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  • 2020-2022  (8)
  • 1
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    INTER-RESEARCH
    In:  EPIC3Diseases of Aquatic Organisms, INTER-RESEARCH, 141, ISSN: 0177-5103
    Publication Date: 2020-11-12
    Description: The brown shrimp Crangon crangon is a key component of the North Atlantic coastal food web and an important target species for the fishery economy. As the brown shrimp contains large amounts of protein and essential fatty acids, its consumption makes it a beneficial choice for humans. Commercially harvested crustaceans like C. crangon are frequently affected by bacterial shell disease, with necrotizing erosions and ulcerations of the cuticle. To determine whether shell disease influences the nutritional value of C. crangon, total protein and lipid contents, as well as fatty acid compositions of muscle tissue and hepatopancreas, together with the hepatosomatic index, were examined in healthy and affected individuals. The biochemical composition of the tissues did not differ significantly between the 2 groups. Also, the hepatosomatic index, as an indicator of energy reserves in shrimps, was similar between healthy and affected animals. Our results indicate that the nutritional value of C. crangon is not affected by shell disease, as long as it remains superficial as in the present study.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    In:  EPIC3Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 248-24, pp. 110465, ISSN: 10964959
    Publication Date: 2020-07-21
    Description: The brown shrimp, Crangon crangon, is well adapted to the variable environmental conditions in the southern North Sea. It is very abundant, has high reproduction rates, and holds a key position in coastal ecosystems. This species has very low lipid deposits in the midgut gland, suggesting that the main function of the midgut gland is metabolic turnover rather than energy storage. Based on seasonal gene expression studies and established transcriptome data, we investigated key components of lipid metabolic pathways. Gene expression of triacylglycerol lipase, phospholipase, and fatty acid desaturase were analyzed and compared with that of other digestive enzymes involved in lipid, carbohydrate, and protein catabolism. Our results suggest that gene expression of digestive enzymes involved in lipid metabolism is modulated by the lipid content in the midgut gland and is related to food availability. Brown shrimp seem to be capable of using cellular phospholipids during periods of food paucity but high energetic (lipid) requirements. Two of three isoforms of fatty acid binding proteins (FABPs) from the midgut gland involved in fatty acid transport showed specific mutations of the binding site. We hypothesize that the mutations in FABPs and deficiencies in anabolic pathways limit lipid storage capacities in the midgut gland of C. crangon. In turn, food utilization, including lipid catabolism, has to be efficient to fulfill the energetic requirements of brown shrimp.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
    Publication Date: 2021-05-25
    Description: Background: Trophic interactions are key processes, which determine the ecological function and performance of organisms. Many decapod crustaceans feed on plant material as a source for essential nutrients, e.g. polyunsaturated fatty acids. Strictly herbivorous feeding appears only occasionally in marine decapods but is common in land crabs. To verify food preferences and to establish trophic markers, we studied the lipid and fatty acid composition of the midgut glands of two marine crab species (Grapsus albolineatus and Percnon affine), one semi-terrestrial species (Orisarma intermedium, formerly Sesarmops intermedius), and one terrestrial species (Geothelphusa albogilva) from Taiwan. Results: All species showed a wide span of total lipid levels ranging from 4 to 42% of the dry mass (%DM) in the marine P. affine and from 3 to 25%DM in the terrestrial G. albogilva. Triacylglycerols (TAG) were the major storage lipid compound. The fatty acids 16:0, 18:1(n-9), and 20:4(n-6) prevailed in all species. Essential fatty acids such as 20:4(n-6) originated from the diet. Terrestrial species also showed relatively high amounts of 18:2(n-6), which is a trophic marker for vascular plants. The fatty acid compositions of the four species allow to clearly distinguish between marine and terrestrial herbivorous feeding due to significantly different amounts of 16:0, 18:1(n-9), and 18:2(n-6). Conclusions: Based on the fatty acid composition, marine/terrestrial herbivory indices were defined and compared with regard to their resolution and differentiating capacity. These indices can help to reveal trophic preferences of unexplored species, particularly in habitats of border regions like mangrove intertidal flats and estuaries.
