appeared in 1981. Six crustaceans occurred in both studies. One freshwater 

 form Cambavus sp. and one estuarine form Callinectes sapidus did not occur in 

 1981, and one estuarine species Covophium sp. occurred in 1981, but not 1976. 

 Overall there were 16 taxa in 1976 and 17 in 1981. Of the five dominant 

 species, four were the same in both studies (oligochaetes, Scolecolepides 

 vividis , Lepidactylus dysticus , and chironomids) . In 1976 Monoculodes sp. 

 was dominant, but not in 1981. In 1981 the Laeoneveis culvevi was dominant 

 but not in 1976. 



In 1976, oligochaetes were not as abundant as in 1981, averaging 1,660 

 per square meter in 1976 and 2,290 per square meter in 1981. For both studies 

 densities for transect IV were higher than the other two transects (the only- 

 exception was in March 1976) . In 1976 Scolecolepides vividis tended to occur 

 at stations farther offshore (stations 5 to 8) and averaged 69 per square 

 meter for the study. In 1981 it averaged 500 per square meter for all 

 collections, but Scolecolepides vividis became very abundant in April 1981 

 when salinity increased over 5 parts per thousand. In November 1980 and 

 January 1981 it averaged 260 per square meter and in April and July 1981, 

 750 per square meter. Laeoneveis culvevi occurred only five times in 1976, 

 in July, at low abundances. In 1981 it was the second numerically dominant 

 species and occurred at almost every station. 



The Lepidactylus dysticus was common and abundant in 1976, averaging 540 

 per square meter. It increased in abundance by a factor of two from October 

 1975 (300 per square meter) to July 1976 (700 per square meter) . In 1981 

 Lepidactylus dysticus was abundant, averaging 1,025 per square meter. The 

 trend in this species is consistent with the increased salinity. Monoculodes 

 sp. was much more abundant in 1976 than in 1981. In 1976 it was a dominant 

 species occurring at 75 percent of all stations over the entire study. In 

 1981 Monoculodes sp. was uncommon occurring at only 22 percent of the 

 stations. In 1976 it averaged 392 per square meter and only 151 per square 

 meter in 1981. The decline in abundance of Monoculodes sp. is not related 

 to the salinity change. It is an estuarine genus that should have been 

 favored by the higher salinity. 



The chironomid larvae were widespread and abundant in 1976, occurring at 

 almost all stations. They averaged 435 per square meter. By 1981 their 

 importance had declined, occurring at 67 percent of all stations with an 

 average abundance of 206 per square meter. While it is not known which 

 chironomid species were abundant in 1976, the species present in 1981 were 

 salt tolerant (Roback, 1974). The decline in chironomid, and possible shift 

 to salt-tolerant forms, from 1976 to 1981 appears to reflect the increased 

 salinity level. 



Species diversity (H* ) for both studies was low. The range of diversity 

 for 1976 was 0.33 to 2.33, compared with 0.00 to 2.52 in 1981. These ranges 

 seem typical for low salinity habitats (Boesch, 1972; Diaz, 1977). Low 

 diversity was due to both low evenness and richness. In 1976 Matta (1977) 

 identified three communities in the sound. However, with the possible 



43 



