Environmental drivers of taxonomic and functional variation in zooplankton diversity and composition in freshwater lakes across Canadian continental watersheds

Abstract

Canada is home to more lakes than any other nation, but there is a fragmented and limited understanding of the ecological status of these water bodies. Zooplankton are excellent bioindicators of lake health, given their central food web position. To date, many studies have investigated the effect of individual stressors on zooplankton communities, mediated through changes in water quality (e.g., macronutrients, temperature, or chemicals). Increasingly, stressors act simultaneously in lakes, often over extended periods of time. As part of the NSERC Canadian Lake Pulse Network project, pelagic zooplankton were sampled in 624 lakes across Canada, spanning six continental drainage basins. We evaluated the effect of 40+ environmental variables on zooplankton diversity and community composition, considering both taxonomic and functional approaches. We also tested specific hypotheses on the relationships between zooplankton communities and environmental conditions, including eutrophication, calcium, chloride, and fish predation. We found that lake morphometry variables were among the most important predictors of zooplankton diversity, while water quality metrics were more critical in explaining variation in community composition. Our results also reveal significant heterogeneity across Canada, with contrasting effects of environmental drivers among continental watersheds, highlighting that response models cannot be assumed to apply universally.

Zooplankton assemblage structure and diversity since pre‐industrial times in relation to land use

“…Interestingly, a positive correlation between FRic and the fraction of agriculture in the watershed, previously observed for entire contemporary crustacean zooplankton communities across 624 Canadian lakes (Paquette et al, 2022), did not emerge in these analyses of the 101 reduced (cladoceran) dataset. This lack of correspondence between studies could be related to differences in taxonomic resolution, given that the positive correlation between FRic and agriculture across all 624 lakes was related to Daphnia pulicaria responses, a taxon that could not be identified to species level in this current subfossil study.…”

“…Instead, species and traits remained as spatially heterogeneous as they were before humans altered the landscape, highlighting the importance of local stressors acting with contrasting regional effects at this large spatial scale. The strong heterogeneous environmental filtering reported across Canadian lakes (Paquette et al, 2022) could thus be driving local communities in different directions, potentially compensating for other homogenizing forces.…”

The investigation of the zooplankton community in the newly formed Ribb Reservoir, Ethiopia: the tropical highland reservoir

“…(2020) , Kuczyńska-Kippen (2020) , Ndah et al. (2022) , and Paquette et al. (2022) , plankton diversity changes rapidly due to the short lifespan of days to weeks and because of other factors such as climatic conditions.…”

“…As shown in Table 2, the occurrence of Cladocera had the highest abundance of the three taxa at 42.86%, which was similar to Pampoo Pond (Singh et al, 2021) but differs from Koka Reservoir, where Rotifers were dominant (Fasil et al, 2011). The occurrence of Mesocyclops aequatorialis similis at first and Brachionus angularis at least abundant might not always be true, because according to most studies such as Richardson (2009), Mojumder et al (2020), Kuczy nska-Kippen (2020), Ndah et al (2022), andPaquette et al (2022), plankton diversity changes rapidly due to the short lifespan of days to weeks and because of other factors such as climatic conditions. Similar to studies conducted by Imoobe and Akoma (2008) and Imoobe and Christopher (2009) in Lake Tana, the zooplankton species reported in this study were a mixture of tropical and temperate species.…”

“…This is due to water abstraction from the reservoir for irrigation and overflow over the spillway, despite being a poorly managed catchment area with high use of inorganic fertilizer, agricultural practices, and pollutants from towns such as Debre Tabor and Hamusit that could affect the water quality of the reservoir. According to Paquette et al (2022), agricultural runoff pollution contains higher concentrations of nutrients and ions, which are significant predictors of zooplankton diversity and aggregation. The outflow of water from the reservoir through these two mechanisms is important to controlling the physicochemical characteristics of the reservoir.…”