ALBERT

Description: Density-driven mass movement deposits (MMDs) were mapped throughout the Quaternary sedimentary record of Lake El'gygytgyn (NE Siberia) using high-resolution acoustic data. Three different acoustic facies types were identified in the lake: (1) pelagic sediment, (2) plastic flow deposits and (3) turbidites. Deposits from plastic flows are dominantly present proximal to the lakes' slopes, whereas deposits from turbidity currents occur more spatially distributed. During glacial times, the distribution of MMDs was more uniform, while during interglacial periods, MMDs were deposited predominantly close to the slope of the northwestern area. Furthermore, the overall number of MMDs and accumulated sediment volume significantly varies between glacial/interglacial periods. About 1.6 times more MMDs were mapped during interglacials, contributing to a 3.5 times higher sediment volume. The main reason for this large difference is that a significant increase in plastic flows were formed during interglacials, which account for a much larger volume of sediments when compared with the glacial intervals characterized by increased amount of turbidites. It appears that the most important source areas for MMDs are located at the northern and western shores. Cycles of lake level changes caused by variations in climate conditions between glacials and interglacials are likely the main trigger mechanism for the generation of these MMDs. The climate-dependent genesis and partly erosive potential influencing the sedimentary record contain implications to consider for future paleo-environmental reconstructions in lacustrine settings.

Description: The Antarctic krill, Euphausia superba, has evolved seasonal rhythms of physiology and behaviour to survive under the extreme photoperiodic conditions in the Southern Ocean. However, the molecular mechanisms generating these rhythms remain far from understood. The aim of this study was to investigate seasonal differences in gene expression in three different latitudinal regions (South Georgia, South Orkneys/Bransfield Strait, Lazarev Sea) and to identify genes with potential regulatory roles in the seasonal life cycle of Antarctic krill. The RNA-seq data were analysed (a) for seasonal differences between summer and winter krill sampled from each region, and (b) for regional differences within each season. A large majority of genes showed an up-regulation in summer krill in all regions with respect to winter krill. However, seasonal differences in gene expression were less pronounced in Antarctic krill from South Georgia, most likely due to the milder seasonal conditions of the lower latitudes of this region, with a less extreme light regime and food availability between summer and winter. Our results suggest that in the South Orkneys/Bransfield Strait and Lazarev Sea region, Antarctic krill entered a state of metabolic depression and regressed development (winter quiescence) in winter. Moreover, seasonal gene expression signatures seems to be driven by a photoperiodic timing system that may adapt the flexible behaviour and physiology of Antarctic krill to the highly seasonal environment according to the latitudinal region. However, at the lower latitude South Georgia region, food availability might represent the main environmental cue influencing seasonal physiology.

Description: Some of the oldest surviving oceanic basins in the world, the Mozambique and West Somali basins, were created during the breakup of Gondwana, starting around 180 Ma. Between the two basins, relative movements of West Gondwana and East Gondwana, including Madagascar, created a shear zone, the Davie Fracture Zone (DFZ) with a topographic elevation (Davie Ridge - DR) marking its centre. The crustal composition of the DFZ and DR is a subject of speculation and debate. In this study, we present seismic refraction data across the prominent topography of the southern DR. Ray tracing of the wide-angle data as well as additional seismic amplitude modelling and 2.5D density modelling constrain its crustal structure and architecture. The data indicate that in the Mozambique Channel the DR consists of fragments of continental crust with a thickness of 10 to 12 km. An oceanic crust indenter extends northward from the Mozambique Basin into the area between the DR and the East African margin at 16.5°S. Northeast of the DR, at 41.8°W/14.5°S, the Somali Basin is probably floored by 6 km thick oceanic crust. Hence, the continental DR separates oceanic crust of the Somali and Mozambique basins. The transitional crustal area at the central Mozambican margin is underlain by high velocity lower crust (HVLC). The HVLC has velocities up to 7.3 km/s and extents along the margin, vanishing northward between 16.5° and 14.5°S. At the Madagascan side of the DR, at 16.5°S, the highly intruded stretched continental crust is 9 km thick and possibly underlain with a smaller HVLC of 2.9 km thickness and an E-W extent of 120 km. The oceanic crust at 14.5°S represents the oldest part the Somali Basin, which formed after the initial NW-SE rifting between East and West Gondwana.

Description: There have been a number of suggested driving factors for Late Miocene expansion of C4 plant coverage, including a decline in atmospheric CO2 concentrations, enhanced aridity and seasonality, shifts in fire regimes, and tectonic uplift. In order to identify and discriminate the driving factors of vegetation changes, continuous records from the same section or basin are required. We present micro-charcoal-based fire history and C4 vegetation abundance records spanning the Miocene from the Yanwan Section in the Tianshui Basin, on the northeastern Tibetan Plateau (NE TP). Based on statistical analyses, the micro-charcoal concentrations were relatively low before ~10Â Ma, and after that time, there was an exponential increase. The C4 plant abundance shows a strong increase after 8Â Ma, about 2 million years after the micro-charcoal concentrations started increasing. We compare our records with published CO2, pollen, seasonality, herbivorous mammalian fossil and tectonic records from the same section and basin. We find that C4 vegetation, fire intensities, and opening landscapes increased simultaneously after 8 Ma. This indicates that a fire-grassland feedback, initially driven by aridification, was the trigger for the Late Miocene expansion of C4 plants. We speculate that herbivorous mammalian species may also have played a minor role. During the Miocene, there is a trend towards enhanced seasonality and a decline in atmospheric CO2 concentrations, which were also necessary preconditions for the expansion.

