in about twenty feet (6.1m) of water. The second transect extended 

 along the 250 foot (76.2 meter) sea wall where the new City Electric 

 plant is being constructed. These two areas correspond closely to 

 transect locations for the earlier 1968-69 study (Clarke et al 1970). 

 Distributions of black tunicates {Asoidia nigra), stone crabs 

 (Menippe mevcenarid) , lobsters (Panulirus argus) , algae, bryozoans, 

 serpulids, sabellids, and barnacles were plotted underwater on 

 plastic sheets imprinted with scale drawings of the transect areas. 



Figure 34 shows the monthly abundance (in numbers of individuals 



per 100 linear feet of sea wall) of A. nigra, M. meroenaria, and 



P. argus along the two transects. The abundance indices in Table 



VII, show that the numbers of all three organisms declined in both 



areas through June, 1971. In September, 1971, A. nigra achieved population 



levels comparable to those obtained for the 1968 study and the numbers 



of P. argus increased to 1970 levels along the City Electric plant 



sea wall. Numbers of M. meraenaria decreased well below 1968 and 



1970 levels. 



Comparisons between the two transect areas in Figure 34 show A. 

 nigra was in lower numbers near the desalination plant (until August, 

 1971); M. mercenaria had similar numbers of individuals in both areas 

 and P. argus tended to congregate in the desalination plant area during 

 cooler months. Fluctuations in the numbers of P. argus were probably 

 due to seasonal migrations in and out of shallow water areas. 



The most notable changes during the monthly transects were a mass 

 mortality of Branahiomma nigromaculata from October to November, 1970, 

 and overall decline of algal turf and bryozoan colonies from October, 

 1970 to April, 1971, and the settlement and subsequent disappearance 

 of Ascidia nigra in July, 1970 and a successful resettlement of A. 

 nigra, algae, and bryozoans in August, 1971. 



Observations were made of the fish populations inhabiting the transect 

 and control areas. Since fish moved freely in and out of the Safe 

 Harbor area and water visibility often limited observations under 

 water, there was no satisfactory way of quantitatively assessing 

 changes in the total fish population. Observations of fish occur- 

 rences made during the preliminary survey (Clarke et al 19 70) remained 

 essentially unchanged for the study period from 1970 to 1971, and few 

 additions were made to the species list presented in the earlier study. 



Observations during the past year confirmed the earlier observations 

 that fish were attracted to the vicinity of the effluent and, in fact, 

 numerous species were observed repeatedly swimming into the core of 

 the effluent discharge. The tarpon (Megalops atlantiaa) , mahogany 

 snapper (Lutjanus mdhogoni) , grey snapper (Lutjanus griseus) , and 

 others were consistantly seen in the hottest portion of the effluent. 

 Indeed, the desalination plant sea wall had the largest number of fish 

 and the greatest number of species seen anywhere in the harbor, turn- 

 ing basin, or control stations. Fish counts were occasionally made 

 when water clarity permitted but these were of questionable accuracy 



95 



