Spatiotemporal Survey of the 2016 Lake Okeechobee and St. Lucie River Cyanobacterial Bloom

Session: 16. - How can Microbial Metagenomics Inform Management of Great Lakes Ecosystems?

Timothy Davis, Bowling Green State University, [email protected]
Benjamin Kramer, Stony Brook University, [email protected]
Kevin Meyer, University of Michigan, [email protected]
Genesok Oh, Stony Brook University, [email protected]
Barry Rosen, US Geological Survey, [email protected]
Christopher Gobler, Stony Brook University, [email protected]

Abstract

In late June, 2016, a cyanobacterial harmful algal bloom (cyanoHAB) was transported from Lake Okeechobee (LO) through the St. Lucie River (SLR) into the coastal Atlantic Ocean causing environmental, recreational and economic issues.  In response, spatial surveys were conducted from LO to the SLR in early July and late September.  Samples were collected for general physiochemical parameters, algal pigments, phytoplankton community composition, molecular analysis and nutrient amendment experiments.  Results indicated that Microcystis was the dominant cyanobacterium but other potentially-toxic cyanobacteria were also present (e.g. Cylindrospermopsis and Dolichospermum).  Molecular analysis of the July samples indicated that the bloom was comprised of both potential-microcystins and potential-saxitoxins producers.Metagenomic analysis suggested that Microcystis was the likely microcystin-producer whereas Dolichospermum was the likely saxitoxin-producer.   ELISA toxin analyses revealed that microcystins were detected at up to 34 µg L^-1 in July but levels were low in September and saxitoxins were below detection in all samples.  Inorganic N:P ratios suggested nitrogen limitation across the SLR, a finding confirmed by nutrient amendment experiments that revealed the cyanobacterial community was promoted by nitrogen, but not phosphorus.  Collectively, this study demonstrates that the 2016 cyanoHAB in LO and the SLR was toxic, dominated by Microcystis and nitrogen limited. 

1. Keyword
harmful algal blooms

2. Keyword
genetics

3. Keyword
eutrophication