range 11–13 km within the frame of the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) FP7 European project in November and December 2011. Correlated enhancements of CO, CH4 and the short-lived halogen species (CH3I and CHBr3) were detected when the aircraft crossed the anvils of the four systems. These enhancements were interpreted as the fingerprint of vertical transport from the boundary layer by the convective updraft and then horizontal advection in the outflow. For the four observations, the fraction f of air from the boundary layer ranged between 15 and 67%, showing the variability in transport efficiency depending on the dynamics of the convective system.

Description: Range expansions can lead to increased contact of divergent populations, thus increasing the potential of hybridization events. Whether viable hybrids are produced will most likely depend on the level of genomic divergence and associated genomic incompatibilities between the different entities as well as environmental conditions. By taking advantage of historical Baltic cod (Gadus morhua) otolith samples combined with genotyping and whole genome sequencing, we here investigate the genetic impact of the increased spawning stock biomass of the eastern Baltic cod stock in the mid 1980s. The eastern Baltic cod is genetically highly differentiated from the adjacent western Baltic cod and locally adapted to the brackish environmental conditions in the deeper Eastern basins of the Baltic Sea unsuitable for its marine counterparts. Our genotyping results show an increased proportion of eastern Baltic cod in western Baltic areas (Mecklenburg Bay and Arkona Basin)—indicative of a range expansion westwards—during the peak population abundance in the 1980s. Additionally, we detect high frequencies of potential hybrids (including F1, F2 and backcrosses), verified by whole genome sequencing data for a subset of individuals. Analysis of mitochondrial genomes further indicates directional gene flow from eastern Baltic cod males to western Baltic cod females. Our findings unravel that increased overlap in distribution can promote hybridization between highly divergent populations and that the hybrids can be viable and survive under specific and favourable environmental conditions. However, the observed hybridization had seemingly no long-lasting impact on the continuous separation and genetic differentiation between the unique Baltic cod stocks.

Description: Within the Jeddah Transect Project, a multidisciplinary marine sampling program has been performed on RV Poseidon (P408 cruise) offshore Saudi-Arabia (Red Sea). The sampling program involved three projects (http://www.ifm-geomar.de/index.php?id=jeddahtransectdisc&L=1), covering aspects of marine petrology, biogeochemistry, oceanography and biology.

Description: The DRIVE (Diurnal and RegIonal Variability of Halogen Emissions) campaign to the eastern tropical North Atlantic Ocean and the upwelling off Mauritania (NW Africa) was funded by the BMBF as part of the German SOLAS project SOPRAN II (Surface Ocean Processes in the Anthropocene; www.sopran.pangaea.de): The second leg of the 399th cruise of R/V Poseidon (P399/2) took place from 31 May to 17 June 2010 (Las Palmas-Mindelo (Cape Verde Islands) – Mauritanian upwelling – Las Palmas). It was followed by the transit leg 3 (P399/3) which took place from 18 June to 24 June 2010 (Las Palmas – Vigo (Spain)) with only one stop at ESTOC. Ten scientists from IFM-GEOMAR (Kiel), IfAM (U Kiel), IfBM (U Hamburg) and IUP (U Heidelberg) representing various SOPRAN II subprojects took part in the cruise which was the sixth of a series of German SOLAS cruises to the tropical North Atlantic Ocean. The major objective of P399/2 was to investigate the regional and diurnal atmospheric and oceanic variations of halogenated compounds in the eastern tropical North Atlantic Ocean with a special focus on the Mauritanian upwelling. The main working packages of P399/2 and P399/3 included measurements of - Atmospheric BrO and IO - Atmospheric halocarbons - Other atmospheric trace gases such as ozone, methane etc. - Aerosol composition - Vertical structure of the atmosphere - Dissolved halocarbons, nitrous oxide and carbon dioxide - CTD, dissolved nutrients, O2, and chlorophyll - Microstructure of the upper water column Besides an extensive underway measurement program of dissolved (halocarbons, N2O, CO2) and atmospheric (BrO, halocarbons, other trace gases, aerosol) compounds, six 24h stations were performed and 23 regular CTD stations with depth profiles covering the entire water column were occupied.

Description: The evolution from the Western Mediterranean Sea is inherently governed by (i) plate convergence between Nubia (Africa) / Eurasia and (ii) subduction related slab-roll back. Both processes are responsible for the surface features / topography of the Gulf of Cadiz / Gibraltar Arc / Alboran Sea / Rif / Betic domain and deep-seated features related to the consumption of African lithosphere. The project is part of the ESF-EUROCORES programme TOPO-EUROPE and is aiming to study the interrelation between convergence and major tectonic fault zones in the Gulf of Cadiz and the Alboran Sea (Trans-Alboran- Shear-Zone – Alboran Ridge) and Miocene subduction / deep-seated seismicity at 40-150 km depth. Monitoring networks with ocean bottom seismometers (OBS) and hydrophones (OBH) were installed first in the Alboran Sea (August 2009 to January 2010) and later in the Gulf of Cadiz (January 2010 to July 2010), providing for the first time local earthquake data collected on ocean bottom stations. First results suggest that the collected data are of every good quality to assess seismotectonics in both domains and yielding travel time data for unique tomographic images of the Gibraltar arc area and Alboran domain, providing seismic constraints on the structure of crust and mantle.

Description: The cooperative research project between Chinese and German leading marine research institutions, the Guangzhou Marine Geological Survey (GMGS) and Leibniz-Institut für Meereswissenschaften Kiel (IFM-GEOMAR) addressed the geological methane budget and environmental effects of methane emissions from gas hydrates along the passive margin of the northern South China Sea. Two areas were surveyed of which the NE area (A) was sampled in great detail, whereas area B, after an initial survey, yielded less promising results. Swath map bathymetry, ocean floor observation by continuous video survey (OFOS) and water column methane distribution pattern provided the basis for locating several sites of ongoing methane venting. Outstanding among these was a methane-derived carbonate structure in water depths of 600-900m. Vast accumulations of vent carbonate debris, pavements and edifices standing above the seafloor characterize this structure. A 30-m high edifice, named Jiu Long Methane Reef, proved to be an active cold vent site with chemosynthetic fauna and bacterial mats. At deep sites ( apprx. 3000m) in and adjacent to the Formosa Canyon methane anomalies in the bottom water and clam colonies also indicate active methane venting. Pore water and gas chemistry on gravity cores indicated rather shallow depths of the sulfate-methane-interface (SMI) and documented chloride anomalies. High methane concentrations (exceeding 10.000 μM) in sediments, which when extrapolated, suggest that saturation might be reached at about 16-24 mbsf at which depths the shallowest gas hydrates might be encountered in the area. The project results contribute directly to several major science policy missions. (1) Documentation of vast amounts of methane emmited from the passive margin of the northern South China Sea is seen as evidence for long-term climate forcing by the greenhouse gas methane. (2) The functioning and significance of deep-sea biota as modulating the greenhouse gas budget is convincingly demonstrated by the vast amounts of methane carbon fixed as authigenic carbonates. (3) Further development of TV-guided deep-sea instrumentation, and above all the retrieval of undecompressed sediments, have again been deomonstrated as high a priority topic for the future of marine science. (4) The success of the project has demonstrated how international partnerships can efficiently been implemented.

