Spatiotemporal distribution and population structure of Clibanarius symmetricus (Randall, 1840) (Crustacea, Diogenidae) in an Amazon estuary

Abstract

Rocky outcrops in the intertidal zones of estuaries often contain a highly diverse microbenthic community which includesthe hermit crab, Clibanarius symmetricus, an abundant species on the equatorial Amazon coast. However, the ecology of this anomuranis poorly understood. Given this, the present study investigated the spatiotemporal distribution and structure of the C. symmetricuspopulations that inhabit the rocky outcrops of the Marapanim estuary in northern Brazil. Samples were collected monthly over a yearlycycle covering both the dry and rainy seasons in the upper and lower midlittoral zones during low tide. The distribution and abundanceof C. symmetricus were affected directly by environmental factors such as temperature, seasonality, the intertidal zone, and salinity.The population presented sexual dimorphism, with males being larger than females, a male-biased sex ratio (1.5:1), a nonnormal andunimodal distribution, continuous reproduction, and sexual maturation at a cephalothoracic shield length of 3.6 mm. Despite theunique characteristics of the Amazon coast and the study estuary, the spatiotemporal distribution and structure of the C. symmetricuspopulation were similar to those recorded at higher latitudes.