Researchers Study Links Between Prey Fish, Predators and Algal Blooms

TALLAHASSEE, FL – For the most part, if you’re a fish, you’re either prey or predator, but Florida research is finding the symbiotic relationship is at risk after outbreaks of harmful algal blooms.

Dakota Lewis, a graduate student at the University of Central Florida (UCF) and a 2020 fellow in the Forage Fish Research Program, has studied algal blooms and fish kills in the Indian River Lagoon, which stretches along 40% of Florida’s East Coast.

Using data sets from the Florida Fish and Wildlife Conservation Commission and a new computer-modeling framework, she found faster declines of forage fish, like mullet and anchovies, after an algal bloom, and years of decline for fish-eating species, like trout and redfish.

“And so, there’s a potential for a loss of that balance, due to that decoupling of those two communities that are so intertwined and, in the food web, related to one another,” Lewis outlined.

Lewis thinks shifts in community dynamics for forage fish and sport fish could have harmful effects on popular recreational fisheries, now and in the long term. Lewis’ research is published in the journal Ecological Indicators.

Emily Farrell, another UCF graduate student, uses an emerging new genetic technique, known as environmental DNA or ‘eDNA,’ to help get a high-resolution snapshot of the marine ecosystem in the lagoon.

“The dust in our houses is mostly shed skin cells; that would be environmental DNA,” Farrell explained. “But in a fisheries context, it’s mucus or scales, or other things that fish are releasing into the water by swimming through it.”

Farrell’s method can account for even the smallest species, like forage fish, simply by collecting seawater samples along the lagoon. The eDNA analysis will help create a map of local biodiversity hotspots.

The Forage Fish Research Program is a public-private partnership between Florida Wildlife Research Institute, leading academics and a coalition led by the International Game Fish Association.

Support for this reporting was provided by The Pew Charitable Trusts.