exception of a marsh area on transect IV in 1976 there did not seem to be 

 three distinct communities. There was an overlap of the dominant species 

 between the delineated community boundaries. With the low species number 

 that occurred in the sound it is likely that they formed one basic low 

 salinity community. In 1981, while salinity had increased there was still 

 a single community in the sound. The marsh area on trannect IV had receded 

 shoreward of the first sampling site leaving all three transects with a very 

 uniform physical environment. However, in 1981, transect IV did have higher 

 abundances of individuals compared with the other transects. This is most 

 obvious in the November collections and may be a relic condition associated 

 with the marsh that was once present on the nearby existing marsh or both. 

 There was a gradual shifting of the sound community in 1981, which attributed 

 to increasing salinity. The major taxonomic dominants in both 1976 and 1981 

 were the same, but several of the species did change. 



V. SUMMARY 



1 . Ocean Beach . 



The ocean beach environment at CERC's FRF, Duck, North Carolina, was found 

 to be typical of ocean beaches along the east coast in both physical and 

 biological aspects. The macrofauna formed a single community unit that showed 

 signs of migrating on and off the beach with the seasons. 



Comparing the long-term changes that occurred from 1976 to 1981 (5 years), 

 there were no substantial changes in the carbonate or organic content of the 

 sediments, or the grain-size distributions. The small differences observed 

 from 1976 to 1981 in the physical environment were well within the range of 

 natural variation that open coast systems experience. 



In the macrobenthic community the dominant species were identical from 

 1976 to 1981. The only long-term differences were found in the occurrence 

 of the rare species. Differences observed in the abundance of species were 

 all within natural population variations. There are no changes in the 

 physical or biological nature of the study area that could be attributed to 

 the FRF pier. The fauna present (1981 conditions) were typical for a high 

 energy ocean beach and the data collected did not exhibit any effect of the 

 pier on the beach. 



2. Sound Beach . 



The sound beach environment was found to be biologically similar to other 

 low salinity estuarine habitats along the east coast. The macrofauna community 

 gradually changed throughout the course of the study in response to the 

 increasing salinity (from 3 to 8 parts per thousand) over the year. Salinity 

 was the only physical variable measured that changed significantly throughout 

 the study. During any one season there appeared to be a single community 

 present. Abundances of individuals on transect IV were generally higher than 

 the other two transects, but the species were the same. Higher abundances 

 may be attributed to either the relic marsh or the nearby existing marsh or 

 both. 



44 



