OPPOSING RESPONSES OF STRONGLY INTERACTING SPECIES TO ELEVATED TEMPERATURES SUPPRESS THE HARMFUL PHYTOPLANKTER MICROCYSTIS
Ecological implications of climate warming may be challenging to anticipate due to cascading effects of disrupting species interactions. Harmful cyanobacteria like Microcystis aeruginosa are expected to increase worldwide with climate warming, given their relatively high temperature optima. Furthermore, facilitation by invasive zebra mussels has increased M. aeruginosa in low-nutrient lakes, an uncharacteristic habitat for harmful cyanobacteria. We monitored M. aeruginosa for 13 years in a low-nutrient lake invaded by zebra mussels. In 11 of the years, there was a significantly positive relationship between M. aeruginosa biomass and water temperature, consistent with climate warming forecasts. Surprisingly, we observed very low Microcystis biomass (and associated toxin) during one of the warmest years, following a heat-induced mass mortality event of zebra mussels that grossly limited their density for two years. Upon elimination of its facilitator, the positive relationship between Microcystis biomass and temperature dissolved. Thus, accurately predicting responses of harmful cyanobacteria to climate warming may require, at minimum, quantification of responses of both the focal species and species that strongly interact with it; monitoring intact communities with respect to climatic variables seems essential.
White, J. D., Framingham State University, USA, email@example.com
Hamilton, S. K., Michigan State University, USA, firstname.lastname@example.org
Sarnelle, O., Michigan State University, USA, email@example.com
Location: Sweeney Ballroom B
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