Polychaetes and oligochaetes were the most abundant organisms at Effluent, Giants Neck and 

 Jordan Cove while arthropods were frequently abundant at Intake. Polychaete abundances were generally 

 highest in either September or June and although molluscs and arthropods contributed substantially to 

 the subtidal communities no consistent seasonal trends were seen in these groups. 



During 1986, higher numbers of arthropod species were recorded in September and December 

 samples at Giants Neck and Jordan Cove than in previous years. At Intake, species numbers continued 

 to increase in 1986 continuing a trend begun in 1985 after construction activities (in 1984) eliminated 

 most of the species in this area. In contrast, the numbers of species and individuals of all the major 

 taxa at Effluent were generally lower in 1986 than in the previous two years. 



From March 1 979 to March 1 986, mean quarterly abundance of subtidal communities ranged from 

 9 to 633 (no. /core) and mean species numbers (no. /core) from 5 to 46. Highest quarterly abundances 

 generally occurred in June or September at all stations. After removing naturally induced temporal 

 variation, no significant increasing nor decreasing trends in annual mean abundance were evident at any 

 subtidal station. Species numbers were generally highest in June or September at Effluent, Giants Neck 

 and .lordan Cove; (December at Intake). At Effluent, the mean species number has increased significantly 

 over the monitoring period. 



Over all stations and years, oligochaetes (as a group) were the most consistently dominant taxon, 

 accounting for 4 to 61% of the total individuals collected. Other taxa among the more consistently 

 abundant forms were Pofycirrus eximius, Protodorvillea gaspeensis, Tharyx spp., Aricidea catherinae, and 

 Tharyx aculus. Of all communities, Intake was the most dissimilar; At this station, 29% of top ten 

 dominants were species of amphipods. In addition, other dominant taxa at this station exhibited strong 

 temporal fluctuations in abundance. 



Mean annual species diversity (IT) ranged from 2.6 to 4.6 with lower values generally reflecting 

 short-term pulses in species abundances. High H' values reflected changes in the numbers of individuals 

 or species, but not in the equality of the distribution of individuals among species. 



The subtidal benthic infaunal program has provided data necessary to characterize communities 

 inhabiting areas potentially impacted by power plant operations (Intake, Effluent, and Jordan Cove) and 



