Lake algae ‘not toxic, just a mess’

SALISBURY — Lake Wononscopomuc has seen its fair share of stubborn greenery, from milfoil to algae growth.

This year there was enough algae that the Lake Wonscopomuc Association asked an expert to take a look.

In a July 1 memo by limnologist Larry Marsicano, he reported that the lake is dominated by filamentous green algae, which poses no threat to lake-goers, despite “[making] recreational use of shallow waters undesirable.”

Marsicano’s team collected samples on June 29, and again noticed large amounts of green algae, including Spirogyra spp., Oedogonium spp., and Mougeotia spp. These types are the familiar lime-green, “billowy cloud-like masses” that invade shallow areas of the lake.

Green algae accumulate because of high nutrient content in the water. Marsicano said that the lake’s nutrient levels were generally lower, and that this is a good sign for avoiding further growth of the plants.

Sometimes, algae are simply more abundant in specific years. For instance, another client of Marsicano’s, located just 20 miles from Lake Wononscopomuc, also reported elevated levels of green algae.

The team observed other types of algae, such as diatoms and golden algae — specifically Fragilaria spp and Dinobryon spp. These examples are “good indicators” and will not hurt anybody that runs across them.

Blue-green algae, (Dolichospermum spp), was found as well, but in very small quantities. Blue-green algae could produce unwanted toxins, however Marsicano said there is not enough of the strain to even start considering consequences.

The head of the lake asssociation, Bill Littauer, said “A number of people have seen the large algae blooms in the lake, not knowing if they were hazardous or toxic, so I talked to the limnologist.”

Indeed, it seems as if the recent algae confrontations are with docile green algae. Marsicano cited advice from the New Hampshire Department of Environmental Services on how to mitigate accumulation of the unwanted floaters.

It is important to identify boundaries with the local lake association before engaging with possible removal operations.

The foremost piece of guidance is “to wait them out.” It is OK to scoop away the green algae if it encroaches on swimming areas. However, wind, currents, and rain will naturally move the algae and it will disapear with rotating weather.

Lake users can be grateful for the recent rain that made Fourth of July plans a little spotty. The showers, at least, scattered the slimy blooms, which Littauer said “are not toxic, j ust a mess.”