The cluster analysis did not produce a concise grouping of stations with 

 data trends that could be attributed to season, depth, or sediment statistics. 

 At the group 6 level there was a mixing of stations from different seasons and 

 locations along the transects (Table 26). Group 1, mainly transect IV in 

 November, and the deepest stations (sites 7 and 8) from all transects in July, 

 had the highest densities of the dominant species and also tended to have low 

 evenness. Group 2, mainly transect IV in January and April, and the deeper 

 sites from November, January, and April on all transects, had lower densities 

 of dominant species and occurrences of Rangia cuneata and chironomids . Group : 

 was the only station group to be entirely made up of one collection period, 

 April, and represents stations of low community structure statistics. Group 3 

 was primarily transects V and VI. Group 4 also represented stations with low 

 community structure statistics, but mainly in January, for transect V. Group 

 5 was mainly stations (sites 2 to 5) on transects V and VI in November and 

 transect VI in January. Group 5 appears to be transitional between groups 3 

 and 4 in its character, having low densities of some dominants, but not others 

 (Table 24). Group 6 is mainly stations (sites 1, 2, 4, 5, and 6) from July 

 and represents more the increased salinity through time than the seasonality. 

 The abundance of freshwater forms (Gammarus sp. and chironomids) decline while 

 estuarine forms increase (Lepidactylus dy sties , Rangia cuneata and Laeonereis 

 eulveri) . In July there was also the appearance of additional estuarine forms 

 that did not occur previously (Streblospio benediati and Maeoma sp.). 



Table 



26. Station group 



s from cluster analysis 



of all sound data. 





See text for explanation. 









November 1980 



January 1981 



April 1981 



July 1981 



Transect 



IV V VI 



IV V VI 



IV 



V VI 



IV V VI 



Site 











1 



14 4 



4 4 4 



1 



3 2 



6 6 6 



2 



15 5 



2 6 5 



2 



4 3 



6 6 6 



3 



15 5 



2 4 5 



2 



3 3 



15 6 



4 



15 5 



2 4 5 



3 



3 3 



6 6 6 



5 



15 5 



15 5 



2 



3 3 



6 6 6 



6 



15 6 



2 4 2 



3 



2 3 



6 6 6 



7 



12 2 



12 2 



2 



3 2 



1 1 2 



8 



2 4 2 



12 2 



2 



2 2 



1 1 1 



From the species cluster analysis, four species groups were identified 

 that related to dominance and the increasing salinity. Species group 1 was 

 composed of Limnodrilus spp. , Scolecolepides viridis , Laeonereis eulveri, 

 and Lepidactylus dysticus. These species were the major dominants that 

 occurred at most stations for all collections. They were the most 

 characteristic of station groups 1 and 2. Species group 2 was Cyathura 

 polita, Gammarus sp., Monoculodes sp., and Leptocheirus plumulosus . 

 Group 2 did not seem to be characteristic at any station group, but is 

 diffusely represented in all station groups. Species group 3 was Rangia 

 cuneata and chironomids, which were characteristic of the deeper stations 

 in station groups 1 and 2. Species group 4 was Streblospio benedicti and 

 Maeoma sp., which were the most characteristic of station group 6 for July. 



34 



