lOB were in an uncontaminated environment, 7A and 7B were on the 

 western edge of the turning basin and 3A and 3C were on the channel 

 wall of the desalination plant. 



Species diversity was often greater at the lower stations and the 

 numbers of individuals per unit area of slide surface were generally 

 greater at the shallower stations. The number of species shared in 

 common between any two stations varied considerably. At the highest, 

 it was 46 percent. Stations lOA and 7A on November 13th, 1970. More 

 commonly, species shared in common were few and at the lowest percent. 

 Stations lOA and 7A on December 2nd and December 16th, 1970, between 

 the same two stations. Stations 3C and lOB have had as much as 17 

 percent species similarity on December 2nd, 1970 and as little as 9 

 percent on December 16th, 1970. 



Comparison of plots of percent effluent at the stations and the diver- 

 sity and abundance of organisms on the diatometers showed no clear 

 relation. Figures 48 and 49 show numbers of Vort'ioella sp. and 

 Nitzschia tongissima per mm^ of slide surface settling each month at 

 Safe Harbor and control stations. Compared to the control station, 

 both organisms showed an increase in the numbers of individuals at 

 Safe Harbor shallow stations and a decrease in numbers at the deep 

 station (3C) in Safe Harbor near the effluent discharge (Table VIII). 



TABLE VIII 



Mean abundance of a ciliate protozoan iVortioetZa sp.) and a diatom 

 (Nitzschia tongissima) settling per mm^ on diatometers at Safe Harbor 

 and control stations. 



Station Depth Distance from Vorticella/mm^ Nitzsahia/mnp- 

 Discharge Point 



3A 2.4m 73m 14 73 



7A 2.4m 415m 2.7 47 



IDA 2.4m Control 1.7 15 



3C 7.0m 73m 2.5 1.2 



7B 7.0m 415m 3.9 9.5 



lOB 7.0m Control 3.5 6.0 



Settlements of serpulids , barnacles, and hydroids occurred continuously 

 on diatometers at Station 3C but did not occur on diatometers at Station 

 lOB. The presence of these filter feeding organisms on the glass slides 

 adversely affected the diatom and protozoan populations and made inter- 

 pretation of the results difficult. These filter feeders not only 



116 



