Canandaigua Lake plagued by blue-green algae

Canandaigua Lake, considered one of the cleanest of the Finger Lakes, continues to be plagued by blue-green algae and by streaks and patches of white foam.

The foam, which likely has natural origins, has appeared on the lake before. So has blue-green algae — but never to the extent it does now. The organism, which actually is a form of bacteria, has been spreading through various parts of Canandaigua Lake for three weeks. A report from the lake's watershed manager on Wednesday said "multiple" algal blooms were present in the lake, including at the north and south ends.

Some forms of blue-green algae can proliferate rapidly, or bloom, and release toxins that are harmful to the health of humans, pets and wildlife. Microcystin, an algal liver toxin, has been found in Canandaigua Lake at "high" concentrations, according to a New York state blue-green algae alert website.

Blue-green algae blooms, which have been an increasing problem at many New York lakes, are usually said to be driven by favorable weather conditions and by the presence of relatively high levels of man-made or natural nutrients. Phosphorus, a constituent of animal manure, human waste and some manufactured fertilizers, is the nutrient mentioned most often.

But that's what makes the Canandaigua bloom outbreak puzzling. It has much less phosphorus that other lakes with blue-green problems.

"Canandaigua Lake is very interesting in that the phosphorus levels in that lake are really pretty low and it is not really one that would make you think it would bloom," said Gregory Boyer, a biochemistry professor at the State University College of Environmental Science and Forestry. Boyer, who may be the state's leading experts on blue-green algae, has been contacted to consult on Canandaigua's ongoing problems.

"It may be more of a circulation issue as evidenced by the large foam streaks in the lake," Boyer speculated in an email Thursday.

According to remarks on the Canandaigua Lake Watershed Council website, the foam — so thick in places it looks like a layer of ice — is formed when air and water mix to form bubbles. Dying organisms release material that effectuates the process.

The organisms releasing the material could be quagga mussels, invasive mollusks that have colonized Canandaigua and many other lakes, or blue-green algae, the remarks said.

SORR@DemocratandChronicle.com