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  • PANGAEA  (17)
  • Public Library of Science  (3)
  • 2010-2014  (20)
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  • 1
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    Public Library of Science
    In:  PLoS ONE, 8 (9). e71528.
    Publication Date: 2017-06-22
    Description: Shrinking of body size has been proposed as one of the universal responses of organisms to global climate warming. Using phytoplankton as an experimental model system has supported the negative effect of warming on body-size, but it remains controversial whether the size reduction under increasing temperatures is a direct temperature effect or an indirect effect mediated over changes in size selective grazing or enhanced nutrient limitation which should favor smaller cell-sizes. Here we present an experiment with a factorial combination of temperature and nutrient stress which shows that most of the temperature effects on phytoplankton cell size are mediated via nutrient stress. This was found both for community mean cell size and for the cell sizes of most species analyzed. At the highest level of nutrient stress, community mean cell size decreased by 46% per degrees C, while it decreased only by 4.7% at the lowest level of nutrient stress. Individual species showed qualitatively the same trend, but shrinkage per degrees C was smaller. Overall, our results support the hypothesis that temperature effects on cell size are to a great extent mediated by nutrient limitation. This effect is expected to be exacerbated under field conditions, where higher temperatures of the surface waters reduce the vertical nutrient transport.
    Type: Article , PeerReviewed
    Format: text
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  • 2
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    Public Library of Science
    In:  PLoS ONE, 7 (11). e49632.
    Publication Date: 2018-01-22
    Description: Decreasing body size has been suggested as the third universal biological response to global warming after latitudinal/altitudinal range shifts and shifts in phenology. Size shifts in a community can be the composite result of intraspecific size shifts and of shifts between differently sized species. Metabolic explanations for the size shifts dominate in the literature but top down effects, i.e. intensified size-selective consumption at higher temperatures, have been proposed as alternative explanation. Therefore, we performed phytoplankton experiments with a factorial combination of warming and consumer type (protist feeding mainly on small algae vs. copepods mainly feeding on large algae). Natural phytoplankton was exposed to 3 (1st experiment) or 4 (2nd experiment) temperature levels and 3 (1st experiment: nano-, microzooplankton, copepods) or 2 (2nd experiment: microzooplankton, copepods) types of consumers. Size shifts of individual phytoplankton species and community mean size were analyzed. Both, mean cell size of most of the individual species and mean community cell size decreased with temperature under all grazing regimes. Grazing by copepods caused an additional reduction in cell size. Our results reject the hypothesis, that intensified size selective consumption at higher temperature would be the dominant explanation of decreasing body size. In this case, the size reduction would have taken place only in the copepod treatments but not in the treatments with protist grazing (nano- and microzooplankton).
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2018-12-11
    Description: Our present understanding of ocean acidification (OA) impacts on marine organisms caused by rapidly rising atmospheric carbon dioxide (CO2) concentration is almost entirely limited to single species responses. OA consequences for food web interactions are, however, still unknown. Indirect OA effects can be expected for consumers by changing the nutritional quality of their prey. We used a laboratory experiment to test potential OA effects on algal fatty acid (FA) composition and resulting copepod growth. We show that elevated CO2 significantly changed the FA concentration and composition of the diatom Thalassiosira pseudonana, which constrained growth and reproduction of the copepod Acartia tonsa. A significant decline in both total FAs (28.1 to 17.4 fg cell−1) and the ratio of long-chain polyunsaturated to saturated fatty acids (PUFA:SFA) of food algae cultured under elevated (750 µatm) compared to present day (380 µatm) pCO2 was directly translated to copepods. The proportion of total essential FAs declined almost tenfold in copepods and the contribution of saturated fatty acids (SFAs) tripled at high CO2. This rapid and reversible CO2-dependent shift in FA concentration and composition caused a decrease in both copepod somatic growth and egg production from 34 to 5 eggs female−1 day−1. Because the diatom-copepod link supports some of the most productive ecosystems in the world, our study demonstrates that OA can have far-reaching consequences for ocean food webs by changing the nutritional quality of essential macromolecules in primary producers that cascade up the food web.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 4
