1,721,124 research outputs found
Phytoplankton carbon related biomass of each species/ taxa or group of indoor mesocosm experiment 2014
No full textPrevious studies with Baltic Sea phytoplankton combining elevated seawater temperature with CO2 revealed the importance of size trait-based analyses, in particular dividing the plankton in-to edible (> 5 and 100 µm) size classes for mesozoopankton grazers. While the edible phytoplankton responded predominantly negative to warming and the inedible group stayed unaffected or increased, independent from edibility most phyto-plankton groups gained from CO2. Because the ratio between edible and inedible taxa changes profoundly over seasons, we investigated, if community responses can be predicted according to the prevailing composition of edible and inedible groups. We experimentally explored the combined effects of elevated temperatures and CO2 concentrations on a late-summer Baltic Sea community. Total phytoplankton significantly increased in response to elevated CO2 in particu-lar in combination with temperature, driven by a significant gain of the inedible < 5 µm fraction and large filamentous cyanobacteria. Large flagellates disappeared. The edible group was low as usual in summer and decreased with both factors due to enhanced copepod grazing and overall decline of small flagellates. Our results emphasize that the responses of summer communities are complex, but can be predicted by the composition and dominance of size classes and groups
Temperature, salinity, CO2, dissolved inorganic nutrients, plankton stoichiometry of indoor mesocosm experiment 2014
No full textPrevious studies with Baltic Sea phytoplankton combining elevated seawater temperature with CO2 revealed the importance of size trait-based analyses, in particular dividing the plankton in-to edible (> 5 and 100 µm) size classes for mesozoopankton grazers. While the edible phytoplankton responded predominantly negative to warming and the inedible group stayed unaffected or increased, independent from edibility most phyto-plankton groups gained from CO2. Because the ratio between edible and inedible taxa changes profoundly over seasons, we investigated, if community responses can be predicted according to the prevailing composition of edible and inedible groups. We experimentally explored the combined effects of elevated temperatures and CO2 concentrations on a late-summer Baltic Sea community. Total phytoplankton significantly increased in response to elevated CO2 in particu-lar in combination with temperature, driven by a significant gain of the inedible < 5 µm fraction and large filamentous cyanobacteria. Large flagellates disappeared. The edible group was low as usual in summer and decreased with both factors due to enhanced copepod grazing and overall decline of small flagellates. Our results emphasize that the responses of summer communities are complex, but can be predicted by the composition and dominance of size classes and groups
Trait measurements and long-term experiment on maintenance of intraspecific diversity using genotypes of phytoplankton species Chaetoceros affinis and Emiliania huxleyi
No full textMeasurements of cell density, nutrient concentration and genotype composition in a long term experiment (91 days) with the marine phytoplankton species Chaetoceros affinis and Emiliania huxleyi, each consisting of nine genotypes. Cultivation of species was done separately in mono-cultures and together in mix-cultures at three different nutrient regimes (10N:1P, 20N:1P, and 30N:1P) with increasing nitrate concentration in a semi-continuous batch cycle system. Transfer of part of the cells into bottles with new nutrients every 7 days at fixed batch cycle length and after 7,4, and 10 days in a recurring fashion at variable batch cycle length. With the information about the genotype abundance we assessed how intraspecific diversity is maintained in response to species competition and nutrient fluctuations. Individual trait measurements for growth, nutrient uptake, and cell volume of the genotypes at seven nitrate levels in a 4-day experiment allowed us to connect traits to the genotype sorting of the long term experiment
Culture experiment with microalgae metacommunities on effects of a regional heatwave disturbance on species diversity and turnover
No full textIn a culture experiment with microalgae metacommunities, we tested the effects of a regional heatwave disturbance on species diversity (richness, Shannon diversity) and turnover. The metacommunities consisted of three local communities with different initial community compositions. In our full factorial design, half of the metacommunities were subject to dispersal (every other day) and exposed to an experimental heatwave. Communities were sampled after 5, 12, and 21 days
Plankton and dissolved nutrient data from 2016 mesocosm experiment manipulating Si:N and copepod grazing on Baltic Sea plankton community
No full textPhytoplankton, microzooplankton, copepod and dissolved nutrient data from a mesocosm experiment, which took place in summer 2016. A range of Si:N ratios and two levels of copepod grazing pressure were manipulated on a natural plankton community in Kiel Bay, Southern Baltic Sea, Germany
Intraspecific cell size variability in the marine diatom Chaetoceros affinis along a nutrient gradient
No full textThe role of interspecific variability on the functioning of phytoplankton communities along environmental gradients has been well studied, while today still too little is known about the role of intraspecific variability, which may occur at an inter- and/or intragenotypic level.
