Linking the land and the lake: Maumee River nutrients, cyanobacteria, and toxins

Session: Great Lakes Tributaries: Connecting Land and Lakes (4)

Douglas Kane, Defiance College, Division of Natural Sciences, dkane@defiance.edu
Crista Kieley, University of New England , ckieley@une.edu
Callie Nauman, Bowling Green State University, naumanc@bgsu.edu
Timothy Davis, Bowling Green State University, timdavi@bgsu.edu
Justin Chaffin, Stone Laboratory, Ohio State University, chaffin.46@osu.edu

Abstract

The Maumee River serves as a source of nutrients and potentially cyanobacteria to Lake Erie. Although it has long been known that cyanobacteria in the Maumee River and Lake Erie produce hepatotoxic microcystins, more recently concerns about neurotoxic saxitoxins produced by cyanobacteria have come to the forefront. To determine toxin concentrations and potential biological and chemical drivers of  toxin production, monitoring of six sites along the Maumee River during summer and fall (June-October) of 2018 offered insight into nutrient concentrations, phytoplanktonic community composition, and toxin concentrations (both microcystins and saxitoxins, by ELISA).  Dissolved nutrient concentrations (phosphorus, ammonium, and nitrate) declined as the summer progressed.  The relative composition of major phytoplankton groups varied through time but were relatively consistent among sites.  Finally, while over half of the samples had total microcystin levels above the minimum detection level (0.1 µg/L) only 10% of the samples had saxitoxin levels above the minimum detection level (1.0 µg/L) and these were most prevalent in September. Molecular analysis of the mcyE and sxtA genes is ongoing. Continued monitoring of these parameters will occur in 2019.