Description: Antarctic krill up- and down-regulate their metabolism as a strategy to cope with the strong seasonal environmental fluctuations in the Southern Ocean. In this study, we investigate the impact of this light- and temperature dependent metabolic regulation on growth, reproduction and winter survival of krill. Therefore, we advance a bioenergetic growth model of krill by adding a data-derived scaling function of krill activity. With SERBIK (SEasonally Regulated BIoenergetic Krill growth model), we conduct a numerical experiment which tests the impact of such scaling on krill life history under two different winter food conditions: In the first scenario, we simulate life history of krill when winter food availability is low; in the second scenario, winter food availability is increased within realistic ranges. The results demonstrate that the scaling of metabolism is especially important during low food winters. Reducing metabolism during winter permits individuals to grow to larger body length, reproduce successfully and release a greater number of eggs. It further significantly reduces withinyear size fluctuations caused by starvation during months with low food availability. Finally, SERBIK can be used in future spatial modelling studies which include movement of krill along latitudinal gradients and thus spatiotemporal gradients in light- and temperature.

Description: Acoustic and detailed swath bathymetry data revealed a systematic picture of submarine landslides on the Siberian part of Lomonosov Ridge. Whereas numerous studies on mass movement exist along the margin of the Arctic Ocean less is known from central Arctic. A regional survey comprising swath bathymetry, sediment echo sounder and multichannel seismic profiling was performed on the southeastern Lomonosov Ridge. The data provide constraints on the present-day morphology of the Siberian part of Lomonosov Ridge, between 81°–84°N and 140°–146°E. We mapped twelve crescent-shaped escarpments located on both flanks on the crest of Lomonosov Ridge. The escarpments are 2.1 to 10.2 km wide, 1.7 to 8.2 km long and 125 to 851 m high from which 58 to 207 m are occupied by crescent-shaped headscarps. Subbottom data show chaotic reflections within most of the escarpment areas. The unit is overlain by ~110–340 m of semi-coherent parallel reflections. At its bottom the chaotic reflections are limited by a partly eroded high-amplitude reflection sequence that is inclined with 〈1° basinwards. We find the escarpments to be remnants of submarine landslide events that mobilized 0.09 to 7.58 km3 of sediments between mid Pliocene and mid Miocene. The relatively small amounts of mobilized sediments seem to be typical for the Lomonosov Ridge. The epoch corresponds to the ongoing subsidence of the Lomonosov Ridge below sea level. During that time deposition and the load of sediments changed. We suggest that changes in sediment type preconditioned, and co-occurring earthquakes finally triggered the submarine landslides.

Description: Bioturbation is one of the key mediators of biogeochemical processes in benthic habitats that can have a high contribution to seafloor functioning and benthic pelagic coupling in coastal waters. Previous studies on bioturbation were limited to point locations and extrapolations in single regions, but have not accounted for regional differences under changing environmental conditions, though there are indications that species contributions will differ across regions or with biotic and abiotic context. To capture those differences and assess global patterns and commonalities, multi-regional analyses are imperative. Here for the first time, bioturbation potential (BPc), a functional indicator of benthic community bioturbation, was estimated based on macrofauna data from four regions (i.e. German Baltic Sea, German North Sea, Belgian part of the North Sea and the Eastern English Channel). For each region and sediment type we identified key species contributing to BPc. Comparison within and across regions demonstrated regional differences, and both overlap and mismatch between species that are functionally important and those that are dominant in biomass. Knowledge on the functionally important species is crucial when management objectives include the protection of certain ecosystem functions. Available environmental layers were used as predictors to model the spatial distribution of BPc for each area and to explore the underlying drivers of differences. Random forest models were trained using as response variables either i) BPc initially calculated per station; or ii) BPp – the species-specific contribution to BPc – for key species (with subsequent summation of their predicted full-coverage distributions to BPc). Maps of BPc distribution predicted by random forest were compared with those generated using natural neighbour interpolation. Overall, derived BPc values increased towards the German parts of the North and Baltic Seas. The relevance of BPc for ecosystem processes and functions, however, vary with biotic and abiotic settings. Results revealed a strong association of BPc with species diversity and region, but less with sediment grain size. A large range of BPc occurred when species richness was low. This suggests that the provisioning of high bioturbation activity is possible also under low diversity, where it is vulnerable due to reduced resilience. The executed multi-regional analysis allowed identifying regional differences in performance of macrofauna, suggesting the need for regionspecific conservation and management strategies. https://doi.org/10.1016/j.ecolind.2019.105945 Received 26 July 2019; Received in revised form 12 November 2019; Accepted 14 November 2019 ⁎ Corresponding author. E-mail address: mayya.gogina@io-warnemuende.de (M. Gogina). Ecological Indicators 110 (2020) 105945 1470-160X/ Crown Copyright © 2019 Published by Elsevier Ltd. All rights reserved. T

