PORIFERA BIODIVERSITY IN THE INDIAN RIVER LAGOON: EVALUATING THE LATITUDINAL ECOTONE AND SIMILARITIES WITH SAINT LUCIE REEF

Sponges (Phylum Porifera) are hardy organisms persisting and predicted to become more dominant world-wide under climate change scenarios. However, we lack baseline knowledge on sponge biodiversity in transitional areas (subtropical to warm-temperate) that are more susceptible to climate change such as The Indian River Lagoon (IRL) (estuary) and Saint Lucie Reef (northern most coral reef) ecosystems in south Florida. The aims of this master’s thesis are to 1) evaluate if sponge assemblages reflect the previously defined ecotone between subtropical and warm-temperate biomes in the IRL (Chapter one), 2) determine how porifera communities are associated to their respective environment (temperature, water velocity, photosynthetically active radiation, carbonate chemistry, and nutrients) in the IRL and St. Lucie Reef (Chapter two), and 3) establish a distribution baseline for future studies aiming to assess Porifera range shifts during climate change (Chapter one and two). Porifera biodiversity surveys across the IRL and Saint Lucie reef were carried out at different spatial and time scales. Environmental parameters (ocean acidification, temperature and eutrophication) were obtained and compared for sites in Fort Pierce Inlet and St Lucie Reef. Chapter one results show that sponge assemblages do not reflect the previously defined ecotone between subtropical and warm-temperate biomes in the IRL, instead they structure in relation to the inlets (distance from the inlet). The most diverse sponge assemblages are found in Sebastian, Fort Pierce, and Jupiter Inlets, and are significant different among habitats; oyster reefs host a unique assemblage of excavating sponges.