Description: RV Sonne cruise 206 started on the 31st of May in Caldera (Costa Rica) and ended there on the 18th of June 2010. An international group of 23 scientists and 2 guests from Costa Rica set out to perform geophysical, biogeochemical, and sedimentological investigations at and around a number of submarine cold seeps that are ubiquitous along this convergent continental margin. The cruise was predominantly conducted as a pre-site survey for IODP (proposal 633Full-2; Costa Rica Mounds) in order to fill existing gaps in the seismic record at two of the proposed drill locations. A 2D seismic survey was conducted running over the large-scale seamount subduction slide “Jaco Scarp” yielding a highly improved image of the structural pattern within the upper 1000 m of the sedimentary sequence. In addition, high-resolution 3D seismic data, roughly covering the uppermost 300 m, could be obtained in the Mound 11/12 area, which will allow for a detailed analysis of the internal structure of these mud volcano-like features and help to understand the complex relation to the upward directed material flow. Moreover, a total number of 36 sediment cores (TV-guided multicorer, gravity corer) were successfully retrieved from active cold seeps and submarine slides and a large number of sub-samples were taken for subsequent geochemical and microbiological analyses. Overall, all major tasks of this cruise could successfully be fulfilled and the results will help to further our understanding of mechanisms controlling fluid flow in the deep subsurface of active continental margins.

Description: The research project SO208 PLUMEFLUX (Propagation of Galápagos Plume Material in the Equatorial East Pacific) is funded by the German Ministry of Education and Research (BMBF) and focusses on seamounts on the Cocos Plate, formed at the East Pacific Rise but presently located off the coast of NW Costa Rica and Nicaragua (Leg 1), and on the Cocos-Nazca-Spreading Center(CNS; Leg 2). The studies conducted on cruise SO208 included multi-beam mapping, sediment echo sounding, hard rock sampling, as well as sedimentological and biological sampling. The major geological targets of Leg 1 were (1) to evaluate if the seamounts off northern Costa Rica and Nicaragua were formed by the Galápagos hotspot and thus to constrain the extent of influence by the Galápagos plume on the upper asthenosphere and lithosphere and (2) to constrain better the material input into the Central American subduction zone. Leg 2 aimed to sample profiles of the seafloor perpendicular to the CNS using the mobile drill Rockdrill 2 of the British Geological Survey, in order to reconstruct plume-ridge interaction in the past to complement morphological, petrological and geochemical studies carried out on previous cruises along the ridge axis (e.g. SO158). The integration of the results with existing data should contribute towards a better understanding of transport processes of plume material in the upper mantle and of the geodynamic evolution of the central East Pacific. The sedimentological studies carried out on both Legs of SO208 focussed on radiolarian assemblages. SO208 startet in Caldera/Costa Rica on July 15th, 2010, and ended in Guayaquil/Ecuador on August 29th, 2010. During Leg 1 nineteen seamounts on the Cocos Plate have been mapped and sampled. Within only 12 days at sea, a total of 41 stations(28 dredges, 2 TV grabs, and 11 multicorers) were carried out. Of these deployments, 23 recovered magmatic rocks, 15 volcaniclastics, and 13 Mn-Fe oxides. The samples comprise mainly pillow and sheet lavas, often with fresh glassy margins, and a wide spectrum of volcaniclastic rocks. Notably, we found several indications for explosive volcanic activity at water depths 〉 3,000 m. Due to a series of unfortunate circumstances beyond our control, the planned Rockdrill 2 deployment on Leg 2 had to be cancelled. Instead we mapped and collected samples via dredging from 60 localities along five profiles perpendicular to CNS. A total of 83 stations (76 dredges, 3 TVgrabs, and 4 multicorers) were carried out. Of these deployments, 59 recovered magmatic rocks, 3 volcaniclastics, 51 volcanic glass, and 6 Mn-Fe oxides, making this a successful cruise despite the Rockdrill problem. The first and most detailed profile (with 23 sampled localities) extended from the ridge axis to the north at ~92°W. The morphology shows alternating regions of abyssal ridges and valleys (possibly reflecting less plume input into the ridge) and thicker elevated bands commonly containing seamounts, some of which are tectonically deformed (possibly reflecting axial ridge type morphology and thus greater plume input into the ridge). The second profile was carried out at the shallowest part of the ridge axis, closest to the hotspot, just to the east of the 91° Transform Fault. The third profile extended 30 km north of the ridge (at ~89°30´W), where a formerly on-axis seamount has been split in half. We want to evaluate how far in the past the unique enriched geochemical anomaly associated with the seamount persisted in the past. Thirteen sites were successfully sampled along a fourth profile at 89°10’W, extending 35 km north and 35 km south of the CNS into crust up to 500,000 yrs old. This site was selected, because a major depleted geochemical anomaly exists at that location. A final short profile was carried out to the north and south and east (on the ridge axis) of a lava plateau at 88°20’W that represents an enriched anomaly along the ridge axis. The morphology of the area studied on Leg 2 strongly suggests that the intensity of interaction of the plume with the ridge has varied considerably over the last several hundred thousand years along the entire part of the ridge that we studied. Geochemical data should allow us to constrain better variations in plume-ridge interaction through time. Biological material was obtained successfully as macrofauna and as sediment samples containing meiofaunal organisms with the help of a geological chain bag dredge, sediment traps, a multicorer and a TV-grab. Macrofaunal organisms were recovered at 93 out of 124 stations, 37 stations revealed sediment samples. During the cruise, a total of 8,598 meiofaunal organisms were centrifuged out of about 45 kg of sediment and sorted to animal group. Foraminifera and Nematoda dominated the meiofauna, followed by Copepoda and at a lower abundance by Tardigrada, Kinorhyncha and Loricifera. We also discovered a highly diverse benthic macrofauna, mainly represented by Porifera, Bryozoa, Annelida, Brachiopoda and even a few monoplacophoran molluscs.