Description: An increase in human Vibrio spp. infections has been linked to climate change related events, in particular to seawater warming and heatwaves. However, there is a distinct lack of research of pathogenic Vibrio spp. occurrences in the temperate North Sea, one of the fastest warming seas globally. Particularly in the German Bight, Vibrio investigations are still scarce. This study focuses on the spatio-temporal quantification and pathogenic characterization of V. parahaemolyticus, V. vulnificus and V. cholerae over the course of 14 months. Species-specific MPN-PCR (Most probable number – polymerase chain reaction) conducted on selectively enriched surface water samples revealed seasonal patterns of all three species with increased abundances during summer months. The extended period of warm seawater coincided with prolonged Vibrio spp. occurrences in the German Bight. Temperature and nitrite were the factors explaining variations in Vibrio spp. abundances after generalized additive mixed models. The specific detection of pathogenic markers via PCR revealed trh-positive V. parahaemolyticus, pathogenic V. vulnificus (nanA, manIIA, PRXII) and V. cholerae serotype O139 presence. Additionally, spatio-temporally varying virulence profiles of V. cholerae with multiple accessory virulence-associated genes, such as the El Tor variant hemolysin (hlyAET), acyltransferase of the repeats-in-toxin cluster (rtxC), Vibrio 7th pandemic island II (VSP-II), Type III Secretion System (TTSS) and the Cholix Toxin (chxA) were detected. Overall, this study highlights that environmental human pathogenic Vibrio spp. comprise a reservoir of virulence-associated genes in the German Bight, especially in estuarine regions. Due to their known vast genetic plasticity, we point to the possible emergence of highly pathogenic V. cholerae strains. Particularly, the presence of V. cholerae serotype O139 is unusual and needs urgent continuous surveillance. Given the predictions of further warming and more frequent heatwave events, human pathogenic Vibrio spp. should be seriously considered as a developing risk to human health in the German Bight.

Description: Numerous studies have provided compelling evidence that the Pacific Ocean has experienced substantial glacial/interglacial changes in bottom-water oxygenation associated with enhanced carbon dioxide storage in the glacial deep ocean. Under postulated low glacial bottom-water oxygen concentrations (O2bw), redox zonation, biogeochemical processes and element fluxes in the sediments must have been distinctively different during the last glacial period (LGP) compared to current well-oxygenated conditions. In this study, we have investigated six sites situated in various European contract areas for the exploration of polymetallic nodules within the Clarion-Clipperton Zone (CCZ) in the NE Pacific and one site located in a protected Area of Particular Environmental Interest (APEI3) north of the CCZ. We found bulk sediment Mn maxima of up to 1 wt% in the upper oxic 10 cm of the sediments at all sites except for the APEI3 site. The application of a combined leaching protocol for the extraction of sedimentary Mn and Fe minerals revealed that mobilizable Mn(IV) represents the dominant Mn(oxyhydr)oxide phase with more than 70% of bulk solid-phase Mn. Steady state transport-reaction modeling showed that at postulated glacial O2bw of 35 µM, the oxic zone in the sediments was much more compressed than today where upward diffusing pore-water Mn2+ was oxidized and precipitated as authigenic Mn(IV) at the oxic-suboxic redox boundary in the upper 5 cm of the sediments. Transient transport-reaction modeling demonstrated that with increasing O2bw during the last glacial termination to current levels of ~ 150 µM, (1) the oxic-suboxic redox boundary migrated deeper into the sediments and (2) the authigenic Mn(IV) peak was continuously mixed into subsequently deposited sediments by bioturbation causing the observed mobilizable Mn(IV) enrichment in the surface sediments. Such a distinct mobilizable Mn(IV) maximum was not found in the surface sediments of the APEI3 site, which indicates that the oxic zone was not as condensed during the LGP at this site due to two- to threefold lower organic carbon burial rates. Leaching data for sedimentary Fe minerals suggest that Fe(III) has not been diagenetically redistributed during the LGP at any of the investigated sites. Our results demonstrate that the basin-wide deoxygenation in the NE Pacific during the LGP was associated with (1) a much more compressed oxic zone at sites with carbon burial fluxes higher than 1.5 mg Corg m-2 d-1, (2) the authigenic formation of a sub-surface mobilizable Mn(IV) maximum in the upper 5 cm of the sediments and (3) a possibly intensified suboxic-diagenetic growth of polymetallic nodules. As our study provides evidence that authigenic Mn(IV) precipitated in the surface sediments under postulated low glacial O2bw, it contributes to resolving a long-standing controversy concerning the origin of widely observed Mn-rich layers in glacial/deglacial deep-sea sediments.

Description: Deep-sea regions provide vast ecosystem services such as biological habitat and nutrient cycling. Even though being threatened by climate change and facing possible biodiversity loss, these deep-sea ecosystems are poorly understood. So are macrobenthic communities and their functions within these ecosystems. Biodiversity and ecosystem function relationships as well as their link to environmental drivers can be assessed with the biological trait analysis. We used this approach for the first time for macrofauna assemblages across the deep Fram Strait between Greenland and Svalbard (1000–5500 m water depth) to evaluate their community-specific function from the upper continental slope down to the deepest known Arctic depression, the Molloy Deep. We aimed to investigate whether there are changes in benthic functioning along the bathymetric gradient and if so, which environmental stressors may drive these changes. In total, 16 stations were sampled with a giant box corer (0.25 m2) in 2016 and 2018. Sediments were sieved through a 0.5 mm mesh size sieve and fauna was identified to lowest possible taxonomic entity. Functions of species were characterized by using six traits split in 24 modalities gathered in a fuzzy coded species × traits array. Environmental parameters shaping the benthic habitat and reflecting food availability were gathered from remote sensing, mooring deployments, and sediment sampling. A distance-based redundancy analysis indicated near-bottom water temperature, seabed inclination, water depth as well as phytodetritial matter at the sea surface and seafloor (indicating food availability) to be the best variables explaining the trait and station distribution. Stations clustered into three groups based on their trait composition. Shallower stations characterized by high chlorophyll a concentration with large organisms, living within the sediment as well as predating specimens clustered in one group. A second group was characterized by stations with low chlorophyll a concentration and medium-sized, suspension feeding, epifaunal living macrofauna. A third group comprised stations with water depths ≥ 3000 m and was dominated by medium sized, surface deposit feeding and infaunal living specimens. Overall, the functional structure of macrofauna communities in the Fram Strait followed a food availability-driven gradient. Based on the relationship between sea ice, surface water primary production and food availability at the seafloor, these results point to macrobenthos being sensible to predicted anthropogenically generated environmental variations in polar regions. Alterations in benthic ecosystem functions might be expected when environmental conditions change.

