Macroinfauna of northern New England marine sand. II. Amphipod-dominated intertidal communities

This is a 5-year study of macroinfaunal communities of moderately exposed to sheltered intertidal sands of New Hampshire and southwestern Maine. Habitats also differed in slope, width, predominant sand grain size, and carbon–nitrogen concentrations. Thirty-one species were recorded. Abundance and dry weight biomass at four intensively studied habitats averaged 5000/m2 and 2.1 g/m2, respectively, during 1971. The most exposed habitat yielded twice this standing crop, correlated with intermediate levels of carbon and nitrogen. Over 90% of seasonal numbers and biomass at more exposed habitats were attributable to six species of relatively short-lived amphipods, mostly Haustoriidae. Between-habit at variation in abundance and biomass of amphipods was in general greater than seasonal variation within habitats. Polychaete species increased at sheltered habitats, and bivalve mollusks were restricted to shelter. The typical community of moderately exposed sands south of Penobscot Bay, Maine, is characterized by a recurrent group of nine species (five amphipods). Community stability is assisted by brooding habits of dominant amphipods. Zonation, subtidal connections, seasonal movements, and patterns of amphipod species dominance are discussed. Structural comparisons are made with boreal European and other Atlantic coast intertidal sand communities.