Long-term trends of subtidal macrobenthos in North Inlet, South Carolina

Abstract

Analyses of seasonal and yearly trends in subtidal macrobenthic samples collected bi-weekly at a sandy site (1981–1984) and a muddy site (1981–1985) in North Inlet, South Carolina, show large fluctations in abundance and high variability between replicate samples. Sampling variability at the sandy site, thought to be influenced more by physical disturbance than by biotic interactions, was especially high and prevented the interpretation of seasonal trends in abundance. Increased replication at the muddy site in 1985 revealed abundance patterns of winter/spring maxima and summer minima. Despite short-term (seasonal) and high year-to-year variability, the fauna at both sites were characterized by long-term stability in abundance. That is, although abundances varied considerably between seasons or years only 9 of 22 taxa analyzed showed a directional change in abundance. These 9 taxa increased in abundance over the four (sandy site) or five (muddy site) years of examination while the other 13 taxa fluctuated about a mean value. The taxonomic composition of benthic fauna at both sites was also very stable through time, with the sandy site always numerically dominated, in order, by polychaetes, amphipods, and bivalves and the muddy site by polychaetes, oligochaetes, and bivalves.