Continuous reproduction and recruitment in the narrowback mud crabPanopeus americanus(Brachyura, Panopeidae) in a remnant human-impacted mangrove area

Abstract

The population structure, reproductive period, and juvenile recruitment of Panopeus americanus were studied in order to enhance knowledge of its life cycle and reproductive strategy and promote the maintenance of its natural stocks in an impacted region. Specimens were collected in the remnant human-impacted mangrove at Araçá, state of São Paulo, Brazil, at two-month intervals from January to November 2005, at low tide, with a capture effort by three people. The crabs were measured (carapace width, CW) and sexed. The total catch was 275 animals, including 132 males (48.0%); 127 females (46.2%), of which 39 were ovigerous (14.2% of total catch); and 16 individuals whose sex could not be identified (5.8%). No correlation was observed between water temperature and the number of collected individuals; however, there was a significant, positive correlation with salinity. Males were significantly larger than females. The size-frequency distribution was bimodal, reflecting the occurrende of more than one recruitment pulse and the differential abundance of adults during the period of study. The overall sex ratio was 1:0.97 favoring males, and was not significantly different from the expected value, i.e., this population fits the anomalous pattern of sex occurrence in size classes. Ovigerous females were captured in all sampled months, which explain the continuous recruitment observed. Expected low levels of individuals of different size classes in the population were not confirmed. All population aspects found here allowed us to infer that this population of P. americanus is well established in the impacted mangrove by virtue of its reproductive strategy.

Ecological distribution and population features of Hexapanopeus paulensis Rathbun, 1930 (Crustacea: Decapoda: Xanthoidea) caught by bottom trawling in the southeastern coast of Brazil: implications for its population structure

“…Such a hypothesis is supported by the deviations in the sex ratio of H. paulensis after individuals attaining sexual maturity (from the size class with amplitude of 5.1 to 6.4 mm CW). Similar results were recorded for another xanthoid crab, Panopeus americanus Saussure, 1857 by Vergamini and Mantelatto (2008). Therefore, the occurrence of females in the last size classes may…”

Reproductive plasticity in Petrolisthes armatus (Anomura, Porcellanidae): a comparison between a Pacific and an Atlantic population

“…data). It might be speculated that the low RO for the Brazilian population, living in an environment frequently disturbed by human-produced pollutants (Vergamini and Mantelatto 2008;Miranda and Mantelatto 2009), represents a reproductive adaptation to cope with possible environment impacts. Our data from the Costa Rica population concerning egg volume of P. armatus are in agreement with those reported for the same species in Florida and Panama (Table 4).…”

Population structure and reproductive biology of the crab Sesarma rectum Randall, 1840 (Brachyura, Sesarmidae) in an impacted tropical mangrove in northeast Brazil

“…However, some authors (Díaz & Conde, 1989;Silva et al, 2007) studied crab populations of impacted areas and observed that sesarmid crabs, as well as panopeids and porcellanids, are able to adapt to adverse conditions due to their phenotypic plasticity (Vergamini & Mantelatto, 2008;Miranda & Mantelatto, 2009).…”