ZEBRA MUSSELS ARE HERE; FIRST TIME NORTH OF OHIO RIVER

Zebra mussels may find it difficult to go up the Mississippi River without detection these days. But the "zebras" have finally made it to Cape Girardeau, say Missouri Department of Conservation officials.

"We don't know when the zebra mussels came into the area," said Robert Hrabik, a fisheries biologist with the Missouri Department of Conservation field office in Cape Girardeau. "We don't know why they're here or how long they have been here, but we're concerned."

The Cape Girardeau finding of the bio-fouling organism, a native of Europe, is the first in the Mississippi north of its confluence with the Ohio River at Cairo, Ill.

"We don't know that the mussels will cause much or any damage here," said Hrabik. "But in places where they have been they have been a big headache. We feel that the effects of the zebra mussels in the Cape Girardeau area could be minimal; but, if they go north, they could cause some damage, especially north of St. Louis."

The zebra mussels caused millions of dollars worth of damage in the Great Lakes area by clogging municipal and industrial water intakes.

"This organism can multiply by the thousands," said Hrabik. "They can attach to rocks, barges, and even to our own native mussels.

"Layers of zebra mussels have been discovered in other areas," said Hrabik.

The first zebra mussels here were discovered by accident in the Mississippi River at river mile 47.

"We have monitors in the river," said Hrabik, who heads the field station operated here by the Missouri Department of Conservation. "But we haven't found any of the zebras with our monitors."

The zebra mussels have been discovered on concrete blocks that serve as anchors for the monitoring devices.

Four of them were found Nov. 13 when one of the monitoring devices was damaged and the concrete anchor was pulled from the bottom of the river, said Hrabik.

Since then other anchors have been pulled up for investigation.

"We found two zebra mussels on Nov. 19," said Jennie Rundell, a fisheries biologist in charge of the water-quality crew stationed at the department's 20 S. Sprigg office. "The next day we pulled four more samplers and found 10 zebras on concrete blocks.

"The mussels were found in quiet waters," said Rundell. "Many of our monitors are located behind rock dikes."

During this time workers for the Cape Girardeau municipal water system discovered three of the zebra mussels in its water intake pipe.

"We have been monitoring the water for zebra mussels," said Tom Taggart, water systems manager. "And, when we read in The Missourian that the first four had been discovered here, we increased our surveillance for the organism."

Taggart said he did not anticipate any problems with the zebra mussels.

"Our water intake is different from many," he said. "The design for our intake structure is a tunnel through rocks; thus, we have a larger opening than many intakes. The smallest opening we have will measure about 3-by-5 feet.

"Although there is no reason for alarm, we don't want to ignore the zebra mussels," said Taggart. "We'll continue to monitor the situation. This is a new phenomena. We knew they were coming, but didn't know when."

The clogging of some municipal and industrial intakes is just one of two primary concerns of conservation officials.

"The other potential threat is that posed to native organism like our fresh-water mussels," said Hrabik. "The zebras tend to colonize in a large group. They even attach to the native mussels, smothering them out."

The zebra mussels apparently have no natural predators.

The zebra problem first came to light in 1986, when the organism found its way into the Great Lakes. There, they caused millions of dollars in damages before a chemical control method was devised to ease the situation.

The zebra mussels are believed to have entered the Great Lakes when a European ship released its ballast waters, say conservation officials. They have since been found in the Illinois River and along southern areas of the Mississippi River.

They were discovered in the Ohio River at Paducah, Ky., in early November. A diving team found several adult zebra mussels attached to the Paducah intake water structure. One adult was found within the intake caisson that contains the pumps that move water to the city's treatment plant.

The Paducah water intake was the third find of zebra mussels in the Ohio during the past month. The zebras also were found in the lock chamber of Kentucky Lake Dam a few months ago and at other sites on the Tennessee and Cumberland rivers.