Several nondominant species occurred in these communities. 

 Densities of Donax sp. were high on sites 7, 8, and 9. A second 

 burrowing amphipod and several polychaete species {Glyoeva sp., 

 M. rosea, and 5. bombyx) were common, but their densities were not high. 



Lie (1968) recorded diversities for benthic fauna in offshore areas 

 of the Oregon coast and Boesch (1972) recorded diversities for offshore 

 Virginia waters; however, species diversities have not been reported 

 for the high-energy beach zone. Diversities were low on the study area; 

 15 sites had a diversity of zero, with no organisms on 1 site and only 

 one species on 14 sites. The low diversity was caused by the high-stress 

 conditions on the- beach. The few species adapted to the beach face 

 had high densities, and the relatively large numbers of the dominant 

 species resulted in low species diversities. 



2 . The Sound Beach . 



The community structure on the sound beach was easily defined, and 

 was delineated in both the analyses of variance and the factor analysis. 

 The sample area was divided into three communities (Fig. 5). The marsh 

 community occupies a small area at the base of transect IV, and is 

 characterized by high densities of the oligochaete, Peloscolex sp., by 

 the insect groups, Tabanidae, Ceratopogonidae, and Uvarus sp., and by 

 high densities of chironomid larvae. There were more individuals and 

 more species per sample than in other areas. Species diversity was 

 low because the Peloscolex and the meiofaunal species were dominant in 

 the marsh. 



The two other communities cover the rest of the study site. The 

 S. viri-dis community begins between 90 and 140 meters from shore and 

 extends outward at least 300 meters from shore. No sampling was done 

 beyond this point; however, the bottom beyond site 8 was covered by 

 dense stands of Rupea sp. and the benthic fauna possibly changed. 

 Although S. viri-dis characterized this community, other organisms were 

 significant. The density of oligochaetes {Peloscolex sp.) and 

 chironomid larvae was higher than on inshore sites. Although the brack- 

 ish water clam, R. cuneata, was not present in large numbers, it was 

 significant in terms of biomass and was limited to this community. The 

 shoreward boundary of the community probably depended on exposure by 

 wind tides, and the community started where wind tides seldom exposed 

 the bottom. Shore birds fed at the margin of the community during an 

 extreme tide, and preyed on R. cuneata. Predation may have limited 

 R. cuneata and S. viridis in the nearshore area. 



The third community extended 90 to 140 meters from shore on 

 transects V and VI and into a narrow zone between the marsh and the 

 S. viridis community on transect IV. The community was exposed by wind 

 tides and characterized by the burrowing amphipod, L. dysticus . During 

 exposure, L. dysticus escaped predation by remaining under the sand 

 surface; it scurried over the bottom when water covered the community. 



86 



