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    Publication Date: 2021-04-13
    Description: Global oceanographic monitoring initiatives originally measured abiotic essential ocean variables but are currently incorporating biological and metagenomic sampling programs. There is, however, a large knowledge gap on how to infer bacterial functions, the information sought by biogeochemists, ecologists, and modelers, from the bacterial taxonomic information (produced by bacterial marker gene surveys). Here, we provide a correlative understanding of how a bacterial marker gene (16S rRNA) can be used to infer latitudinal trends for metabolic pathways in global monitoring campaigns. From a transect spanning 7000 km in the South Pacific Ocean we infer ten metabolic pathways from 16S rRNA gene sequences and 11 corresponding metagenome samples, which relate to metabolic processes of primary productivity, temperature-regulated thermodynamic effects, coping strategies for nutrient limitation, energy metabolism, and organic matter degradation. This study demonstrates that low-cost, high-throughput bacterial marker gene data, can be used to infer shifts in the metabolic strategies at the community scale.
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 5
    Publication Date: 2021-02-23
    Description: The meroplanktonic larvae of benthic organisms are an important seasonal component of the zooplankton in temperate coastal waters. The larvae of the reef-building polychaete Lanice conchilega contribute up to 15% of the summer zooplankton biomass in the North Sea. Despite their importance for reef maintenance (which positively affects the benthic community), little is known about the trophic ecology of this meroplanktonic larva. Qualitative and quantitative estimates of carbon (C) transfer between trophic levels and of fatty acid (FA)—specific assimilation, biosynthesis, and bioconversion can be obtained by compound- specific stable isotope analysis of FA. The present work tested the hypothesis that the concept of fatty acid trophic markers (FATM), widely used for studies on holoplankton with intermediate to high lipid contents, is also applicable to lipid-poor organisms such as meroplanktonic larvae. The incorporation of isotopically-enriched dietary C by L. conchilega larvae was traced, and lipid assimilation did not follow FA-specific relative availabilities in the diet. Furthermore, FAs that were unavailable in the diet, such as 22:5(n-3), were recorded in L. conchilega, suggesting their bioconversion by the larvae. The results indicate that L. conchilega larvae preferentially assimilate certain FAs and regulate their FA composition (lipid homeostasis) independently of that of their diet. Their quasi-homeostatic response to dietary FA availability could imply that the concept of FATM has limited application in lipid-poor organisms such as L. conchilega larvae.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 6
    Publication Date: 2016-12-01
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
    Publication Date: 2017-01-24
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
    Publication Date: 2022-10-10
    Description: 〈jats:p〉Consumer regulation of lipid composition during assimilation of dietary items is related to their ecology, habitat, and life cycle, and may lead to extra energetic costs associated with the conversion of dietary material into the fatty acids (FAs) necessary to meet metabolic requirements. For example, lipid-rich copepods from temperate and polar latitudes must convert assimilated dietary FAs into wax esters, an efficient type of energy storage which enables them to cope with seasonal food shortages and buoyancy requirements. Lipid-poor copepods, however, tend to not be as constrained by food availability as their lipid-rich counterparts and, thus, should have no need for modifying dietary FAs. Our objective was to test the assumption that 〈jats:italic〉Temora longicornis〈/jats:italic〉, a proxy species for lipid-poor copepods, does not regulate its lipid composition. Isotopically-enriched (〈jats:sup〉13〈/jats:sup〉C) diatoms were fed to copepods during a 5-day laboratory experiment. Compound-specific stable isotope analysis of algae and copepod samples was performed in order to calculate dietary FA assimilation, turnover, and assimilation efficiency into copepod FAs. Approximately 65% of the total dietary lipid carbon (C) assimilated (913 ± 68 ng C ind〈jats:sup〉-1〈/jats:sup〉 at the end of the experiment) was recorded as polyunsaturated FAs, with 20 and 15% recorded as saturated and monounsaturated FAs, respectively. As expected, 〈jats:italic〉T. longicornis〈/jats:italic〉 assimilated dietary FAs in an unregulated, non-homeostatic manner, as evidenced by the changes in its FA profile, which became more similar to that of their diet. Copepods assimilated 11% of the total dietary C (or 40% of the dietary lipid C) ingested in the first two days of the experiment. In addition, 34% of their somatic growth (in C) after two days was due to the assimilation of dietary C in FAs. Global warming may lead to increased proportions of smaller copepods in the oceans, and to a lower availability of algae-produced essential FAs. In order for changes in the energy transfer in marine food webs to be better understood, it is important that future investigations assess a broader range of diets as well as lipid-poor zooplankton from oceanographic areas throughout the world’s oceans.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 9
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    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Aquaculture Research, WILEY-BLACKWELL PUBLISHING, 47(9), pp. 3001-3015, ISSN: 1355-557X
    Publication Date: 2023-06-21
