By Adam Kovac Published April 7, 2025 | Comments (0) | Image of a stranded dolphin from Florida's Indian River Lagoon. Hubbs-SeaWorld Research Institute. Stranding response conducted under a Stranding Agreement In 2013, dozens of dolphins living in Floridas Indian River Lagoon mysteriously began to die. Their remains washed up, showing the animals had been emaciated. Now, over a decade later, ecologists believe theyve figured out the cause of the bizarre die-off. While the deaths have long been linked to gigantic algae blooms in the water, it took until now to determine exactly how the two events were connected, and it turns out, its mostly humanitys fault. This might be hard to believe, but apparently dumping massive amounts of human waste and fertilizer into waterways can be bad. As the ecologists note in the journal Frontiers in Marine Science, the long-lasting phytoplankton blooms began in 2011. The spread of the tiny plant-like organisms led to a widespread change in the Indian River Lagoons ecology. Their presence caused the amount of seagrass in the water to decrease by over 50%, and a 75% loss of macroalgae (better known as seaweed). That alone wouldnt have killed off the dolphins, but when the ecologists examined isotopic ratios in teeth samples taken from the carcasses, and compared them to teeth taken from 44 dolphins that hadnt been part of the die-off, they realized their diets had been drastically altered. The dolphins had eaten 14% to 20% fewer ladyfish, a key dolphin prey animal, but had eaten up to 25% more sea bream, a less nutritious fish. In essence, the presence of such large amounts of phytoplankton had reduced the amount of food available for the dolphins usual prey. As the prey numbers dwindled, the dolphins had to catch more prey to consume the same amount of energy. The effects werent felt just by those dolphins that died, but by the areas dolphin population as a whole. At the time, 64% of observed dolphins were underweight, while 5% were classified as emaciated. In combination, the shift in diets and the widespread presence of malnourishment suggest that dolphins were struggling to catch enough prey of any type, said Wendy Noke Durden, a research scientist at the Hubbs-SeaWorld Research Institute, who worked on the research, in a statement. The loss of key structural habitats may have reduced overall foraging success by causing changes in the abundance and distribution of prey.The historic record bears this out. According to records kept of the recorded causes of death for stranded dolphins, starvation was the cause of death in 17% of recorded dolphin deaths in the area between 2000 and 2020. That number spiked to 61% in 2013. Blooms of phytoplankton are part of productive ecological systems, said Charles Jacoby, strategic program director at the University of South Florida, who also worked on the study. Detrimental effects arise when the quantities of nutrients entering a system fuel unusually intense, widespread, or long-lasting blooms. In most cases, peoples activities drive these excess loads. Managing our activities to keep nutrients at a safe level is key to preventing blooms that disrupt ecological systems. There is a small silver lining to this grisly finding. As the researchers noted, waste and other crap dumped into Indian River Lagoon is being gradually reduced and is expected to hit safe levels in 2035. Still, its no surprise that human activity can be harmful to ecosystemsfrom chopping down shocking amounts of rainforest, to the melting of polar ice, to the inadvertent introduction of thousands of invasive species to new territories. This latest example shows that beyond the obvious primary effects, our habit of dumping God-knows-what into natural environments can have all sorts of trickle-down resultsincluding killing some of our most beloved wildlife.Daily NewsletterYou May Also Like By Ed Cara Published March 20, 2025 By Matthew Gault Published March 5, 2025 By AJ Dellinger Published February 27, 2025 By Margherita Bassi Published February 19, 2025 By Thomas Maxwell Published February 13, 2025 By Isaac Schultz Published January 15, 2025