Martinelli, J.C., M.A. Kosnik, and J.S. Madin. 2015. Encounter frequency does not predict predation frequency in tropical dead-shell assemblages. Palaios 30:818-826.

Predation is frequently suggested to be a key biotic process that can shape ecological communities and drive coevolution. The premise behind these hypotheses is that predators select prey to ensure maximum gain per unit effort; for example, by selecting species that are more abundant or accessible. In this study, we tested for predator selectivity in a tropical molluscan assemblage by quantifying the influence of relative abundance (encounter frequency) on predation frequencies. We collected macromolluscs (> 4 mm) from 15 sites in three soft-sediment reef lagoons at One Tree Reef (southern Great Barrier Reef, Australia). Dead molluscs were counted and identified to species level (61 species, n = 8131), and species predation frequencies were calculated as the proportion of shells with drill holes. We found that in this infauna-dominated community, levels of drilling predation were low (7.14% on average), and there was no evidence that predators selected prey based on encounter frequency. This result was consistent across prey species and lagoons. Overall, drilling predators do not specialize on more accessible prey species and are not a major cause of mortality in this modern macromollusc assemblage. However, encounter frequencies and predator selectivity could vary if a broader prey size range was considered. Detailed studies of prey morphological traits as well as accounting for predator non-consumptive effects could shed light on the relevance of drilling gastropods in this soft-sediment carbonate reef assemblage.