The Phenology of Sand Crabs, Lepidopa benedicti (Decapoda: Albuneidae)

Albuneid sand crabs are widespread on sandy beaches around the world, but because they conceal themselves by digging in sand and are often found at low densities, little is known about their basic biology. Lepidopa species were collected from the beaches of South Padre Island, Texas, on the western coast of Gulf of Mexico, a location that had previously been suggested to act as a population sink. The site contained Lepidopa benedicti and L. websteri, although the latter was extremely rare (collected three times in 5 years). There was significant variation in abundance across the year, with higher densities in summer and lower in winter. Ovigerous females, carrying up to almost 2000 eggs, were found from late spring through summer, with most of the young of the year appearing in autumn. The sex ratio was biased toward females. The average size of L. benedicti in South Texas was smaller than individuals in Florida, but the population density appeared to be higher in Texas. The presence of reproductive individuals and even distribution of size classes weakens an earlier hypothesis that the western Gulf of Mexico acts as a population sink for L. benedicti. The changes in abundance suggest that the L. benedicti actively repositions itself at different depths in the swash zone at different times of the year, possibly for reproduction.