Seagrass Die-Off Carries Fears Of Another Collapse For Florida Bay

WLRN Public Media | By Nancy Klingener

Published December 8, 2015 at 4:23 PM EST

State biologists make their way through a mat of dead seagrass on Florida Bay in late September. Researchers say the die-off is now affecting at least 40,000 acres.

Almost 30 years ago, a seagrass die-off in Florida Bay led to massive algae blooms in the famous fishing grounds that form the southernmost end of Everglades National Park.

The collapse of the bay, and its impact on the recreational and commercial fishing industries of South Florida, helped garner support for Everglades restoration at the state and federal levels.

Starting the in late '90s, the bay recovered. But after a prolonged drought, the seagrass has started to die again, bringing fears that another cascade of impacts will follow.

"We may be looking at something that's set up to happen every 25 years or so," Florida International University marine science professor Jim Fourqurean said Tuesday in a report to the Florida Keys National Marine Sanctuary Advisory Council, "which means half of Florida Bay and a large part of the sanctuary is going to have impaired fishing, impaired water quality for at least half the time."

Fourqurean said researchers have found about 40,000 acres of the bay showing some symptoms from the die-off.

"That doesn't mean there's 40,000 acres of dead bottom," Fourqurean said. "But there's at least 40,000 acres in which there is active seagrass die-off happening right now."

Seagrasses provide habitat for prized gamefish and for many species of fish larvae, which later go on to populate the Keys reef. Algae blooms can also wipe out sponge populations, which help filter the water and are used by young lobster.

Scientists suspect the causes of the die-off is similar to that of 1987: prolonged drought and high temperatures, leading to water that is too salty and hot for seagrasses to survive. And the northern part of the bay is still not receiving the right amount of freshwater at the right times from the mainland Everglades, scientists say.

Recent rains may have come too late, Fourqurean said.

"Even though salinity's decreased, the trigger looks like it's been pulled," he said, "and the grass die-off areas still seem to be expanding."