Description: In this study, organic geochemical analyses of two sediment cores (BL16 and LV63–23) recovered from the western Bering Sea were carried out to examine the sea-ice variability and its relationship to phytoplankton community evolution over the past century. Bulk stable organic carbon isotopic composition (δ13CTOC) showed pronounced depletion on the northern shelf since the late 1970s, indicating greater terrigenous organic matter (OM) under warming during recent decades. Variation in sedimentary OM in the southward core was closely associated with marine primary productivity and regional deposition processes. Arctic sea-ice proxy IP25 throughout the two cores with different temporal profile patterns demonstrated sea-ice presence with the spatiotemporal variability across the study area over the past century. The phytoplankton marker-IP25 index (PIP25), a proxy for estimating semi-quantitatively sea-ice concentrations, reflected a decreased sea-ice cover with more distinct interannual fluctuations between 0.7 and 0.2 (especially in core BL16) after the late 1970s, coinciding with the recent warming scenario. Increased concentrations of phytoplankton biomarkers (brassicasterol and dinosterol) and their ratios as well as the PIP25 record in core BL16 indicated a synchronous variability of reduced sea-ice cover with the enhancement of phytoplankton productivity since the late 1970s. These results suggested a coupled interaction of the sea-ice condition and planktonic ecosystem in the north Bering shelf. Our results also revealed recent (since the 2000s) spatial heterogeneity in sea-ice coverage between the northern and southern parts of the Bering Sea.

Description: recent study using Fe-limited phytoplankton strains, showed that iron (Fe) uptake rates normalized by cellular surface area were best related to dissolved iron (dFe) concentrations as the inorganic Fe (Fe’) supply rates were not sufficient to satisfy the Fe biological demand. Short-term (24 h) shipboard incubations with the in-situ phytoplankton community were used to measure Fe uptake rates that were normalized per biomass (as particulate organic carbon, POC). Fe uptake rates measured following 55FeCl3 additions (0.05 to 0.9 nM) were fitted to different Fe pools (dFe, Felabile, and Fe’) using the Michaelis-Menten equation. Data showed a similar high conditional stability constant for biological transporters across all sites and phytoplankton size classes, with only a 2-fold variation in the concentrations of cellular transporters. These observations are in line with previous reports that eukaryotic phytoplankton takes up Fe close to the limit imposed by transporters cellular density and uses similar high-affinity Fe uptake systems. To further explore the link between Fe uptake rates and Fe chemistry, we also studied the effect of Fe additions preequilibrated with different Fe-binding ligands (L) including: the siderophore desferrioxamine B, two carbohydrates (glucuronic acid and carrageenan) and two different bacterial exopolycarbohydrates (L6 and L22, referred as EPS). For all stations, phytoplankton were able to acquire Fe associated to DFB as previously reported, however, different Fe:L ratios prevent quantitative comparison with other studies. Iron bound to carbohydrates, glucuronic acid, carrageenan and EPS could enhance or decrease Fe uptake rates in comparison to equimolar FeCl3 addition. These results illustrate that the effect of such L on Fe uptake rates will depend on the in-situ plankton community and their chemical structure. The variation of the Fe’ concentrations was able to explain up to 69% of the Fe uptake rates observed for the Antarctic communities. This relationship with Fe’ was related to the fact that the Fe’ maximal supply, due to the dissociation of FeL, was enough to satisfy the measured Fe uptakes rates. Calculations using previous reports in contrasted regions of the Southern Ocean, showed that Fe’ maximal supply was greater than Fe uptake rates measured in 80% of the cases. Moreover, considering photo- and redox-chemistry as well as kinetical situations prevailing in the field, Fe’ should not be overlooked as a pool able to satisfy most of the Fe biological demand. Finally, this study points towards the potential that the GEOTRACES Fe chemical speciation data represent to explore Fe uptake rates at a larger scale in this vast Fe-limited oceanic region.

Description: We assessed the qualitative composition of fluorescent dissolved organic matter (FDOM) in Arctic Ocean surface water and in sea ice north of the Svalbard Archipelago (in the Sophia Basin, the Yermak Plateau and the north Spitsbergen shelf) in May and June 2015, during the “TRANSSIZ” expedition (Transitions in the Arctic Seasonal Sea Ice Zone). Samples collected in open lead waters (OW), under-ice waters (UIW) and from the sea ice (ICE) were analyzed by fluorescence spectroscopy and subsequently by multivariate statistical methods using Parallel Factor Analysis (PARAFAC). Statistical analyses of all measured DOM fluorescence excitation and emission matrices (EEMs) enabled four components to be identified and validated. The spectral characteristics of the first component C1 (λEx/λEm 282(270)/335) corresponded to those of tryptophan. The spectral properties of the other three components corresponded to those of humic-like substances: components two (C2 − λEx/λEm 315(252)/395) and three (C3 − λEx/λEm 357(258)/446) corresponded to humic-like substances of marine origin, whereas component four (C4 − λEx/λEm 261(399)/492) resembled terrestrial humic-like substances. Changes in FDOM composition were recorded in OW, in contrast to UIW and sea ice. In the OW the sum of fluorescence intensities of humic-like components (C2, C3 and C4) was two times higher than the fluorescence intensity of protein-like component (C1). Component C2 exhibited the highest fluorescence intensity. In the UIW and particularly in the sea ice the fluorescence intensity of the protein-like component, IC1, was the highest. The IC1 in the sea ice increased toward the sea ice bottom, reaching maximum values at the sea ice-water interface. The calculated spectral indices (SUVA(254) and HIX) and ratios of fluorescence intensities of protein-like to humic-like components, Ip/Ih, suggested that FDOM in water and sea ice was predominantly autochthonous, characterized by low molecular weight organic compounds and low aromatic ring saturation. Enrichment factors Dc, calculated from salinity-normalized values of the optical DOM properties and dissolved organic carbon concentrations, indicated the significant fractionation of FDOM in the sea ice relative to the parent open waters. The humic-like terrestrial component C4 was enriched the least, whereas the protein-like component C1 was enriched the most. A statistically significant (p 〈 0.0001) and relatively strong (R = 63) correlation between IC1 and the total chlorophyll a concentration Tchla was found in the sea ice, which suggests that sympagic algal communities were producers of the protein-like FDOM fraction.

