Red tides are caused by an explosive growth and accumulation of certain microscopic algae, predominantly in coastal waters. Some species produce toxins that are among the most potent known to man. The most troublesome species in the Gulf of Mexico is Karenia brevis. K. brevis can kill large numbers of fish and other sea life including dolphins and manatees and can make shellfish poisonous to humans. It also produces airborne toxins that can cause respiratory and skin irritations. These harmful algae blooms, or HABs for short, pose a serious and recurring threat to human health, wildlife, marine ecosystems, fisheries, coastal aesthetics and our economy.
In our August e-newsletter we reported on a current red tide bloom that then was around 20 miles off the southwestern coast of Florida, stretching 60 miles wide, 90 miles long and at least 100 feet down. While the appearance of red tide is not unusual as it occurs almost every year, one this size has not been seen since 2005. FWC’s Fish Kill Hotline has received calls to report observations of thousands of dead and dying bottom dwelling reef fish, including grouper, hogfish, white grunt, triggerfish and snapper, as well as sea turtles and crabs.
The business community is worried about the economic cost of this bloom to northwest Florida. Coastal communities that rely on tourism can lose million of dollars when dead fish wash up on their beaches or tourists become ill. Commercial fishing and shellfish businesses lose income when shellfish beds are closed or harmful algae toxins are contaminating the fish they catch. Dr. Steidinger in a 1999 study estimated economic impacts from red tide blooms in Florida to be at least $15-25 million per year. A bad event in 1971, similar in magnitude but shorter in duration than the 2005 karenia bloom, was estimated to cause about $20 million in economic impacts, primarily to the tourism industry, in a study done in 1974 by Habas and Gilbert. Given the inflation that has occurred in the decades since, the cost in today’s dollars would be significantly higher.
While predicting when red tides are going to be bad would be helpful to commercial fishermen and beach businesses, much of our current information comes from satellite images which are often obscured by clouds. Dr. Robert Weisberg, an ocean scientist with the University of South Florida, is one of a team of researchers developing a prediction model based on ocean currents data, rather than satellite images. The model tracks the currents that bring natural nutrients that red tide needs to gain a foothold. Dr. Weisberg used this method in March to predict the current bloom. He said the research team is still trying to develop a model that can look further into the future.
The President has asked for a $6 million increase for research related to red tide forecasting in the 2015 budget, but Congress still has to approve it.