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Turning the tide on red-tide toxins

by Amy Ettinger

From AnimalNews 9.2

In 2005, a red tide poisoned Florida's ocean waters for
months, killing large numbers of fish, sea turtles, dolphins
and other marine life. It was one of the worst red-tide
events ever recorded for the area.

Harmful algal blooms, which occur along Florida's southwest coast, caused this ecological disaster. The most prevalent of these blooms is the red-tide organism Karenia brevis, a species of phytoplankton with chlorophyll molecules. Karenia brevis multiplies as it moves in warm, nutrient-abundant coastal
waters where, when it blooms, it creates a red tide. The bigger the bloom, the greater the potential for poisoning marine life.

With Morris Animal Foundation funding, researchers at the Mote Marine Laboratory in Sarasota, Florida, studied the levels of red-tide intoxication in endangered sea turtles and sea birds that were stranded during red-tide events in 2005 and 2006. The research team found that the majority of the animals sampled tested positive for the red-tide toxin.

"This indicates that red-tide intoxication plays a larger role than previously recognized in causing illness and death in sea birds and sea turtles off the west coast of Florida," says Dr. Deborah Fauquier, adjunct scientist at the laboratory and lead researcher on the study.

Red-tide intoxication stranded 69 percent of sea birds and a staggering 94 percent of the sea turtles. Researchers discovered that the animals may become intoxicated with brevetoxin several months after an active bloom simply by eating contaminated prey such as thread herring, scaled sardines, Spanish sardines and juvenile pinfish.

The team also learned critical information for marine life
rehabilitators—it can take rescued sea birds 10 days of rehabilitation to clear the red-tide toxin from their bodies and five times that long for sea turtles to become healthy.

With a second grant from MAF, the research team is now looking at ways to help endangered loggerhead sea turtles and double-crested cormorants recover more quickly from the effects of the toxins. The researchers are studying cholestyramine, a drug that binds bile acids and stops those acids bound to the brevetoxin from being reabsorbed in the animal's intestines. They hope to determine whether the drug helps lead to a quicker elimination of the deadly toxin from the body.

"If this treatment regime is successful, it would prove
useful in future red-tide events to increase the successful
treatment for these and other endangered or threatened
species," says Fauquier.

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