Comparing Feeding Patterns among Two Sponge Species in the Lower Florida Keys

The sand flats off the islands of the Lower Florida Keys represent a harsh environment for sessile marine invertebrates, with high food variability and high light intensities. This habitat is home to two taxonomically distinct sponge species that share similar morphologies: Cliona varians forma varians and Ircinia cf. felix. Despite sharing a habitat, these two species differ in their symbiont regime, with C. varians hosting dinoflagellate photosymbionts, and Ircinia hosting cyanobacterial photosymbionts. We conducted experiments to measure several aspects of their feeding patterns. The sponges were all assayed for pumping rates using dye-video analysis and microbiome composition. Inhalant and exhalant water samples were collected from each individual and analyzed for bacterial composition. The results indicated that Ircinia had a significantly higher pumping rate than C. varians. The microbiomes of both species were significantly different. Analysis of the bacterial composition of water samples revealed significant differences, both between species and between inhalant and exhalant samples. This data suggests that despite being two morphologically similar species, their difference in feeding patterns leads them to occupy different ecological roles