Description: Scotia Sea and the Drake Passage is key towards understanding the development of modern oceanic circulation patterns and their implications for ice sheet growth and decay. The sedimentary record of the southern Scotia Sea basins documents the regional tectonic, oceanographic and climatic evolution since the Eocene. However, a lack of accurate age estimations has prevented the calibration of the reconstructed history. The upper sedimentary record of the Scotia Sea was scientifically drilled for the first time in 2019 during International Ocean Discovery Program (IODP) Expedition 382, recovering sediments down to ∼643 and 676 m below sea floor in the Dove and Pirie basins respectively. Here, we report newly acquired high resolution physical properties data and the first accurate age constraints for the seismic sequences of the upper sedimentary record of the Scotia Sea to the late Miocene. The drilled record contains four basin-wide reflectors – Reflector-c, -b, -a and -a' previously estimated to be ∼12.6 Ma, ∼6.4 Ma, ∼3.8 Ma and ∼2.6 Ma, respectively. By extrapolating our new Scotia Sea age model to previous morpho-structural and seismic-stratigraphic analyses of the wider region we found, however, that the four discontinuities drilled are much younger than previously thought. Reflector-c actually formed before 8.4 Ma, Reflector-b at ∼4.5/3.7 Ma, Reflector-a at ∼1.7 Ma, and Reflector-a' at ∼0.4 Ma. Our updated age model of these discontinuities has major implications for their correlation with regional tectonic, oceanographic and cryospheric events. According to our results, the outflow of Antarctic Bottom Water to northern latitudes controlled the Antarctic Circumpolar Current flow from late Miocene. Subsequent variability of the Antarctic ice sheets has influenced the oceanic circulation pattern linked to major global climatic changes during early Pliocene, Mid-Pleistocene and the Marine Isotope Stage 11.

Description: Aquaculture development in Europe, while critical to the European Union (EU) Blue Growth strategy, has stagnated over the past decades due largely to high competition for space in the nearshore coastal zone among potential uses and the lack of clear priorities, policy, and planning at EU and national scales. Broad Marine Spatial Planning, including the designation of Allocated Zones for Aquaculture, requires spatial data at the corresponding broad spatial scale, which has not been readily available, as well as model projections to assess potential impacts of climate change. Here, daily chlorophyll-a, water temperature, salinity, and current speed outputs from a marine ecosystem model encompassing the coastal North East Atlantic, the North Sea, and the Mediterranean Sea (the pan-European POLCOMS-ERSEM model configuration) are used to drive a Dynamic Energy Budget growth model of Pacific oyster (Crassostrea gigas). Areas broadly suitable for growth were identified using threshold tolerance range masking applied using the model variables mentioned above, as well as bathymetry data. Oyster growth time series were transformed into simplified indicators that are meaningful to the industry (e.g., time to market weight) and mapped. In addition to early-century indicator maps, modelling and mapping were also carried out for two contrasting late-century climate change projections, following representative concentration pathways 4.5 and 8.5. Areas found to have good oyster growth potential now and into the future were further assessed in terms of their climate robustness (i.e., where oyster growth predictions are comparable between different future climate scenarios). Several areas within Europe were highlighted as priority areas for the development of offshore Pacific oyster cultivation, including coastal waters along the French Atlantic, the southern North Sea, and western Scotland and Ireland. A large potential growth hot spot was also identified along northwestern Africa, associated with a cool, productive upwelling coastal zone. The framework proposed here offers a flexible approach to include a large range of ecological input data, climate and ecosystem model scenarios, aquaculture-related models, species of interest, indicator types, and tolerance thresholds. Such information is suggested to be included in more extensive spatial assessments and planning, along with further socioeconomic and environmental data.