    Description: Octopus vulgaris is a viable candidate for commercial aquaculture, but rearing procedures might stress individuals and result in diminished growth and survival. This study investigated the relationship between possible stress sources (tank transposition and syphoning) when rearing O. vulgaris paralarvae and the deposition pattern of growth increments in their beak microstructure. Light intensity at the facility was heterogeneous, and accounted for with an experimental design consisting of blocks without replicates. Growth and survival were estimated and possible effects of handling were tested for both parameters. Increments and stress marks were counted in 120 paralarval upper jaws (UJ), and the number of UJs with a mark on the day of stress application (day 8) was quantified. Differences in light intensity, diet quantity and total number of marks in the UJ were also compared between treatments. Growth and survival were statistically similar between treatments, although the control treatment showed a tendency for higher survival rates. Age at first increment deposition coincided with day 1 of experiment, and a 1 increment day−1 deposition rate was validated for the experiment duration. The number of stress marks was significantly different between the control and other treatments, indicating that handling might cause stress and that marks can be used as a biomarker for stress, although the occurrence of stress marks on day 8 was not significantly different. Light intensity and diet might have also been relevant stressors and confounded the results. The results herein presented are important for improving rearing conditions for O. vulgaris paralarvae.Octopus vulgaris is a viable candidate for commercial aquaculture, but rearing procedures might stress individuals and result in diminished growth and survival. This study investigated the relationship between possible stress sources (tank transposition and syphoning) when rearing O. vulgaris paralarvae and the deposition pattern of growth increments in their beak microstructure. Light intensity at the facility was heterogeneous, and accounted for with an experimental design consisting of blocks without replicates. Growth and survival were estimated and possible effects of handling were tested for both parameters. Increments and stress marks were counted in 120 paralarval upper jaws (UJ), and the number of UJs with a mark on the day of stress application (day 8) was quantified. Differences in light intensity, diet quantity and total number of marks in the UJ were also compared between treatments. Growth and survival were statistically similar between treatments, although the control treatment showed a tendency for higher survival rates. Age at first increment deposition coincided with day 1 of experiment, and a 1 increment day−1 deposition rate was validated for the experiment duration. The number of stress marks was significantly different between the control and other treatments, indicating that handling might cause stress and that marks can be used as a biomarker for stress, although the occurrence of stress marks on day 8 was not significantly different. Light intensity and diet might have also been relevant stressors and confounded the results. The results herein presented are important for improving rearing conditions for O. vulgaris paralarvae. Volume 47, Issue 9 September 2016 Pages 3001–3015
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 10
    Publication Date: 2023-06-21
    Description: Zooplanktonic organisms are often vulnerable to fluctuations in food supply. Their population dynamics is directly influenced by changes in phytoplankton availability and nutritional quality, which in turn is affected by changes in parameters such as nutrient loading. The aim of this study was to investigate how nitrogen (N) limitation in prey (i.e., food quality) affects the performance of zooplankton. Females of the copepod Temora longicornis and larvae of the polychaete Lanice conchilega were sampled in May and June 2016 off the German island of Helgoland, in the southern North Sea, for five-day laboratory feeding experiments. They were fed with diets of different quality - diatoms and dinoflagellates cultured in nutrient-replete (Diat and Dino , respectively) and in N-depleted (Diata and Dinoa , respectively) conditions. Sodium bicarbonate enriched with the 13C isotope (NaH13CO3) was added to prey cultures in order to label dietary fatty acids (FA) and to follow carbon (C) transfer into copepods and polychaetes. Zooplankton performance was assessed by analysis of the elemental and biochemical compositions and of the assimilation and turnover of C in copepods and polychaetes, and by measuring copepod physiological rates. Copepods feeding on Dino had the highest investment in somatic and reproductive growth. Copepods feeding on Diata had the highest N excretion rates. Egestion was a major pathway for eliminating excess C, and low food quality affected respiration rates and the intensity and speed with which dissolved organic carbon leaked from faecal pellets. Copepod physiological rates indicated that dinoflagellates are a food source of superior or similar quality to diatoms under nutrient-replete or N-depleted conditions, respectively. In addition, copepods feeding on Diata showed the highest lipid C assimilation and turnover rates. These results suggest a shift in copepod resource allocation (reproductive output or lipid accumulation) depending on food quality. Experiments with the polychaete revealed that larvae are able to regulate their lipid C content (homeostasis) regardless of the availability of dietary FA via selective accumulation and biosynthesis of FA. Lipid C assimilation results from both species, together with literature data, were used to formulate a hypothesis on different patterns of lipid homeostasis in zooplankton. These results present a robust contribution towards a better understanding of how zooplanktonic organisms might be affected by changes in the quality of their prey in the near future.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Thesis , notRev
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