News

By Wayne Hartley, Manatee Specialist, & Cora Berchem, Dir. of Multimedia and Manatee Research Associate

Many of our readers are very familiar with our photo-ID research at Blue Spring State Park during the winter, when we count and identify the manatees that come to the protected, warm-water refuge. But what happens after the counting? Well, during the summer months, our research team compiles and analyzes all the data, redraws the scar charts, logs the footage and photos obtained during the winter research, compiles attendance sheets, and compares sighting data with other researchers. For example, we have several manatees at Blue Spring that also winter at other springs along the St. Johns River or who migrate in from the East Coast.

Once all the photos are logged and labeled, we submit them to the Manatee Individual Photo-identification System (MIPS), a statewide database for manatees. MIPS was formerly run by the U.S. Geological Survey Sirenia Project, but is now managed by the Florida Fish and Wildlife Conservation Commission. While we have been submitting sightings from Blue Spring for many decades, this past winter—for the first time ever—we were also able to submit photos taken by our webcams at Homosassa Springs Wildlife State Park. While the webcams are wonderful for the public to watch manatees live, they also provide an important research tool for us and our co-researchers. During the summer months, our above-water webcam at Blue Spring remains on for research purposes, so we can log any manatee sightings during those months as well.

During the winter, we also collect data on dark water intrusion at Blue Spring. While the spring water is very clear, the water of the St. Johns River (which is partially fed by Blue Spring) is tannic, giving it a brownish appearance due to decaying leaves in the water. In the summer, the water in the St. Johns River is much warmer than the 72°F spring water, so when it flows into the spring, it will usually settle on top of the heavier, cooler spring water. In the winter, it reverses: the cooler river water will be on the bottom with the (now warmer) 72°F spring water on the top. Each morning, we record the dark water intrusion by visually measuring how far the darker, colder river water enters the spring run. This can be influenced by both temperature and spring flow. This data has helped the St. Johns River Water Management District to set minimum flows and levels (MFLs) for Volusia Blue Spring Basin. MFLs are important as they dictate how much water can be withdrawn from the spring for human consumption while still trying to maintain sustainable flow levels of the spring.

Manatees depend on the warm water of the spring during winter, when the St. Johns River can drop into the 50s or even 40s, which is much too cold for manatees to survive. Reduced spring flow can lead to more dark-water intrusion into the spring, affecting the total area manatees are able to use to stay warm. While our main research focuses on the photo-ID work of manatees, tracing genealogies, and recording new calves and boat strikes, a lot more research goes on behind the scenes.