Diel Variation of Cyanotoxins: Are Potent Neurotoxins a Risk Outside of Daylight Hours?

Primary Investigators

USGS Investigators: Victoria Christensen

NPS Investigators: Ryan Maki

Project Details

Start Year: 2021

Category: Technical Assistance

Project Location

NPS Park: Voyageurs NP

USGS Center: Upper Midwest Water Science Center

States: MN

Several dog and cattle deaths in the region indicate that the potent neurotoxin, anatoxin-a, is a concern in pre-dawn hours and on cloudy days. In addition, the only suspected human anatoxin-a death occurred following an after-dark swim. However, most sampling is completed midday. We propose to sample neurotoxins and other cyanotoxins over 24-hour periods, along with photosynthetically active radiation to assess the relation between sunlight and these potent toxins, so that resource managers can make more informed decisions about recreational water use.

Since neurotoxins have proven to be extremely toxic and their production and release from cyanobacteria may have a diurnal component, we propose to study the diel variation of multiple cyanotoxins at one recurring bloom site in VOYA to better estimate the risk of exposure to park visitors.
Specific objectives of this study are to:

  1. Use FY2020 (collected in-kind) and FY2021 data to assess whether neurotoxin and other cyanotoxin concentrations exhibit diel variation and if levels exceed safety thresholds for recreational water use.
  2. Outfit one site with an in situ buoy system in order to assess variation in environmental factors that may contribute to toxin production or degradation and give future warnings of potentially toxic conditions.