3 STAGES OF SEASONAL SUCCESSION ON THE SAVIN-HILL COVE MUDFLAT, BOSTON HARBOR

The benthic infaunal mudflat community of Boston Harbor's Savin Hill C ove was sampled every other week from January though December 1986. Ei ghty replicate samples per data allowed precise estimates of the abund ances of juvenile and adult stages of all macrofaunal taxa and many me iofaunal taxa. We describe the multivariate structure of the seasonal succession of this community with a faunal distance metric approach. T here were three groups of species that produced a three-stage or trian gular succession pattern. Stage 1 is defined by a March bloom of harpa cticoid copepods that closely follows a benthic diatom bloom. Harpacti coid copepod abundance rapidly declines in late spring and is followed by the recruitment of four opportunistic annelids, marking the break between stages 1 and 2. Stage 2 is a dense assemblage of four surface- deposit feeding and shallow subsurface-deposit-feeding annelids that r each peak abundance in June and decline in late summer, marking the br eak between stages 2 and 3. Stage 3 populations are more diverse than stage 2, reach peak abundance in fall, and decline in late fall. The i nfaunal community structure of December resembles that of the communit y the previous January. Succession on this mudflat is a fast-paced and dynamic process affected by epipelic diatom production, the timing an d duration of juvenile recruitment, and the ability of the infauna to survive in dense assemblages of tube builders.