QUANTIFICATION OF MICROCYSTINS AND OLIGOPEPTIDES IN AN ACIDIC TANNIN – STAINED LAKE EXPANDS THE ECOLOGICAL RANGE OF CYANOBACTERIAL HARMFUL ALGAL BLOOMS

Cyanobacterial harmful algal blooms (cyanoHABs) are a growing problem in aquatic environments. Tannins and specifically polyphenols have been shown to inhibit the growth of cyanoHAB species in laboratory cultures and have been used as an in-lake mitigation tool. Here we describe unusual toxic cyanoHABs caused by Microcystis and Dolichospermum species in a tannin - stained acidic lake in the northern highlands of Wisconsin, USA. CyanoHAB events were observed concomitantly with reductions in thermal stability and entrainment of soluble reactive phosphorus into surface waters during the open water season.  The cyanotoxins microcystins (MC), anabaenopeptins (AP), cyanopeptolins (CP) and microginin-690 were measured by liquid chromatography tandem mass spectrometry. MCs occurred in all but two samples at an average concentration of 26.8 µg/L at the deep hole whereas nearshore scum samples contained a maximum of nearly 4000 µg/L with greater congener diversity.  The MC congener MC-LA was most abundant followed by MC-LR > MC-LY > MC-LF >  [Dha⁷]MC-LR. AP’s were detected at an average of 4.0 +/- 17.2 µg/L at the deep hole and exceeded 800 µg/L in nearshore scum samples. CP’s and microginin-690 were detected in several nearshore locations, although at lower concentrations. Total polyphenols averaged 12.54 +/- 0.56 mg/L gallic acid equivalents, which is higher than concentrations previously shown to inhibit the growth of Microcystis and Dolichospermum. These results extend the ecological range of lake habitats supporting highly toxic cyanoHABs.

Primary Presenter: Todd Miller, University of Wisconsin - Milwaukee (trexmiller@gmail.com)

Authors:

Todd Miller, University of Wisconsin - Milwaukee  (millertr@uwm.edu)

Donald Olson, Tug Lake District  (dwoslo@msn.com)

Reid Badeau, Tug Lake District  (rbad0@frontier.com)

Cutler Nowak, University of Wisconsin - Stevens Point  (nowakcutler@gmail.com)

Scott Van Egeren, Wisconsin Department of Natural Resources  (Scott.VanEgeren@wisconsin.gov)

John Greenwood, Tug Lake District  (jgreenwood@uwsa.edu)