ABSTRACT
The effects of a small sewage outfall on intertidal and shallow subtidal polychaete assemblages at Wilson Cove, San Clemente, were examined during 1973. The outfall discharges approximately 95,000 liters/day of raw sewage effluent onto the rocky shoreline 1.5 m above MLLW. Quarterly collections were conducted at 15 outfall and 9 control stations; a single 0.02 m 2 sample from the corralline algal mat was collected at each station from which all polychaetes were identified and counted. Classification analysis showed that three general assemblages predominated: (1) an intertidal outfall group dominated at different times of the year by Boccardia proboscidea and Tharyx sp.; (2) an intertidal group away from the outfall dominated by Nothria stigmatis intermedia; and, (3) a large subtidal assemblage characterized by Platynereis bicanaliculata, Microspio microcera, and flabelligerids. Exogone lourei and Nereis grubei were abundant in all groups. Species of classification groups were placed into feeding guilds to elucidate further the effects of sewage disposal. Subtidally, feeding guilds were most diverse; the intertidal outfall assemblage of guilds was more diverse than the intertidal control. Particulate consumer and herbivorous guilds dominated at the outfall. These results are discussed in conjunction with previous studies at the outfall.
