Non-toxic blue-green algae lingers

Non-toxic blue-green algae lingers
Four spots tested in Manatee County waters this week had non-toxic blue-green algae. - Florida Department of Environmental Protection | Submitted

ANNA MARIA ISLAND – Blue-green algae lingers in local waters, but is non-toxic, unlike some places in Florida, according to a Friday, May 24 report from the Florida Department of Environmental Protection (DEP).

The report shows that blue-green algae was found in Holmes Beach waters on Monday, May 20 in Anna Maria Sound at Key Royale and in the Intracoastal Waterway south of Grassy Point. The same type of algae, filamentous cyanobacteria (Lyngbya-like), also remained in Palma Sola Bay near San Remo Shores. A different type of blue-green algae, Lyngbya majuscule, persists in Sarasota Bay near Whitfield Avenue.

The algae are less prevalent than in the previous May 9 report, according to DEP, which indicated that no toxins have been detected in any of the blue-green algae samples collected in Manatee County through May 20.

Blue-green algae can be blue, green, brown or red and emit a foul, rotten egg odor caused by the production of hydrogen sulfide gas, according to DEP.

Non-toxic blue-green algae lingers
Blue-green algae, which can appear brown, was evident near Key Royale on May 9. – Christine Wright | Submitted

The two algae species found in Manatee County waters are not the same species that has plagued Lake Okeechobee, Microcystis aeruginosa, according to DEP. About one-third of Lake Okeechobee may have blue-green algae present, according to the report, which states that the algae can be seen from space.

Of the 22 sites tested statewide from May 17-23 by DEP, seven were positive for toxins. Inland waters in Putnam and St. Johns counties near St. Augustine on Florida’s east coast tested positive for toxic algae, the report shows, citing an unconfirmed report that a dog died after swimming in Lake Broward in Putnam County.

Even non-toxic blooms can harm the environment by depleting oxygen levels in the water column and reducing the amount of light that reaches submerged plants, according to DEP.

The growth of blue-green algae typically increases in the spring and summer months when water temperatures and daylight hours increase.

Red tide report

Background concentrations of red tide were found in water samples off Beer Can Island in Longboat Pass on Sunday, May 19 and 4.6 miles off Coquina Beach in the Gulf of Mexico on Tuesday, May 21, according to the Florida Fish and Wildlife Conservation Commission (FWC).

Background concentrations of the algae that causes Florida red tide, Karenia brevis, have no discernable effects on people or marine life, according to the FWC. However, in very low concentrations and above, red tide cells emit a neurotoxin when they bloom that can cause shellfish closures and respiratory irritation in people, especially those with asthma, COPD or emphysema. In low concentrations and above, red tide can be deadly to marine life.

No fish kills were reported this week.

Very low concentrations of red tide are predicted in Longboat Key waters through at least Monday, May 27, according to the University of South Florida/Florida Fish and Wildlife Conservation Commission Collaboration for Prediction of Red Tides.

Scientists say that salinity, currents, temperature and light play a part in the formation of red tide blooms, as do nutrients from Florida’s natural phosphate and limestone deposits, Caribbean seawater brought to Florida’s west coast on the Loop Current, the Mississippi River, Saharan dust blown across the Atlantic Ocean to Florida’s waters, and fertilizer and animal waste runoff.

To help keep algae growth at bay, Florida law bans the use of phosphorus and nitrogen fertilizers during the rainy season, June 1 through Sept. 30.

Report algae blooms to DEP at 855-305-3903 or online. Report fish kills to FWC at 800-636-0511.