The Indian River Lagoon at Titusville: the 2011 superbloom and what followed

The Indian River Lagoon is a 156-mile estuary on Florida’s east coast, and Titusville sits on its northern reach, with Kennedy Space Center across the water. Florida Atlantic University’s Harbor Branch Oceanographic Institute notes that the lagoon has been cited as among the most biologically diverse estuaries in North America: its watershed is home to more than 2,100 plant species and more than 2,200 animal species, including some 700 fish and 310 birds, and about 50 threatened or endangered species. It is one of 28 estuaries in the country designated an Estuary of National Significance. Six counties lie in its watershed, and five inlets through the barrier islands connect it to the Atlantic.

In 2011 the water off Titusville lay inside the worst bloom the lagoon had on record.

The 2011 superbloom

From early spring through late fall of 2011, according to the St. Johns River Water Management District, a massive phytoplankton bloom and loss of seagrass spread through most of the lagoon system, from southern Mosquito Lagoon to just north of Fort Pierce Inlet. The district’s scientists wrote that it “far exceeded any past events remembered or documented.”

There were really two blooms. The larger one, which they called the superbloom, covered about 53,000 hectares of open water, roughly 130,000 acres: the Banana River Lagoon, the southern Mosquito Lagoon, and the northern Indian River from Eau Gallie up to the Turnbull and Scottsmoor area, which takes in the river at Titusville. It was dominated by pico-cyanobacteria and a microflagellate the scientists couldn’t yet identify, and its chlorophyll readings often topped 100 micrograms per liter, beyond any bloom documented before.

The seagrass went under. By the end of June 2011, the district found, seagrass beds in the Banana River Lagoon and the northern and central Indian River had shrunk by about 45 percent from summer 2010, a loss of roughly 31,600 acres measured against the 70,230 acres mapped in 2009. Because the bloom lasted seven months, the district warned, the year’s total loss may have been greater. At its estimate of $5,000 to $10,000 in fishery value per acre of seagrass per year, that meant a potential loss of $150 million to $320 million in commercial and recreational fisheries value in 2011 and 2012.

The cause puzzled the district. The years 2009 to 2011 were dry, and treated wastewater discharges into the lagoon had been falling. Roughly 75 to 80 percent of the lagoon’s outside nutrient load normally arrives with rainfall runoff, so a drought should have starved a bloom. The district’s 2012 plan suggested instead that nutrients released from inside the lagoon itself may have been the main fuel, and set out to find the source and the trigger.

The years after

Brevard County’s own record of what followed, written into the 2026 ordinance renewing its lagoon sales tax, lists brown tides in 2012, 2013 and 2015, unusual mortality events for dolphins, manatees and pelicans, and then, from January through March 2016, “the most extensive and intensive algal bloom ever recorded in the Indian River system during winter to spring months.” When that bloom collapsed in March 2016, it left one of the most extensive fish kills ever recorded in the county.

The manatee die-off

The loss of seagrass eventually reached the lagoon’s manatees. The Florida Fish and Wildlife Conservation Commission records an Unusual Mortality Event on the Atlantic coast from December 1, 2020, to April 30, 2022, in which 1,255 manatee carcasses were documented and 137 manatees were rescued. The state and federal investigators determined the cause was starvation from a lack of forage in the Indian River Lagoon. Most of the deaths, 1,039 of the 1,255, came in the two winters, when cold added stress to animals already starving.

The FWC and the U.S. Fish and Wildlife Service ran a supplemental feeding trial through the winters of 2021-22 and 2022-23, supplying at least 600,000 pounds of leafy greens to manatees at a feeding site. The last starvation death linked to a lack of forage was documented in March 2023, and the agencies closed the event administratively on March 14, 2025. The FWC credits the improvement partly to seagrass slowly recovering in some key areas, including what it calls remarkable recovery in parts of Mosquito Lagoon, while noting that conditions in parts of the lagoon remain a concern.

Save Our Indian River Lagoon

The county’s response came in 2016. After the winter bloom and fish kill, the Brevard County Commission approved a Save Our Indian River Lagoon Project Plan on August 9, 2016, and adopted Ordinance 2016-15 two weeks later to put a half-cent infrastructure sales tax on the ballot. Voters approved it on November 8, 2016, for the ten years from January 1, 2017, through December 31, 2026. Every city and town in the county, Titusville among them, signed the agreement on how the money would be used.

The plan is updated every year on the advice of a Citizen Oversight Committee. The county describes the program’s work as reducing pollution, removing legacy nutrient loads such as muck, and restoring natural filtration, with septic system upgrades and sewer projects among its project types. With the tax due to expire at the end of 2026, the county put a ten-year renewal before voters on the November 3, 2026, general election ballot.

For the lagoon as a whole, see Old Space Coast’s Indian River Lagoon page.

Further Reading

• Florida Manatees: Biology, Behavior, and Conservation by John E. Reynolds III
• Florida’s Fabulous Natural Places by Tim Ohr