During 1983, tlio major groups of infaunal organisms and their relative 

 contributions to community composition were consistent with past years. 

 No long-term changes in the contribution of any major group have occurred 

 at any of the intertidal monitoring stations. 



Numbers of Species and Community Density 



The quarterly numbers of species comprising intertidal communities 

 during 1983 ranged from 3-7/core at GN, 4-13/core at JC and 1-6/core at WP 

 (Fig. 3). All stations exhibited peak species numbers in September 

 followed by declines through March and slight increases in June. This 

 seasonal pattern has generally occurred at all intertidal stations since 

 1976. Although variable within a year, the numbers of species have 

 remained similar among years, particularly at GN and JC. The community at 

 WP has exhibited a general increase in species numbers since September 

 1979, soon after the sieve mesh used to process samples was changed from 

 0.71 mm to 0.5 mm. The additional species obtained at this station have 

 been small polychaetes (e.g. Streptosyllis arenae , Exogone hebes , and 

 Parapionosyllis longicirrata ) . It is probable that these species were 

 present at this station prior to 1979 but were not adequately sampled by 

 our methods. 



Quarterly infaunal densities in 1983 averaged from 1.6/core (WP) 

 769/core at JC (Fig. A). Densities were lowest at all stations in March; 

 however, periods of highest density occurred in different months at all 

 stations (GN in September, JC in June, WP in December). Infaunal 

 abundances at GN and WP in March and particularly in June during 1983 were 

 substantially lower than those obtained since 1979, although similarly low 

 values have been observed in previous years. At JC , in contrast, record 

 high levels of abundance occurred in June 1983; this was due almost 

 exclusively to the high density of oligochaetes . 



Biomass 



Biomass (ash-free dry weight) at the intertidal monitoring stations in 1983 

 ranged from 0.002 g/core at GN to 0.06 g/core at JC (Fig. 5). Seasonal 

 fluctuations were evident at all stations and no pattern was common to all. 

 At GN, seasonal shifts in biomass during 1983 closely followed those of 



