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Red tide is back

By Staff | Dec 2, 2015

CROW hospital workers prep a Cormorant to get its blood drawn. The double-crested cormorant was one of 42 which were brought to CROW with symptoms of red tide poisoning. BRIAN WIERIMA

The Karenia brevis algae bloom made a visit off of Sanibel Monday, Nov. 16, as one of the area’s first red tide event occurred, resulting in a modest fish kill.

The most affected marine life were bait fish and some redfish, along with some other deeper water fish. This certain red tide event was caused by just a patch of algae which potentially came from the Sarasota source.

There also have been 42 cormorants which have been brought into CROW since Nov. 20, with symptoms of red tide poisoning, as 16 have either died within 24 hours or were euthanized.

Karenia brevis produce brevetoxins, which poison fish, birds and other marine wildlife. Blooms occur every year in the Gulf of Mexico and may last three to five months and affect hundreds of square miles.

“This event may have started on Nov. 2, when we saw a low concentration of red tide in our Causeway samples,” said the Sanibel Captiva Conservation’s research scientist Dr. Rick Bartleson. “On Nov. 16, when we took the red tide counts on the Causeway and Sanibel Ramp, they were medium concentrations, so there was a decent sized patch which came through the Causeway.”

The next day on Nov. 17, samples were taken at all the Sanibel beaches and there was strong signs of a patch of algae bloom at the Lighthouse Beach, but by Thursday, those measurements went down.

There is a concern, which is yet unproven, that the patch made its way into Pine Island Sound. Tests showed a medium concentration of red tide in the Sound, but it doesn’t mean it will be sticking around.

“Sometimes it will wash in and then back out with the tide,” Dr. Bartleson said. “That’s what happened last year.”

Wednesday, Nov. 25, had samplings done in Tarpon Bay, which was low concentration and the beaches remained very low, as well.

City of Sanibel Natural Resource Director James Evans, said there were many fish which washed ashore which had signs of decomposition and missing eyes, signifying the fish which died were much more off shore.

Most of the fish picked up were bait fish, like red herring, but there were other species, as well. Fish kill was reported from Algiers Beach west to near Bowman’s Beach and up to Lighthouse Beach.

“There were not a lot of large marine animals which washed ashore, most of the fish overall were the bait fish, some game fish and some unique looking reef fish,” Evans said. “There has been red tide detected just off of North Florida like off of Franklin and Bay counties, and off the coast of Sarasota. We just received a patch here off of Sanibel.”

As of now, the readings for red tide are low, but there hasn’t been enough testing done in Pine Island Sound to make an educated guess of how much is still there.

“There hasn’t been enough sampling done in Pine Island Sound, but the Gulf water can also take away the tide and disperse it,” Dr. Bartelson said. “There wasn’t as bad a fish kill as some areas (on the Florida Gulf coast) and luckily, we do have satellite images to give us an idea where the red tide is and how dense and patchy it is. So far here near Sanibel, it’s just patchy, there isn’t a blob of red tide off the coast, either.”

With the red tide now starting to affect the Gulf waters, just having minimal affect off of Sanibel and Captiva is a good thing, thus far.

“We are pretty happy it’s just a patchy bloom and we will continue to monitor and watch it,” Evans added.