Digital Extra

5.27.2000
In R.I.'s marshes, man vs. mosquito in trench warfare
The threat of West Nile virus heightens concerns that more communities need to address the problem of breeding grounds grows.

By PETER B. LORD
Journal Environment Writer

Douglas Rayner remembers when mosquitoes were such a big problem in Barrington that every town meeting was dominated by complaints from outraged residents.

"For three or four years, all people were talking about was mosquitoes and spraying," says Rayner, a long-time environmental activist. People hated the mosquitoes swarming out of the town's salt marshes, and then they got upset about all the insecticides the town was spraying on the marshes.

Though this was more than 20 years ago, Rayner recalls that he and the other members of the town's Conservation Commission quit in protest of the spraying.

The town responded by embracing a new technique called "marsh water management" -- an effort to clean out, fill in or otherwise alter the miles of drainage ditches that were first dug in the state's salt marshes during the Depression to kill mosquitoes.

The plan back then was to drain the salt marshes, depriving the mosquitoes of places to breed, but eventually the ditches themselves were sources of standing water. When the water flow was properly restored, mosquito larvae were quickly consumed by fish -- without a drop of insecticide being used.

Today, as the state girds for a possible outbreak of mosquito-borne West Nile virus, Alan D. Gettman, the state's mosquito abatement coordinator, says he wishes more communities had taken steps to reduce mosquito breeding in their salt marshes.

"We have two species produced in huge numbers in salt marshes all around the Bay," says Gettman. "They come every year whether we have rain or not, because they are hatched by the moon tides [the highest water level of the month]. Last summer, despite the drought, mosquito production was outrageous.

"So here are areas where many Rhode Islanders live . . . and where the tourism industry is centered, and we have hordes of mosquitoes biting people very aggressively -- and they are unusual because they bite in the middle of the day and in open sunshine."

The outbreak of the West Nile virus in New York City last fall has caused Rhode Island and all other East Coast states to take unprecedented measures to curb mosquito populations.

West Nile virus -- a form of encephalitis or brain inflammation -- was never seen in the United States until last fall, when it suddenly erupted in New York and killed seven elderly people, as well as horses and numerous birds.

Because the virus appeared to come from a species of mosquitoes that hatches in storm drains, Rhode Island in recent weeks has distributed to local public works departments enough larvicide to treat more than 70,000 catch basins.

The Department of Environmental Management has also distributed bacteria-based pesticides to deposit in ditches and small ponds.

But there remain thousands of acres of salt marshes that are difficult to treat.

Several communities have taken steps, at a time when state and federal governments are becoming interested in restoring important habitats, such as salt marshes. Mosquito-reduction efforts can readily be made while working to restore marshes damaged by road construction or pollution, Gettman said.

The state General Assembly is considering creating a fund for habitat restoration this session. And last week, U.S. Rep. Patrick J. Kennedy helped persuade a congressional committee to pass legislation that would finance the restoration of habitats around estuaries.

During the Depression, the Civilian Conservation Corps dug miles of trenches in nearly every marsh along the coast. The idea was to drain the marshes to reduce mosquitoes.

"It was some engineer's dream," Gettman said. The ditches were straight as an arrow, 200 feet apart, and dug with no consideration of where the mosquitoes were actually breeding.

What's more, with no maintenance over the years, those ditches have become so clogged that many breed mosquitoes rather than kill them.

"Many of these have become strings of puddles where mosquitoes breed, and that's the grand irony," Gettman said.

Some communities have worked to reduce mosquitoes in their salt marshes.

Westerly, using a special mechanical shovel that the DEM acquired to clean up oil spills, worked on the ditches in its Winnapaug and Weekapaug salt marshes last year.

"We have a consultant who goes into the marshes biweekly," said Public Works Director John Fusaro. "He keeps his eyes on the full moon and high tides. We also are planning additional work in the Watch Hill area."

Recent projects to restore the salt marshes in Galilee and Sachuest Point also included measures to reduce mosquitoes, and they worked, according to Gettman.

"We were wildly successful at Sachuest," Gettman said. "We went from zillions of mosquitoes and no fish, to exactly the opposite."

Gettman says he enjoys consulting on the salt marsh jobs, but he's frustrated because he's so busy with the West Nile campaign that he has little time for marsh work. So several projects he is supposed to review are sitting on his desk.

"Another person could lead these things," Gettman said. "I don't care where that person sits, as long as it's someone with a decent understanding of marsh ecology who can help line up finances and steer the projects through the permit process."

He stresses that the work is more complicated than simply restoring the Depression-era ditches.

"It's not simple ditch maintenance anymore," says Gettman. "We do a more enlightened form of water management. It's a combination of soil movements that ultimately result in fish gaining better access to mosquito larvae. Where you find fish, you don't find larvae.

"We might clean out an existing ditch. We might fill it in. We might deepen it in sections and turn them into a fish reservoir. We might dig new ditches to connect an existing creek to a low spot that makes mosquitoes. Every marsh parcel is different. It's a case-by-case basis."