Cyanobacteria bloom on Lake Mendota, June 7

On June 7, Arlene Koziol reported "Jeff and I are water quality monitors for Lake Mendota for the Clean Lakes Alliance. We live in Spring Harbor where there is an extensive Blue-Green Algae bloom. This morning when we did our water testing at 7:30 am, the air temperature was 72.5, water temperature 71.7, turbidity 55 Units, At 4:52 pm the changes were shocking. The air temperature was 83.2, water temperature 86.8, turbidity 5 cm. I was heartbroken to see a family of mallard ducks foraging in the scum. Also saw people recreating and working in the bloom". The scum and foul smell were horrific. All photos Arlene Koziol.

Scum of algae blooms washing against the shore, with Eagle Heights Woods in the background

That day, Arlene consulted John Magnuson, who reported "It was a bluegreen bloom. Bluegreen are photosynthetic cyanobacteria. Bluegreen stay in the sunlight (they need light for photosynthesis) with gas vacuoles for flotation. If it is calm they float to the surface, if there is a slight breeze they tend to accumulate on the downwind side of a lake. When the cells age their membranes breakdown and the water turns into a bluegreen paint-pot appearance from the release of their photosynthetic pigments. The grey you saw is bacterial growth growing off and decomposing the bluegreens. That is what smells. A good wind mixes bluegreens downward in the water column and there would be none of the surface signs but the decomposition could be occurring beneath the surface. My guess is that what you are smelling in University Bay. 
    Not all cyanophytes have toxins. There is a diverse set of species living in Lake Mendota when the water has warmed and the nutrients pour in as they have in the last week. An extensive bloom can cause a decrease in dissolved oxygen in the waters because the bacteria decomposing the dying bluegreen algae need and use oxygen in the process. Sometimes this also causes a fish kill if the dissolved oxygen levels become too low.
    The Dane County muck removal project to remove phosphorus loaded sediments from the lower reaches of streams near near their outlet to Lake Mendota, will reduce the phosphorus that enters from these storms. It should have a more immediate effect than, for example, cleaning up a particular farm high in the watershed."

The scum of the algae blooms forms pancake-like patterns

The photos cannot truly portray thermal situation, with sound and smells added. "The blooms do form pancake-like patterns. The pancakes are maintained by growth (cell division) in the mid-pancake and shearing by currents at the edge. A boundary occurs where  the loss rate by shearing exceeds the expansion rate due to growth of the alga," according to Steve Carpenter.

The blue-green algae bloom forced the closure of several Madison-area beaches including a stretch of Lake Mendota from UW-Madison to Middleton. Kynala Phillips reported in the Wisconsin State Journal. She also interviewed Jeff and Arlene and you can read last weeks front page article about the issue in the Wisconsin State Journal. 
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   "The toxins can cause issues such as upset stomach, rashes and respiratory problems. Such blooms can also lead to fish kills once the bacteria sinks, according the UW Center for Limnology. Their website reports: "The conditions were ripe for an algae bloom. .... [Our area] received anywhere from 4 to 5 inches of rain more than the long-term average for the month of May. ... Rain, especially the “gullywashers,” carry tons of phosphorus-laden soil into nearby creeks and streams, where it eventually ends up in our lakes and is just as good at growing algae as it is soybeans. The weather got warm... Cyanobacteria like it warmer than other algae and they grow fast in warm water... the wind stopped...these kinds of algae are boyant and they just floated to the top in this awful scum." 
   The Public Health Department takes water samples weekly, but the department also depends on citizen reports and organizations like the Clean Lakes Alliance to get a real-time understanding of the lakes’ conditions.
​    You can learn more on July 11, 9:05 am, when Trina Mahon will speak about Blue-Green Algae Bloom at the monthly Yahara Lakes 101 event organized by Clean Lakes Alliance (at the Edgewater Hotel).
  
Arlene is consulting with a host of scientists and government agencies in an effort to summarize the causes, toxins released, effects, and possible actions regarding cyanobacteria blooms on our lakes. – Gisela