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

The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment. Here we present a 1500-year multiproxy record of near-bottom water redox changes from the coastal zone of the northern Baltic Sea, encompassing the climatic phases of the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), and the Modern Warm Period (MoWP). Our reconstruction shows that although multicentennial climate variability has modulated depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented, and besides gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. Alongside the anthropogenic nutrient input, the progressive deoxygenation since the beginning of the1900s was fueled by the combined effects of gradual shoaling of the basin and warming climate, which amplified sediment focusing and increased the vulnerability to hypoxia. Importantly, the eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s. We find no evidence of similar anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal water quality. Furthermore, this study highlights the need for combined use of sedimentological, ichnological, and geochemical proxies in order to robustly reconstruct subtle redox shifts especially in dynamic, non-euxinic coastal settings with strong seasonal contrasts in the bottom water quality.

The geochemical measurements within the long-lived, crustose coralline red alga Clathromorphum compactum in calibration experiments, and the environmental conditions selected for the controlled laboratory aquaria.

Data from pore water (subterranean estuary) and seawater from Spiekeroog south (near ICBM time series station and campsite, 53°45'13.5"N 7°40'22.5"E) and west beach ("Sturmeck", 53°46'10.0"N 7°40'26.2"E). South beach data were collected in August 2012, and west beach data were collected in November 2012. Sample abbreviations: SB=South Beach, WB=West Beach. DUNE=most landward station near dunes, MIX=mid-way station between dune base and low water line, LTWL=low tide water line. Pore water (DUNE, MIX, LTWL) sample collection was conducted at different sediment depths (50, 100, 150 cm below sediment surface). Stainless steel push-point lancets were insetred into the sediment, and pore water was withdrawn via vacuum (hand pumps) into nalgene polycarbonate bottles. Filtration was done using inline PES cartridge filters. The vacuum bottles were argon gas-flushed to avoid oxygen contamination. Sea water (SW) was collected with polycarbonate bottles and from LDPE seepage meter bags (SP) and filtered upon return to the laboratory (same day, PES filter cartridges). Sample collection was trace organic and metal clean (soaking and rinsing of bottles, tubing, and filters with diluted HNO3 and HCl suprapur), with sample materials consisting of polyethylene, polypropylene, and polycarbonate. Solid-phase extraction was done with BOND Elut PPL cartridges and elution with Methanol Optima grade. Measurements were done with VA Computrace 757 (Cu ligand concentrations and stability constants), HR-ICP-MS (Cu, Fe, and Mn concentrations), FT-ICR-MS (DOM), spectrophotometry (nutrients), and TOC analyzer (DOC and TDN). Trace metal concentrations (Fe, Cu, Mn) and speciation (oxidation state, size fractions, and organic association), as well as nitrogen species and concentrations: "Spiekeroog beach subterranean estuary environmental data". Concentrations (µM or nM) are denoted in the headers. CuL1=Cu-binding ligands concentrations (nM), logK1=Cu-binding ligand stability constant. Molecular composition of dissolved organic matter and associated Fe and Cu: "Spiekeroog beach STE_ESI_x_Crosstab_x". pos & neg = positive and negative ionization mode. BSA & NWA = basic/strong acidic and neutral/weak acidic, refer to the extracted DOM fraction. Processed figures and tables based on the original data are published here: https://doi.org/10.1016/j.gca.2019.06.004

Biochemical data from 3 different regions; Cape Verde, the Baltic Sea, and Norwegian fjords/Sea. discreet samples for TEP, Chl a, POC, PON and nutrients as well as 2 and 24 hour average data on sea state parameters; temperature, salinity, PAR and wind speed. Vertical profile data for TEP, POC, TCN, small autotrophs and Chl a are also presented for depths of 0-2m, sampled in the Baltic and Norwegian Seas.

Attempts have been made to study the entire growth history of a manganese nodule from the northern part of Peru Basin in the Pacific using radiochemical profiles of 230Th232Th, 227Th230Th, and 10Be9Be. Combined with the observations on Fe-Mn contents and textural variation, the radiochemical data indicate that the nodule grew more or less concentrically throughout most of its existence since it formed 1.5 my ago, receiving Mn from both bottom water and pore water. This condition appeared to have changed about 180 ky ago when the growth became asymmetric in that the top and bottom sides became fixed in their relative positions on the sea floor. Since then, the bottom side accreted with a fast rate of close to 200 mm/my, apparently fueled by the supply of diagenetically remobilized Mn in pore water from the sediment substrate. In the meantime, the top side accumulated at about 6 mm/my, a value which is in the normal range for deep-sea nodules having their Mn supplied from the hydrogenous source.

Halocarbons, halogenated short-chained hydrocarbons, are produced naturally in the oceans by biological and chemical processes. They are emitted from surface seawater into the atmosphere, where they take part in numerous chemical processes such as ozone destruction and the oxidation of mercury and dimethyl sulfide. Here we present oceanic and atmospheric halocarbon data for the Peruvian upwelling obtained during the M91 cruise onboard the research vessel Meteor in December 2012. Surface waters during the cruise were characterized by moderate concentrations of bromoform (CHBr3) and dibromomethane (CH2Br2) correlating with diatom biomass derived from marker pigment concentrations, which suggests this phytoplankton group as likely source. Concentrations measured for the iodinated compounds methyl iodide (CH3I) of up to 35.4 pmol L-1, chloroiodomethane (CH2ClI) of up to 58.1 pmol L-1 and diiodomethane (CH2I2) of up to 32.4 pmol L-1 in water samples were much higher than previously reported for the tropical Atlantic upwelling systems. Iodocarbons also correlated with the diatom biomass and even more significantly with dissolved organic matter (DOM) components measured in the surface water. Our results suggest a biological source of these compounds as significant driving factor for the observed large iodocarbon concentrations. Elevated atmospheric mixing ratios of CH3I (up to 3.2 ppt), CH2ClI (up to 2.5 ppt) and CH2I2 (3.3 ppt) above the upwelling were correlated with seawater concentrations and high sea-to-air fluxes. The enhanced iodocarbon production in the Peruvian upwelling contributed significantly to tropospheric iodine levels.