Description: Cruise SO210 with RV SONNE to the active continental margin off Chile was conducted by shiptime exchange with RV METEOR. Funds for mobilizing the research team were provided by the German Science Foundation (DFG) in conjunction with the Collaborative Research Centre (SFB) 574 of the University of Kiel. In the first years, the SFB 574 investigated the pathways and fluxes of volatiles through the erosive subduction zone off Central America. For comparison, the studies were extended to the accretionary margin off Central Chile. Cruise SO210 is the last cruise conducted in the framework of SFB 574 and based on investigations of previous SFB-cruises on the RVs VIDAL GORMAZ and JAMES COOK. The first leg of cruise SO210 was dedicated to long gravity coring for volcanic ash layers from the erruptive Southern Volcanic Zone (SVZ) of the Andes that were either deposited as fallouts onto the incoming Nazca Plate or transported down the slope and across the Chile Trench. Eight gravity cores of 12 m length were retrieved seaward of the Chile Channel on the outer rise of the Nazca Plate. The second goal for coring was the description and dating of previously mapped submarine landslides as well as retrieval of slide-related material for geo-technical experiments. As the deployment frame for long coring had to be removed on the second leg we continued coring for mass-wasting and geochemistry with short cores. Ten gravity cores of 3 or 6 m barrel length were retrieved upslope of slides, the glide plane and redeposited material downslope of the slide evacuation area. This sampling activity was supported by detailed acoustic surveys with Parasound and multibeam to remap critical areas for mass wasting in search for events, e.g. triggered by the recent Mw 8.8 Maule Earthquake, such as flanks of submarine canyons or previously detected submarine slides and to fill data gaps in the existing bathymetric data. The major activity of the entire cruise was dedicated to the search and detailed sampling of manifestations of fluid discharge activity on the Chilean forearc. A total of 11 deployments with the video sled OFOS and 12 dives by the ROV KIEL 6000 were conducted for ground-truthing of information which indicated possible seep activity and has been obtained during previous cruises to the Chilean forearc. In five working areas we found manifestations of fluid discharge. In these areas the survey was followed by an intense sampling of bottom water, sediments, carbonates, mega and meiofauna and the deployment of instrumentation on the seafloor. The goal of these deployments was to measure in situ seabed methane emission rates and associated fluxes of sulfide and major electron acceptors such as oxygen at seep sites along the Chilean margin and to understand its controls. This was accompanied by CTD casts to trace oxygen and the fate of methane discharge in the water column. Sediment cores obtained by multicorer or ROV were used for the geochemical characterization of the pore water and microbiological studies which include turnover rate measurements, molecular studies, flow through experiments and sampling of active sediments. Authigenic carbonates obtained by TV-Grab or ROV were sampled for fauna, biomarker studies and investigations to reconstruct the growth structures, calcification processes and fluid-pathway systematic. The sampling of sediments and carbonates recovered a unique fauna with 79 different taxa, several of them appear to be species new to science.

Description: Cruise SO-214 of R/V SONNE headed by IFM-GEOMAR served two legs of project NEMESYS, funded through the German Ministry of Education and Research (BMBF). Major partners of the project are Leibniz Institute of Marine Science (IFM-GEOMAR) and the Federal Institute of Geosciences and Natural Resources (BGR) Germany, as well as the Institute of Geological and Nuclear Sciences (GNS) and the Royal Netherlands Institute for Sea Research (NIOZ). NEMESYS aims to extend understanding and modelling of cold vents along the Hikurangi Margin (HM) off the east coast of the North Island of New Zealand. Since the first findings in the late 80´s several cruises have been dedicated to map and investigate the active seepage of Methane in this area. Results of these cruises headed by New Zealand and international scientists provided the database for the first joint German – New Zealand expedition SO-191 in 2007. During this cruise with R/V SONNE the HM was investigated within three legs comprising all marine geo-scientific disciplines. The major findings in geophysical, geological, geo-chemical, and biological research were published in a special issue by Marine Geology (Vol. 272, 2010). Nevertheless a lot of questions remained or were raised by the upcoming results. Still lateral continuation of feeder channels and a possible relation between internal structure, activity and tectonic regime of a seep site were not understood. The geological, geo-chemical and biological analysis has been related to the overall description and study of the seep sites along the margin. Detailed studies across a seep site and high-resolution sampling to study the internal variation of Methane production and the influences to chemistry and habitat have not been complete with the required intensity. These exemplary listed investigations together with an additional list of questions to seepage led to the follow-up project SO-214 NEMESYS, which was funded through the German Ministry of Education and Research (BMBF). Aim of the project NEMESYS is to confirm derived models of seep structures and to extend the existing database and knowledge by high-resolution sampling in all disciplines. Based on the findings of the SO-191 New Vents project Opouawe Bank and Omakere Ridge were identified as the areas with the highest interest for our additional studies. Opouawe Bank provides a high density of active seep sites with various expressions of feeder channels in seismic images. Omakere did provide the only seep sites that were found without feeder channels underneath. In between the Porangahau Ridge was selected as third target due to the indications of either gas or hydrate formation without active gas expulsion. Cruise SO-214 with R/V SONNE was split into two legs. The seismic part started on 09th March 2011 in the port of Wellington. Two 3D seismic cubes were acquired above active seep sites at Omakere and Opouawe Bank. A third cube at Porangahau Ridge could not be completed due to technical problems with the equipment and rough weather conditions. Intensive Parasound Profiling and extended 2D seismic with high resolution (up to 1.2 m migration grid) were undertaken. Many more feeder channels were identified than previously known from the SO-191 data, although not all of them terminate in a seafloor expression. The second leg left the port of Wellington on 6th April 2011 dedicated to intensive geological, geo-chemical and biological investigations. The major work was completed at Opouawe Bank. Based on images of the seismic data compilation North and South Tower seeps and seep site Takahe were chosen for the intensive sampling program. CTD and gravity cores were taken in dense spacing to investigate the local interaction of seepage and surrounding seafloor and water column. The water column showed limited stratification but seemed to be influenced from stormy weather. Biologic investigations showed limited variations compared with the SO-191 expedition, mainly in the distribution of fauna. The variety of amphipods seems to be a unique feature of the NZ seeps. The second leg suffered from bad weather conditions, which anticipated work during 100 hrs. out of scheduled 330 hrs. All meta data of the cruise are available through the IFM-GEOMAR Data Management Portal (https://portal.ifm-geomar.de/web/guest/home)

Description: We investigated the scaling and topology of engineered urban drainage networks (UDNs) in two cities, and further examined UDN evolution over decades. UDN scaling was analyzed using two power-law scaling characteristics widely employed for river networks: (1) Hack's law of length ( L )-area ( A ) [ L ∝ A h ], and (2) exceedance probability distribution of upstream contributing area ( δ ) [ P ( A  ≥ δ) ∼ aδ –ε ]. For the smallest UDNs (〈 2 km 2 ), length-area scales linearly ( h ∼ 1), but power-law scaling ( h ∼ 0.6) emerges as the UDNs grow. While P ( A  ≥ δ) plots for river networks are abruptly truncated, those for UDNs display exponential tempering [ P ( A  ≥ δ)= aδ –ε exp (- cδ )]. The tempering parameter c decreases as the UDNs grow, implying that the distribution evolves in time to resemble those for river networks. However, the power-law exponent ε for large UDNs tends to be greater than the range reported for river networks. Differences in generative processes and engineering design constraints contribute to observed differences in the evolution of UDNs and river networks, including subnet heterogeneity and non-random branching.

