Persistent Toxic Red Tide Causes Rapid Die-Off for Seagrass in Florida

According to experts, Florida's persistently toxic red tide is to blame for the rapid die-off of seagrass.

The toxic red tides and other environmental stresses have been killing off seagrass that used to thrive in the waters off Florida's Gulf Coast at a rapid rate over the past few years, which is harming marine wildlife.

Rapid Die-Off in Florida Seagrass

The nearby Sarasota Bay has lost 26% of its seagrass since 2016, according to research by the Southwest Florida Water Management District.

Tampa Bay's seagrass decreased by over 4,000 acres, or about 12%, from 2020 to 2022 alone.

According to the Miami Herald, David Tomasko, executive director of the Sarasota Bay Estuary According to the program, 5% of the seagrass meadows were lost between 2020 and 2022. 18% was lost in the previous two years.

The so-called red tides that result from water pollution are believed to be the root of these declines.

Persistent Toxic Red Tide

Red tides are harmful algal blooms that are frequently brought on by the algae Karenia brevis.

Low concentrations of it naturally occur in the Gulf of Mexico, but occasionally they grow into dense blooms. According to Larry Brand, a University of Miami professor of marine biology in the Rosenstiel School of Marine and Atmospheric Science, the coastline between Tampa Bay and Naples is the hotspot for these blooms.

Since their ability to grow is constrained by the amount of light they can receive, seagrasses are marine plants that thrive on the seafloor, typically in the shallows.

Seagrass cover may be drastically reduced as a result of red tides. Large mats of red tide algae can form during large blooms, obstructing sunlight from reaching seafloor plants, causing them to wither, and eventually rot and feeding the algal bloom.

Red tides caused the loss of over 32,000 acres of seagrass in the Indian River Lagoon on Florida's east coast between 2009 and 2012, resulting in a 60% local reduction in seagrass cover.

These seagrass meadows, about 2.7 million acres along the coastline of Florida, are crucial to the health of the marine ecosystem because they provide homes and food for a variety of marine species, including the manatee, as well as protect the coast from erosion and store carbon.

Kindling Red Tides with Nitrogen

Environmental pollution comprising nitrogen and phosphorous exacerbates red tides and, as a result, has a negative impact on seagrasses. The algae's growth is accelerated by these chemical fertilizers. The Florida Department of Environmental Protection approved the release of 215 million gallons of contaminated water from a Piney Point industrial site in 2021.

With a 126% increase from the first three months of 2022, the Florida Fish and Wildlife Conservation Commission (FWC) reports that 59 manatee deaths have been recorded in Lee County alone in 2023. So far in 2023, 215 fatalities have been reported in the entire state.

Regarding the recent manatee deaths, James Douglass, a Florida Gulf Coast University Water School professor, noted that seagrasses, which the manatees eat, have been declining in Lee County. It's also possible that manatees are starving to death, FOX4 reports.

This is caused by brevetoxins, which are produced by red tides and can be inhaled by marine mammals or eaten if the algae would coat the seagrass blades, in addition to the loss of seagrass, which is the main diet of the manatees. These toxins can also kill fish, sea turtles, dolphins, seabirds, and fish, sometimes resulting in thousands of dead fish washing up on beaches.

Tomasko asserts that if too much seagrass is lost, algae will take control of the ecosystem, according to Newsweek.