These datasets were used to describe the diversity, ecology and role of non-scleractinian corals on scleractinian cold-water coral carbonate mounds in the Logachev Mound Province, Rockall Bank, NE Atlantic. Cold-water coral carbonate mounds, created by framework-building scleractinian corals, are also important habitats for non-scleractinian corals, whose ecology and role are understudied in deep-sea environments. In total ten non-scleractinian species were identified, which were mapped out along eight ROV video transects. Eight species were identified as black corals (three belonging to the family Schizopathidae, one each to the Leiopathidae, Cladopathidae, and Antipathidae and two to an unknown family) and two as gorgonians (Isididae and Plexauridae). The most abundant species were Leiopathes sp. and Parantipathes sp. 2. Areas with a high diversity of non-scleractinian corals are interpreted to offer sufficient food, weak inter-species competition and the presence of heterogeneous and hard settlement substrates. A difference in the density and occurrence of small vs. large colonies of Leiopathes sp. was also observed, which is likely related to a difference in the stability of the substrate they choose for settlement. Non-scleractinian corals, especially black corals, are an important habitat for crabs, crinoids, and shrimps in the Logachev Mound Province.

Kelp forests represent a major habitat type in coastal waters worldwide and their structure and distribution is predicted to change due to global warming. Despite their ecological and economical importance, there is still a lack of reliable spatial information on their abundance and distribution. In recent years, various hydroacoustic mapping techniques for sublittoral environments evolved. However, in turbid coastal waters, such as off the island of Helgoland (Germany, North Sea), the kelp vegetation is present in shallow water depths normally excluded from hydroacoustic surveys. In this study, single beam survey data consisting of the two seafloor parameters roughness and hardness were obtained with RoxAnn from water depth between 2 and 18 m. Our primary aim was to reliably detect the kelp forest habitat with different densities and distinguish it from other vegetated zones. Five habitat classes were identified using underwater-video and were applied for classification of acoustic signatures. Subsequently, spatial prediction maps were produced via two classification approaches: Linear discriminant analysis (LDA) and manual classification routine (MC). LDA was able to distinguish dense kelp forest from other habitats (i.e. mixed seaweed vegetation, sand, and barren bedrock), but no variances in kelp density. In contrast, MC also provided information on medium dense kelp distribution which is characterized by intermediate roughness and hardness values evoked by reduced kelp abundances. The prediction maps reach accordance levels of 62% (LDA) and 68% (MC). The presence of vegetation (kelp and mixed seaweed vegetation) was determined with higher prediction abilities of 75% (LDA) and 76% (MC). Since the different habitat classes reveal acoustic signatures that strongly overlap, the manual classification method was more appropriate for separating different kelp forest densities and low-lying vegetation. It became evident that the occurrence of kelp in this area is not simply linked to water depth. Moreover, this study shows that the two seafloor parameters collected with RoxAnn are suitable indicators for the discrimination of different densely vegetated seafloor habitats in shallow environments.

Two high-resolution sediment cores from eastern Fram Strait have been investigated for sea subsurface and surface temperature variability during the Holocene (the past ca 12,000 years). The transfer function developed by Husum and Hald (2012) has been applied to sediment cores in order to reconstruct fluctuations of sea subsurface temperatures throughout the period. Additional biomarker and foraminiferal proxy data are used to elucidate variability between surface and subsurface water mass conditions, and to conclude on the Holocene climate and oceanographic variability on the West Spitsbergen continental margin. Results consistently reveal warm sea surface to subsurface temperatures of up to 6 °C until ca 5 cal ka BP, with maximum seawater temperatures around 10 cal ka BP, likely related to maximum July insolation occurring at that time. Maximum Atlantic Water (AW) advection occurred at surface and subsurface between 10.6 and 8.5 cal ka BP based on both foraminiferal and dinocyst temperature reconstructions. Probably, a less-stratified, ice-free, nutrient-rich surface ocean with strong AW advection prevailed in the eastern Fram Strait between 10 and 9 cal ka BP. Weakened AW contribution is found after ca 5 cal ka BP when subsurface temperatures strongly decrease with minimum values between ca 4 and 3 cal ka BP. Cold late Holocene conditions are furthermore supported by high planktic foraminifer shell fragmentation and high d18O values of the subpolar planktic foraminifer species Turborotalita quinqueloba. While IP25-associated indices as well as dinocyst data suggest a sustained cooling due to a decrease in early summer insolation and consequently sea-ice increase since about 7 cal ka BP in surface waters, planktic foraminiferal data including stable isotopes indicate a slight return of stronger subsurface AW influx since ca 3 cal ka BP. The observed decoupling of surface and subsurface waters during the later Holocene is most likely attributed to a strong pycnocline layer separating cold sea-ice fed surface waters from enhanced subsurface AW advection. This may be related to changes in North Atlantic subpolar versus subtropical gyre activity.