September 14, 2011

Hydrilla Called ‘Number One Lake Issue’

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Some Ithacans say they are worried about the encroaching presence of hydrilla, an invasive seaweed-like species, near Cayuga Lake. Spotted in areas near the lake, the plant forms dense mats of vegetation which shade out native plant species and harm fish and waterbirds.

Wade Wykstra, commissioner of the Board of Public Works and chair of the Ownership Committee for the Ithaca Area Wastewater Treatment Plant, called hy­dril­la “the number one lake issue right now.”

The densest infestations are currently in Cascadilla Creek, Cass Park and around the Cornell and Ithaca College rowing team boathouses, according to Prof. Holly Menninger, natural resources, senior extension associate and coordinator of the New York Invasive Species Research Institute. The plant was first spotted this August, and as of Sept. 5, hydrilla has been found in Cayuga Inlet but not in the lake.

According to Wykstra, it will cost tens of millions of dollars to manage hydrilla if it spreads into the Finger Lakes.

Similarly, Menninger said that hydrilla spreading into Cayuga Lake is a “huge concern” because the lake is connected to the other Finger Lakes by canals, rivers and streams. The plant could then potentially travel via canal all the way to Lake Ontario, which connects to the other Great Lakes.

According to Menninger, hydrilla probably reached the Cayuga inlet by “hitchhiking” on boats and equipment.

This is the first time hydrilla has been found in Central New York, although it has been sighted in Orange County and Long Island, according to Menninger.  Hydrilla has been identified in 31 states, and Florida alone spends $18 to 30 million annually to manage it.

Menninger said that hydrilla produces blue-green algae blooms that could kill waterbirds that ingest them. In turn, bald eagles could die from eating poisoned waterfowl, she said.

“The implications [of hydrilla] can be profound,” she said, as the plant grows fast, spreads quickly and adapts to a wide range of conditions, including cool temperatures and low lighting.

Hydrilla shades out native species of pond weed and wild celery, which provide habitats for plants, fish and waterbirds. Dense mats of hydrilla also reduce the levels of oxygen in the water, harming fish, Menninger said.

“We know that when hydrilla comes in and takes over, there are impacts on recreation,” Menninger said. “Potentially, the whole Cayuga Inlet could fill up with hydrilla.”

Lost recreational opportunities, including boating, fishing and swimming can cost millions of dollars in revenue and decreased property values, in addition to the cost of managing the hydrilla, officials said.

According to Menninger, hydrilla reproduces by fragmenting, so each time a boat goes through and chops up a mat, the hydrilla population increases.

Wykstra said that the New York State Department of Environmental Conservation needs to be more involved in determining what to do about the plant.

“If it was up to me, I would consider shutting down the inlet to contain it,” Wykstra said, acknowledging that this would hurt local commerce. “The shutdown could be worthwhile because we have an opportunity to prevent it from spreading throughout New York State.”

Another strategy for eradicating hydrilla would be using divers to uproot and vacuum the plant before sending it to digesters at a wastewater treatment plant, Wykstra said.

According to Menninger, herbicide chemicals are “well-tested” for use in aquatic environments and are a viable way to suppress hydrilla. She noted that the herbicides are not specific to hydrilla and could kill other plants, but she said she believes that the inlet would recover.

Wykstra is opposed to using herbicides, citing a lack of independent chemical analysis, but noted that this would be the DEC’s decision.

Both officials said that immediate action is needed to prevent hydrilla from spreading. However, the city has not passed any resolutions deciding what to do yet.

Menninger stressed that it is important to act this fall because the plant reproduces in October, so there will be a lot more to deal with in the spring.

“It may make us feel uncomfortable now, but if we don’t act and we let the hydrilla take over and spread, I think the problems will be monumentally worse,” Menninger said. “We have an opportunity here with the infestation in the inlet to control hydrilla, keep it contained and eliminate it.”

Original Author: Laura Shepard