Description: Whereas fungal symbionts of terrestrial plants are among the most widespread and well-studied symbioses, relatively little is known about fungi that are associated with macroalgae. To fill the gap in marine fungal taxonomy, we combined simple culture methods with amplicon sequencing to characterize the fungal communities associated with three brown (Sargassum muticum, Pelvetia canaliculata, Himanthalia elongata) and two red (Mastocarpus stellatus, Chondrus crispus) macroalgae from one intertidal zone. In addition to characterizing novel fungal diversity, we tested three hypotheses: fungal diversity and community composition vary (i) among species distributed at different tidal heights, (ii) among tissue types (apices, mid-thallus, and stipe), and (iii) among ‘isomorphic’ C. crispus life cycle stages. Almost 70% of our reads were classified as Ascomycota, 29% as Basidiomycota, and 1% that could not be classified to phylum. Thirty fungal isolates were obtained, 18 of which were also detected with amplicon sequencing. Fungal communities differed by host and tissue type. Interestingly, P. canaliculata, a fucoid at the extreme high intertidal, did not show differences in fungal diversity across the thallus. As found in filamentous algal endophytes, fungal diversity varied among the three life cycle stages in C. crispus. Female gametophytes were also compositionally more dispersed as compared to the less variable tetrasporophytes and male gametophytes. We demonstrate the power of combining relatively simple cultivation and sequencing approaches to characterize and study macroalgal-fungal associations and highlight the need to understand the role of fungi in near-shore marine ecosystems.

Description: This study performed the first assessment of the volcanic gas output from the Central Volcanic Zone (CVZ) of northern Chile. We present the fluxes and compositions of volcanic gases (H2O, CO2, H2, HCl, HF, and HBr) from five of the most actively degassing volcanoes in this region—Láscar, Lastarria, Putana, Ollagüe, and San Pedro—obtained during field campaigns in 2012 and 2013. The inferred gas plume compositions for Láscar and Lastarria (CO2/Stot = 0.9–2.2; Stot/HCl = 1.4–3.4) are similar to those obtained in the Southern Volcanic Zone of Chile, suggesting uniform magmatic gas fingerprint throughout the Chilean arc. Combining these compositions with our own UV spectroscopy measurements of the SO2 output (summing to ~1800 t d−1 for the CVZ), we calculate a cumulative CO2 output of 1743–1988 t d−1 and a total volatiles output of 〉20,200 t d−1.

Description: Genetic data have great potential for improving fisheries management by identifying the fundamental management units—that is, the biological populations—and their mixing. However, so far, the number of practical cases of marine fisheries management using genetics has been limited. Here, we used Atlantic cod in the Baltic Sea to demonstrate the applicability of genetics to a complex management scenario involving mixing of two genetically divergent populations. Specifically, we addressed several assumptions used in the current assessment of the two populations. Through analysis of 483 single nucleotide polymorphisms (SNPs) distributed across the Atlantic cod genome, we confirmed that a model of mechanical mixing, rather than hybridization and introgression, best explained the pattern of genetic differentiation. Thus, the fishery is best monitored as a mixed-stock fishery. Next, we developed a targeted panel of 39 SNPs with high statistical power for identifying population of origin and analyzed more than 2,000 tissue samples collected between 2011 and 2015 as well as 260 otoliths collected in 2003/2004. These data provided high spatial resolution and allowed us to investigate geographical trends in mixing, to compare patterns for different life stages and to investigate temporal trends in mixing. We found similar geographical trends for the two time points represented by tissue and otolith samples and that a recently implemented geographical management separation of the two populations provided a relatively close match to their distributions. In contrast to the current assumption, we found that patterns of mixing differed between juveniles and adults, a signal likely linked to the different reproductive dynamics of the two populations. Collectively, our data confirm that genetics is an operational tool for complex fisheries management applications. We recommend focussing on developing population assessment models and fisheries management frameworks to capitalize fully on the additional information offered by genetically assisted fisheries monitoring.

Description: The identification of native sources and vectors of introduced species informs their ecological and evolutionary history and may guide policies that seek to prevent future introductions. Population genetics provides a powerful set of tools to identify origins and vectors. However, these tools can mislead when the native range is poorly sampled or few molecular markers are used. Here, we traced the introduction of the Asian seaweed Gracilaria vermiculophylla (Rhodophyta) into estuaries in coastal western North America, the eastern United States, Europe, and northwestern Africa by genotyping more than 2,500 thalli from 37 native and 53 non-native sites at mitochondrial cox1 and 10 nuclear microsatellite loci. Overall, greater than 90% of introduced thalli had a genetic signature similar to thalli sampled from the coastline of northeastern Japan, strongly indicating this region served as the principal source of the invasion. Notably, northeastern Japan exported the vast majority of the oyster Crassostrea gigas during the 20th century. The preponderance of evidence suggests G. vermiculophylla may have been inadvertently introduced with C. gigas shipments and that northeastern Japan is a common source region for estuarine invaders. Each invaded coastline reflected a complex mix of direct introductions from Japan and secondary introductions from other invaded coastlines. The spread of G. vermiculophylla along each coastline was likely facilitated by aquaculture, fishing, and boating activities. Our ability to document a source region was enabled by a robust sampling of locations and loci that previous studies lacked and strong phylogeographic structure along native coastlines.

Description: Communities are shaped by scale dependent processes. To study the diversity and variation of microbial communities across scales, the invasive and widespread seaweed Agarophyton vermiculophyllum presents a unique opportunity. We characterized pro‐ and eukaryotic communities associated with this holobiont across its known distribution range, which stretches over the northern hemisphere. Our data reveal that community composition and diversity in the holobiont vary at local but also larger geographic scales. While processes acting at the local scale (i.e., within population) are the main structuring drivers of associated microbial communities, changes in community composition also depend on processes acting at larger geographic scales. Interestingly, the largest analysed scale (i.e., native and non‐native ranges) explained variation in the prevalence of predicted functional groups, which could suggest a functional shift in microbiota occurred over the course of the invasion process. While high variability in microbiota at the local scale supports A. vermiculophyllum to be a generalist host, we also identified a number of core taxa. These geographically independent holobiont members imply that cointroduction of specific microbiota may have additionally promoted the invasion process.

