SEASONAL CHANGES IN THE COMMUNITY STRUCTURE OF THE MACROBENTHOS INHABITING THE INTERTIDAL SAND AND MUD FLATS OF BARNSTABLE HARBOR, MASSACHUSETTS

Abstract

A quantitative survey of the benthic macrofauna of Barnstable Harbor, Massachusetts, was conducted to describe general community structure and examine temporal changes in species composition. Classification analysis delimited coarse and fine sand, mud, muddy-sand and gravel-mud species associations. The 32 spp. used in the inverse classification analysis were partitioned into 10 species groups, reflecting spatial distributional patterns. Many of the species were both dominant and ubiquitous, masking discrete species groupings. The majority of macrobenthos at Barnstable Harbor were deposit-feeders which normally comprised more than 90% of all organisms sampled. The deposit-feeders normally dominate mud and muddy-sand sediments. Suspension-feeders were most abundant in fine sands. The relationship of sedimentary parameters affecting the distribution of trophic groups proposed by Sanders is generally supported. While no significant changes were evident in species diversity, evenness or species number throughout a 19 mo. sampling period, classification analysis delimited seasonal clustering of samples and species groupings. These patterns were repeatable over a 2 yr period, suggesting that dynamic "equilibrium" was occurring, not successional changes. Seasonal clustering patterns of some species were related to the appearance of different zoogeographic faunal province elements. Typical warm-water Virginian components and cold-temperate Virginian components were commonly found in late summer and winter, respectively.