NUTRIENT DISTURBANCES AND HARMFUL ALGAL BLOOMS IN GREEN BAY: IMPLICATIONS FOR THE NORTH AMERICAN GREAT LAKES

This research investigates the role of nutrients (nitrate, ammonia, and phosphorus) in promoting harmful algal blooms (HABs) and the production of cyanotoxins in Green Bay, an estuary of Lake Michigan. We conducted bioassays in which water samples from Green Bay were spiked with nitrogen and phosphorus. The samples were analyzed for toxins using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). Microcystins (MCRR), cyanopeptolins (C1007 and C1041), and anabaenopeptins (AptB and AptF) were the dominant toxins detected. The samples spiked with N-rich nutrients and at elevated temperatures showed higher concentrations of cyanotoxins than samples spiked with P-nutrients or at ambient temperature. The quantified range of cyanotoxins was between 0.3 - 1.5 µg/L for MC, 0.5 - 27 µg/L for Apt, and toxin concentration showed seasonal variations. The study showed that nutrients, primarily nitrogen, and increasing temperature impacted algal growth and cyanotoxin production. The results provide some insights into the impacts of nutrient management strategies and climate change on algal blooms and toxin production.  

Primary Presenter: Anjana Adhikari, University of Wisconsin-Milwaukee (adhikar8@uwm.edu)

Authors:

Anjana Adhikari, University of Wisconsin-Milwaukee  (adhikar8@uwm.edu)

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