Biological aspects of the nonindigenous portunid crab Charybdis hellerii in the western tropical south Atlantic

The species of Indo-West Pacific origin, Charybdis hellerii, was recently i ntroduced to the Brazilian fauna. The size of individuals, sex-ratio, sexua l maturity, molting and spawning period of this species was characterized i n order to better understand their occupation, reproduction and development in invasive areas in the western tropical south Atlantic. The sex ratio wa s 1:1.2, and estimated size at sexual maturity was 35.0 mm of carapace widt h. Individuals in the intermolt phase were predominant, and no crabs in the process of ecdysis were captured. Ovigerous females were present throughou t most of the year, with the peak of spawning activity during the winter. T he studied population, characterized by moderate densities of adult, juveni le and ovigerous female specimens, and the temporal and spatial sampling al ong the western Atlantic, principally along the Brazilian coast, confirm th e hypothesis that C. hellerii is well established in this area, and has arr ived in recent times. The rapid expansion along the southwestern Atlantic O cean as well as the potential relationships with other brachyuran species s hould be monitored in order to anticipate possible negative impacts.