which very low numbers of species were collected. The annual mean at IN in 1984 was significantly 

 lower than in 1^80 and 1982. At JC, the mean number of species in 1982 was significantly lower than 

 those in 1980, 1981, 1984 and 1985, and the low mean values obtained in 1981 and 1983, were lower 

 than 1984 and 1985. Only at EF did this pattern differ; 1984 and 1985 values were significantly higher 

 than all previous years. 



Dominance 



Since 1980, a composite list of all taxa present among the ten numerically abundant forms in any 

 samplng year, included 18, 19, 21 and 24 taxa at GN, JC, EF and IN, respectively (Table 6). Among 

 these, eight taxa were dominant at all stations: Thary>x ac.utus, oligochaetes, Aricidea catherlnae, Capitella 

 spp., Gammarus lawrencianus, Prionospio steestrupi, Leptocheims pinguis and Mediomastus amhiseta. 



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

 accounting for 17 to 51% (EF), 1.3 to 31% (GN), 4 to 19% (IN) and 21 to 61% (.IC) of the total 

 individuals collected and thus had the highest BIV's (93.1-99.1%). Aricidea catherinae was also consis- 

 tently found among the dominants at GN, IN and .IC, where it ranked second in terms of the six-year 

 BIV and generally accounted for over 10% of all the individuals collected. Other taxa among the more 

 consistently abundant forms (i.e., BIV > 80%) were Polycirms eximius and Protodorvillea gaspeensis at 

 EF, Tharyx spp. at GN and Tharyx acutus at JC. 



Of all communities, that of IN was the most spatially dissimilar; 29% of the taxa included among 

 the ten dominants collected over the last six years, were amphipods. In addition, species type was 

 highly variable and only oligochaetes had a BIV > 80%. Many other dominant taxa at this station 

 exhibited strong temporal fluctuations in abundance. For example, the relative abundance of Tellina 

 agilis ranged from 1-15%, Mediomastus amhiseta from 1-20%, Ampelisca verrilli from < 1-24% and 

 Polydora ligni from 0-19%. No other sampling station has exhibited this degree of variability. 



36 