    Repository Name: EPIC Alfred Wegener Institut
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  • 4
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    royalsocietypublishing.org/journal/rstb
    In:  EPIC3Philosophical Transactions of the Royal Society B: Biological Sciences, royalsocietypublishing.org/journal/rstb, 375(1804), pp. 20190647, ISSN: 0962-8436
    Publication Date: 2020-06-17
    Description: The study revealed species- and stage-specific differences in lipid accumulation of the dominant Antarctic copepods, the primarily herbivorous Calanoides acutus (copepodite stage V (CV), females) and the more omnivorous Calanus propinquus (females) storing wax esters and triacylglycerols, respectively, which were collected in summer (end of December). Feeding carbon-labelled diatoms to these copepods, 13C elucidated assimilation and turnover rates of copepod total lipids as well as specific fatty acids and alcohols. The 13C incorporation was monitored by compound-specific stable isotope analysis (CSIA). CV stages of C. acutus exhibited an intense total lipid turnover and 55% of total lipidswere labelled after 9 days of feeding. By contrast, total lipid assimilation of female C. acutus and C. propinquus was lower with 29% and 32%, respectively. The major dietary fatty acids 16:0, 16:1(n − 7) and 20:5(n − 3) had high turnover rates in all specimens. In C. acutus CV, the high rates of the de novo synthesized long-chain monounsaturated fatty acids and alcohols 20:1(n − 9) and 22:1(n − 11) indicate intense lipid deposition, whereas these rates were low in females. The differences in lipid assimilation and turnover clearly show that the copepod species exhibit a high variability and plasticity to adapt their lipid production to their various life phases. This article is part of the theme issue ‘The next horizons for lipids as ‘trophic biomarkers’: evidence and significance of consumer modification of dietary fatty acids’.
    Repository Name: EPIC Alfred Wegener Institut
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  • 5
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    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Global Ecology and Biogeography, WILEY-BLACKWELL PUBLISHING, 29(6), pp. 1008-1019, ISSN: 1466-822X
    Publication Date: 2020-06-17
    Description: Aim Biodiversity dynamics comprise evolutionary and ecological changes on multiple temporal scales from millions of years to decades, but they are often interpreted within a single time frame. Planktonic foraminifera communities offer a unique opportunity for analysing the dynamics of marine biodiversity over different temporal scales. Our study aims to provide a baseline for assessments of biodiversity patterns over multiple time-scales, which is urgently needed to interpret biodiversity responses to increasing anthropogenic pressure. Location Global (26 sites). Time period Five time-scales: multi-million-year (0-7 Myr), million-year (0-0.5 Myr), multi-millennial (0-15 thousand years), millennial (0-1,100 years) and decadal (0-32 years). Major taxa studied Planktonic foraminifera. Methods We analysed community composition of planktonic foraminifera at five time-scales, combining measures of standing diversity (richness and effective number of species, ENS) with measures of temporal community turnover (presence-absence-based, dominance-based). Observed biodiversity patterns were compared with the outcome of a neutral model to separate the effects of sampling resolution (the highest in the shortest time series) from biological responses. Results Richness and ENS decreased from multi-million-year to millennial time-scales, but higher standing diversity was observed on the decadal scale. As predicted by the neutral model, turnover in species identity and dominance was strongest at the multi-million-year time-scale and decreased towards the millennial scale. However, contrary to the model predictions, modern time series show rapid decadal variation in the dominance structure of foraminifera communities, which is of comparable magnitude as over much longer time periods. Community turnover was significantly correlated with global temperature change, but not on the shortest time-scale. Main conclusions Biodiversity patterns can be to some degree predicted from the scaling effects related to different durations of time series, but changes in the dominance structure observed over the last few decades reach higher magnitude, probably forced by anthropogenic effects, than those observed over much longer durations.
