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73 results for “phytoplankton community”

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dryad36/100

Community composition and photosynthetic physiology of phytoplankton in the western subarctic Pacific near the Kuril Islands with special reference to iron availability

The western subarctic Pacific (WSP) is known as one of the most productive regions among the world's oceans in spring. However, its oceanic waters are also known as a High Nutrient, Low Chlorophyll (HNLC) region during summer due to low iron (Fe) availability in seawater. Indeed, recent studies have demonstrated that the distribution of Fe in the WSP is complex and heterogeneous. This study thus investigated the effects of Fe availability on the community composition and photophysiology of surface phytoplankton from coastal to offshore waters in the WSP in the summer of 2014. Although relatively high concentrations (>2 mg m–3) of chlorophyll (chl) a were found in the Sea of Okhotsk and some coastal waters, low chl a concentrations (<1 mg m–3) were commonly observed. Based on dissolved Fe and macronutrient concentrations, we deduced that low Fe availability limited phytoplankton growth in offshore waters, whereas low silicate and/or nitrate levels limited growth in the shelf areas. Scanning electron microscopy also revealed that the centric diatom Chaetoceros exclusively dominated the diatom assemblages in the shelf and coexisted with pennate diatoms in offshore waters, respectively. Primary productivity in surface waters was negatively correlated with the bottom of the euphotic layer or the light saturation index of the photosynthesis–irradiance curve, which indicates that the phytoplankton assemblages were well acclimated to in situ light conditions regardless of the water masses.

opencc-zeroMay 2020View details →

zenodo36/100

Light spectrum matters: Interactive effects of light and nutrients on phytoplankton communities and trophic transfer

Phytoplankton is highly sensitive to both the quantity (intensity) and quality (spectrum) of available light, due to a large range of light-absorbing pigments. While light is considered as a main driver for trophic energy transfer, focus has been primarily on the intensity of light. This study investigated the role of different light spectra on the community structure and biochemical composition of natural phytoplankton. We found that light spectrum affects the species composition and biochemistry of phytoplankton communities with these effects being highly dependent on light intensity and nutrients. Additionally, we tested for potential nutritional constraints for the zooplankton species Daphnia pulex in response to changes in the phytoplankton community and found different growth responses of D. pulex as a result of changing mineral and biochemical growth contraints for the Daphnia species. We conclude that, beyond nutrients and light intensity, also the light spectrum influences plankton dynamics and trophic transfer in aquatic systems.

opencc-by-4.0Nov 2024View details →

dryad36/100

Environmental stoichiometry mediates phytoplankton diversity effects on communities' resource use efficiency and biomass

Positive biodiversity-ecosystem functioning (BEF) relationships are predicted to increase in strength when high environmental variability allows for complementarity between resource use strategies in diverse communities. This environmental variability can be represented by spatial or temporal variation in nutrient ratios, but resource use efficiency (RUE) and therefore biomass build up of primary producers might be restricted when nutrient ratios are highly imbalanced (i.e., limitation by one nutrient and beyond optimal ratios for growth). Whereas the linkages between ecosystem functioning, diversity and nutrient availability are theoretically well understood, we lack experimental evidence on how phytoplankton diversity affects resource use and biomass under variable nutrient ratios (N:P ratios). Combining a mesocosm and a microcosm experiment we tested diversity effects on ecosystem functioning by exposing a species diversity gradient generated by the loss of rare species in a natural community to different N:P ratios (uniform vs a gradient). The N:P supply ratio gradient also allowed us to evaluate responses across balanced and imbalanced ratios. We found that increased species diversity led to increased community RUE when supplied a gradient of N:P ratios; but restricted to the highest diversity level. However, diversity did not affect RUE under uniform nutrient ratios. The overall phytoplankton biomass and carbon:nutrient ratios responses to diversity reflected the patterns detected for RUE. Contrary to theoretical predictions, RUE was maintained under highest N:P supply ratios (extreme phosphorous limitation) suggesting that imbalanced N:P ratios do not necessarily decrease function. Thus, we showed that the nutrient context influences diversity effects on RUE and biomass. Synthesis. Overall, our results suggest that the effect of rare phytoplankton species losses on community RUE and biomass can be compensated by the persistent species when nutrient ratios are uniform, but leads to decreases in ecosystem functioning under variable nutrient ratios. This work provides a first attempt for testing interactions between the nutrient context (including concentrations and ratios) and the diversity of (natural) communities experimentally, which is conceptually understood but poorly tested for phytoplankton.

opencc-zeroNov 2021View details →

zenodo36/100

Biovolumes data of the phytoplankton communities in mesocosm experiments

To test the short-term response of the phytoplankton community of an African lake, Lagoon Aghien (Ivory Coast), to the addition of nutrients (phosphorus and nitrogen, alone or in combination) and Nile tilapia, we implemented an in situ mesocosm experiment in two stations of this lagoon. The composition of the phytoplankton communities in these mesocosms was estimated at Day 0, Day 3 and Day 7 and the biovolume values of each genus were reported in the table.

opencc-by-4.0Mar 2022View details →

dryad36/100

Data from: Snail communities increase submerged macrophyte growth by grazing epiphytic algae and phytoplankton in a mesocosm experiment

The relationships between producers (e.g., macrophytes, phytoplankton and epiphytic algae) and snails play an important role in maintaining the function and stability of shallow ecosystems. Complex relationships exist among macrophytes, epiphytic algae, phytoplankton and snails. We studied the effects of snail communities (consisting of Radix swinhoei, Hippeutis cantori, Bellamya aeruginosa and Parafossarulus striatulus) on the biomass of phytoplankton and epiphytic algae as well as on the growth of three species of submerged macrophytes (Hydrilla verticillata, Vallisneria natans and one exotic submerged plant, Elodea nuttallii) in a 90-day outdoor mesocosm experiment conducted on the shore of subtropical Lake Liangzihu, China. This dataset including morphological data of three group organisms: freshwater snails, macrophytes and epiphytic algae. In addition, the environmental parameters were included. Morphological data of snails is including biomass (g) and number (ind.). Morphological data of macrophytes is including biomass (g). Epiphytic algae data is including abundance (N, cells). Phytoplankton data is including biomass (Chl-a, μg/L).

opencc-zeroApr 2022View details →

dryad36/100

Ecology and evolution of competitive trait variation in natural phytoplankton communities under selection

Competition for limiting resources is a major force structuring ecological communities. Species minimum resource requirements (R*s) can predict competitive outcomes and evolve under selection in simple communities under controlled conditions. However, whether R*s predict competitive outcomes or demonstrate adaptive evolution in naturally complex communities is unknown. We subjected natural phytoplankton communities to three types of resource limitation (nitrogen, phosphorus, light) in outdoor mesocosms over ten weeks. We examined the community composition weekly and isolated 21 phytoplankton strains from seven species to quantify responses to selection of R* for these resources. We investigated evolutionary change in R*s in the dominant species, Desmodesmus armatus. R*s were good predictors of species changes in relative abundance, though this was largely driven by the success of D. armatus across several treatments. This species also demonstrated evolutionary change in R*s under resource limitation, supporting the potential for adaptive trait change to modify competitive outcomes in natural communities.

opencc-zeroAug 2022View details →

zenodo36/100

Individual-level trait diversity predicts phytoplankton community properties better than species richness or evenness

This archive includes the final summary tables used for the analyses.

opencc-by-4.0Aug 2017View details →

zenodo36/100

Dataset: Quantifying cell densities and biovolumes of phytoplankton communities and functional groups using scanning flow cytometry, machine learning and unsupervised clustering

This dataset contains all relevant data for the manuscript (in submission) "Quantifying cell densities and biovolumes of phytoplankton communities and functional groups using scanning flow cytometry, machine learning and unsupervised clustering". Code written to analyse this dataset (which may be adapted for other flow cytometry datasets) is found at https://zenodo.org/record/999747 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Naming convention for raw flow cytometry data files (located in /Script 3. Generating raw data subset/input/): [Allparameters] _ [Year] - [Month] - [Date] [Hour] [u] [Minute] _ [Depth] e.g: Allparameters_2014-07-31 08u08_1.0m The date, time and depth indicate the location and time at which the measurement was taken.

opencc-by-4.0Sep 2017View details →

dryad36/100

Heatwave responses of Arctic phytoplankton communities are driven by combined impacts of warming and cooling

Marine heatwaves are increasing in frequency and intensity as climate change progresses, especially in the highly productive Arctic regions. Although their effects on primary producers will largely determine the impacts on ecosystem services, mechanistic understanding on phytoplankton responses to such extreme events is still very limited. We experimentally exposed Arctic phytoplankton assemblages to stable warming, as well as to repeated heatwaves, and measured temporally resolved productivity, physiology and composition. Our results show that even extreme stable warming increases productivity, while the response to heatwaves depends on the specific scenario applied, and are not predictable from stable warming responses. This appears to be largely due to the underestimated impact of the cool phase following a heatwave, which can be at least as important as the warm phase for the overall response. We show that physiological and compositional adjustments to both, warm and cool phases drive overall phytoplankton productivity, and need to be considered mechanistically to predict overall ecosystem impacts.

