Effluent was also characterized by the absence of cold water species, e.g., Laminaria sacc.harina, and by 

 the presence of a warm water shipworm, Teredo barlschi. 



Teredo hartschi also maintained a reproductive population in panels located 100 m outside the 

 quarry, exposed to the effluent produced by 2-unit operation. Exposure to elevated temperatures may 

 be required for larval settlement. Teredo navalis, the native shipworm, was also found in the MNPS 

 thermal effluent; there was a trend of increasing abundance with decreasing distance from the quarry. 



Results from the Timber Study show that untreated wood is rapidly degraded in local waters, 

 primarily by Teredo navalis; Red Oak is more resistcnl than Douglas Fir, but blocks with a minimum 

 dimension of 6.4 cm have a survival time on the order of 2-3 yrs. 



Chemical treatment can deter woodborer attack, but if timbers are cut after treatment, unprotected 

 surfaces are exposed, and are susceptible to woodborers. This susceptibility is less for creosote treated 

 wood than for CCA treated wood, as creosote is a better penetrant. 



Characteristics of fouling and woodboring communities in the vicinity of MNPS have been estab- 

 lished during 2-unit operation. Comparisons of community and population parameters determined after 

 Unit 3 is operational will permit assessment of the potential added impact. 



FISH ECOLOGY 



The construction and operation of MNPS could affect fish assemblages in several ways. Lxirger 

 fish may be removed from the population by impingement on the intake screens; eggs, larvae and small 

 fish may be removed during entrainment through the cooling water system; and spatial distribution of 

 local fish populations may change in response to the cooling water effluent. 



Several programs were established to provide baseline data for assessing impacts of MNPS on fish 

 assemblages. Ihese include studies of planktonic, demersal, pelagic and shore-zone fish assemblages, and 

 estimates of the number offish impinged and entrained. Plankton studies conducted since 197.3 included 

 collections of fish larvae at various stations, and entrainment mortality and thermal tolerance research 

 on selected larval fish taxa. The trawl sampling program was established in 1973 to monitor spatial 



