Understanding the frequency, distribution, and regulating mechanisms of HABs in Minnesota lakes

Session: 37. - Harmful Algal Blooms (HABs) and their Toxicity: Remote Sensing and Modeling Approaches

Matthew Bambach, Natural Resources Research Institute- The University of Minnesota Duluth, [email protected]
Andrew Bramburger, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]

Abstract

Harmful algae blooms (HABs) have been implicated in fish kills, wildlife poisonings, and human health impacts related to consumption and recreational use.  HAB reports are increasing both globally and within the Great Lakes basin, including wilderness areas with pristine lakes.  Warm temperatures and excess nutrient runoff have been shown to favor the proliferation of HAB- forming taxa, yet we still understand little about the mechanisms that regulate HABs in freshwater systems.  We sampled six inland MN lakes spanning gradients of latitude, lake size, and productivity to examine the relative influences of geophysical parameters, weather, and water quality on cyanobacterial abundance and HAB proliferation.   All study lakes had high relative abundances (up to ~90%) of pico- and nano-cyanobacteria species, while southern lakes had more toxin-producing cyanobacteria (up to 25% R.A.) and experienced consistent blooms (Microcystis sp., Dolichospermum sp. and Aphanizomenon flos-aquae).  We also observed blooms in “pristine” northern lakes that included species characteristic of warmer environments (Wolskyella sp. and Raphidiopsis mediterranea).  These findings indicate that weather and land use are important drivers of HAB occurrence and potency.  Understanding HAB forcing agents will become more critical as freshwater resources become increasingly stressed by the effects of changing climate and land use patterns.

1. Keyword
harmful algal blooms

2. Keyword
nutrients

3. Keyword
water quality