Algal Investigations in the Vicinity of Plymouth, Massachusetts

Abstract

Algal investigations were conducted in the vicinity of Pilgrim Nuclear Power Station, Plymouth, Massachusetts from 1974 through 1981 to assess the impact of the cooling water discharge on the intertidal and subtidal flora.

An intertidal experimental station was established near the mouth of the discharge canal, and a subtidal (3.3 m below MLW) experimental station was positioned in the path of the discharge plume; control stations were established north and south of the station. Species occurrence, total number of species, species dominance, and community structure were determined; at each station intertidal data were evaluated as to primary percent cover; subtidal station assessments were evaluated using biomass determinations.

Control stations were dominated by Ascophyllum nodosum, whereas the Effluent (experimental) station was dominated by fucus vesiculosus. The Effluent station had more species than control stations in the intertidal zone, reflecting increased colonization by ephemeral species in the absence of a dense fucoid population. The control stations, with similar substratum, had considerable similarity in species composition. The occurrence at Effluent station of four taxa not normally seen north of Cape Cod was attributed to the thermal release.

Subtidal habitats were dominated by chondrus crispus and phyllophora spp. The Effluent station showed significantly lower chondrus biomass but with significantly higher Phyllophora biomass than control stations, a pattern attributed to a higher percentage of sand and gravel at the Effluent station and the scouring effects of the discharge plume.