Biscayne Bay fish kill is a warning sign, researcher says

A fish kill this week is a clear sign the health of Biscayne Bay is at risk, FIU Institute of Environment researchers said.

Researchers set out Wednesday to survey Biscayne Bay between the 79^th Street and Julia Tuttle causeways, where dead fish were seen bobbing along the surface.

“It is an emergency. The bay is not in a good place right now,” said Piero Gardinali, a chemistry professor who is director of the institute’s Freshwater Resources Division. “It’s a warning sign more than anything else. People have been predicting that things like this could happen. I think it’s time for us to sit at the table and say ‘OK, let’s do something about it.’”

Researchers believe fish were killed when the bay’s saltwater became so hot, it could no longer retain oxygen in the amounts necessary for marine life to thrive.

They are using an autonomous surface vehicle equipped with sensors to measure temperature, dissolved oxygen, turbidity and chlorophyll, which can be an indicator for algae. What they find could provide more details on the health of the bay. The vessel allows researchers to collect more data over a larger area.

“You’ve heard people say that we are at a tipping point,” Gardinali said. “It might be just that we have done so much damage to the bay that it’s at a tipping point and anything that changes could put us over that tipping point.”

Many factors over time have contributed to the current state of Biscayne Bay, Gardinali said. Sea grass is dying, temperatures have been rising, nutrients have been entering the bay and there have been sewage leaks. After years and decades, all of these factors could have contributed to the fish kill. 

Students and faculty from the FIU CREST Center for Aquatic Chemistry and Environment will also collect samples to determine whether nitrogen, phosphorus or other potentially harmful nutrients or pollutants may have played a role.

Results from the survey should be available the week of Aug. 17.