Capaha pond's natural solution

Thursday, July 10, 2003

Nobody likes pond scum.

Unless they're starving, not even the 30 grass carp introduced into the Capaha Park Lagoon last week will eat the green filamentous algae floating atop the lagoon. Grass carp will eat the leafy pond weed currently covering 50 to 60 percent of the lagoon's bottom, and that's why they've been brought in.

Reducing leafy pond weed will make the lagoon healthier and eventually could make the floating algae less noticeable.

In a healthy pond, only about 15 to 20 percent of the bottom is covered in vegetation, says Chris Kennedy, a fisheries and management assistant for the Missouri Department of Conservation. Too much vegetation gives fish too many places to hide. If too many bluegill survive, they only grow to about 4 inches. And if bass can't find bluegill to feed on, their numbers and size also will be reduced.

Kennedy recommended the grass carp solution when the Cape Girardeau Parks Department went looking for a way to control vegetation in the lagoon. Both he and parks department director Dan Muser are opposed to using chemicals to control the weeds in water because they harm the water quality. Muser says chemicals also are expensive.

Some people think the algae on the lagoon is the real problem. "It's pretty nasty," John Davis of Cape Girardeau said Wednesday while fishing at the park. "One side of the pond is covered with it. Something really needs to be done about it."

Aerators in the lagoon help keep the water moving. But they don't work all the time, said Antonio Primer, another fisherman.

"I fish here a lot because I'm staying just down the road, and the fishing is not as good as it used to be before all this scum," he said.

Not as bad as before

Algae is the first plant to begin growing in the lagoon in the spring, and it thrives in warmer weather. But Muser points out that algae can be found floating on even free-flowing bodies of water. He says the algae is not as prevalent this year as in past years.

He recalls that city workers one year removed the algae by hand and says that could be done again. But Kennedy says the leafy pond weed needs to be addressed first, not the algae.

The lagoon is 9 feet deep at its deepest point and much shallower around the edges. The algae floats on the top of the lagoon until it encounters vegetation beneath the water. When that happens, the algae sits on the water and does not disperse.

The city already has grass carp in the lakes at the Jaycee Municipal Golf Course. Grass carp shouldn't be put into a pond or lakes unless there is a problem with too much vegetation, Kennedy says. "Those plants are the basis of the food chain. They feed the insects and the insects feed the fish," he said.

Reducing vegetation too much can shrink oxygen levels in the water, producing a fish kill. Kennedy said the problem has to be solved slowly. He estimates it will take more than a year and a half for the carp to have an effect.

One reason the algae grows well on the lagoon is that the water is so fertile.

"What would really help, but what the public doesn't want to see, is getting rid of the geese and ducks," Kennedy said.

Muser doubts anyone will catch a grass carp, but both he and Kennedy hope that anyone who does releases it. "We need them in there," Kennedy said.

sblackwell@semissourian.com

335-6611, extension 182

Respond to this story

Posting a comment requires free registration: