Have you ever came across to see a turtle sitting on a log around Kings Bay? Yes, these shell back creatures seem to be abundant throughout Crystal River. They are fun to watch, will sunbathe with beach goers, and swim deep with snorkelers. It almost seems that each turtle has its own personality. The one thing that the turtles all have in common is their love for eelgrass.

A turtle munches on vegetation in Three Sisters Springs.       

Fresh water turtles loved the newly planted grasses. We are thrilled that the Kings Bay Restoration Project is bringing back this valuable food source to their population. However, the hungry turtles have grazed so much on eelgrass in Canal 4 during the July 2018 monitoring efforts, that there is a statistical difference in plant density. We took a look to find other studies of turtle populations grazing on eelgrass plants.

A 2013 study (Adler et al, 2013) titled An aggregation of turtles in a Florida spring yields insights into effects of grazing on vegetation was the exact study to answer our question. Our question is: Do turtles have a strong effect on plant density in spring settings?

The study assesses the Suwannee Cooters (a species of freshwater turtle) effects on vegetation in Blue Spring. This study found that turtles can graze rather heavily on all aquatic vegetation. Seen in the photos below, picture A shows the study site before turtle arrived, picture B shows after the turtles have arrived to graze, and picture C shows the study site 1 week later. The group of turtles ate all of the Hydrilla verticillata before moving further on in the spring run. Vegetation in Florida springs is shifting from native, rooted macrophytes (i.e. eelgrass and other subaquatic vegetation) to filamentous macroalgae (ie Lyngbya) which may be causing the turtle species to graze heavier on a food source when available. However, this theory and other potential harmful effects of Lyngbya on turtle population and food source would need to be studied further.

Adler J, Barry S, Johnston G, Jacoby C, Frazer T (2013) An aggregation of turtles in a Florida spring yields insights into effects of grazing on vegetation. Available at https://www.journals.uchicago.edu/doi/pdfplus/10.1086/697541 [Verified 26 August 2018]