A more detailed characterization of the benthic community 

 structure at Brenton Reef resulted from analysis of the grab 

 samples from the twelve "transect" stations (Figure 2-4) . 

 Descriptions of sample residues from these stations are given in 

 Table 3-1. Samples from stations on or close to the disposal mound 

 (3 through 10) had larger volumes than edge samples (1,2,11,12) 

 with the exception of sample 6, in which well-sorted fine sand was 

 not retained by the sieve. Bay scallops ( Aequipecten irradians ) , 

 jingle shells (Anomia simplex ) , oysters ( Crassostrea virqinica ) , 

 and other estuarine shells were abundant in samples 1 through 10; 

 these samples also contained rounded pebbles and small rock 

 fragments. All samples contained fine detritus from terrestrial 

 plants. Most of the residue in samples 11 and 12 consisted of the 

 flat, flexible tubes of ampeliscid amphipods. 



Previous observations of the site, the gross appearance 

 of the sample, and the sample residues suggested that the sediment 

 at stations 1 and 2 consisted of fine-grained material which may 

 have been deposited both during disposal operations and during 

 subsequent erosion of the disposal mound. Samples on the mound (3 

 through 10) varied from relatively unmodified estuarine sediments 

 to winnowed sand and/or shell lag deposits. The presence of shells 

 of offshore species, frosted sand grains, and glauconite grains in 

 samples 11 and 12 indicated that the ambient bottom has not been 

 covered by disposal materials. 



The number of organisms recovered and the time required 

 to initially sort each sample are also shown in Table 3-1. The 

 most time-consuming samples were 2 and 3 where very large numbers 

 of small polychaetes had to be separated from fine plant debris. 

 The fine portion of samples 11 and 12 contained a mass of very 

 small tubes and fragments of ampeliscid tubes which slowed sorting. 

 The least amount of time was required for sample 7 in which 

 organisms could be separated from sand and pebbles using suspension 

 and flotation. 



The number of species per sample ranged between 38 and 

 64, but the total for all samples was 135, reflecting that 

 different habitat types with unique assemblages of organisms were 

 sampled (Table 3-2) . The large number of species (28) being 

 represented by only 1 or 2 individuals is another result of limited 

 replication of samples from different habitats (Table 3-3) . The 

 number of species per sample is similar to those found in other 

 stable-bottom shelf habitats, and the large total number of species 

 is similar to that found in studies of the Massachusetts Bay 

 Disposal Site (SAIC, 1987) . 



The number of individuals per sample varied from 598 to 

 5,342 (5,980 - 53,420/m 2 ). The higher densities reflected the 

 small size of many of the dominant species and the large number of 

 juveniles present; during the normal course of events, many of 



10 



