Spatial variability in decapod community structure and recruitment in sub-tidal habitats

Abstract

Sub-tidal populations of decapod crustaceans from 5 distinct benthic habitats were sampled at the end of the main settlement season. Divers, using SCUBA equipment, estimated substrate characteristics and complexity, removed sediment samples, and collected quantitative samples of the resident communities using suction sampling at each of the sites. Adult and young-of-the-year (YOY) components of the decapod assemblages were identified. Univariate and multivariate statistical techniques were used to detect between-site differences in the community structure and community statistics of each component. Although YOY individuals were detected at each of the sites, community structure and statistics for the YOY component varied significantly among sites. Between-site differences in the adult component of the community were also identified. Between-site differences in the YOY assemblages varied from that of the adult component, indicating that post-settlement processes, such as predation and migration, play an important role in shaping the community. Variation in physical complexity and other habitat characteristics appeared to contribute to the significant differences in the YOY and adult assemblages. Due to the close proximity of the sample sites to one another, it seems unlikely that restrictions or spatial and temporal variations in larval supply resulted in the between-site differences observed. Substrate choice at settlement would appear to vary between species, with most species rejecting more marginal areas that offer little shelter to either post-larvae or individuals at later stages of development.