168 
A significant alteration in the composition of natural sediments by the 
eroducticn of dredged material may chenge the suitability of the substrate 
for benthic fama, and eventually alter the benthic commmmity. The sizes of 
the interstitial spaces between sediment grains are critical to mary smaller 
infaunal species which occupy a narrow range of sediment sizes. Various 
deposit-feeding benthic animals are highiy specific in their particle size 
selection. Furthermore, certzin benthic species have planktonic larvae waich 
must settle on specific types of substrate in order to continue development. 
The CE (1977) observed that animals can burrow up through deposited 
sediments wnich resemble those in their habitat, but may suffocate under 
dissimila> sediments. Active burrowers and epifauna are aore likely ta 
excavate themselves than sluggish or sedentary animals, such as those living 
in permanent burrows. The thickness of the layer through which the amimals 
must travel affects the possibility of escape. 
Following disposal operations, Hirsch er al. (1978) noted am immediate 
decrease in the abundance and number of species, caused by physical burial, 
although chemical factors may have had an influence. Recolonization of the 
affected azea usually takes place within months; the colonizing organisms ere 
often different feem those which had been present prior to disposal. After 
some time (if the sediments are similar), the original communities may return. 
conversely, habitat alteration (i.e., a chamge in the pnysical nature of the 
substrate) by disposal may favor the establishment of a community different 
irom that which previously existed. Hirsch et ‘al. (1978) documented 2 amber 
of instances where habitat change and succession have taken place following 
dredged material disposal. 
The above effects are restricted to the site itself, and have not bees 
observed beyond the disposal area. Recent (1979) and past (1973-1974) ‘surveys 
show that the actual area of the Mud Dump is nearly barren due to the frequency 
and volume of dredged material dumped, but that effects are largely containes 
within the size boundaries (see Appendix B). 
