The Effects of Ultraviolet Radiation and Nutrient Additions on Periphyton Biomass and Composition in a Sub-Alpine Lake (Castle Lake, USA)

Multiple factors operating across different spatial and temporal scales affect β‐diversity, the variation in community composition among sites. Disentangling the relative influence of co‐occurring ecological drivers over broad biogeographic gradients and time is critical to developing mechanistic understanding of community responses to natural environmental heterogeneity as well as predicting the effects of anthropogenic change. We partitioned taxonomic β‐diversity in phytoplankton communities across 75 north‐temperate lakes and reservoirs in Alberta, Canada, using data‐driven, spatially constrained null models to differentiate between spatially structured, spatially independent, and spuriously correlated associations with a suite of biologically relevant environmental variables. Phytoplankton β‐diversity was largely independent of space, indicating spatial processes (e.g., dispersal limitation) likely play a minor role in structuring communities at the regional scale. Our analysis also identified seasonal differences in the importance of environmental factors, suggesting a general shift toward greater relevance of local, in‐lake (e.g., nutrients and Secchi depth) over regional, atmospheric and catchment‐level (e.g., monthly solar radiation and grassland coverage) drivers as the open‐water growing season progressed. Several local and regional variables explained taxonomic variation jointly, reflecting climatic and land‐use linkages (e.g., air temperature and water column stability or pastureland and nutrient enrichment) that underscore the importance of understanding how phytoplankton communities integrate, and may serve as sentinels of, broader anthropogenic changes. We also discovered similar community composition in natural and constructed water bodies, demonstrating rapid filtering of regional species to match local environmental conditions in reservoirs comparable to those in natural habitats. Finally, certain factors related to human footprint (e.g., cropland development) explained the composition of bloom‐forming and/or toxic cyanobacteria more than the overall phytoplankton community, suggesting their heightened importance to integrated watershed management.

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Multiscale drivers of phytoplankton communities in north‐temperate lakes

Loewen

Wyatt

Mortimer

et al. 2020

Ecological Applications

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Quantifying seasonal succession of phytoplankton trait‐environment associations in human‐altered landscapes

Loewen

Vinebrooke

Zurawell

2021

Limnology & Oceanography

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Integration of species traits in direct gradient analysis generates insights into how communities are assembled and may respond to environmental changes. We investigated phytoplankton trait‐environment relationships for over 300 taxa during the open‐water season across 75 north‐temperate lakes and reservoirs in Alberta, Canada. An innovative, data‐driven approach was applied using iterative model selection for RLQ optimization to reveal key monthly associations. Fourth‐corner analysis then tested the significance of relationships using spatially and phylogenetically constrained null models derived by Moran spectral randomization. Both local‐ and regional‐scale drivers of succession were found with evidence of deterministic filtering by traits increasing in mid‐summer. Trait associations to land‐use and water quality highlighted potential anthropogenic cross‐scale interactions, such as logging and pasture development affecting phytoplankton via allochthonous nutrient inputs. Biogeographic factors (e.g., elevation and habitat size) and associated temperature and chemical gradients (e.g., pH and bicarbonate) were also linked to multiple morphological, physiological, and behavioral traits, including potential toxin production. Several correlated traits emphasized importance of trait syndromes corresponding to distinct taxonomic groups (e.g., cyanobacteria and green algae). However, rather than clustering species with shared ecological preferences or roles, our study builds on past trait‐based approaches to phytoplankton by testing for explicit trait associations with a range of environmental factors. Thus, we provide a novel, quantitative means of revealing environmental constraints on communities and translating their compositional changes under climate and other human influences into functional impacts on freshwater ecosystems.

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Responses of periphyton to artificial nutrient enrichment in freshwater kettle ponds of Cape Cod National Seashore

Smith

Lee

2006

Hydrobiologia

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Nutrient enrichment bioassays, in conjunction with sampling and analysis of surface water chemistry, were conducted in freshwater lakes (kettle ponds) of Cape Cod National Seashore (Massachusetts, USA) to ascertain the importance of nitrogen (N) and phosphorus (P) in regulating the growth of periphyton. Arrays of nutrient diffusing substrata (NDS) were suspended 0.5 m below the water surface in a total of 12 ponds in July and August 2005. Algal biomass developing on each NDS after $3 weeks of exposure in each month was assessed by quantifying chlorophyll a + phaeophyton pigments. In both July and August, strong responses to N+P and N enrichments were observed in the majority of ponds, while P had no stimulatory effect. These responses correspond well with low atomic ratios (1-18) of dissolved inorganic nitrogen (DIN) to total phosphorus (TP) in ambient surface waters. The results suggest that conditions in the kettle ponds develop whereby nitrogen is the primary limiting nutrient to periphyton growth. While this may be a seasonal phenomenon, it has implications for nutrient management in individual ponds and within the larger watershed.

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The Effects of Ultraviolet Radiation and Nutrient Additions on Periphyton Biomass and Composition in a Sub-Alpine Lake (Castle Lake, USA)

Cited by 16 publications

References 50 publications

Multiscale drivers of phytoplankton communities in north‐temperate lakes

Multiscale drivers of phytoplankton communities in north‐temperate lakes

Quantifying seasonal succession of phytoplankton trait‐environment associations in human‐altered landscapes

Responses of periphyton to artificial nutrient enrichment in freshwater kettle ponds of Cape Cod National Seashore

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