JACKSON OFFICIALS FIGHT `GREEN SCUM'

JACKSON -- Its scientific name is filamentous algae, but it is commonly referred to as the "green scum" that is seen at this time of the year on the surface of farm ponds and shallow lakes.

It looks unsightly, but other than causing problems for fishermen and clogging up aerator pumps, it is a harmless, free-floating aquatic plant. Some fish and most ducks and geese eat it.

Unfortunately, the algae tends to grow rapidly from early spring to midsummer, and at times covers nearly all of the surface of farm ponds and other small, shallow bodies of water, including Jackson's Rotary Lake in the main city park.

Park Supt. David Bierer said the algae is particularly bad this year. He said that about 25 percent of the lake surface is covered with algae. "The amount of coverage changes with the wind direction," he said. "Sometimes the algae covers the entire north half of the lake, while other times it covers the south half. And at other times, it is spread along the edge of the lake, but clear in the middle."

Although it is unsightly and has a definite odor, Bierer said the algae is not a health problem, and serves a useful purpose as part of the food chain for fish, ducks, geese, and other wildlife in the lake.

Brian Todd, a fisheries biologist with the Missouri Department of Conservation Department's Southeast Missouri regional office at Cape Girardeau, says the algae is found worldwide.

"It's a seasonal plant," Todd said. "It starts to grow in the spring and becomes a real nuisance from mid-May to the end of its growing season in mid-June to July."

Todd said he's received "tons" of complaints about the algae this year. "A lot more than usual," he added. "Most of the problems are in small farm ponds in the region and the smaller, shallow-depth lakes, such as the lake in Jackson."

Todd said the growth of the algae is promoted by the presence of rich nutrients, suspended in the water and on the lake bottom, that come from fertilizer run-off from farm fields, and droppings from ducks and geese.

"Because these bodies of water are shallow, they allow sunlight to filter in to the bottom, and that also helps accelerate the growth of the algae," Todd said.

There are several methods to control the growth of the algae, Todd said. "We recommend a herbicide called Cutrine Plus," he said. "It is environmentally safe, not toxic to fish or waterfowl, but it does kill the algae."

Todd said the only precaution in using Cutrine Plus is not to apply so much so as to kill large quantities of the algae. "We recommend that you kill off no more than one-third of the coverage area at one time," he said. "As the algae begins to decay after it has been killed, it uses up large amounts of oxygen in the water. That could harm the fish, or cause fish kill."

Todd said the department recommends the herbicide be applied to algae-covered ponds and lakes every two weeks.

Todd said the department's Cape Girardeau office has additional information on the herbicide and its proper application. The office also maintains a list of dealers who sell Cutrine Plus in this area. Those persons interested in obtaining further information can call the office at 290-5730.

Todd said another method, although more expensive, is to apply a chemical dye to the water. It is also harmless to fish and wildlife, but colors the water a deep green, which prevents sunlight from filtering to the bottom.

Another way to control the growth of algae is to promote the growth of a single-cell algae. "This algae is different from the filamentous algae, which is connected into a chain, end-to-end," Todd explained. "The single-cell algae are individual plants that provide shade on the water. That prevents the growth of waterlilies and other plants that are rooted to the bottom of the lake. The single-cell algae also produces oxygen in the water."

Todd said that if left alone, the algae begins to die off in midsummer or late summer.

Bierer said the amount of algae in the Rotary Lake forced the park department to shut down the floating aerators, but he said there is no indication of oxygen depletion in the lake. "With all the rainfall and surface water coming into the lake the past couple of weeks, the oxygen level in the water remains at a safe level," he said. "We've seen nothing to indicate any significant fish kills."

Bierer said park department employees have applied a chemical that darkens the water in order to retard the growth of the algae. He said the first application was made in April and the second last month. Why hasn't it done the job? "That's the same question we're asking," he said.