opencc-zeroMay 2024View details →

dryad36/100

Data from: Riverine transport and nutrient inputs affect phytoplankton communities in a coastal embayment

1. Rivers often transport phytoplankton to coastal embayments and introduce nutrients that can enrich coastal plankton communities. We investigated the effects of the Nottawasaga River on the nearshore (i.e., within 500 m of shore) phytoplankton composition along a 10 km transect of Nottawasaga Bay, Lake Huron in 2015 and 2016. Imaging flow cytometry was used to identify and enumerate algal taxa, which were resolved at sizes larger than small nanoplankton (i.e., > 5 mm). Multivariate analysis (perMANOVA and RDA) and a dilution model were used to examine how nutrients and the transport of algal taxa affected community composition in the bay. 2. Sampling stations with different percentages of river water had significantly different phytoplankton communities. Phytoplankton community composition was also strongly associated with nutrients, including total phosphorus, which also varied with the percentage of river water. The majority of the 51 phytoplankton taxa identified in 2016 had numerical abundances in the bay that could be explained simply by the dilution of incoming river water. 3. Phytoplankton transported from the river had a higher proportion of "edible-sized" cells (< 30 mm), particularly in summer when colonial cyanobacteria were numerically dominant in the bay. Six taxa were more abundant than expected from the dilution of river water and included some cyanobacteria with late summer maxima. Five of the taxa that were transported from the river were less abundant than expected in the bay. 4. Whereas impacts of fertilization due to the characteristically higher nutrient concentration in the river are to be expected, the strong and highly correlated effects of transport within the narrow coastal band of this study largely concealed any distinct fertilization effects. 5. Riverine inputs may strongly influence the near-shore assemblage of phytoplankton in oligotrophic embayments in large lakes, creating hotspots for productivity, species turnover and trophic dynamics.

opencc-zeroOct 2019View details →

dryad36/100

Macrosystem community change in lake phytoplankton and its implications for diversity and function

Aim: We use lake phytoplankton community data to quantify the spatio-temporal and scale-dependent impacts of eutrophication, land-use, and climate change on species niches and community assembly processes while accounting for species traits and phylogenetic constraints. Location: Finland Time period: 1977-2017 Major taxa: Phytoplankton Methods: We use Hierarchical Modelling of Species Communities (HMSC) to model meta-community trajectories at 853 lakes over four decades of environmental change, including a hierarchical spatial structure to account for scale-dependent processes. Using a 'region of common profile' approach, we evaluate compositional changes of species communities and trait profiles and investigate their temporal development. Results: We demonstrate the emergence of novel and widespread community composition clusters in previously more compositional homogeneous communities, with cluster-specific community trait profiles, indicating functional differences. A strong phylogenetic signal of species' responses to the environment implies similar responses among closely related taxa. Community cluster-specific species prevalence point to lower taxonomic dispersion within the current dominant clusters compared to the historically dominant cluster and overall higher prevalence of smaller species sizes within communities. Our findings denote profound spatio-temporal structuring of species co-occurrence patterns and highlight functional differences of lake phytoplankton communities. Main conclusions: Diverging community trajectories have led to a nationwide reshuffling of lake phytoplankton communities. At regional and national scales, lakes are not single entities but metacommunity hubs in an interconnected waterscape. The assembly mechanisms of phytoplankton communities are strongly structured by spatio-temporal dynamics, which have led to novel community types but only a minor part of this reshuffling could be linked to temporal environmental change.

opencc-zeroDec 2022View details →

zenodo36/100

Dissolved storage glycans shaped the community composition of abundant bacterioplankton clades during a North Sea spring phytoplankton bloom

In 2020 we sampled a complete spring bloom in the German Bight over a 90-day period. Bacterioplankton metagenomes from 30 time-points allowed reconstruction of 251 metagenome-assembled genomes (MAGs). Corresponding metatranscriptomes highlighted 50 particularly active MAGs of the most abundant clades. Saccharide measurements together with bacterial polysaccharide utilization loci (PUL) expression data identified β-glucans (diatom laminarin) and α-glucans as the most prominent dissolved polysaccharide substrates metabolized by the bacterioplankton. Here we are depositing all supporting environmental data for the analyzed  2020 Helgoland spring algal bloom. This includes physicochemical data, data on algal abundances and biovolumes, data on copepod and flagellate abundances, data on monosaccharide and antibody-based polysaccharide measurements, and 16S rRNA-based bacterial diversity data. The corresponding metagenome, metatranscriptome and MAG sequence data of this project are available from the European Nucleotide Archive (accession PRJEB52999).

opencc-by-4.0Mar 2023View details →

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