Description: “Flip‐flop” detachment mode represents an endmember type of lithosphere‐scale faulting observed at almost amagmatic sections of ultraslow‐spreading mid‐ocean ridges. Recent numerical experiments using an imposed steady temperature structure show that an axial temperature maximum is essential to trigger flip‐flop faults by focusing flexural strain in the footwall of the active fault. However, ridge segments without significant melt budget are more likely to be in a transient thermal state controlled, at least partly, by the faulting dynamics themselves. Therefore, we investigate which processes control the thermal structure of the lithosphere and how feedbacks with the deformation mechanisms can explain observed faulting patterns. We present results of 2‐D thermo‐mechanical numerical modeling including serpentinization reactions and dynamic grain size evolution. The model features a novel form of parametrized hydrothermal cooling along fault zones as well as the thermal and rheological effects of periodic sill intrusions. We find that the interplay of hydrothermal fault zone cooling and periodic sill intrusions in the footwall facilitates the flip‐flop detachment mode. Hydrothermal cooling of the fault zone pushes the temperature maximum into the footwall, while intrusions near the temperature maximum further weaken the rock and promote the formation of new faults with opposite polarity. Our model allows us to put constraints on the magnitude of two processes, and we obtain most reasonable melt budgets and hydrothermal heat fluxes if both are considered. Furthermore, we frequently observe two other faulting modes in our experiments complementing flip‐flop faulting to yield a potentially more robust alternative interpretation for existing observations. Plain Language Summary At mid‐ocean ridges, two plates diverge and new seafloor is created. The nature and appearance of this new seafloor strongly depend on spreading velocity and the availability of magmatic melts. At one of the melt‐poorest and slowest‐spreading ridges, a special form of large‐scale tectonic faults, so‐called flip‐flop detachments, can be observed. Tectonic faults can act as pathways for fluids circulating through the seafloor, which provides a significant cooling effect for the young plate. The interplay of magmatic activity, faulting and fluid circulation is evident at many different ridges with different magmatic activity and spreading rates. Flip‐flop faulting is restricted to only a few ridge sections worldwide, and we here investigate the prerequisites for this special spreading mode. To do so, we set up a computer model of an ultraslow‐spreading mid‐ocean ridge including the effects of sparse magmatism as well as the cooling effect associated with fluid circulation. We find that feedbacks between faulting dynamics, hydrothermal cooling and magmatic activity control the magnitude and spatial location of each individual process. Seafloor and subsurface observations are best explained by calculations with moderate melt input and hydrothermal circulation acting together. Key Points We implemented hydrothermal cooling and magmatic intrusion in a thermo‐mechanical model to explain detachment faulting at ultraslow ridges Stable flip‐flop detachment faulting is observed for setups considering both melt input and hydrothermal heat fluxes at realistic magnitudes Two other faulting modes frequently observed in our model offer potential alternative interpretations for existing seafloor observations

Description: The unique male pregnancy in pipefishes and seahorses ranges from basic attachment (pouch-less species: Nerophinae) of maternal eggs to specialized internal gestation in pouched species (e.g. Syngnathus and Hippocampus) with many transitions in between. Due to this diversity, male pregnancy offers a unique platform for assessing physiological and molecular adaptations in pregnancy evolution. These insights will contribute to answering long-standing questions of why and how pregnancy evolved convergently in so many vertebrate systems. To understand the molecular congruencies and disparities in male pregnancy evolution, we compared transcriptome-wide differentially expressed genes in four syngnathid species, at four pregnancy stages (nonpregnant, early, late and parturition). Across all species and pregnancy forms, metabolic processes and immune dynamics defined pregnancy stages, especially pouched species shared expression features akin to female pregnancy. The observed downregulation of adaptive immune genes in early-stage pregnancy and its reversed upregulation during late/parturition in pouched species, most notably in Hippocampus, combined with directionless expression in the pouch-less species, suggests immune modulation to be restricted to pouched species that evolved placenta-like systems. We propose that increased foeto-paternal intimacy in pouched syngnathids commands immune suppression processes in early gestation, and that the elevated immune response during parturition coincides with pouch opening and reduced progeny reliance. Immune response regulation in pouched species supports the recently described functional MHC II pathway loss as critical in male pregnancy evolution. The independent co-option of similar genes and pathways both in male and female pregnancy highlights immune modulation as crucial for the evolutionary establishment of pregnancy.

Description: Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While early warning systems are frequently used to predict the magnitude, location and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services or financial loss. Complementing early warning systems with impact forecasts has a two‐fold advantage: it would provide decision makers with richer information to take informed decisions about emergency measures, and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multi‐hazard early warning systems. This review discusses the state‐of‐the‐art in impact forecasting for a wide range of natural hazards. We outline the added value of impact‐based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe. Plain language summary Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While such systems are frequently used to predict the magnitude, location and timing of potentially damaging events, they rarely provide impact estimates, such as the expected physical damage, human consequences, disruption of services or financial loss. Extending hazard forecast systems to include impact estimates promises many benefits for the emergency phase, for instance, for organising evacuations. We review and compare the state‐of‐the‐art of impact forcasting across a wide range of natural hazards, and outline opportunities and key challenges for research and development of impact forecasting.

Description: Predation is a pervasive force that structures food webs and directly influences ecosystem functioning. The relative body sizes of predators and prey may be an important determinant of interaction strengths. However, studies quantifying the combined influence of intra‐ and interspecific variation in predator–prey body size ratios are lacking. We use a comparative functional response approach to examine interaction strengths between three size classes of invasive bluegill and largemouth bass toward three scaled size classes of their tilapia prey. We then quantify the influence of intra‐ and interspecific predator–prey body mass ratios on the scaling of attack rates and handling times. Type II functional responses were displayed by both predators across all predator and prey size classes. Largemouth bass consumed more than bluegill at small and intermediate predator size classes, while large predators of both species were more similar. Small prey were most vulnerable overall; however, differential attack rates among prey were emergent across predator sizes. For both bluegill and largemouth bass, small predators exhibited higher attack rates toward small and intermediate prey sizes, while larger predators exhibited greater attack rates toward large prey. Conversely, handling times increased with prey size, with small bluegill exhibiting particularly low feeding rates toward medium–large prey types. Attack rates for both predators peaked unimodally at intermediate predator–prey body mass ratios, while handling times generally shortened across increasing body mass ratios. We thus demonstrate effects of body size ratios on predator–prey interaction strengths between key fish species, with attack rates and handling times dependent on the relative sizes of predator–prey participants. Considerations for intra‐ and interspecific body size ratio effects are critical for predicting the strengths of interactions within ecosystems and may drive differential ecological impacts among invasive species as size ratios shift.

Description: A significant increase in sea surface temperature (SST) is observed over the midlatitude western boundary currents (WBCs) during the past century. However, the mechanism for this phenomenon remains poorly understood due to limited observations. In the present paper, several coupled parameters (i.e., sea surface temperature (SST), ocean surface heat fluxes, ocean water velocity, ocean surface winds and sea level pressure (SLP)) are analyzed to identify the dynamic changes of the WBCs. Three types of independent data sets are used, including reanalysis products, satellite-blended observations. and climate model outputs from the fifth phase of the Climate Model Intercomparison Project (CMIP5). Based on these broad ranges of data, we find that the WBCs (except the Gulf Stream) are intensifying and shifting toward the poles as long-term effects of global warming. An intensification and poleward shift of near-surface ocean winds, attributed to positive annular mode-like trends, are proposed to be the forcing of such dynamic changes. In contrast to the other WBCs, the Gulf Stream is expected to be weaker under global warming, which is most likely related to a weakening of the Atlantic Meridional Overturning Circulation (AMOC). However, we also notice that the natural variations of WBCs might conceal the long-term effect of global warming in the available observational data sets, especially over the Northern Hemisphere. Therefore, long-term observations or proxy data are necessary to further evaluate the dynamics of the WBCs.

