On June 17, 2019, Arlene and Jeff Koziol reported the first blue-green algae blooms of the year. The lake temperature was 69°F. The photos of near shore blooms shown here were taken at Raymer's Cove in the Preserve. The bloom extended from Marshall Park boat ramp to Raymer’s cove. Spring Harbor Beach was closed.
This year's first cyanobacteria bloom is late compared to last year. It will be of interest to compare dates of lake stratification for these two years. After the winter of uniform water temperatures of 4°C below the ice cover, surface water warms up in spring, and the colder water begins to sink, the spring turnover. Eventually, summer stratification sets in with three layers: the upper, well-mixed warmer water, a middle transitional zone with rapidly decreasing temperatures, the thermocline, and the lowest cold and dark layer, undisturbed and extending to the lake bottom.
Last year, the Koziols observed the first bloom at their monitoring site a month earlier, on May 16! Arlene reports, "Our big blooms last year were June 7, 8, 27 and Sept 7th and 15th, 2018. We were late getting out for our measurements of the Mendota Central Deep Hole this year because of bad weather and boat issues. Our first readings at the Deep Hole was June 12th and the lake had already stratified. Last year I was told that the data from the Mendota buoy is not available.
Here is a question, yesterday when I looked at the bloom early in the day, the algae seemed to be floating up from a lower level. Below is a little video clip from my phone. Can one tell if it is cyanobacteria?"
See more of Arlene's photos on her Flickr Site.
Gisela Kutzbach and contributors