WATSON and DAVIS: LARVAL FISH DIETS IN SHALLOW COASTAL WATERS 



DISTANCE FROM SHORE (KM) 

 5 4 3 2 



100 



DISTANCE FROM SHORE (KM) 

 5 4 2 1 



J i_ 



Gastropod Veliger Larvae 



Figure 1.— Zones of significantly higher concentration of four zooplankton taxa near SONGS. Shaded areas represent higher 

 concentration as determined by nonparametric one-way ANOVA (P < 0.05) on number per m'* data. RedrawTi from Marine 

 Review Committee Document 78-01, Annual report to the California Coastal Commission, September 1977-August 1978: 

 Updated estimated effects of SONGS Unit 1 on marine organisms. August 1978. 



highest abundance in the neuston shoreward of 

 the 9 m isobath. 



Thus the distributions of the fish larvae and 

 their prey are broadly similar. However, the 

 sharp vertical gi'adients in abundance patterns 

 for the atherinids and the older sciaenid larvae 

 apparently do not closely match the vertical pat- 

 terns of their prey. In discussing the results of 

 their respective larval fish feeding studies, both 

 of which utilized concurrent larval fish and zoo- 

 plankton sampling during the day and night, 

 Brewer and Kleppel (1986) and Jahn et al. (1988) 

 remarked on this lack of a close match between 

 the vertical distributions of fish larvae and their 

 prey in the shallow nearshore zone. They sug- 

 gested that factors other than, or in addition to, 

 feeding must be important in determining larval 

 distributions in the nearshore zone. Avoidance of 

 dispersal seaward, away from the shallow 

 coastal zone, is likely to be one of the most im- 



portant factors (e.g.. Brewer and Kleppel 1986). 

 Nearshore currents off southern California are 

 mainly parallel to shore, tend to reverse at 

 roughly tidal frequency, and have only a weak 

 cross-shelf component (e.g., Winant and Bratko- 

 vich 1981; Jackson 1986). A comparison of the 

 variances of the longshore and cross-shelf cur- 

 rent speeds off San Onofre (the variance of the 

 current speed is a good measure of the energy of 

 the coastal current) indicates that the variance of 

 the longshore current (102 cm"/s") is about four 

 times that of the cross-shelf current (25 cm^/s^) 

 (Elwany et al. in press). This stronger longshore 

 cuiTent has a net southerly motion, while the 

 weak cross-shelf current has a net shoreward 

 motion (Marine Review Committee 1977'^). Thus 



"Marine Review Committee. 1977. Annual report to the 

 California Coastal Commission, August 1976 — August 1977. 

 summary of the estimated effects on marine Life of Unit 1, 



589 



