Seasonal variation in community structure and recruitment of benthic decapods in a sub-tidal cobble habitat

Abstract

Quantitative suction samples of benthic decapod fauna were taken in the south of Ireland during 1997. Some species settled into the area, but failed to persist to the first winter, while others were present in high numbers throughout the year. The duration of settlement was species-specific, ranging from several weeks to several months. Body size at settlement decreased with increasing temperature during larval development. Growth potential and early mortality of a number of decapod species was examined by separation of successive moult instars from length-frequency distributions. Seasonal lows in abundance and biomass of young of the year and for previously established decapod individuals were identified at the end of July and early August, which may represent the most suitable time to release juveniles for stock-enhancement purposes. Community structure differed between settlement season and over-wintering periods. Young-of-the-year community structure differed from that of previously established individuals, with higher abundance and number of species recorded for the former. The data represent a baseline study of a widely distributed community and may support further work on species interactions, improving the accuracy of prediction of annual recruitment fluctuations.