INFERRING CLIMATE CHANGE EFFECTS ON LAKES THROUGH COMPARISON OF PHYTOPLANKTON AND PHYTOTOXINS FROM TWENTY LAKES SPANNING A PRONOUNCED PRECIPITATION GRADIENT

With global warming, there is need for better understanding of mechanisms that sustain ecosystem health, specifically biodiversity and ecosystem functioning. In this research, we infer climate change effects on lakes, specifically altered hydrology, through comparison of phytoplankton and phytotoxins from lakes that span a pronounced precipitation gradient. The lakes are warm-monomictic systems of the southcentral USA. In-lake conditions, phytoplankton composition, microcystin concentrations, and microbial functions were explored. Our data revealed widespread microcystins in lakes across this region, some of which exceeded regulatory limits. Microcystins were higher in the spring than summer, indicating that these lakes, even across a large range of precipitation, do not follow the trends of temperate dimictic lakes. Microcystins were found in surface waters and bottom waters well below the photic zone, reflecting the persistence of these toxins in the environment. Our analyses showed strong association between microcystins, nitrate + nitrite, Planktothrix abundance, and transcriptional activity. Many systems exhibited strong denitrification in the spring, perhaps contributing to the decreased toxin concentrations in the summer. Counter to most of the lakes, one lake, positioned on the drier end of our precipitation gradient and which had the highest microcystin concentrations, indicated nitrogen cycle disruption, including inhibited denitrification. These findings suggest that with climate change in this area, ecosystem health is likely to change for the worse.

Primary Presenter: Daniel Roelke, Texas A&M University Galveston (droelke@tamu.edu)

Authors:

Daniel Roelke, Texas A&M University Galveston  (droelke@tamu.edu)

Smita Pal, Texas A&M University Galveston  (smita30@tamug.edu)

Crista Kieley, Texas A&M University Galveston  (ckieley@tamu.edu)

Royoung Park, Texas A&M University Galveston  (parkro9946@tamu.edu)

Kathryn Campbell, Texas A&M University Galveston  (klcampbell@tamu.edu)

N. Hagen Klobusnik, Texas A&M University Galveston  (nathanklo@tamu.edu)

Jordan Walker, Texas A&M University Galveston  (jronwalker@tamu.edu)

Sierra Cagle, Texas A&M University Galveston  (sec1414@tamug.edu)

Marissa Kneer, US Army Corps of Engineers ERDC-EL, Vicksburg  (Marissa.L.Kneer@usace.army.mil)

Kevin Stroski, Environmental Science, Institute of Biomedical Studies, Center for Reservoir and Aquatic Systems Research, Baylor University, Waco, TX  (kevin_stroski1@baylor.edu)

Bryan Brooks, Environmental Science, Institute of Biomedical Studies, Center for Reservoir and Aquatic Systems Research, Baylor University, Waco, TX  (Bryan_Brooks@baylor.edu)

Jessica Labonte, Texas A&M University Galveston  (labontej@tamug.edu)