Characterizing Internal Morphology and Infauna of the Loggerhead Sponge, Spheciospongia vesparium, from the Nearshore Habitats of the Florida Keys

The loggerhead sponge (Spheciospongia vesparium) is a historically abundant species in the nearshore waters of the Florida Keys and has been used to develop strategies to restore sponge habitat in Florida Bay. These sponges harbor a diverse assortment of infauna and occur on both the ocean and bayside of the islands, where potentially contrasting environmental conditions (e.g., hydrodynamics and sedimentation) may influence sponge growth, morphology, and infaunal community composition. This study examined these differences in the Florida Keys' bayside and oceanside locations, where oceanside sponges exhibited larger canals, possibly attributed to environmental variables such as water flow and sediment depth. A positive correlation was identified between sponge volume and mean canal diameters across all sites, suggesting a link between sponge size and structural features. A total of 29,923 organisms from five phyla were collected from 48 whole S. vesparium specimens, representing 15 taxonomic groups. Synalpheus snapping shrimps represented 68% of all taxa identified and enumerated. Although no significant differences in overall infaunal community diversity were found across bayside and oceanside locations, multivariate analysis indicated that infaunal communities were generally distinct at each site and showed a greater influence of environmental factors on the sponges themselves. These results imply that sponges adapt to their habitats morphologically and that infauna likely change in conjunction. A reciprocal transplantation study of sponges between bayside and oceanside environments, where growth, morphology, and infaunal communities are monitored, is recommended to understand these relationships further. In addition, efforts should focus on discerning if the reduced sponge size and infaunal biodiversity observed on the bayside are natural or the result of recent ecological disruptions. Affirming this could direct efforts into cultivating larger sponges with rich infaunal communities more closely resembling oceanside sponges.