Reduced Phytoplankton and Zooplankton Diversity Associated with Increased Cyanobacteria in Lake Champlain, USA

Abstract

Anthropogenic inputs of nutrients threaten water quality around the world, causing eutrophication and altering phytoplankton communities. In freshwater systems, certain physiochemical conditions, including high TP, low TN:TP, and warm temperatures, can lead to problematic cyanobacteria blooms. Cyanobacteria can decrease phytoplankton diversity and phytoplankton diversity has been positively linked to zooplankton diversity, suggesting that cyanobacteria may have indirect negative effects on zooplankton diversity. Using monitoring data from Lake Champlain, we tested three hypotheses: (1) cyanobacteria density and phytoplankton diversity are inversely related; (2) phytoplankton diversity and zooplankton diversity are positively related; and by extension (3) cyanobacteria density and zooplankton diversity are inversely related. Relationships were investigated separately at shallow (4–15 m) and deep (25–100 m) sites using several diversity metrics. At deep sites, cyanobacteria density was only related (positively) to zooplankton Shannon diversity. At shallow sites, all three hypotheses were supported by three of four diversity metrics; low phytoplankton richness appears to be the link between high cyanobacteria density and low zooplankton diversity. Our results suggest that cyanobacteria may indirectly reduce zooplankton diversity by decreasing resource heterogeneity, although our results based on observational data were also consistent with well‐known direct pathways. Because low biodiversity can alter ecosystem processes and impair functioning, our results suggest that shallow systems may be more responsive to global change than deeper systems.

The Role of External Factors in the Variability of the Structure of the Zooplankton Community of Small Lakes (South-East Kazakhstan)

“…The diversity of zooplankton communities in mountain lakes was lower than in lakes at a lower altitude. The similar values of Shannon's diversity index were noted in some moderately polluted water bodies of Kazakhstan and other regions [26,37,85,86].…”

Cyanobacteria species dominance and diversity in three Australian drinking water reservoirs

“…Cyanobacterial diversity and richness may also be related to nutrient availability, as observed in Donqian Lake, China, where a significant decrease in richness was attributed to nutrient reduction following sediment dredging (Jing et al, 2013), although decreased recruitment from overwintering or akinete sources may be possible. Interaction with other organisms can also affect cyanobacteria diversity during cyanoHABs (Amorim & Moura, 2021;Bockwoldt et al, 2017;Chellappa & Costa, 2003), with findings of positive correlations of cyanobacteria richness with other prokaryotes (Song et al, 2017;Zhang et al, 2021), and with zooplankton grazing and fish predation (Ekvall et al, 2014;Ger et al, 2014;Lampert, 1987;Urrutia-Cordero et al, 2015). We lacked data to test such responses in our study.…”

Blue light irradiation increases the relative abundance of the diatom Nitzschia palea in co‐culture with cyanobacterium Microcystis aeruginosa

“…The negative impacts of water blooms on various organisms are well known. For example, phytoplankton diversity decreases during cyanobacterial blooms (Niu et al, 2011; Toporowska & Pawlik-Skowro nska, 2014) as it is inversely related to cyanobacterial density (Bockwoldt et al, 2017).…”