Phytoplankton community responses to temperature fluctuations under different nutrient concentrations and stoichiometry

Gerhard, Miriam; Koussoroplis, Apostolos‐Manuel; Hillebrand, Helmut; Striebel, Maren

doi:10.1002/ecy.2834

Cited by 37 publications

(27 citation statements)

References 48 publications

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“…To assess suspended algal biomass, chlorophyll a (Chl a) was extracted from the water samples, while Chl a content of diatoms attached to the substrate was used to evaluate diatom attachment. Chl a measurements are well established as a proxies for monitoring water quality, assessing phytoplankton biomass, and estimating primary production [61][62][63], while fluorometric measurements of Chl a concentrations are an efficient proxy to monitor the total biomass of diatoms in the water column and on the substrate. To determine the anti-fouling effects of the holothurian's crude extracts, a logarithmic response ratio (LRR; see Section 4.1.5) of measured Chl a concentrations was calculated.…”

Section: Anti-fouling Effects Of the Crude Extractsmentioning

confidence: 99%

Anti-Fouling Effects of Saponin-Containing Crude Extracts from Tropical Indo-Pacific Sea Cucumbers

et al. 2020

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Sea cucumbers are bottom dwelling invertebrates, which are mostly found on subtropical and tropical sea grass beds, sandy reef flats, or reef slopes. Although constantly exposed to fouling communities in these habitats, many species are surprisingly free of invertebrate epibionts and microfouling algae such as diatoms. In our study, we investigated the anti-fouling (AF) activities of different crude extracts of tropical Indo-Pacific sea cucumber species against the fouling diatom Cylindrotheca closterium. Nine sea cucumber species from three genera (i.e., Holothuria, Bohadschia, Actinopyga) were selected and extracted to assess their AF activities. To verify whether the sea cucumber characteristic triterpene glycosides were responsible for the observed potent AF activities, we tested purified fractions enriched in saponins isolated from Bohadschia argus, representing one of the most active anti-fouling extracts. Saponins were quantified by vanillin-sulfuric acid colorimetric assays and identified by LC-MS and LC-MS/MS analyses. We were able to demonstrate that AF activities in sea cucumber extracts were species-specific, and growth inhibition as well as attachment of the diatom to surfaces is dependent on the saponin concentration (i.e., Actinopyga contained the highest quantities), as well as on the molecular composition and structure of the present saponins (i.e., Bivittoside D derivative was the most bioactive compound). In conclusion, the here performed AF assay represents a promising and fast method for selecting the most promising bioactive organism as well as for identifying novel compounds with potent AF activities for the discovery of potentially novel pharmacologically active natural products.

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Section: Anti-fouling Effects Of the Crude Extractsmentioning

confidence: 99%

Anti-Fouling Effects of Saponin-Containing Crude Extracts from Tropical Indo-Pacific Sea Cucumbers

et al. 2020

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“…2017; Gerhard et al . 2019) or biotic factors, e.g. predators (Holt & Bonsall 2017) can allow for much higher dimensional coexistence than the number of resources can account for.…”

Section: Introductionmentioning

confidence: 99%

Beyond nitrogen: phosphorus – estimating the minimum niche dimensionality for resource competition between phytoplankton

Hofmann¹,

Clark

Hoffmann

et al. 2021

Ecology Letters

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The niche dimensionality required for coexistence is often discussed in terms of the number of limiting resources. N and P limitation are benchmarks for studying phytoplankton interactions. However, it is generally agreed that limitation by small numbers of resources cannot explain the high phytoplankton diversity observed in nature. Here, we parameterised resource competition models using experimental data for six phytoplankton species grown in monoculture with nine potential limiting resources. We tested predicted species biomass from these models against observations in two‐species experimental mixtures. Uptake rates were similar across species, following the classic Redfield ratio. Model accuracy levelled out at around three to five resources suggesting the minimum dimensionality of this system. The models included the resources Fe, Mg, Na and S. Models including only N and P always performed poorly. These results suggest that high‐dimensional information about resource limitation despite stoichiometric constraints may be needed to accurately predict community assembly.

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“…These two environmental factors were chosen as they are both likely to vary over space and time in the natural habitat (freshwater bodies), where T. thermophila feeds on bacteria. Furthermore, with increasing temperature, metabolism accelerates leading to higher resource demand (Gerhard, Koussoroplis, Hillebrand, & Striebel, 2019). This effect can be compensated by higher nutrient supply.…”

Section: Introductionmentioning

confidence: 99%

A multidimensional approach to the expression of phenotypic plasticity

et al. 2020

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Phenotypic plasticity is increasingly recognized as a key element of eco‐evolutionary dynamics, but it remains challenging to assess because of its multidimensional nature. Indeed, organisms live in complex environments where numerous factors can impact the phenotypic expression of traits (inter‐environment axis), possess multiple traits that can influence each other's expression (inter‐trait axis) and differ in their genetic background (inter‐genotype axis), which can not only impact the traits' values but also their plasticity. We addressed six questions related to phenotypic plasticity: (a) do different environmental gradients show similar effects on a given trait? (b) Are the effects of two environmental gradients on a trait additive? (c) Do different traits show similar plastic response to a given environmental gradient? (d) Do the (co)variances between traits vary across environmental gradients? (e) Do genotypes differ in their plastic response to a given environmental gradient? (f) Are some genotypes more plastic than others across all traits? We designed a microcosm experiment using the protist Tetrahymena thermophila aimed at encompassing all these aspects of phenotypic plasticity. We exposed 15 distinct genotypes to 25 combinations of temperature and nutrient availability and assessed the plasticity of five phenotypic traits. Our results show strong differences in the plastic response depending on the environmental gradient, not only regarding the shape of the reaction norm of the different traits tested, but also in the overall plasticity of the organisms. We did not find any covariance between traits that was consistent across all environments. Overall, our results suggest independent impacts of the environmental dimension considered on the observed plastic response. These results underline potential difficulties in generalizing findings about plasticity to all environments and all traits. A free Plain Language Summary can be found within the Supporting Information of this article.

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Phytoplankton community responses to temperature fluctuations under different nutrient concentrations and stoichiometry

Cited by 37 publications

References 48 publications

Anti-Fouling Effects of Saponin-Containing Crude Extracts from Tropical Indo-Pacific Sea Cucumbers

Anti-Fouling Effects of Saponin-Containing Crude Extracts from Tropical Indo-Pacific Sea Cucumbers

Beyond nitrogen: phosphorus – estimating the minimum niche dimensionality for resource competition between phytoplankton

A multidimensional approach to the expression of phenotypic plasticity

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