Deciphering culprits for cyanobacterial blooms and lake vulnerability in north-temperate lakes

TL;DR

This study develops a stoichiometric model to understand cyanobacterial bloom dynamics and toxicity in north-temperate lakes, highlighting eutrophication and warming as key drivers of bloom proliferation and toxin bioaccumulation.

Contribution

The paper introduces a novel stoichiometric model that links cyanobacterial population dynamics, toxicity, and environmental factors specific to north-temperate lakes.

Findings

Eutrophication is a key catalyst for bloom proliferation.

Warming scenarios predict earlier blooms and higher toxin levels.

Bioaccumulation of toxins varies among fish species and lakes.

Abstract

Harmful cyanobacterial blooms (CBs) are increasingly prevalent worldwide, posing significant environmental and health concerns. We derive a stoichiometric model describing the population dynamics and toxicity of cyanobacteria in north-temperate freshwater ecosystems. Our model quantifies the hypoxic effects of CBs on fish mortality and evaluates the impact of microcystin-LR (MC-LR) on aquatic macro-invertebrates, phytoplankton, and fish species. Analyzing data from diverse north-temperate lakes with varying physical characteristics, we identify eutrophication as a pivotal catalyst in bloom proliferation. Under predicted warming scenarios coupled with increased eutrophication, peak MC-LR concentrations will surge dramatically, and blooms will occur earlier in the year. We uncover severe bioaccumulation of MC-LR in higher trophic species; the response to CBs among fish at intermediate trophic levels was heterogeneous across lakes. We compare our model against observations from several north-temperate lakes, demonstrating its robustness and applicability. Our insights are critical for informing targeted interventions to mitigate CBs.