Mollusks

A nearshore ridge complex (NRC) sits less than 250 m from the coast of Pompano Beach in Southeast Florida, and the varied bottom types within this complex may represent critical habitat for benthic mollusks. In order to document the diversity of mollusks within the NRC, SCUBA-based roving surveys were conducted between 2011 and 2019. Between 2021 and 2022, sediment samples were also collected from each of the bottom types to study mollusk diversity patterns. This combination of survey methods resulted in the identification of 325 species of hard-shelled mollusks, representing 103 families and 4 classes. To test for differences in community structure between bottom types, relative abundance data from the sediment samples was used for multivariate analyses including NMDS ordination, ANOSIM, and hierarchical cluster analysis. Results indicated statistically significant differences in mollusk species composition between NRC bottom types.

By regulating the abundance of prey populations, predators can directly and indirectly influence food web interactions in ways that influence ecosystem function. Predator functional responses quantify how predator foraging rate changes with prey abundance. Due to the large numbers of individuals needed for these experiments, most studies are conducted on small, abundant taxa. Consequently, we know relatively little about the functional responses of many marine taxa, especially those that are large and highly mobile. We present a novel method for studying predator foraging behaviors by integrating two innovative approaches: passive acoustics to document the occurrence of underwater predation events in concert with a recently developed statistical method that uses the times between predation events to estimate functional response parameters. We demonstrate and expand on the application of these methods by quantifying the shape of the predator functional responses for whitespotted eagle rays (Aetobatus narinari) preying on hard clams (Mercenaria mercenaria).

Healing of wounds in the foot of Siphonaria petinata (Linne) was compared with healing vertebrates and in other molluscs. Wounds were two mm long and one mm deep. Animals were maintained in the laboratory in artificial sea water at 25C and were observed and sectioned at intervals for 28 days. Within one day, the wound filled with fluids, leucocytes and debris. Within two days, leucocytes formed a cot against the damaged muscle tissues. By the eighth day, some repair tissue had formed and epithelium covered most of the wound surface. Epithelium and supporting tissues regenerated within 18 days. Muscle and granulated cells had partially regenerated within 28 days. Healing of wounds in S. pectinata is more similar to healing in prosobranch molluscs than to healing in bihalves or in vertebrates.