Resumen de The Black Murex Snail, Hexaplex Nigritus (Mollusca, Muricidae), in the Gulf of California, Mexico: I. Reproductive Ecology and Breeding Aggregations
Richard Cudney-Bueno, R. Prescott, O. Hinojosa-Huerta
We studied the reproductive ecology and behavior of the black murex snail, Hexaplex nigritus (Philippi, 1845), a species heavily harvested in the Gulf of California, Mexico. We found that H. nigritus is dioacious and highly gregarious, capable of forming breeding aggregations with a biomass of 3 mt. Snails aggregated in subtidal waters between April and September, laying egg masses on shells of male and female conspecifics. Egg masses on any one snail could be from multiple females and contain an average of 285 capsules. Eggs incubated in capsules for 18-31 d, at which time they hatched as veliger larvae (mean = 3603; 95% CI = 3382-3825 larvae per capsule). Seventy-four percent of aggregations formed adjacent to or within 25 m of a rocky, coquina (beach rock) or mussel bed reef. While aggregated, snails ceased feeding but preyed on at least 10 species of mollusks prior and after aggregating. During winter, snails buried in the sand and emerged in early spring to feed. Breeding aggregations formed on or near (< 20 m) sites used the preceding year, suggesting fidelity to reproductive sites. The species' reproductive behavior has facilitated the removal of much of the reproductive biomass and juveniles newly settled within aggregation sites, likely causing a rapid decline in harvestable stocks. We discuss the implications of our findings in the context of biology and ecology of muricid snails and management and conservation of H. nigritus.