Description: Millennial scale variations of terrigenous provenance in marine realm are closely related to regional environment and climate changes. Therefore, a wealth of information of past environment and climate can be constrained via fingerprinting sediment provenance. The Sea of Japan is a unique marginal sea in the North Pacific due to its high sill and distinct thermohaline circulation. The modern hydrography in the Sea of Japan is mainly affected by the East Asian Monsoon and Tsushima Warm Current, one branch of the Kuroshio Current. The Sea of Japan communicates with neighboring seas through four shallow and narrow straits, indicating great effects of global eustatic sea level change on its environment over glacial-interglacial cycles. Here we examine the terrigenous provenance in fine-grained fraction (〈63 μm) of core KCES1, located near one end of the Tsushima Strait of the Sea of Japan over the last 48 ka, using radiogenic isotopes of strontium (Sr) and neodymium (Nd). Our data suggest that the terrigenous provenance in core KCES1 was mainly derived from the Yangtze River after 7 ka and a mixture of Yangtze and Yellow Rivers during the last glacial and deglacial periods. Notably, pronounced negative excursions of εNd values at HS1 were attributed to minor additions of unradiogenic Nd contribution from China-Korea cratonic hinterland. A binary mixing model further reveals that 〉85% terrigenous material is derived from the Yangtze and Yellow Rivers over the last 48 ka. Moreover, abrupt variations in sediment provenance occurred at ~18 ka and ~ 7 ka, which coincide with variations in oceanic surface circulation and deep ventilation recorded in the Sea of Japan. We suggest that paleo-Tsushima Warm Current invaded into the Sea of Japan with reopening of the Tsushima Strait at HS1 and the Tsushima Warm Current substantially entered the Sea of Japan after 7 ka due to intensified Kuroshio Current and rising eustatic sea level. The inflow of Tsushima Warm Current gives rise to a range of changes in surface hydrography, deep ventilation, ecological communities and productivity and sediment texture. The combination of fluxes of paleo-rivers and the intensity of Kuroshio Current, which are closely tied to the eustatic sea level and the East Asian Monsoon, plays a key role in controlling the variations in sediment provenance in the Ulleung Basin. Our study provides unique insight into the tight coupling between changes in sediment provenance and oceanic environment over the last 48 ka in the Sea of Japan.

Description: Brown shrimp, Crangon crangon, inhabit highly productive sandy and muddy grounds of the southern North Sea. The stomachs of the shrimp contain variable and often high numbers of sediment grains. The function of sediment grains inside the stomach and the purpose of their ingestion are only poorly understood. We tested in laboratory experiments whether sediment and associated organic material complement the natural food of C. crangon or if sand grains may be used by the shrimp to support trituration and maceration of ingested food. The shrimp showed no notable preference for sediment with natural organic content over sediment with reduced organic content, limited ingestion of sediment upon starvation, and no additional uptake of sand grains after feeding. Instead, C. crangon took up sediment only while feeding on regular food, suggesting that sand grains are not ingested intentionally but rather incidentally as a side effect of hasty gobbling. This conclusion is supported by the highly variable uptake of sand grains among individuals. Under experimental conditions, sand grains from sediments do not seem to have a crucial function in food processing and digestion in brown shrimp.

Description: Ocean sediment drifts contain important information about past bottom currents but a direct link between the study of sedimentary archives and ocean dynamics is not always possible. To close this gap for the North Atlantic, we set up a new coupled Ice-Ocean-Sediment Model of the N. Atlantic - Arctic region. In order to evaluate the potential dynamics of the model, we conducted decadal sensitivity experiments. In our model contouritic sedimentation shows a significant sensitivity towards climate variability for most of the contourite drift locations in the model domain. We observe a general decrease of sedimentation rates during warm conditions with decreasing atmospheric and oceanic gradients and an extensive increase of sedimentation rates during cold conditions with respective increased gradients. We can relate these results to changes in the dominant bottom circulation supplying deep water masses to the contourite sites under different climate conditions. A better understanding of northern deep water pathways in the Atlantic Meridional Overturning Circulation (AMOC) is crucial for evaluating possible consequences of climate change in the ocean.

Description: Rivers are an important transport route of anthropogenic litter from inland sources toward the sea. A citizen science approach was used to evaluate the litter pollution of rivers in Germany: schoolchildren within the project “Plastic Pirates” observed floating macrolitter at 282 sites and took meso-/microplastic samples (i.e. particles 1 mm - 25 mm) at over 164 sites across the entire country during the years 2016 and 2017. Floating macrolitter quantities ranged from 0 to 8.25 items m -1 h -1 (average of 0.34 ± 0.89 litter items m -1 h -1 ) and floating macrolitter was sighted at 54% of sampling sites. The quantities of floating meso-/microplastics ranged from 0 to 220 particles h -1 (average of 6.86 ± 24.11 meso-/microplastics h -1 ). They were present at 57% of the sampling sites. Given that only particles 〉 1 mm were sampled and analyzed, the pollution of rivers in Germany by microplastics is likely a ubiquitous problem, regardless of the size of the river. We identified six plastic pollution hotspots where 60% of all meso-/microplastics collected in the present study were found. The composition of the particles at these hotspots indicates plastic producers and possibly the construction industry and wastewater treatment plants as point sources. An identification of litter hotspots would enable specific mitigation measures, adapted to the respective source, and thereby prevent the release of large quantities of small plastic particles in rivers. The adopted large-scale citizen science approach was especially suitable to detect pollution hotspots by sampling a variety of rivers, large and small, and enabled a national overview of litter pollution in German rivers.

Description: We present a five-year (1997-2001) numerical simulation of daily mean chlorophyll a concentrations at station Geesthacht Weir on the lower Elbe River (Germany) using an extremely simple Lagrangian model driven by (a) water discharge, global radiation, water temperature, and (b) silica observations at station Schmilka in the upper reach of the Elbe River. Notwithstanding the lack of many mechanistic details, the model is able to reproduce observed chlorophyll a variability surprisingly well, including a number of sharp valleys and ascents/descents in the observed time series. The model's success is based on the assumption of three key effects: prevailing light conditions, sporadic limitation of algal growth due to lack of silica and algae loss rates that increase above an empirically specified temperature threshold of 20 degrees C. Trimmed-down model versions are studied to analyse the model's success in terms of these mechanisms. In each of the five years the model consistently fails, however, to properly simulate characteristic steep increases of chlorophyll a concentrations after pronounced spring minima. Curing this model deficiency by global model re-calibration was found to be impossible. However, suspension of silica consumption by algae for up to 10 days in spring is shown to serve as a successful placeholder for processes that are disregarded in the model but apparently play an important role in the distinctly marked period of model failure. For the remainder of the year the very simple model was found to be adequate

