ABSTRACT:

Manatees may provide material subsidies to spring-fed freshwater ecosystems via excretion and egestion when they migrate to and congregate around the springs in large numbers during the winter for thermal refuge. These nutrient inputs may then relieve biofilms from nutrient limitation, increasing biofilm biomass (chl a). However, manatee bioturbation effects may also be large, limiting light availability for biofilm growth, and ultimately decreasing biofilm biomass. The data published here are the results of a bioassay study using nutrient diffusing substrata (NDS) in six coastal springs ecosystems located within and in proximity to Kings Bay, FL, USA to assess how migrating Florida manatees may affect biofilm chl a. Three of springs had large manatee congregations in winter (January), and manatees did not congregate at the other three springs. The study took place during three time points that occurred before, during, and after the manatee migration. This study also included a long-term dataset on total suspended solids data obtained from the Southwest Florida Water Management District.