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  • 1
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (49 Seiten)
    Series Statement: Maria S. Merian-Berichte MSM 21/3
    Language: English
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  • 2
    Keywords: Forschungsbericht
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (13 Seiten, 386,74 KB)
    Language: German
    Note: Förderkennzeichen BMBF 01LS1714A , Verbundnummer 01180468 , Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden
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  • 3
    Publication Date: 2019-09-23
    Description: This study aimed to reveal the dynamics of inducible anti-herbivory traits in the brown seaweed Fucus vesiculosus, in response to grazing by the isopod Idotea baltica. As the molecular basis of defence induction in seaweeds is poorly understood, a transcriptomic approach was used to gain insight into cellular processes underlying defence induction and thus promote the mechanistic understanding of anti-herbivory responses in seaweeds. In a 27 day feeding-assayed induction experiment, temporal patterns of the induced anti-herbivory resistance of F. vesiculosus were assessed under laboratory conditions. Feeding assays were performed at three day intervals, using fresh and reconstituted food. Microarray hybridizations investigating the expression of genes 3 days before, as well as at the same time as, feeding assays revealed a decreased palatability of previously grazed F. vesiculosus pieces compared with non-grazed control pieces. Despite permanent exposure to grazers, F. vesiculosus palatability varied over time. Non-grazed F. vesiculosus pieces were significantly preferred to grazed pieces after 18 and again after 27 days of previous grazing, while their relative palatability for isopods was comparable at all other times during the experiment. Relative to controls, 562/402 genes were ≥ 1.5-fold up-/down-regulated in seaweed pieces that were grazed for 18 days, i.e. when induction of defences was detected in feeding assays. Massive reprogramming of the regulatory expression orchestra (translation, transcription) as well as up-regulation of genes involved in lipid and carbohydrate metabolism, intracellular trafficking, defence and stress response was found. At the same time, down-regulation of photosynthesis was observed in grazed seaweed pieces. This study suggests a high level of temporal variability in induced anti-herbivory traits of F. vesiculosus and reveals increased expression of genes with putative defensive functions in conjunction with the reallocation of resources from primary to secondary metabolism.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
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  • 4
    Publication Date: 2014-04-22
    Description: Ocean acidification is considered a major threat to marine ecosystems and may particularly affect calcifying organisms such as corals, foraminifera and coccolithophores. Here we investigate the impact of elevated pCO2 and lowered pH on growth and calcification in the common calcareous dinoflagellate Thoracosphaera heimii. We observe a substantial reduction in growth rate, calcification and cyst stability of T. heimii under elevated pCO2. Furthermore, transcriptomic analyses reveal CO2 sensitive regulation of many genes, particularly those being associated to inorganic carbon acquisition and calcification. Stable carbon isotope fractionation for organic carbon production increased with increasing pCO2 whereas it decreased for calcification, which suggests interdependence between both processes. We also found a strong effect of pCO2 on the stable oxygen isotopic composition of calcite, in line with earlier observations concerning another T. heimii strain. The observed changes in stable oxygen and carbon isotope composition of T. heimii cysts may provide an ideal tool for reconstructing past seawater carbonate chemistry, and ultimately past pCO2. Although the function of calcification in T. heimii remains unresolved, this trait likely plays an important role in the ecological and evolutionary success of this species. Acting on calcification as well as growth, ocean acidification may therefore impose a great threat for T. heimii.
    Type: Article , PeerReviewed
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  • 5
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    In:  [Talk] In: Wissenschaftliche Tagung der Sektion Phykologie der Deutschen Botanischen Gesellschaft, 23.-26.02.2014, Stralsund, Germany .