Nine different genotypes of Chaetoceros affinis were incubated under different nitrate concentrations: first altogether and with another stably coexisting species, the coccolitophore Emiliania huxleyi, through a long-term community experiment (199 days); then individually, through a short-term plasticity experiment (7 days). A significant intraspecific variability in cell size of Chaetoceros affinis was detected in both the experiments. According to a trait-based perspective, while no correspondence was observed among the cell size and nitrate concentrations at the intergenotypic level, the biggest cells were detected at the highest nitrate concentrations at the intragenotipic level in the community experiment in the long-term. This drove an increase in C. affinis mean cell size and total biomass along the nitrate gradient. In the plasticity experiment, significant differences in cell size along the nitrate gradient determined important variations in cellular nutrient content and stoichiometry at both the inter- and intragenotypic level.
This work provides new findings on the intraspecific variability in phytoplankton morpho-functional traits and underlines the importance of considering this when phytoplankton responses to environmental changes are investigated
Intraspecific variability in cell size and nutrient uptake-related traits of Chaetoceros affinis in different nutrient regimes
No full textIntraspecific trait variability can determine how phytoplankton species respond to environmental changes, and ultimately can influence the food web structure in aquatic ecosystems.
In this study, we individually incubated each of nine genotypes of the diatom Chaetoceros affinis in seven different nitrate regimes, spanning a gradient from nitrate limitation (2.5N:1P) over Redfield ratio to phosphate limitation (40N:1P). After seven days, we measured cell size, cellular carbon (POC) and nitrogen (PON) contents, stoichiometry (nitrogen to phosphorus ratio, N:P, and carbon to nitrogen ratio, C:N) as well as their potential correlations in each treatment. The aim was to investigate, if changes in cell size along the nitrate gradient determined variations in cellular nutrients and stoichiometry at two intraspecific levels, i.e. the inter- and intragenotypic level. According to preliminary results, cell size correlated positively with C:N at both levels of intraspecific variability, positively with POC at the intergenotypic level, and negatively with PON at the intragenotypic level. This translated into larger cells accumulated more C than N under stoichiometrically N-limited conditions.
These findings add insights on the importance of intraspecific cell size variability on cellular nutrients and stoichiometry along nutrient gradients, highlighting the need to study intraspecific dynamics both among and within genotypes
Experimentally assessing ecological and evolutionary relative importance to abundance changes observed in an artificial phytoplankton community consisting of E. huxleyi and C. affinis exposed to increased CO2
No full textThis dataset includes only information specific to the Eco-Evo assay applied to a long term community selection experiment. The community contained Emiliania huxleyi and Chaetoceros affinis (detailes about Species and genotypes used can be found in DOI:10.1098/rsbl.2016.0774). The long term community selection phase to ambient and high CO2 (400 and 1250ppm, respectively) started on the 10th of January 2017, details about the first 10 semi-continuous batch cycles can be found in DOI:10.1594/PANGAEA.887780. Further the raw data from the subsequent Eco-Evo assay are presented as well as the calculated relative importances of species and genotype sorting. To validate the novel Eco-Evo assay also Reaction Norm based approaches were applied and raw data and calculated values are included in this dataset. Details on assay setup and calculation procedures and validation can be found in the related manuscript. Additional data show abundances in mono species cultures of the same species as used in the community of the long-term experimental selection and their nutrient uptake over one Batch cycle
Mesocosm experiment on warming and acidification effects in 2012: Nutrients and elemental composition
No full textlow = 560 ppmhigh = 1400 pp
- …
