INTERTIDAL DISCUSSION 



Intertidal infaunal beach communities were dominated by annelids, with arthropods, molluscs and 

 rhynchocoels being locally abundant. The structure and composition of these communities contrasts 

 sharply with haustoriid amphipod communities that have been reported as typical of more exposed 

 sandy beaches along the coasts of North America (Croker et al. 1975; Croker 1977; Dexter 1969) and 

 are more typical of annelid dominated communities reported from more sheltered estuarine areas (Withers 

 and Thorpe 1978; Mauer and Aprill 1979; Tourtellotte and Dauer 1983). 



Although the level of wave exposure within LIS is probably lower than ocean exposed beaches, 

 wind and wave energy appears to be a major structuring force within the Millstone area. Throughout 

 the monitoring program, all measures used to describe infaunal communities have consistently illustrated 

 the spatial similarity of the GN and WP communities and their dissimilarity from that of JC. The 

 shallow-sloping, clean sandy beaches of GN and WP, reflect their constant exposure to wind and 

 wave-induced scour. Generally low numbers of species and individuals are found at these beaches and 

 dominant components include Haploscoloplos fragilis, Paraonis fulgens, rhynchocoels, and Streptosyllis 

 arenae, taxa which are typically found in sandy habitats (Dexter 1969; Whitlatch 1977; Maurer and 

 Aprill 1979; Tourtellotte and Dauer 1983). 



The clean medium sands consistently found at GN and WP contrasts sharply with the sedimentary 

 environment at .IC. The .IC station is protected from constant wave scour, except during periods of 

 strong southeast winds. Flere the sediments are less uniform in size, exhibit larger seasonal shifts in 

 size, contain higher amounts of silt/clay and are frequently covered by large amounts of algae or eelgrass. 

 Infaunal abundance and numbers of species have been typically much higher at .IC than at either CjN 

 or WP; differences in density are primarily caused by very high densities of oligochaetes. Other organisms, 

 including molluscs and arthropods have been frequently more abundant at .IC than at other stations. 

 In intertidal sand habitats, higher numbers of these organisms generally occur in areas of increased shelter 

 from wind-induced stress (Croker 1977, Maurer and Aprill 1979). The dominant components of the 

 .IC community include oligochaetes, Hediste diver.sicolor, Capitella spp. and Polydora ligni, species which 

 can utilize fine organic matter as a food source (Sanders et al. 1962; Whitlatch 1977; Caspers 1980; 

 Knott et al. 1983). High abundances of these taxa may also be enhanced by the detrital mat which 



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