Post by smead on Jun 23, 2010 23:09:05 GMT -5
Visitors warned about algae in Grand Lake St. Marys
Monday, June 21, 2010 11:41 PM
By Vince Bond Jr.
THE COLUMBUS DISPATCH
New and potentially dangerous algae have moved into Grand Lake St. Marys, joining a toxic bloom that forced state officials to warn visitors last year to keep their distance.
The 13,000-acre lake has long been considered one of the state's most polluted. Fertilizers and manure from farms in Mercer and Auglaize counties have helped turn the lake green with algae. But now a second strain of algae has officials worried.
Friday, Department of Natural Resources officials placed warning signs urging visitors to be cautious around the lake's three beaches, said Heidi Hetzel-Evans, department spokeswoman. The signs say visitors should avoid touching "visible surface scum."
The new algae are called Aphanizomenon gracile and are capable of producing three toxins. The Ohio Environmental Protection Agency has sent samples out of state to see if this bloom is dangerous.
Last year, the algae were planktothrix, which produce a neurotoxin called microcystin. It was so thick in May 2009 that the state warned that it could cause skin rashes, sicken people and kill small animals, including dogs.
Officials put up warning signs at the lake last year, but they took them down this April when toxins declined.
In 2008, the lake attracted more than 737,000 visitors. Last year, the number fell to 687,000.
Though common in Lake Erie, the algae previously had not been discovered in an inland lake in Ohio. They later were discovered in Buckeye Lake. In Erie's western basin, the algae grow into dense "blooms" that help create a vast, oxygen-depleted dead zone where no plant or fish life can survive.
In humans, the toxin can cause skin rashes, sore throats and watery eyes. In high concentrations, it can cause weakness, dizziness, breathing problems, convulsions and liver and kidney damage.
Both planktothrix and Aphanizomenon gracile are cyanobacteria, or blue-green algae.
Aphanizomenon gracile can produce clyindrospermopsin, which can cause liver tumors and gastrointestinal distress, and anatoxin and saxitoxin, toxins that affect the nervous system.
It isn't clear if Aphanizomenon gracile is the only species present.
The study of cyanobacteria "is an emerging science," said Dina Pierce, an EPA spokeswoman. "It's not uncommon for different species to dominate at different times."
Joe Logan, agricultural director for the advocacy group Ohio Environmental Council, said residents can't catch a break.
Last year, levels of microcystin were four times higher than the World Health Organization's "low-risk" mark for swimmers and 82 times higher than its standard for drinking water.
"We don't know if this is more dangerous than last year," Logan said. "We have a lot to learn about this species, but what we know so far is alarming."
Joseph Conroy, an ODNR fisheries biologist, said toxins can build up in fish tissue and kill them, while decaying algae blooms can suck oxygen from the water during decomposition.
"Things seemed really low in productivity," Conroy said. "In the last few weeks, things have shot up."
vbond@dispatch.com
www.dispatch.com/live/content/local_news/stories/2010/06/21/algae-in-grand-lake-st-marys.html?sid=101