Description: Krüger, L. C., Paus, A., Svendsen, J. I. & Bjune, A. E. 2011: Lateglacial vegetation and palaeoenvironment in W Norway, with new pollen data from the Sunnmøre region. Boreas , 10.1111/j.1502-3885.2011.00213.x. ISSN 0300-9483. Two sediment sequences from Sunnmøre, northern W Norway, were pollen-analytically studied to reconstruct the Lateglacial vegetation history and climate. The coastal Dimnamyra was deglaciated around 15.3 ka BP, whereas Løkjingsmyra, further inland, became ice-free around 14 ka BP. The pioneer vegetation dominated by snow-bed communities was gradually replaced by grassland and sparse heath vegetation. A pronounced peak in Poaceae around 12.9 ka BP may reflect warmer and/or drier conditions. The Younger Dryas (YD) cooling phase shows increasing snow-bed vegetation and the local establishment of Artemisia norvegica . A subsequent vegetation closure from grassland to heath signals the Holocene warming. Birch forests were established 500–600 years after the YD–Holocene transition. This development follows the pattern of the Sunnmøre region, which is clearly different from the Empetrum dominance in the Lateglacial interstadial further south in W Norway. The Lateglacial oscillations GI-1d (Older Dryas) and GI-1b (Gerzensee) are hardly traceable in the north, in contrast to southern W Norway. The southern vegetation was probably closer to an ecotone and more susceptible to climate changes.

Description: Along ultraslow spreading ridges melt is distributed unequally, but melt focusing guides melt away from amagmatic segments toward volcanic centers. An interplay of tectonism and magmatism is thought to control melt ascent, but the detailed process of melt extraction is not yet understood. We present a detailed image of the seismic velocity structure of the Logachev volcanic center and adjacent region along the Knipovich Ridge. With travel times of P- and S-waves of 3,959 earthquakes we performed a local earthquake tomography. We simultaneously inverted for source locations, velocity structure and the Vp/Vs-ratio. An extensive low velocity anomaly coincident with high Vp/Vs-ratios 〉1.9 lies underneath the volcanic center at depths of 10 km below sea level in an aseismic area. More shallow, tightly clustered earthquake swarms connect the anomaly to a shallow anomaly with high Vp/Vs-ratio beneath the basaltic seafloor. We consider the deep low-velocity anomaly to represent an area of partial melt from which melts ascent vertically to the surface and northwards into the adjacent segment. By comparing tomographic studies of the Logachev and Southwest Indian Ridge Segment-8 volcano we conclude that volcanic centers of ultraslow spreading ridges host spatially confined, circular partial melt areas below 10 km depth, in contrast to the shallow extended melt lenses along fast spreading ridges. Lateral feeding over distances of 35 km is possible at orthogonal spreading segments, but limited at the obliquely spreading Knipovich Ridge. Key Points - Active volcanic centers at ultraslow spreading ridges host deeper and more confined partial melt areas than faster spreading ridges - Earthquake swarms delineate melt ascent paths from the partial melt area to the surface - Lateral feeding at shallow depths into subordinate segments is prevented by ridge obliquity

Description: Spreading centers in the proximity of back‐rolling subduction zones constitute an ideal natural laboratory to investigate the interaction of magmatism and tectonism during the early evolution of back‐arc basins. Using 32 days of ocean bottom seismometer data, we located 697 microeathquakes at the southern Fonualei Rift and Spreading Center (S‐FRSC). The majority of epicenters concentrate along the central region of the axial valley, marking the active ridge axis. Only odd events were associated with the prominent faults bounding the axial valley. About 450 events are spatially clustered around 17°42’S and their waveforms show a pronounced similarity. Most of these events are associated with a 138 hours lasting earthquake swarm. The tectonic structure of the ridge axis in the S‐FRSC resembles a series of left‐stepping en echelon segments, expressed at the seafloor by numerous volcanic ridges. The recorded earthquake swarm is located at the stepover of two en echelon segments suggesting that the earthquake swarm is mainly tectonically driven. The events directly beneath our seismic network indicate a maximum depth of brittle faulting down to about 14 km below the seafloor. This is within the maximum depth range of brittle faulting at ultraslow mid‐ocean ridges. Since the thickness of the brittle lithosphere is mainly controlled by temperature, our results suggest a sub‐axial thermal structure similar to that of ultraslow mid‐ocean ridges of similar opening rates.

Description: The stratospheric climate and variability from simulations of sixteen chemistry-climate models is evaluated. On average the polar night jet is well reproduced though its variability is less well reproduced with a large spread between models. Polar temperature biases are less than 5 K except in the Southern Hemisphere (SH) lower stratosphere in spring. The accumulated area of low temperatures responsible for polar stratospheric cloud formation is accurately reproduced for the Antarctic but underestimated for the Arctic. The shape and position of the polar vortex is well simulated, as is the tropical upwelling in the lower stratosphere. There is a wide model spread in the frequency of major sudden stratospheric warnings (SSWs), late biases in the breakup of the SH vortex, and a weak annual cycle in the zonal wind in the tropical upper stratosphere. Quantitatively, “metrics” indicate a wide spread in model performance for most diagnostics with systematic biases in many, and poorer performance in the SH than in the Northern Hemisphere (NH). Correlations were found in the SH between errors in the final warming, polar temperatures, the leading mode of variability, and jet strength, and in the NH between errors in polar temperatures, frequency of major SSWs, and jet strength. Models with a stronger QBO have stronger tropical upwelling and a colder NH vortex. Both the qualitative and quantitative analysis indicate a number of common and long-standing model problems, particularly related to the simulation of the SH and stratospheric variability.

Description: A generalist strategy, as an adaptation to environmental heterogeneity, is common in Arctic freshwater systems, often accompanied, however, by intraspecific divergence that promotes specialization in niche use. To better understand how resources may be partitioned in a northern system that supports intraspecific diversity of Lake Trout, trophic niches were compared among four shallow-water morphotypes in Great Bear Lake (N65 ° 56′ 39″, W120 ° 50′ 59″). Bayesian mixing model analyses of stable isotopes of carbon and nitrogen were conducted on adult Lake Trout. Major niche overlap in resource use among four Lake Trout morphotypes was found within littoral and pelagic zones, which raises the question of how such polymorphism can be sustained among opportunistic generalist morphotypes. Covariances of our morphological datasets were tested against δ 13 C and δ 15 N values. Patterns among morphotypes were mainly observed for δ 15 N. This link between ecological and morphological differentiation suggested that selection pressure(s) operate at the trophic level (δ 15 N), independent of habitat, rather than along the habitat-foraging opportunity axis (δ 13 C). The spatial and temporal variability of resources in Arctic lakes, such as Great Bear Lake, may have favored the presence of multiple generalists showing different degrees of omnivory along a weak benthic–pelagic gradient. Morphs 1–3 had more generalist feeding habits using both benthic and pelagic habitats than Morph 4, which was a top-predator specialist in the pelagic habitat. Evidence for frequent cannibalism in Great Bear Lake was found across all four morphotypes and may also contribute to polymorphism. We suggest that the multiple generalist morphs described here from Great Bear Lake are a unique expression of diversity due to the presumed constraints on the evolution of generalists and contrast with the development of multiple specialists, the standard response to intraspecific divergence. Major overlap in dietary niches among Lake Trout morphotypes were found within littoral and pelagic zones, which raises the question how such polymorphism can be sustained in this opportunistic generalist feeder. The spatial and temporal variability of resources of Arctic lakes, such as Great Bear Lake, may have favored the presence of multiple generalists showing different degrees of omnivory polymorphism along a weak benthic-pelagic gradient. We suggest that the multifaceted generality detected in Great Bear Lake should be considered as a unique expression of diversity due to the presumed constraints on the evolution of generalists, as multiple specialists is the standard response to intraspecific divergence.

