Dolphins Face Starvation Amid Seagrass Decline in Florida’s Indian River Lagoon
A new scientific study has uncovered alarming evidence that dolphins in Florida’s Indian River Lagoon are suffering from starvation due to widespread seagrass die-offs—similar to the plight faced by the state’s manatees.
Seagrass Loss Leads to Nutritional Crisis for Dolphins
Conducted by researchers from the University of South Florida and the University of Central Florida, the study analyzed tooth and tissue samples from stranded dolphins between 1993 and 2013. The findings show a significant dietary shift in dolphins following destructive algae blooms that wiped out vast areas of seagrass meadows.
Seagrass plays a critical role in supporting the lagoon’s biodiversity by providing habitat for numerous marine species including shrimp, pinfish, and ladyfish—key components of the dolphin diet. As seagrass vanished, dolphins were forced to feed on less nutritious prey, leading to widespread malnutrition.
Dolphin Diet Shift: From Ladyfish to Low-Energy Prey
The study revealed that after a major algae bloom and subsequent seagrass loss in 2011, dolphins consumed fewer high-energy species like ladyfish and relied more heavily on sea bream, which offers significantly lower nutritional value. This dietary shift was confirmed by chemical analysis and matched trends in fish populations caught by local fishermen.
Spike in Dolphin Deaths Due to Malnutrition
Between 2000 and 2020, malnutrition accounted for 17% of all dolphin deaths recorded in the Indian River Lagoon. However, in 2013, just two years after the 2011 algae bloom, that figure soared to 61%. Additional surveys of 377 live dolphins in 2013 found that 64% were underweight and 5% were severely emaciated.
Why Dolphins Don’t Migrate to Find Food
Although dolphins theoretically could migrate to healthier ecosystems, they typically remain within a defined home range. This site fidelity makes it difficult for them to relocate when food sources collapse, further exacerbating the survival challenge posed by seagrass loss.
Seagrass Die-Offs Driven by Nutrient Pollution
The root cause of Florida’s seagrass crisis is nutrient pollution. Runoff containing nitrogen and phosphorus—from farms, golf courses, urban streets, and septic systems—enters estuaries and fuels algae blooms. These blooms block sunlight and deplete oxygen levels, effectively suffocating the seagrass beds.
As the water becomes murkier and more algae-dense, remaining seagrass struggles to survive, setting off a chain reaction that destabilizes the entire coastal food web.
Other Impacted Areas: Biscayne Bay, Tampa Bay, and Manatee Mortality
Beyond the Indian River Lagoon, regions such as Biscayne Bay and Tampa Bay have also experienced severe seagrass loss since 2011. In the winters of 2020 and 2021, manatee deaths surged in the Indian River Lagoon, largely due to starvation. In 2021, Florida reported a record 1,052 manatee deaths—well above the previous five-year average of 682.
Signs of Recovery and Conservation Efforts
There is a glimmer of hope. Some parts of the Indian River Lagoon have shown signs of seagrass recovery. In March 2025, the U.S. Fish and Wildlife Service officially declared an end to the manatee Unusual Mortality Event, suggesting ecosystem conditions may be slowly improving.