Diatom Algae bloom

http://www.tcpalm.com/news/2009/may/19/algae-in-atlantic-could-move-southward-from/

Algae in Atlantic could move southward from Brevard County
By Tyler Treadway

TREASURE COAST — It looks bad, it smells bad, and it may be heading our way.

The algae floating in the Atlantic off Brevard, Flagler and Volusia counties isn't dangerous; but it deserves monitoring, say scientists.

"It's not red tide," said Cindy Heil, senior research scientist and leader of the red tide group at the Fish and Wildlife Research Institute in St. Petersburg, "that's the main thing. It's not toxic and it's not harmful."

But Brian LaPointe, a research professor at Harbor Branch Oceanographic Institute at Florida Atlantic University in Fort Pierce, said the current algae bloom could be a precursor of a red tide bloom.

Red tide can cause eye, nose and throat irritations similar to a cold. People with severe or chronic respiratory conditions are cautioned to avoid red tide areas. When red tide is present in large concentrations, it can produce toxins that kill fish. Shellfish from areas with red tide shouldn't be eaten.

"You can get what we call a series succession," said LaPointe, who's been studying algae blooms for more than 25 years. "First you have a diatom bloom like the one we're seeing now, then you see other species becoming dominant. It's not unusual for a red tide to follow a diatom bloom."

The clouds have discolored water since late April and, have been identified as the diatom algae, Thalassiosira.

"It's a single-cell plant that's the basis of the food chain," Heil said. "What's causing the problem is that there's just so many of them."

Heil said the algae isn't formed in a single mass but is "lots of little masses" that can be as small as "tens of yards across. But I've also seen them a couple of miles long."

The bloom potentially could kill sea life if it sucks up more oxygen than it produces through photosynthesis, Heil said, "but there haven't been any reports of impacts due to a net loss of oxygen."

In extremely rare instances, she added, the algae also can kill fish and shellfish by clogging their gills.

LaPointe said the recent rains along the Treasure Coast and Space Coast to the north could exacerbate the situation by flushing nutrients into coastal waters.

"Historically, red tides follow rainfall and discharges," LaPointe said, "and since we've had a drought for a while, that first flush of fresh water will be carrying a lot of nutrients."

It's possible, Heil said, that the algae blooms could travel south to the Treasure Coast.

The Treasure Coast's last outbreak of red tide, in December 2007, moved south from Volusia and Brevard counties; and the current diatom algae bloom could do the same.

"Although the Gulfstream moves south to north," Heil said, "coastal currents tend to go north to south. It gets moved around by tides and currents. It's already moved around quite a bit."