Florida drought has an upside for coastal marine life

Zac Anderson, Herald Tribune 6 Jan 08;
Lack of rain has left waters cleaner and healthier

SARASOTA BAY -- Drinking water supplies are low. Farmers and lawns are struggling. But Rick Grassett said his charter fishing business has been "very good," and he believes Florida's severe drought is helping.

Grassett sees the drought's positive impacts on local estuaries during near-daily fishing excursions throughout the region.

"It's been great out on the water," said Grassett, a fishing guide who has operated out of CB's Saltwater Outfitters in Sarasota for 18 years. "Sea grass is thicker and more abundant. Fish are more plentiful."

Grassett's observations are supported by a variety of environmental researchers. Statewide, rainfall is 20 inches below average over the last two years, diminishing the flow of fresh water into coastal estuaries.

Environmental experts say the drought is neutralizing harmful drainage from farms and old developments, reducing water pollution and boosting marine life in local bays.

Scallops have been found in some bays for the first time in years, and are expanding in most areas.

Oysters are thriving as well, with the highest survivability rates since Sarasota County began monitoring them in 2003.

Researchers also predict a banner year for sea grass, a key habitat for juvenile fish and other marine life.

And red tide,, a harmful algae bloom which can feed on pollutants in storm-water runoff, has been noticeably absent along the Southwest Florida coast, although the drought's impact is debatable.

The results provide evidence backing ecological restoration efforts and environmental protection measures such as lawn fertilizer restrictions, environmentalist experts say.

"Florida has spent the last 100 years trying to drain off the fresh water -- and we've done a great job of that -- but there were some serious consequences," said Jack Merriam, Sarasota County's environmental manager. "The drought illustrates why we need to restore a more natural hydrology."

To be sure, the drought is having negative ecological effects as well, especially in freshwater ecosystems like the Everglades and Lake Okeechobee, according to scientists.

And extreme conditions are never good in the long run, said Catherine Corbett, senior scientist with the Charlotte Harbor National Estuary Program.

"What you really hope for is balance," Corbett said.

But some species are seeing clear short-term benefits, in habitats such as Dona Bay, in Nokomis.

In the 1960s, the land around Dona Bay's tributaries was drained for agriculture. Area streams were straightened to funnel storm-water and irrigation runoff quickly into the bay.

The result: Dona Bay's watershed expanded from 15 square miles to 75 square miles, dumping millions of gallons of excess fresh water into the bay and disrupting the ecosystem.

With less fresh water and pollutants flowing in, oysters and sea grass this year are thriving and scallops have been found for the first time.

Similar drainage practices were employed from Sarasota Bay to Charlotte Harbor, where miles of canals were dug to drain land and provide waterfront real estate.

Most of the canals in Port Charlotte and North Port drain into Charlotte Harbor, carrying pollutants from roads and lawns.

Especially troublesome are algae-feeding nutrients from lawn fertilizer and from human waste in septic systems.

Dense algae blocks light that sea grasses need to grow, said Jon Perry, a Sarasota County environmental expert who organizes the county's annual sea grass survey.

"Water clarity is very important for sea grass," Perry said. "How much light is available for photosynthesis and growth? If you block the light, then the grass will have degradation."

Sea grass also thrives in more salty water, a trait shared with scallops and other species.

"We've seen a really dramatic increase in scallops this year," said Jay Leverone, a staff scientist for Mote Marine Laboratory in Sarasota, who has studied bay scallops in Southwest Florida for 15 years. "We can't confirm the reasons; we can only observe. But we do know that we don't have those stressors like excessive freshwater and nutrients."

Another factor helping scallops is the lack of red tide in the region. Red tide often kills sea life.

Grassett, the charter boat captain, said red tide nearly wiped out spotted sea trout in the region in 2005. The fish has rebounded nicely this year.

"It's just an observation, but red tide seems to be worse when it rains," Grassett said.

Despite the lack of storm-water runoff that can feed red tide,, Cindy Heil, a senior scientist with the Florida Fish and Wildlife Research Institute in St. Petersburg, said the drought is having a minimal effect on whether blooms come near shore.

"There was a red tide bloom off the coast of Sarasota earlier this year, but the reason it did not come to shore was mostly oceanographic conditions," Heil said.

But if a bloom did come to shore, it likely would be worse during rainy years. Near-shore nutrients can increase the strength of a bloom by 20 percent, Heil said.

Local governments are taking steps to reduce nutrients in local waterways. They range from replacing septic tanks with sewer systems to banning certain lawn fertilizers.

"If we can clean up the runoff, we can clean up our waterways so we're not worried every time it rains," Merriam said.