settled at deep stations than shallow stations except for Station 3C. 

 Figure 26 shows that the amount of effluent reaches a peak at Station 

 3C, averaging about three percent by volume throughout the year. 

 Figures 42 and 43 show the number of serpulid worms settling per 

 thirty day period compared vjith exposure to effluent. Since the 

 seasonal availability of larvae, water currents, and larval behavior 

 all interacted with water quality to determine numbers of individuals 

 settling at any particular station, a 'serpulid index' was derived 

 by comparing settlement at the "B" stations with the "A" stations directly 

 above them. At any given time, both the "A" station and "B" station, 

 separated by about 16 feet (4.8 meters), should have had similar 

 exposure to larvae. By comparing the two stations for each month, 

 differences due to availability of larvae were eliminated and the 

 resulting differences in the abundance of larvae at the two stations 

 reflected the influence of the effluent at the deeper station. 



A-B 

 Use of the formula J = -r—r (where I is the serpulid index, A the 



A-rD 



number of serpulid worms settling during a thirty day period on 50cm^ 

 at the "A" station, and "B" the number of serpulid worms settling in the 

 same time period on 50cm^ at the "B" station) permitted direct compari- 

 son of the relative effect of the effluent throughout the year. If 

 all of the serpulids settled at the deeper stations, the index would 

 be -1 and if they all settled at the shallow station the index would 

 be +1. 



For the first six months of observation more serpulid worms settled 

 on the shallower panels as the amount of exposure to effluent increased 

 at the deeper panels (Fig. 42). In May, exposure to effluent was rela- 

 tively constant throughout the harbor and the relative amount of settle- 

 ment was also constant (Fig. 43). July and August were notable excep- 

 tions to the pattern shown in previous months. Relative numbers of 

 serpulid worms settling in the different stations varied greatly, but 

 were not related to the amount of effluent present (Fig. 43). During 

 these two months the amount of copper discharged by the desalination 

 plant was at a minimum (see section on copper and nickel above). 



Settlement of the barnacle (Balanus amphitrite niveus) was seasonal 

 with almost no settlement during the colder months of December through 

 March. The adult barnacles on boats entering and mooring in the harbor 

 contributed numerically to the local stock of adults in the inner har- 

 bor and so, the inner harbor was probably the major source of barnacle 

 larvae. Tide and wind currents dispersed the larvae seaward, past the 

 desalination plant. Most larval settlement was at shallow stations 

 with Stations 2A and 3A receiving the highest number (Fig. 44). Few 

 barnacles were able to settle on the seaward side of the effluent 

 with the notable exception of Station 5B. At Stations 7A and 7B in 

 the turning basin, only six specimens settled on the test panels from 

 November, 1970 until July, 1971. This indicated that the desalination 

 plant discharge formed a barrier to the movement of barnacle larvae 

 out of the harbor. 



108 



