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8 Sep 07
Drought reawakens ailing Southwest Florida estuaries
By Julio Ochoa
What a difference a year — and a drought — makes for local estuaries.
A year ago, thousands of gallons of water flowed down the Caloosahatchee River from Lake Okeechobee.
A year ago, persistent blooms of red tide killed scores of fish in local waters. A year ago, seagrass beds in local estuaries were thinning out and dying off because sunlight couldn’t penetrate the murky waters.
Then, the drought hit.
It’s been nearly a year since officials released damaging amounts of water from Lake Okeechobee.
One of the longest lingering red tide blooms in Southwest Florida’s recent history vanished by March. Seagrass beds are coming back strong and the fish are following.
“In this case it seems like it’s starting to bounce back,” said Rick Bartleson, a research scientist for the Sanibel-Captiva Conservation Foundation.
“Estuaries in general are resilient. This means that we didn’t kill it and that it’s got a chance to come back.”
The improvements are good for business, said Capt. Dave Lanier, owner of Hickory Island Fish Company, a bait wholesaler and charter fishing operation.
Last year, Lanier had to go a few miles offshore to trap pinfish, which he sells to local bait shops. Red tide had killed much of the pinfish stock in Estero Bay. This year, the bait has been all over the flats, he said.
“Let’s see, no releases from Lake Okeechobee, no red tide and no (brown) water,” Lanier said. “Hmmmm, could there be a connection?”
In an estuary, everything is connected, scientists say.
Game fish feed on bait fish. Bait fish and juvenile gamefish seek shelter in seagrass beds and feed on invertebrates that grow on the grass’ blades. And the grass needs the right mixture of saltwater and lots of sunlight to grow.
Large volumes of murky water released from Lake Okeechobee flood local estuaries, blocking out sunlight. The local basin also contributes to the problem with polluted runoff flowing directly into estuaries, instead of being filtered through the natural process.
Freshwater and lack of sunlight causes seagrass beds to thin out or even die off in some areas.
Department of Environmental Protection scientists working for the Estero Bay Aquatic Preserve noticed significant decreases in seagrass coverage a couple of years ago.
The scientists monitor the same five sites in Estero Bay every year. Within a square meter, they measure the percentage of area covered by seagrass, the different types of seagrass found and the length of the blades.
The scientists still are conducting their research, but they are finding signs of improvement, especially compared to two years ago, said Stephanie Erickson, an environmental specialist for the Estero Bay Aquatic Preserve.
“A majority of what we’re seeing this year is not only an increase in the percent coverage but in the length of the blades,” Erickson said. “It’s thicker.”
Two years ago, Erickson may have found between 5 and 25 percent coverage in an area; now she is finding between 50 and 75 percent. A few grass beds have even grown, covering more territory, she said.
Scientists for the Sanibel-Captiva Conservation Foundation also have seen improvements in the areas they monitor around Sanibel, Pine Island Sound and the Caloosahatchee River, Bartleson said.
“We’re seeing more grass in monitoring sites,” he said. “It looks like areas that have been hit hard are starting to come back.”
The hardest-hit area of them all — the mouth of the Caloosahatchee River — has improved the most, Bartleson said. But Bartleson warned that the area isn’t in the clear yet.
Scientists still are finding globs of algae stuck to some of the area’s seagrass, Erickson said. A recent outbreak of an algae called Trichodesmium, which dies water brown, means red tide may not be far behind, Bartleson said.
And a good drenching from a tropical storm or hurricane could foster the need to open Lake Okeechobee’s flood gates once again, he said.
“We don’t know when the next time we’ll get the dark water,” Bartleson said.
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Join TeamSeagrass, volunteers who conduct the kind of monitoring mentioned above and make a difference for understanding our shores.
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