since the larger fish could easily move ahead of the divers and 

 avoid being counted or, in some cases, be counted more than once. 

 Relative numbers of fish per unit distance, however, were obtained. 

 In January, 1971, for example, 120 fish were counted per 100 feet 

 (33m) of sea wall at the City Electric sea wall. 



Fish showed definite avoidance reactions to turbid effusions from 

 the desalination plant which followed the onset of operations after 

 the plant had been shut down for maintenance. Large schools of 

 snapper, mullet, and anchovies, as well as other species of fish, 

 were observed swimming away from the turbid effusions or hovering 

 in the adjacent clearer waters. Schools of mullet and anchovies, 

 trapped by the turbid effusions in the inner canal entrance, were 

 observed swimming in a distressed manner rapidly towards the harbor 

 mouth. It could not be ascertained if fish were avoiding water 

 turbidity or if they were responding to some other chemical contam- 

 inant. Sprague (1964) has made some observations along those lines, 

 discussing the reactions of salmonid fishes to copper and zinc solu- 

 tions at levels of 20 ppb in freshwater. 



Many species of fish become inactive at night (Starck and Davis 1967). 

 Night dives in the Safe Harbor canal revealed specimens of snook 

 (Centropomus undecimalis) inactive on the floor of the canal and a 

 variety of other fishes quietly resting along the rocky walls of the 

 canal. These fish, presumably, would not flee high levels of contami- 

 nants should they be released at night. Many smaller species retreated 

 into holes and crevices in the canal wall when alarmed during the day 

 and were also unlikely to escape the contaminants in the effusions when 

 they engulfed the area. 



While it was true that fish congregated in the vicinity of the effluent 

 when the desalination plant was operating normally, it does not necess- 

 airly follow that this was beneficial to them. Attractive parameters 

 of the effluent such as heat and entrained plankton may have lured fish 

 into the area while toxic parameters may have physiologicall damaged 

 them. Several fish were observed with epidermal lesions and histolog- 

 ical examination of livers from Safe Harbor fish, discussed below, 

 indicate that, in fact, copper toxicity was deleterious to some of the 

 smaller fishes inhabiting the harbor. 



In addition to the transects in Safe Harbor Canal, a series of transects 

 were made both east and west of the turning basin, to determine effects 

 of effluent moving over the western edge of the turning basin and onto 

 the turtle grass flats. Observations by divers indicated that the 

 echinoid population in the path of the effluent decreased markedly during 

 1970. The numbers per square meter of Lytechinus variegatus and Trip- 

 neustes ventricosus found in transects east and west of the turning 

 basin are shown in Figure 35. 



98 



