Spatial overlap in lake phytoplankton: Relations with environmental factors and consequences for diversity

Beisner, Beatrix E.; Longhi, Maria Lorena

doi:10.4319/lo.2013.58.4.1419

Cited by 19 publications

(20 citation statements)

References 46 publications

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“…The DCM will be referred here according to the definition of Camacho (): ‘the maximal chlorophyll a concentration that is found at a certain depth, usually at the thermocline or close to the upper part of the hypolimnion', usually far from the surface. Deep chlorophyll maxima are found in clear, vertically stratified fresh and marine oligotrophic waters (Fee, ; Cullen, ; Estrada et al ., ; Beisner & Longhi, ), with thicknesses varying from a few cm to several metres and lasting from days to years. The ratio between stabilising forces, such as the vertical temperature gradient of the water mass, and destabilising forces, such as wind forcing, are thought to control the spatiotemporal dynamics of the DCM (Fee, ).…”

Section: Introductionmentioning

confidence: 99%

Macrozooplankton and the persistence of the deep chlorophyll maximum in a stratified lake

2015

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International audience1. Deep chlorophyll maxima (DCM) are common in deep, oligotrophic stratified lakes. The DCM refer to the maximal chlorophyll a concentration found at depth, and not at the lake surface. While control of the DCM is thought to be via physicochemical factors in many lakes, a role for zooplankton grazing in epilimnetic waters remains a possibility. The occurrence and dynamics of DCM are poorly documented in smaller lakes, where zooplankton grazing is likely to have a stronger structuring effect. In small, shallow stratified lakes, biological control by grazing may be magnified by the short vertical gradient and overall higher water temperature. 2. The respective contributions of several physical, chemical and biological parameters to the vertical distribution of phytoplankton biomass in a small stratified lake were examined. Associations between phytoplankton depth distribution and vertical gradients in temperature, light and nutrients and the density of herbivorous zooplankton were established through regressions and generalised linear models.3. Colimitation of the DCM by light from above and nutrients from below was detected. A threshold was detected at 3% incident light (100 lmol photon m 2 s 1), below which the DCM disappeared. Epilimnetic biomass was related to nutrient availability, with a threshold concentration at 4 lg P L 1, below which the DCM dominated.4. Greater stability of the water mass and more zooplankton were associated with higher phytoplankton biomass in the DCM. Stability is likely to have controlled vertical nutrient fluxes, which were intercepted by the metalimnetic phytoplankton. Zooplankton grazing of epilimnetic biomass could have increased incident light reaching the top of the metalimnion, thereby favouring proliferation of photosynthetic biomass in the DCM.5. Wind mixing events, as detected by a reduction in Lake number (LN, a measure of the influence of wind forcing on vertical structure), induced vertical intrusions of metalimnetic water, rich in nutrients and phytoplankton, into the epilimnion. We can infer that dominance of phytoplankton in the epilimnion would have occurred earlier during the summer if grazing by zooplankton had not removed epilimnetic phytoplankton. Our results suggest that, while stable stratification is necessary for initial DCM formation, zooplankton grazing may promote the persistence of a DCM

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Section: Introductionmentioning

confidence: 99%

Macrozooplankton and the persistence of the deep chlorophyll maximum in a stratified lake

2015

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“…Whole-ecosystem experiments are inherently fraught with difficulty, as they are challenging to replicate. However, we argue that we can still derive important insights from whole-ecosystem manipulations that cannot be deduced from laboratory or mesocosm experiments, provided that we proceed cautiously with our interpretation of results [44][45][46]. Keeping this caveat in mind, we posit that the increase in biomass and biovolume across multiple spectral groups and MBFGs in FCR after EM1, which was not observed after EM2, may be due to entrainment of turbidity from upstream regions of FCR to the deepest site after EM1.…”

Section: Discussionmentioning

confidence: 94%

Whole-Ecosystem Experiments Reveal Varying Responses of Phytoplankton Functional Groups to Epilimnetic Mixing in a Eutrophic Reservoir