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    PANGAEA
    In:  EPIC3Bremerhaven, PANGAEA
    Publication Date: 2014-12-18
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
    Format: application/pdf
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  • 5
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    PANGAEA
    In:  Supplement to: Paul, Carolin; Matthiessen, Birte; Sommer, Ulrich (2015): Warming, but not enhanced CO2 concentration, quantitatively and qualitatively affects phytoplankton biomass. Marine Ecology Progress Series, 528, 39-51, https://doi.org/10.3354/meps11264
    Publication Date: 2023-04-25
    Description: We investigated the impacts of predicted ocean acidification and future warming on the quantity and nutritional quality of a natural phytoplankton autumn bloom in a mesocosm experiment. Since the effects of CO2-enrichment and temperature have usually been studied independently, we were also interested in the interactive effects of both aspects of climate change. Therefore, we used a factorial design with two temperature and two acidification levels in a mesocosm experiment with a Baltic Sea phytoplankton community. Our results show a significant time-dependent influence of warming on phytoplankton carbon, chlorophyll a as well as POC. Phytoplankton carbon for instance decreased by more than a half with increasing temperature at bloom time. Additionally, elemental carbon to phosphorus ratios (C:P) increased significantly by approximately 5-8 % under warming. Impacts of CO2 or synergetic effects of warming and acidification could not be detected. We suggest that temperature-induced stronger grazing pressure was responsible for the significant decline in phytoplankton biomass. Our results suggest that biological effects of warming on Baltic Sea phytoplankton are considerable and will likely have fundamental consequences for the trophic transfer in the pelagic food-web.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 6
    Publication Date: 2023-03-25
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; Cell biovolume; Cryptophyta, cell biovolume; Diatom, cell biovolume; Identification; Species; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 160 data points
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  • 7
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    PANGAEA
    In:  Supplement to: Sommer, Ulrich; Paul, Carolin; Moustaka-Gouni, Maria (2015): Warming and Ocean Acidification Effects on Phytoplankton—From Species Shifts to Size Shifts within Species in a Mesocosm Experiment. PLoS ONE, 10(5), e0125239, https://doi.org/10.1371/journal.pone.0125239
    Publication Date: 2023-02-24
    Description: While the isolated responses of marine phytoplankton to climate warming and to ocean acidification have been studies intensively, studies on the combined effect of both aspects of Global Change are still scarce. Therefore, we performed a mesocosm experiment with a factorial combination of temperature (9 and 15°C) and pCO2 (560 ppm and 1400 ppm) with a natural autumn plankton community from the western Baltic Sea. Temporal trajectories of total biomass and of the biomass of the most important higher taxa followed similar patterns in all treatments. When averaging over the entire time course, phytoplankton biomass decreased with warming and increased with CO2 under warm conditions. The contribution of the two dominant higher phytoplankton taxa (diatoms and cryptophytes) and of the 4 most important species (3 diatoms, 1 cryptophyte) did not respond to the experimental treatments. Taxonomic composition of phytoplankton showed only responses at the level of subdominant and rare species. Phytoplankton cell sizes increased with CO2 addition and decreased with warming. Both effects were stronger for larger species. Warming effects were stronger than CO2 effects and tended to counteract each other. Phytoplankton communities without calcifying species and exposed to short-term variation of COO2 seem to be rather resistant to ocean acidification.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 8
    Publication Date: 2023-02-24
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; Cell biovolume; DATE/TIME; Day of experiment; Diameter; Identification; Name; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 5815 data points
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  • 9
    Publication Date: 2023-02-24
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; Cell biovolume; Cell size; Identification; Species
    Type: Dataset
    Format: text/tab-separated-values, 9232 data points
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  • 10
    Publication Date: 2023-02-24
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; Cell density; DATE/TIME; Day of experiment; Identification; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 3962 data points
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