Population structure and dynamics of Petrolisthes armatus (Gibbes, 1850) (Anomura: Porcellanidae) in an Amazon estuary

Abstract

The aim of this study was to assess the environmental factors that modulate the spatiotemporal distribution of Petrolisthes armatus and analyze their population structure, dynamics and secondary production in an Amazon estuary. Monthly samplings were carried out over one year in the intertidal rocky outcrop considering the following environmental features; season (dry and rainy), areas (middle and lower estuary), banks (east and west), substrate with different rock sizes, and the upper and lower intertidal zones. Crab density was positively correlated with salinity and negatively correlated with temperature. Higher densities occurred during dry season, on the eastern bank, in the lower estuary, in the lower intertidal zone, and in the larger rock substrate. The high abundance of P. armatus indicates that this estuary is a suitable habitat for the development of this anomuran, and salinity and substrate were the most important factors driving population structure. High production reflects high density and biomass and the fast growth of this crab indicated that this filter feeder generates substantial production to the benthos. This study corroborated the hypothesis that the high metabolism of P. armatus combined with the high temperature in the Amazon region results in short life span (∼one year), high mortality rate (∼6 year −1), and high P/B ratio (∼4 year −1).