Lofton

McClure

Chen

et al. 2019

Water

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Water column mixing can influence community composition of pelagic phytoplankton in lakes and reservoirs. Previous studies suggest that low mixing favors cyanobacteria, while increased mixing favors green algae and diatoms. However, this shift in community dominance is not consistently achieved when epilimnetic mixers are activated at the whole-ecosystem scale, possibly because phytoplankton community responses are mediated by mixing effects on other ecosystem processes. We conducted two epilimnetic mixing experiments in a small drinking water reservoir using a bubble-plume diffuser system. We measured physical, chemical, and biological variables before, during, and after mixing and compared the results to an unmixed reference reservoir. We observed significant increases in the biomass of cyanobacteria (from 0.8 ± 0.2 to 2.4 ± 1.1 μg L−1, p = 0.008), cryptophytes (from 0.7 ± 0.1 to 1.9 ± 0.6 μg L−1, p = 0.003), and green algae (from 3.8 to 4.4 μg L−1, p = 0.15) after our first mixing event, likely due to increased total phosphorus from entrainment of upstream sediments. After the second mixing event, phytoplankton biomass did not change but phytoplankton community composition shifted from taxa with filamentous morphology to smaller, rounder taxa. Our results suggest that whole-ecosystem dynamics and phytoplankton morphological traits should be considered when predicting phytoplankton community responses to epilimnetic mixing.

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“…Using explicitly defined traits lends itself well to the estimation of functional diversity indicators (such as functional dispersion, richness, diversity and evenness; Weithoff, 2003;Villéger et al, 2008;Laliberté and Legendre, 2010) as well as community weighted means to characterize functional composition of communities (e.g., Beisner and Longhi, 2013;Moser et al, 2017). It also enables the examination of trade-offs between different continuously measured traits such as those associated with nutrient uptake and storage (Litchman et al, 2007;Edwards et al, 2012).…”

Section: Explicitly-defined Traitsmentioning

confidence: 99%

“…In freshwater studies, size is often expanded to a more complex measure of shape, taking morpho-functional differences between species into account (e.g., Kruk et al, 2010), often in combination with phylogenetic/taxonomic relatedness (Huszar and Caraco, 1998;Cellamare et al, 2013;Segura et al, 2013). In studies investigating the vertical structure of lakes, the pigment composition (Beisner and Longhi, 2013) and the motility of cells (by gas vacuoles or flagella) are further relevant traits (e.g., Pomati et al, 2012), likely less important in the well-mixed surface layer of the open ocean.…”

Section: Traits Used In Marine and Freshwater Researchmentioning

confidence: 99%

“…Trait-based approaches become particularly helpful in such cases, as they are ataxonomic, facilitating the detection of common response patterns within these potentially disparate communities. Another aspect of freshwater trait-based studies is the analysis of the vertical distribution of phytoplankton (Pomati et al, 2012;Beisner and Longhi, 2013;Santana et al, 2017), when steep physical-chemical gradients exist. One drawback we noted in several studies is that they lack a clear rationale as to why they use trait-based approaches in relation to the ecological goals (as also argued by Hébert et al, 2017 for zooplankton).…”

Section: Comparing Freshwater and Marine Trait Studies: Assembly Vs mentioning

confidence: 99%

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Measures and Approaches in Trait-Based Phytoplankton Community Ecology – From Freshwater to Marine Ecosystems

Weithoff

Beisner

2019

Front. Mar. Sci.

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Trait-based approaches to investigate (short-and long-term) phytoplankton dynamics and community assembly have become increasingly popular in freshwater and marine science. Although the nature of the pelagic habitat and the main phytoplankton taxa and ecology are relatively similar in both marine and freshwater systems, the lines of research have evolved, at least in part, separately. We compare and contrast the approaches adopted in marine and freshwater ecosystems with respect to phytoplankton functional traits. We note differences in study goals relating to functional trait use that assess community assembly and those that relate to ecosystem processes and biogeochemical cycling that affect the type of characteristics assigned as traits to phytoplankton taxa. Specific phytoplankton traits relevant for ecological function are examined in relation to herbivory, amplitude of environmental change and spatial and temporal scales of study. Major differences are identified, including the shorter time scale for regular environmental change in freshwater ecosystems compared to that in the open oceans as well as the type of sampling done by researchers based on site-accessibility. Overall, we encourage researchers to better motivate why they apply trait-based analyses to their studies and to make use of process-driven approaches, which are more common in marine studies. We further propose fully comparative trait studies conducted along the habitat gradient spanning freshwater to brackish to marine systems, or along geographic gradients. Such studies will benefit from the combined strength of both fields.

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Spatial overlap in lake phytoplankton: Relations with environmental factors and consequences for diversity

Cited by 19 publications

References 46 publications

Macrozooplankton and the persistence of the deep chlorophyll maximum in a stratified lake

Macrozooplankton and the persistence of the deep chlorophyll maximum in a stratified lake

Whole-Ecosystem Experiments Reveal Varying Responses of Phytoplankton Functional Groups to Epilimnetic Mixing in a Eutrophic Reservoir

Measures and Approaches in Trait-Based Phytoplankton Community Ecology – From Freshwater to Marine Ecosystems

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