METHODS FOR QUANTIFYING MOLLUSK PREDATION BY DUROPHAGOUS PREDATORS

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).