Biscayne Bay Is Slowly Becoming the Ocean

A 20-year record reveals an estuary tipping toward a saltier, more acidic state. These conditions threaten its hammerhead shark nursery and the aquifer that supplies Miami’s drinking water. By Kate Waxman In the shadow of Miami’s skyline, in water churned daily by boats and jet skis, juvenile great hammerhead sharks—a critically endangered species—spend the first two years of their lives. A few miles from downtown, researchers recently pulled a 12-foot critically endangered sawfish from the same shallows. The species has been dying off in alarming numbers across South Florida’s waters since 2024, in an event scientists suspect was set in motion by record ocean heat.&nbsp;