Recruitment of polychaetes and bivalves: long-term assessment of predictability in a soft-bottom habitat

Abstract

A 5 yr record (1981 to 1985) of polychaete and bivalve abundance in North Inlet. South Carolina. USA, was examined to estimate whether the timing of peaks in abundance of planktonic larvae was a reliable predictor of settlement timing and abundance of meiobenthic and macrobenthic recruits. Biweekly collections of zooplanktonic larvae, meiobenthos, and macrobenthos were made in close proximity to each other. Both smoothing and regression techniques were used to characterize the recruitment patterns of each life-history category. Despite year-to-year variability in both estimated peak abundance and the time of the peak's appearance, an annual cycle in the pattern for these major taxa was apparent. The interval between appearance of planktonic larval peaks and subsequent peaks in abundance of meiobenthos and macrobenthos varied greatly during 5 years. We conclude that, despite variability in the timing of settlement and recruitment of soft-bottom benthos, the temporal windows during which recruitment activity is highest are very predictable for polychaetes and bivalves in North Inlet. This will allow more efficient investigation of these fundamental events with higher frequency samplings in the future. The stock-recruitment problem, a lack of predictable correspondence between planktonic larval and adult abundances, is no less complex in benthic ecology than in fishenes ecology.