CITY ISLAND – There may be a breath of fresh air on the red tide-stained horizon.
Mote Marine Laboratory is testing ozone as a way to kill red tide algae and remove the toxins it produces from seawater.
Red tide, an algae bloom caused by the microscopic organism Karenia brevis, can cause respiratory irritation, especially in people with asthma or COPD, and can kill fish, marine mammals, sea turtles and shorebirds.
Red tide reached Anna Maria Island shores on Aug. 3, drifting north from Southwest Florida, where it has persisted since November 2017. The bloom affects six counties, from Collier north to Pinellas, including Manatee.
Aimed at restoring canals, like those in Coral Shores recently inundated with fish killed by red tide, the method pumps red tide water into an ozone conductor, where the ozone kills the red tide and re-oxygenates the water without releasing ozone into the environment, according to Mote Senior Scientist Dr. Richard Pierce.
Mote already uses a similar patented method to filter seawater from the Gulf pumped into Mote’s marine mammal and sea turtle hospital tanks and its aquarium.
Mote tested ozone in June in a 25,000-gallon saltwater pool. The results showed that, with one ozone system processing 150 gallons of water per minute, the red tide algae cells in the pool were wiped out rapidly and their toxins cleared in a day. Water quality was monitored, showing no ozone released, and other water chemistry changes returned to normal within a day.
The system is now being tested in a Boca Grande canal filled with dead fish, with two ozone systems working together to process 300 gallons of water per minute to filter out red tide algae cells and toxins. Water quality is being monitored for nutrients, temperature, dissolved oxygen and alkalinity, and suitability for sensitive marine invertebrate animals like shrimp.
While clay, copper, herbicides and other substances proven to kill red tide also kill marine life, ozone treatment does not, according to Mote.
The ozone method is not intended for large bodies of water, like the Gulf of Mexico, and is still in the research stage, according to Mote.
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