Description: A simple Lagrangian water quality model was designed to investigate the hypothesis of sporadic silica limitations of diatom growth in the lower Elbe River in Germany. For each fluid parcel a limited reservoir of silica was specified to be consumed by diatoms. The model's simplicity notwithstanding, a set of six selected model parameters could not be fully identified from existing observations at one station. After the introduction of prior knowledge of the ranges of meaningful parameter values, calibration of the over-parameterised model manifested itself primarily in the generation of posterior parameter covariances. Estimations of the covariance matrix based on (a) second order partial derivatives of a quadratic cost function at its optimum and (b) Monte Carlo simulations exploring the whole space of parameter values gave consistent results. Diagonalisation of the covariance matrix yielded two linear parameter combinations that were most effectively controlled by data from periods with and without lack of silica, respectively. The two parameter combinations were identified as the essential inputs that govern the successful simulation of intermittently decreasing chlorophyll a concentrations in summer. A satisfactory simulation of the pronounced chlorophyll a minimum in spring, by contrast, was found to be beyond the means of the simple model.

Description: We studied the impact of the last glacial (late Weichselian) sea level cycle on sediment architecture in theinner Kara Sea using high-resolution acoustic sub-bottom profiling. The acoustic lines were ground-truthedwith dated sediment cores. Furthermore we refined the location of the eastern LGM ice margin, by new subbottom profiles. New model results of post-Last Glacial Maximum (LGM) isostatic rebound for this area allowa well-constrained interpretation of acoustic units in terms of sequence stratigraphy. The lowstand (orregressive) system tract sediments are absent but are represented by an unconformity atop of Pleistocenesediments on the shelf and by a major incised dendritic paleo-river network. The subsequent transgressiveand highstand system tracts are best preserved in the incised channels and the recent estuaries while onlyminor sediment accumulation on the adjacent shelf areas is documented. The Kara Sea can be subdividedinto three areas: estuaries (A), the shelf (B) and (C) deeper lying areas that accumulated a total of 114 x1010 t of Holocene sediments.

Description: Monitoring changes in eukaryotic microbial communities is critical for understanding ecosystem dynamics, trophic interactions and the impacts of climate change. Long-term time series are an important tool for monitoring changes in ecological communities, but time series from a single location may not be representative of regional dynamics. In the German Bight, the Helgoland Roads time series is such a long-term series. Here, we consider the spatial dynamics of the eukaryotic microbes as an indicator of the representativeness of the Helgoland Roads site for the coastal German Bight, which is located in the North Sea. The eukaryotic microbial community in the German Bight was analysed at Helgoland Roads and two coastal stations (Cuxhaven and Wilhelmshaven) between March and October 2016 using metabarcoding. In addition, an oceanographical model was used to check for potential hydrological connectivity between the stations during the sampling period. Our results showed that the communities were different at the three stations. Helgoland was dominated by dinoflagellates, whereas the coastal stations had more diverse communities. Furthermore, differences were observed in the dinoflagellate and diatom communities between the three stations. Lagrangian particle tracking applied to the model results, showed limited connectivity between Helgoland and the coastal stations in 2016. The differences between Helgoland and the coastal stations were correlated with the different hydrological regimes and associated nutrient contents. Our observations suggest the presence of different eukaryotic microbial communities separated by complex hydrological conditions in the coastal German Bight.

Description: For most fish species raised in marine aquaculture, the use of live feeds cannot be replaced by formulated diets. Artemia nauplii and rotifers are still the most commonly used live feeds. A good alternative lies in the use of copepods which could lead to the cultivation of new fish species. Cold stored subitaneous eggs from the continuously cultured calanoid copepod Acartia tonsa were used to investigate the effect of storage upon the viability of the eggs, the development of the copepod community originating from the cold stored eggs. Finally a 3 days snapshot of the egg production of the first generation of females was followed. This was done in order to develop a database usable within copepod dependent hatcheries. The viability of cold stored A. tonsa eggs remained high (〉 70% hatching rate) for 11 months of storage. Generally, the period of storage was observed to decrease the viability (hatching rate) of the eggs and no hatching was observed after twenty months of cold storage. Hatched populations of copepods experienced increased mortality rate with longer storage of the eggs from which they originated. This mortality ranged from 0.035 to 0.13 d− 1 for non-stored (fresh) and 12 months stored eggs, respectively. However, all copepod communities originating from fresh to 12 months stored eggs reached adulthood. Additionally, the egg production from the stored generation was apparently normal and the viability of their eggs was not statistically different when compared to productions from non-stored communities. Contents of total fatty acids decreased during the storage period. Contents of free amino acids were not statistically different for eggs cold stored up to 12 months, but had decreased severely by 20 months. In conclusion, we consider it safe to store the eggs for up to one year at 2–3 °C during which the eggs retain their viability and biochemical composition. Cold storage of calanoid copepod eggs is relevant for aquaculture as inoculum for culturing live food.

