Naticid Predation and Community Structure in the Late Miocene of the Dominican Republic

Naticid gastropods are important predators in shallow marine ecosystems. Due to the characteristic marks left on their hard-shelled prey, naticid predation dynamics have been well studied in both extant and extinct marine communities. Our study examines naticid drilling frequency in stratigraphically adjacent bulk samples of marine mollusc communities from the Late Miocene Dominican Republic in order to better understand how these predators respond to changing biotic communities. All gastropod and bivalve shells complete enough to be identified to family were counted in each sample. Each of these shells were then assigned to species and parameterized ecologically based on diet, position relative to substrate and motility. Presence or absence of a complete naticid drillhole was noted for each shell. Gastropod and bivalve prey diversity is consistent across all four samples. Relative abundance is not, with changes in both predator and prey abundances. There is a strong positive correlation between the number of complete drillholes and total molluscan abundance per sample. For bivalve prey, drilling frequency is more strongly correlated with abundance than with diversity. This correlation holds for both the class as well as within each bivalve ecological guild. For gastropod prey the relationship is less clear, with drilling frequency correlated with both abundance and diversity of prey. Intraguild naticid predation is more strongly correlated with diversity than with abundance. These results suggest that naticids may change their consumption patterns of bivalve prey based on availability but consumption of gastropod prey may depend on both diversity as well as abundance.