    Publication Date: 2014-04-24
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 6
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 7
    Publication Date: 2020-02-06
    Description: We studied the effect of ocean acidification (OA) on a coastal North Sea plankton community in a long-term mesocosm CO2-enrichment experiment (BIOACID II long-term mesocosm study). From March to July 2013, 10 mesocosms of 19 m length with a volume of 47.5 to 55.9 m3 were deployed in the Gullmar Fjord, Sweden. CO2 concentrations were enriched in five mesocosms to reach average CO2 partial pressures (pCO2) of 760 μatm. The remaining five mesocosms were used as control at ambient pCO2 of 380 μatm. Our paper is part of a PLOS collection on this long-term mesocosm experiment. Here, we here tested the effect of OA on total primary production (PPT) by performing 14C-based bottle incubations for 24 h. Furthermore, photoacclimation was assessed by conducting 14C-based photosynthesis-irradiance response (P/I) curves. Changes in chlorophyll a concentrations over time were reflected in the development of PPT, and showed higher phytoplankton biomass build-up under OA. We observed two subsequent phytoplankton blooms in all mesocosms, with peaks in PPT around day 33 and day 56. OA had no significant effect on PPT, except for a marginal increase during the second phytoplankton bloom when inorganic nutrients were already depleted. Maximum light use efficiencies and light saturation indices calculated from the P/I curves changed simultaneously in all mesocosms, and suggest that OA did not alter phytoplankton photoacclimation. Despite large variability in time-integrated productivity estimates among replicates, our overall results indicate that coastal phytoplankton communities can be affected by OA at certain times of the seasonal succession with potential consequences for ecosystem functioning.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 8
    Publication Date: 2024-04-03
    Description: Climate change is opening the Arctic Ocean to increasing human impact and ecosystem changes. Arctic fjords, the region’s most productive ecosystems, are sustained by a diverse microbial community at the base of the food web. Here we show that Arctic fjords become more prokaryotic in the picoplankton (0.2–3 µm) with increasing water temperatures. Across 21 fjords, we found that Arctic fjords had proportionally more trophically diverse (autotrophic, mixotrophic, and heterotrophic) picoeukaryotes, while subarctic and temperate fjords had relatively more diverse prokaryotic trophic groups. Modeled oceanographic connectivity between fjords suggested that transport alone would create a smooth gradient in beta diversity largely following the North Atlantic Current and East Greenland Current. Deviations from this suggested that picoeukaryotes had some strong regional patterns in beta diversity that reduced the effect of oceanographic connectivity, while prokaryotes were mainly stopped in their dispersal if strong temperature differences between sites were present. Fjords located in high Arctic regions also generally had very low prokaryotic alpha diversity. Ultimately, warming of Arctic fjords could induce a fundamental shift from more trophic diverse eukaryotic- to prokaryotic-dominated communities, with profound implications for Arctic ecosystem dynamics including their productivity patterns.
    Type: Article , PeerReviewed
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  • 9
    Publication Date: 2021-08-27
    Description: Population substructure of the cuttlefish Sepia officinalis (Mollusca: Cephalopoda), as investigated by genetic variation of microsatellite loci, has been reported to be significantly extensive around the Iberian Peninsula with FST = 0.061 [Pérez-Losada, M., Guerra, A., Carvalho, G.R., Sanjuan, A., Shaw, P.W., 2002. Extensive population subdivision of the cuttlefish Sepia officinalis (Mollusca: Cephalopoda) around the Iberian Peninsula indicated by microsatellite DNA variation. Heredity 89, 417–424] and panmictic in the semi-enclosed Adriatic Sea with FST = 0.011 [Garoia, F., Guarniero, I., Ramsak, A., Ungaro, N., Landi, M., Piccinetti, C., Mannini, P., Tinti, F., 2004. Microsatellite DNA variation reveals high gene flow and panmictic populations in the Adriatic shared stocks of the European squid and cuttlefish (Cephalopoda). Heredity 93, 166–174]. Yet, no verified genetic information on population substructure existed for the northern distribution range of this species in the English Channel and the Bay of Biscay. So far, reproductive and migration behaviour and in vitro oxygen binding properties of haemocyanin have suggested the existence of separate populations in the English Channel and the Bay of Biscay. Examination of genetic variation at seven microsatellite loci within samples from the Bay of Biscay, the English Channel and the southern North Sea indicated low levels of genetic differentiation in this area but also a breakdown of free gene flow at highly significant average FST = 0.018. Although there is a considerable genetic exchange between populations of S. officinalis in the English Channel and the Bay of Biscay, they cannot be regarded as a single, freely interbreeding population. Earlier reported biological differences might thus be due to genetic variability between the populations.
    Type: Article , PeerReviewed
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  • 10
    Publication Date: 2022-01-31
    Description: The physiological processes driving the rapid rates of calcification in larval bivalves are poorly understood. Here, we use a calcification substrate-limited approach (low dissolved inorganic carbon, CT) and mRNA sequencing to identify proteins involved in bicarbonate acquisition during shell formation. As a secondary approach, we examined expression of ion transport and shell matrix proteins (SMPs) over the course of larval development and shell formation. We reared four families of Mytilus edulis under ambient (ca. 1865 µmol/kg) and low CT (ca. 941 µmol/kg) conditions and compared expression patterns at six developmental time points. Larvae reared under low CT exhibited a developmental delay, and a small subset of contigs was differentially regulated between ambient and low CT conditions. Of particular note was the identification of one contig encoding an anion transporter (SLC26) which was strongly upregulated (2.3–2.9 fold) under low CT conditions. By analyzing gene expression profiles over the course of larval development, we are able to isolate sequences encoding ion transport and SMPs to enhance our understanding of cellular pathways underlying larval calcification processes. In particular, we observe the differential expression of contigs encoding SLC4 family members (sodium bicarbonate cotransporters, anion exchangers), calcium-transporting ATPases, sodium/calcium exchangers, and SMPs such as nacrein, tyrosinase, and transcripts related to chitin production. With a range of candidate genes, this work identifies ion transport pathways in bivalve larvae and by applying comparative genomics to investigate temporal expression patterns, provides a foundation for further studies to functionally characterize the proteins involved in larval calcification.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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