Description: Seaweeds are colonized by a microbial community, which can be directly linked to their performance. This community is shaped by an interplay of stochastic and deterministic processes, including mechanisms which the holobiont host deploys to manipulate its associated microbiota. The Anna Karenina principle predicts that when a holobiont is exposed to suboptimal or stressful conditions, these host mechanisms may be compromised. This leads to a relative increase of stochastic processes that may potentially result in the succession of a microbial community harmful to the host. Based on this principle, we used the variability in microbial communities (i.e., beta diversity) as a proxy for stability within the invasive holobiont Gracilaria vermiculophylla during a simulated invasion in a common garden experiment. Independent of host range, host performance declined at elevated temperature (22°C) and disease incidence and beta diversity increased. Under thermally stressful conditions, beta diversity increased more in epibiota from native populations, suggesting that epibiota from non-native holobionts are thermally more stable. This pattern reflects an increase in deterministic processes acting on epibiota associated with non-native hosts, which in the setting of a common garden can be assumed to originate from the host itself. Therefore, these experimental data suggest that the invasion process may have selected for hosts better able to maintain stable microbiota during stress. Future studies are needed to identify the underlying host mechanisms.

Description: Ozonesonde data from four sites are analyzed in relation to 191 solar protons events (SPEs) from 1989-2016. Analysis shows ozone depletion (~10-35 km altitude) commencing following the SPEs. Seasonally-corrected ozone data demonstrate that depletions occur only in winter/early-spring above sites where the northern hemisphere polar vortex (PV) can be present. A rapid reduction in stratospheric ozone is observed with the maximum decrease occurring ~10-20 days after SPEs. Ozone levels remain depleted in excess of 30 days. No depletion is observed above sites completely outside the PV. No depletion is observed in relation to 191 random epochs at any site at any time of year. Results point to the role of indirect ozone destruction, most likely via the rapid descent of long-lived NOx species in the PV during the polar winter.

Description: Continuous high-resolution underway measurements of dimethyl sulfide (DMS) and isoprene in the ocean surface were conducted from Germany to South Africa in November 2008. DMS, total dimethylsulfoniopropionate (DMSPt), isoprene and 19'-hexanoyloxyfucoxanthin (19'-hex) correlated in nitrogen-depleted regions when they were clustered by nitrogen to phosphorous ratio (N:P). The 19'-hex-containing algae groups might be a common source of DMS, DMSPt, and isoprene in the low N: P regions. Additionally, DMS and isoprene correlated in nitrate-depleted regions when they were clustered against nitrate concentrations. Correlations between DMS and isoprene were also found within nitrate-depleted eddies encountered along the cruise track. Eddies with N: P of similar to 2.8 showed the highest positive correlations between DMS and isoprene. We conclude that the DMS/isoprene relationships in the eastern Atlantic Ocean were influenced by nutrient availability, with implications for using nutrients to predict the DMS and isoprene concentrations over a range of oceanographic areas depleted in nitrogen

Description: Stratospheric sudden warmings (SSWs) are extreme events in the polar stratosphere that are both caused by and have effects on the tropospheric flow. This means that SSWs are associated with changes in the angular momentum of the atmosphere, both before and after their onset. Because these angular momentum changes are transferred to the solid Earth, they can be observed in the rate of the Earth's rotation and the wobble of its rotational pole. By comparing observed Earth rotation variations to reanalysis data, we find that an anomaly in the orientation of the Earth's rotational pole, up to 4 times as large as the annual polar wobble, typically precedes SSWs by 20-40 days. The polar motion signal is due to pressure anomalies that are typically seen before SSW events and represents a new type of observable that may aid in the prediction of SSWs. A decline in the length of day is also seen, on average, near the time of the SSW wind reversal and is found to be due to anomalous easterly winds generated in the tropical troposphere around this time, though the structure and timing of this signal seems to vary widely from event to event.

Description: Since 2009, unprecedented comprehensive long-term gas hydrate observations have become available from Ocean Networks Canada's NEPTUNE cabled ocean observatory at the northern Cascadia margin. Several experiments demonstrate the scientific importance of permanent power and Internet connectivity to the ocean floor as they have advanced the field of gas hydrate related research. One example is the cabled crawler Wally at Barkley Canyon, enabling live in situ exploration of the hydrate mounds and its associated benthic communities through the crawler's mobility and permanent accessibility throughout the year. Another example is a bubble-imaging sonar at Clayoquot Slope, revealing the strong relationship between ebullition of natural gas and tidal pressure, without apparent correlation to earthquakes, storms, or temperature fluctuations, in year-long continuous recordings. Finally, regular observatory maintenance cruises allow additional science sampling including echo-sounder surveys to extend the observatory footprint. Long-term trends in the data are not yet apparent but can also become evident from continuous measurements, as ocean observatories such as NEPTUNE are built for a 25-year lifetime, and expansion of the observatory networks makes these findings comparable and testable. Plain Language Summary Natural gas near the ocean floor creates a rapidly changing environment where it is important to collect data continuously in order to determine the magnitude, speed, and potential mechanism of change. This long-standing challenge of year-round access to the deep ocean has been tackled by Ocean Networks Canada through cabling the northern Cascadia seafloor, providing power and Internet communication-ideal for power-hungry instruments, large data volumes, and real-time access. The presence of gas influences the shape of the seafloor, animal activity, and potential escape of methane, a potent greenhouse gas. A seafloor crawler Wally was operated around deep canyon mounds of gas hydrate (a solid gas-water composite) since 2009 and helped discover environmental changes influencing sea life. Further along the continental slope, an acoustic sonar monitored rising methane bubbles where the bubbling appears to be controlled neither by earthquakes, winter storms, nor subtle temperature changes but actually strongly by tidal pressure. Regular maintenance of the observatory by ship allows more data to be collected near the cabled seafloor sites, extending the observations to a larger area. Ocean observatories are built to last decades and therefore more data for more research can be collected, potentially detecting relatively slow processes as well.

