FEEDING HABITS OF BLACKSMITH, CHROMIS PUNCTIPINNIS, 

 ASSOCIATED WITH A THERMAL OUTFALL 



Pamela A. Morris 1 



ABSTRACT 



The availability and use of food by blacksmith, Chromispunctipinnis, were examined at a thermal outfall and 

 a control site in King Harbor, California. Stomach analysis showed that blacksmith from the outfall area con- 

 sumed a significantly greater amount of food, consist ing of larger prey items, than control fish. Movements of 

 water created by the outflow may provide dietary benefits by reducing zooplankton predator avoidance and 

 by entraining and entrapping organisms not normally planktonic. This dietary enrichment may result in 

 attraction of blacksmith to the King Harbor outfall. 



An increased demand for energy resulting in growth 

 of coastal power plant activity has created concern 

 for the effects of heated effluents upon the fish com- 

 munity (Miller 1977; Stephens 1978, 2 1980 3 ; 

 Stephens and Palmer 1979 4 ). Few studies have 

 examined the factors attracting fish to outfall areas. 

 White et al. (1977) found less diversity and lower 

 abundance of fish at an outfall station, while Kelso 

 (1976) and Minns et al. (1978) reported a clustering 

 offish in the vicinity of thermal outfalls. Underwater 

 observations suggest that fish are attracted to ther- 

 mal outfalls to feed. Kelso (1976) found that fish in 

 proximity to a thermal discharge exhibited a complex 

 swimming behavior that could represent feeding 

 activity. Moreover, this behavior continued when 

 unheated effluent was discharged. 



The blacksmith, Chromis punctipinnis (family 

 Pomacentridae), an abundant planktivorous tem- 

 perate reef inhabitant, has been regularly observed 

 feeding at the thermal outfall of a steam electrical 

 generating station in King Harbor, Redondo Beach, 

 Calif. Recent studies on the effects of thermal effluents 

 upon blacksmith have concentrated on behavioral 



'VANTUNA Research Group, Department of Biology, Occidental 

 College, Los Angeles, CA 90041. 



'Stephens, J. S., Jr. 1978. Effects of thermal effluent from 

 Southern California Edison's Redondo Beach steam generating 

 plant on the warm temperate fish fauna of King Harbor Marina. Fish 

 and laboratory study reports for Phase III. VANTUNA Research 

 Group, Department of Biology, Occidental College, Los Angeles, CA 

 90041. 



'Stephens, J. S., Jr. 1980. Effects of thermal effluent from 

 Southern California Edison's Redondo Beach steam generating 

 plant on the warm temperate fish fauna of King Harbor Marina. Fish 

 and laboratory study reports for 1977-1978. VANTUNA Research 

 Group, Department of Biology-, Occidental College, Los Angeles, CA 

 90041. 



4 Stephens, J. S., Jr., and J. B. Palmer. 1979. Can coastal power 

 stations be designed to offset impacts by habitat enrichment? Gen. 

 Tech. Rep. RM-65, p. 446-450. Paper presented at Mitigation 

 Symposium, U.S. Department of Agriculture, Fort Collins, Colo. 



responses to intermittent chlorination (Hose and 

 Stoffel 1980; Hose et al. in press). The objective of 

 this study was to examine the feeding habits of black- 

 smith and determine whether the discharge was 

 attracting them through dietary enrichment. 



MATERIALS AND METHODS 



This study was conducted at King Harbor, Redondo 

 Beach, Calif., at the southern end of Santa Monica 

 Bay, just north of the Palos Verdes Peninsula (Fig. 1, 

 lat. 33°51'N, long. 188°24'W) (Terry and Stephens 

 1976; Stephens and Zerba 1981). Situated just 

 offshore is the head of the Redondo Submarine 

 Canyon, a source of cold upwelling water for the har- 

 bor. In contrast, thermal effluent from Units 7 and 8 

 of Southern California Edison's Redondo Beach 

 steam electrical generating plant is discharged just 

 inside the harbor mouth. 



The thermal outfall study site consists of a vertical 

 conduit, 4 m in diameter, out of which the effluent is 

 pumped. The circular outlet is level with the sub- 

 strate at a depth of 7 m. Effluent is discharged at a 

 rate of 1.78 X 10 6 1/min during peak operation. 



A control site was chosen about 500 m from the dis- 

 charge. This area, referred to as the Point, is located 

 at the tip of the breakwater that partially encloses the 

 harbor. This site has been surveyed by Stephens and 

 Zerba (1981) who note that blacksmith are an abun- 

 dant resident species. 



A form of presence/absence monitoring was used as 

 an indicator offish abundance at the discharge. Mean 

 estimates (0-25, 26-50, 51-75, 76-100, or >100) were 

 made by two scuba divers swimming a circular tran- 

 sect around the discharge. The position of fish was 

 recorded: in the plume (the column of water directly 

 over the discharge), in the outer plume (the area of 



Manuscript accepted June 1983. 



FISHERY BULLETIN: VOL. 82. NO. 1. 1984. 



199 



