Many St. Lucie River advocates fear freshwater discharges from Lake Okeechobee could eventually destroy the estuary’s ecosystem. When Lake Okeechobee rises too quickly, freshwater is released into the St. Lucie River for flood control purposes. Many water managers believe that by studying oysters they can determine how much freshwater the estuary can handle and still be healthy. Oysters, along with two types of seagrass that grow in the estuary, are considered indicator species for the health of the river because, unlike fish, they can’t swim away when the environment gets harsh.
   Oysters can be killed or diseased when the amount of salt in the estuary becomes too high or too low. They are also important because they naturally filter sea grass-damaging sediments and provide habitat for many other species. Dan Haunert, a lead scientist with the South Florida Water Management District, said a five-year study of the oysters in the estuary has already begun. The study, which will cost at least $330,000 will be done with researchers from Florida Atlantic University, Harbor Branch Oceanographic Institution, as well as students at the Gumbo Limbo Nature Center in Boca Raton. Haunert said it doesn’t take a five-year study to agree with many activists who are concerned with the health of the estuary. "We don’t need anymore water, Haunert said. "It’s dangerous for the oysters right now."