166 
BIOTA. 
PLANKTON : i 
ij ‘f 
Phytoplankton and zooplankton (particularly larval forms) exhibit mortalities 
or growth abnormalities when heavy metals, pesticides, and other substances are 
present. However there is no evidence of any major effects on the planktonic 
communities in the vicinity of the disposal sites in the Bight. 
In a laboratory study by Young and Barber (1973), bottom waters collectay 
from the Mud Dump were not inhibitozy to initial phytoplankton g=owch. 
Sedinerrs from the site, however, did cause a slight to moderate (up te 
5 days) lag before exponential growth began; the degree of inhibition depended 
on sezsonal changes in bottom water characteristics. This tempozary 
inhibiticn did not occur woen the sediments were heated to destroy orzzani: 
matter; consequently, the lag vas probably. due to toxic organic materials 
rather than to heavy metals. Even a slight lag is not biologically importa: 
because shytoplanktom are most abundant in surface waters and do not photo 
synthesize in close association with sediments in the Apex. 
Sullivan and Hancock (1977) etated that “natural fluctuations :: 
zooplankton populations are so large, field surveys would practically never & 
useful." Earlier, the Sandy Zook Laboratory of the National Marine Fisherie: 
Service reported that dredged marcerial did not appear to afiect zooplankt= 
populations (SEL, 1972). 
NEKION 
The transient turbidity plume associated with the disposal of dzedér 
materizl poses no signiSicane threat to fishes. Suspended particles can ¢a>* 
Acod! 
gill damage, reducing fisa respiratory surface area (Ritchie, 1970), but =* 
type of gill damage has cot been positively identified as harmful tc fist 
terms of overall survival. The functional decrease in gill surface e243 
be offset by using reserve surface area (not all of the gill surface is 