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
    Publication Date: 2020-03-09
    Description: In this study, a three-dimensional, coupled ocean ecosystem model (FESOM- REcoM2) is used to investigate the effect of krill on the biogeochemistry of the Southern Ocean. The implementation of Antarctic krill in the model was done in three steps. 1) A second zooplankton group was implemented, which grazes on diatoms, mesozooplankton and nanophytoplankton (in order of descending preference). 2) A new detritus group was added to the model, which represents faster-sinking krill fecal pellets. 3) The grazing impact of both zooplankton groups on detritus was described. Afterward, four different simulations (control and three krill simulations for previously described steps) were conducted to evaluate, how the implementation of the new zooplankton group and additional features affected biogeochemical processes in the Southern Ocean. In our krill simulation, the spatial distribution of krill biomass in the Southern Ocean was reasonably reproduced. Preliminary results showed that the proportion of living compartments (phytoplankton and zooplankton groups) in the model changed, which led to different POC (particulate organic carbon) flux pathways to the deep ocean. Zooplankton biomass contribution to total carbon biomass increased from 2.4% to 10% in our model in the Southern Ocean. The contribution of zooplankton to POC production doubled. The implementation of krill in the ecosystem model enhanced nutrient recycling in the upper ocean layer. Therefore, our novel krill implementation improved the bias between model and observations in surface spatial distributions of the macronutrients silicic acid and nitrate.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 7
    Publication Date: 2021-09-06
    Description: Submesoscale structures, characterized by intense vertical and horizontal velocities, potentially play a crucial role in oceanographic dynamics and pelagic fluxes. Due to their small spatial scale and short temporal persistence, conditions for in situ measurements are challenging and thus the role of such structures for zooplankton distribution is still unclear. During RV Polarstern expedition PS107 to Arctic Fram Strait in July/August 2017, a submesoscale filament was detected, which initiated an ad hoc oceanographic and biological sampling campaign. To determine zooplankton taxonomic composition, horizontal and vertical distribution, abundance and biomass, vertical MultiNet hauls (depth intervals: 300–200–100–50–10–0 m) were taken at four stations across the filament. Zooplankton data were evaluated in context with the physical-oceanographic observations of the filament to assess submesoscale physical-biological interactions. Our data show that submesoscale features considerably impact zooplankton dynamics. While structuring the pelagial with distinct zooplankton communities in a vertical as well as horizontal dimension, they accumulate abundance and biomass of epipelagic species at the site of convergence. Further, high-velocity jets associated with such dynamics are possibly of major importance for species allocation and biological connectivity, accelerating for instance processes such as the ‘Atlantification’ of the Arctic. Thus, submesoscale features affect the surrounding ecosystem in multiple ways with consequences for higher trophic levels and biogeochemical cycles.
    Repository Name: EPIC Alfred Wegener Institut
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  • 8
    Publication Date: 2021-12-08
    Description: Macrozooplankton and its grazing pressure shape ecosystem structures and carbon pathways in the Southern Ocean. Here, we present the implementation of “polar macrozooplankton” as a plankton functional type and a related fast-sinking detritus class (fecal pellets) into the biogeochemical model REcoM-2. We use the model to assess major carbon pathways and ecosystem structure in the Southern Ocean south of 50°S. The model represents zooplankton biomass and its spatial distribution in the Southern Ocean reasonably well in comparison to available biomass data. A distinct difference of our model from previous versions is the seasonal pattern of particle formation processes and ecosystem structures in the Southern Ocean. REcoM-2 now captures high zooplankton biomass and a typical shift from a dominance of phytodetrital aggregates in spring to zooplankton fecal pellets later in the year. At sites with high biomass of macrozooplankton, the transfer efficiency of particulate organic carbon can be as high as 50%, and the carbon content of the exported material increases. In our simulations, macrozooplankton is an important component of the Southern Ocean plankton community, contributing up to 0.12 Pg C per year (14%) to total modeled carbon export across 100 m depth. Macrozooplankton changes the phytoplankton composition and supports the recycling of macronutrients. These results support the important role of macrozooplankton such as krill in the Southern Ocean and have implications for the representation of Southern Ocean biogeochemical cycles in models.
    Repository Name: EPIC Alfred Wegener Institut
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