Description: Our knowledge of the absolute S wave velocities of the oceanic lithosphere is mainly based on global surface wave tomography, local active seismic or compliance measurements using oceanic infragravity waves. The results of tomography give a rather smooth picture of the actual S wave velocity structure and local measurements have limitations regarding the range of elastic parameters or the geometry of the measurement. Here, we use the P wave polarization (apparent P wave incidence angle) of teleseismic events to investigate the S wave velocity structure of the oceanic crust and the upper tens of kilometres of the mantle beneath single stations. In this study, we present an up to our knowledge new relation of the apparent P wave incidence angle at the ocean bottom dependent on the half space S wave velocity. We analyse the angle in different period ranges at ocean bottom stations (OBS) to derive apparent S wave velocity profiles. These profiles are dependent on the S wave velocity as well as on the thickness of the layers in the subsurface. Consequently, their interpretation results in a set of equally valid models. We analyse the apparent P wave incidence angles of an OBS data set which was collected in the Eastern Mid Atlantic. We are able to determine reasonable S wave velocity-depth models by a three step quantitative modelling after a manual data quality control, although layer resonance sometimes influences the estimated apparent S wave velocities. The apparent S wave velocity profiles are well explained by an oceanic PREM model in which the upper part is replaced by four layers consisting of a water column, a sediment, a crust and a layer representing the uppermost mantle. The obtained sediment has a thickness between 0.3 km and 0.9 km with S wave velocities between 0.7 km s−1 and 1.4 km s−1. The estimated total crustal thickness varies between 4 km and 10 km with S wave velocities between 3.5 km s−1 and 4.3 km s−1. We find a slight increase of the total crustal thickness from ∼5 km to ∼8 km towards the South in the direction of a major plate boundary, the Gloria Fault. The observed crustal thickening can be related with the known dominant compression in the vicinity of the fault. Furthermore, the resulting mantle S wave velocities decrease from values around 5.5 km s−1 to 4.5 km s−1 towards the fault. This decrease is probably caused by serpentinization and indicates that the oceanic transform fault affects a broad region in the uppermost mantle. Conclusively, the presented method is useful for the estimation of the local S wave velocity structure beneath ocean bottom seismic stations. It is easy to implement and consists of two main steps: (1) measurement of apparent P wave incidence angles in different period ranges for real and synthetic data, and (2) comparison of the determined apparent S wave velocities for real and synthetic data to estimate S wave velocity-depth models.

Description: Carbon cycling by Antarctic microbial plankton is poorly understood but it plays a major role in CO2 sequestration in the Southern Ocean. We investigated the summer bacterioplankton community in the largely understudied Weddell Sea, applying Illumina amplicon sequencing, measurements of bacterial production and chemical analyses of organic matter. The results revealed that the patchy distribution of productive coastal polynyas and less productive, mostly ice-covered sites was the major driver of the spatial changes in the taxonomic composition and activity of bacterioplankton. Gradients in organic matter availability induced by phytoplankton blooms were reflected in the concentrations and composition of dissolved carbohydrates and proteins. Bacterial production at bloom stations was, on average, 2.7 times higher than at less productive sites. Abundant bloom-responsive lineages were predominately affiliated with ubiquitous marine taxa, including Polaribacter, Yoonia-Loktanella, Sulfitobacter, the SAR92 clade, and Ulvibacter, suggesting a widespread genetic potential for adaptation to sub-zero seawater temperatures. A co-occurrence network analysis showed that dominant taxa at stations with low phytoplankton productivity were highly connected, indicating beneficial interactions. Overall, our study demonstrates that heterotrophic bacterial communities along Weddell Sea ice shelves were primarily constrained by the availability of labile organic matter rather than low seawater temperature.

Description: Genome sequencing enables answering fundamental questions about the genetic basis of adaptation, population structure and epigenetic mechanisms. Yet, we usually need a suitable reference genome for mapping population-level resequencing data. In some model systems, multiple reference genomes are available, giving the challenging task of determining which reference genome best suits the data. Here, we compared the use of two different reference genomes for the three-spined stickleback (Gasterosteus aculeatus), one novel genome derived from a European gynogenetic individual and the published reference genome of a North American individual. Specifically, we investigated the impact of using a local reference versus one generated from a distinct lineage on several common population genomics analyses. Through mapping genome resequencing data of 60 sticklebacks from across Europe and North America, we demonstrate that genetic distance among samples and the reference genomes impacts downstream analyses. Using a local reference genome increased mapping efficiency and genotyping accuracy, effectively retaining more and better data. Despite comparable distributions of the metrics generated across the genome using SNP data (i.e. π, Tajima's D and FST), window-based statistics using different references resulted in different outlier genes and enriched gene functions. A marker-based analysis of DNA methylation distributions had a comparably high overlap in outlier genes and functions, yet with distinct differences depending on the reference genome. Overall, our results highlight how using a local reference genome decreases reference bias to increase confidence in downstream analyses of the data. Such results have significant implications in all reference-genome-based population genomic analyses.

Description: The Red Sea is a deep marine basin often considered as small‐scale version of the global ocean. Hydrographic observations and ocean‐atmosphere modeling indicate Red Sea deep water was episodically renewed by wintertime open‐ocean deep convections during 1982–2001, suggesting a renewal time on the order of a decade. However, the long‐term pacing of Red Sea deep water renewals is largely uncertain. We use an annually resolved coral oxygen isotope record of winter surface water conditions to show that the late twentieth century deep water renewals were probably unusual in the context of the preceding ~100 years. More frequent major events are detected during the late Little Ice Age, particularly during the early nineteenth century characterized by large tropical volcanic eruptions. We conclude that Red Sea deep water renewal time is on the order of a decade up to a century, depending on the mean climatic conditions and large‐scale interannual climate forcing.

Description: 1. Geolocating aquatic animals with acoustic tags has been ongoing for decades, relying on the detection of acoustic signals at multiple receivers with known positions to calculate a 2D or 3D position, and ultimately recreate the path of an aquatic animal from detections at fixed stations. 2. This method of underwater geolocation is evolving with new software and hardware options available to help investigators design studies and calculate positions using solvers based predominantly on time-difference-of-arrival and time-of-arrival. 3. We provide an overview of the considerations necessary to implement positioning in aquatic acoustic telemetry studies, including how to design arrays of receivers, test performance, synchronize receiver clocks and calculate positions from the detection data. We additionally present some common positioning algorithms, including both the free open-source solvers and the ‘black-box’ methods provided by some manufacturers for calculating positions. 4. This paper is the first to provide a comprehensive overview of methods and considerations for designing and implementing better positioning studies that will support users, and encourage further knowledge advances in aquatic systems.

Description: We consider that here are four key issues and priorities for hydrological sciences in respect to sidement, phosphorus and colloid transfers from intensive grasslands (Table I). These are inadequate inventories, analytical challenges, the neglected role of organic matter and challenges for modelling and integration. We need to change the way in which grassland systems are perceived and monitored; this commentary and the ones that follow may help start to achieve this. There is also a critical requirement for a wider acceptance of a 'continuum' of sediment and particles and processes from molecular to 〉1 μm, including clarity with operational definitions and an acceptance of the strenghts and weakness of analytical tools. A variety of new tracer techniques are avaliable for helping assess the role of organic matter in contributing to transfers and these must be applied. Field scientists must fully appreciate the variability of observations, and modellers need to understand the uncertainty in model processes and model outputs. Overall, however, the critical message is that integrated inter-disciplinary team working is encourage, discipline polarization is discourage because it undermines progress. To that end, in the assembly of commentaries that follow (Bilotta et al., 2007; Gimbert et al., 2007; Granger et al.; 2007; Krueger et al., 2007) we are presenting ideas as part of an integrated project team that is attempting to improve our knowledge and ability to model sediment, colloids and phosphorus losses from intensive grassland, with - we hope - some wider generic relevance for the hydrological community. Copyright © 2006 John Wiley & Sons, Ltd.