169 
tf toxic substances are present in the disposed material in a bislogically 
wtive and/or available form, the benthic community mzy be adversely affected. 
wrentially toxic substances include trace aetals, organohalogens, and oil and 
57228e GELS 1976). Aiter disposal, these substances may also move across the 
ydimemt-water interface into the water colimm. Modeling studies ‘indicate 
7 : 
sat changes in water parameters are brief and restricted to the immediate 
neiaity (within several hundred meters) of the site (Conner et al., 1979; see 
wperdix 5). Simpson (1979) reported that the Hudson estuary was the dominant 
source o£ soluble metals to the Apex, and that release of soluble metals from 
sediments in dumping areas did net seem to be a significant source. 
Contaminant uptake is -of considerable importance in the benthic 
comunity because the organisms are exposed to potentially toxic 
substances. Many benthic organisms are deposit feeders. While sediments 
are passing through ‘their digestive tracts, changes in pH, digestive 
; : 
enzymes, and other factors may increase the mobility of some substances 
(especially metals) and cause them to be absorbed into the tissues or 
2xcreated in a form available to other organisms (ZPA, 1976). 
Soecies found in the sediments ac the ChrisCiaensen Basin “ite and Mud 
Dump are characterized as pollution tolerant deposit and suspension feeders 
(Pearce. et al., 1976d). Biomass end species diversity in both areas will 
de low. Dredged material disposal has caused low absolute numbers of 
individuals at che Mud_ Dump, but this affece is limited to che actual 
Tegion of repeated disturbdance. The Outer Apex Sica will be afiected 
Initially by mortality of the benthic organisms because the site has noc 
been previously used for the disposal of dredged material. 
Benthic commmities serve a critical role in the normal autrient cycling 
and energy pathways found in a marine ecosystem, but it eppears that continued 
disposal at a site would directly affect only a relatively small area of the 
bottom. Lf dredged material disposal were discontinued at a site, persistent 
COntaminants or pollution from other sources in the Apex might delay recovery 
Of the benthos at the site. 
11-267 O—82——12 
