Population biology of the mole crab Emerita brasiliensis (Decapoda: Hippidae) at Fora Beach, Brazil

Abstract

The population biology of Emerita brasiliensis (Decapoda: Hippidae) was studied by means of biweekly sampling from October 1990 through March 1993 at Praia da Fora Beach, Rio de Janeiro, Brazil (22°57'S, 43°10'W). Two transects were established in the swash zone, and divided into 4 strata parallel to the waterline. From each stratum, 4 replicates were taken with a 0.04-m2 sampler. Highest population densities were observed at the end of spring and during summer. The presence of ovigerous females and juveniles during the entire sampling period indicated continuous reproduction of the population. The sex ratio was 1.82 for males: 1.00 for females. Batch size varied from 610-1,093 eggs, for females 10-23 mm long, respectively. Growth and mortality rates were higher for females than for males. Longevity for 99% of the population varied approximately from 6-10 months.