Again, many people reported seeing lots of “little green dots” in the water this summer. Yes, it is a Blue-Green Algae but it also seems to be a relatively benign kind. Was here last summer in large numbers and for the past 4 or 5 in smaller numbers.
The Algae, called Gloeotrichia, was found throughout the lake most of the summer in low densities. Last year, there was a reasonably large bloom of this algae so it was expected this year. There are places with higher densities, most likely associated with the direction of winds. Last year, samples were sent to UNH to test for toxins (this species can produce toxins at times) but this species doesn’t seem to be as dangerous as other forms of blue green algae. There have been reports on this lake of rashes and some digestive issues after swimming which might have been due to this bloom or another cause (such as duck itch or normal indigestion). The bloom will probably disappear in a week or so but it is quite likely to come back next year because it has a life cycle that allows it to winter over at the bottom of the lake. More information is available in a brochure produced by the Lake Sunapee Assoc. with regard to their bloom of Gloeotrichia. The link is: Lake Sunapee Bloom. Click on the “attachment link=1976” and you will get a PDF separate from this web page that has a lot of information about the algae.
What individuals can do…reduce phosphorus input to lake. The Lake Wentworth Watershed Plan is designed to do just that. Gloeotrichia is tough to get rid of because it forms resting cells on the sediments and can draw from sediment phosphorus (accumulated from past loading) to start the cycle again. This species seems to be found in lakes that are relatively pure like Lake Wentworth, according to people from the New Hampshire Lakes Assoc., but the more phosphorus available, the worse the blooms may become.
Other links with information: