Is the abundance of the red brocade hermit crab <i>Dardanus insignis </i>(Decapoda: Anomura: Diogenidae) in the infralittoral region of southern Brazil determined by reproductive potential?

Abstract

The present study investigated if Dardanus insignis abundance along the southern region of Brazil is maintained by their reproductive potential characteristics. Crabs were collected monthly from July 2001 to June 2003 offshore of Ubatuba and Caraguatatuba regions, Brazil. Females with eggs at an early stage of development were selected for fecundity analysis. This species presented a discontinuons or seasonal reproduction with peak in spring in the Southern Hemisphere. Relatively more females with eggs in the initial developmental stages were collected than those with eggs in late developmental stages, suggesting that brood time was shorter than other species of hermit crabs. Fecundity of individuals was not influenced by the species of shells occupied. Fecundity also increased with increasing crab size. Strategically, the relatively small size of eggs was compensated for by the larger number of eggs produced per brood as well as the possibility that individuals spawned multiple times during the reproductive season. The reproductive activity of D. insignis was characterized by a low frequency of ovigerous females, a seasonal pattern of egg production, a large number of eggs produced per ovigerous female, a relatively low commitment of metabolic reserves to reproduction, a high reproductive output, and a relatively brief embryonic development. These parameters contribute to the maintenance of the population in the study area, but do not explain the success of the species as evidenced by the large numbers of individuals observed in the study area.