Description: The seawater temperature rise promotes the growth of potentially human pathogenic Vibrio species. In the North Sea, V. parahaemolyticus strains have been isolated and characterized. These strains contain prophages that may contribute to the emergence of pathogenic strains in the marine environment. Here, we present the genome structure and possible biological functions of the inducible phage vB_VpaI_VP-3218, a novel filamentous phage carried by the V. parahaemolyticus strain VN-3218. Prophages of the strain VN-3218 were induced with mitomycin C and the DNA from the phage induction was sequenced. Two incomplete prophages were identified, only one complete phage genome with length of 11,082 bp was characterized. The phage vB_VpaI_VP-3218 belongs to the Inoviridae family and shows close homology to the Saetivirus genus. This phage can integrate into the chromosomal host genome and carries host-related regions absent in similar phage genomes, suggesting that this phage integrates within other host genomes. Furthermore, this phage might have a role in pathogenicity due to potential zonula occludens toxin genes. Based on genomic similarity, this phage is an episomally reversible integrated lysogenic phage. This study complements prophage induction and bioinformatic studies applied to non-model species of potentially pathogenic Vibrio species. The characterization of this phage provides new insights with respect to the presence of filamentous phages in environmental V. parahaemolyticus strains, which might have a role in the emergence of new pathogenic strains in the North Sea.

Description: The abundance of the alien, Indo-Pacific damselfish Neopomacentrus cyanomos on an oil-loading platform in the southwest Gulf of Mexico indicates that widely distributed platforms could facilitate the expansion of its geo- graphic range across the western and northern fringes of the Gulf. From there it likely will spread to other areas of the Greater Caribbean. The lionfish example demonstrates that it eventually happens, and can do so rapidly. Reduced temperature effects on the physiology of this species were examined to better predict its survivability in the northern Gulf during winter, when sea surface temperatures fall as low as 15 °C along the coast. Overall, our results show that when the degree of experimental temperature decline was large and rapid, no compensation occurred and the stress response observed mostly reflected cellular processes that minimized damage. Integrated biomarker response values were significantly different between fish rapidly exposed to colder vs. warmer temperatures (declines of −4 °C each day, from 26 to 14 °C), reflected in higher values of blood metabolites and routine metabolic rates observed in fish exposed to 14 and 18 °C respectively, and lower activity of all enzymes, lower protein carbonylation, and higher oxidative damage to lipids in fish exposed to 14 °C. While the phy- siological proxies responded to minimize damage during the rapid-decrease experiment, the same proxies re- flected the consequences of compensation when fish were thermally challenged after a 45 days acclimation at 18 °C. In this case, lower values of blood metabolites and high antioxidant levels and indicators of damages underpinned its pejus lower range. Based on the results of the present work, it seems clear that low winter SSTs in the northern Gulf will slow down the colonization of the inshore area of N. cyanomos. We suggest that the use of physiological cellular stress markers on specimens acquired at the beginning of an invasion should be im- plemented in new standardized experimental protocols, including both rapid increases/decreases of temperature and post-acclimation temperature challenges, to assess the invasiveness potential of aquatic species such as this.

Description: The marine-based West Antarctic Ice Sheet (WAIS) is considered the most unstable part of the Antarctic Ice Sheet, with particular vulnerability in the Amundsen Sea sector where glaciers are melting at an alarming rate. Far-field sea-level data and ice-sheet models have pointed towards at least one major WAIS disintegration during the Late Quaternary, but direct evidence for past collapse(s) from ice-proximal geological archives remains elusive. In order to facilitate geochemical and mineralogical tracing of the two most important glaciers draining into the Amundsen Sea, i.e. Pine Island Glacier (PIG) and Thwaites Glacier (TG), we here provide the first multi-proxy provenance analysis of 26 seafloor surface sediment samples from Pine Island Bay. Our data show that the fingerprints of detritus delivered by PIG and TG are clearly distinct near the ice-shelf fronts of both ice-stream systems for all grain sizes and proxies investigated. Glacial detritus delivered by PIG is characterised by low εNd values (~−9), high 87Sr/86Sr ratios (~0.728), low smectite content (〈10%), and hornblende and biotite grains with Late Permian to Jurassic (170–270 Ma) cooling ages. In contrast, glacigenic detritus delivered by TG is characterised by higher εNd values (~−4), lower 87Sr/86Sr ratios (0.714), higher smectite (20%) and kaolinite content (37%), biotite and hornblende grains with 40Ar/39Ar cooling ages of 〈40 Ma and ~115 Ma, and high content of mafic mineral. The geochemical and mineralogical fingerprints for PIG and TG reported here provide novel insights into sub-ice geology and allow us to trace both drainage systems in the geological past, under environmental conditions more similar to those envisioned in the next 50 to 100  years.

Description: Harmful algal blooms (HABs) are occurring more frequently in the world’s oceans, probably as a consequence of climate change. HABs have not been considered a serious concern in the Arctic, even though the Arctic warms faster than any other region. While phycotoxins and toxin-producing phytoplankton have been found in Arctic waters on several occasions, there is a lack of information on seasonal succession of species and whether the occurrence of harmful species correlates with the presence of their respective phycotoxins. Hence, there is no baseline to assess future changes of HABs in this area. Here, we investigated two periods, from winter to spring and from the spring bloom until summer, in Disko Bay, West Greenland and followed the succession of toxins and their producers using metabarcoding, as well as analyses of particulate and dissolved toxins. We observed a typical seasonal succession with a spring bloom dominated by diatoms, followed by dinoflagellates in summer, with the two most important potentially toxic taxa found being Pseudo-nitzschia spp. and Alexandrium ostenfeldii. The Pseudo-nitzschia spp. peak correlated with a clear increase in particulate domoic acid, reaching 0.05 pg/L. Presence of Alexandrium ostenfeldii could be linked to an increase in spirolides, up to 56.4 pg/L in the particulate phase. Generally, the majority of detected dissolved toxins followed the succession pattern of the particulate toxins with a delay in time. Our results further show that Arctic waters are a suitable habitat for various toxin producers and that the strong seasonality of this environment is reflected by changing abundances of different toxins that pose a potential threat to the ecosystem and its beneficiaries.