VALENTINE and SOULE: EFFECT OF p.p'-DDT ON GRUNION 



DDT and Asymmetry 



In our earlier report we showed that adult 

 grunion from Belmont Shore were 4.08 times as 

 asymmetrical as San Quintin fish. In the present 

 study, the ratio of asymmetry variances in un- 

 treated fry is almost the same, 4.46. This consis- 

 tency may be more than coincidence. This result 

 and our experimental data support our hypo- 

 thesis based on data from wild-caught fish that 

 environmental stress may produce statistically 

 detectable changes in asymmetry (Valentine, 

 Sou-le, and Samollow, 1973). Perhaps the most 

 important result is that extremely low concen- 

 trations of DDT (< 1 ppb) cause a very sig- 

 nificant deterioration in the symmetry of fin 

 rays. When it is noted that in all probability the 

 control fry from Belmont Shore were already 

 carrying a stressful load of DDT, the signifi- 

 cance of the results is enhanced. 



Our rationale for utilizing p.p'-DDT as a 

 stressant was that it (and its metabolic prod- 

 ucts) are known to occur in high concentra- 

 tions in southern California marine organisms 

 (Burnett, 1971; Castle and Woods, 1972; Duke 

 and Wilson, 1971; Munson, 1972; Risebrough 

 et al., 1967). The White's Point outfall, situated 

 about a mile north of Point Fermin, was shown 

 to be releasing effluent containing DDT 

 approaching 100 ppb in late 1970, and also simi- 

 lar quantities of polychlorinated biphenyls 

 (Schmidt, Risebrough, and Gress, 1971). These 

 polychlorinated biphenyls may themselves pro- 

 duce increases in asymmetry since they have 

 properties similar to DDT (Risebrough, Reiche, 

 Peakall, Herman, and Kirven, 1968; Gustafson, 

 1970; Peakall and Lincer, 1970). We would, in 

 any case, expect to find a diversity of agents in 

 southern California's marine waters capable of 

 producing increases in asymmetry, among them 

 DDT. 



Grunion fry exposed to increasing levels of 

 p,p'-DDT in water yielded results in accord 

 with our environmental stress hypothesis (Val- 

 entine, Soule, and Samollow. 1973). At 

 p,p'-DDT levels greater than 0.01 ppb, asym- 

 metry values increased. Increases in the asym- 

 metry of bilateral structures are easily quanti- 

 fied and monitored. We hope other workers will 

 test this system with other pollutants that may 



affect calcium metabolism. The funding situa- 

 tion precludes our doing so. 



ACKNOWLEDGMENTS 



We dedicate this paper to our colleague, E. W. 

 Fager, a constructive and creative critic and a 

 good friend. This research was supi)orted by a 

 contract from the Southern California Coastal 

 Water Research Project (NO. 02304). The 

 second author, Michael Soule, was supported 

 by National Science Foundation Grants 

 GB-27358 and GB-8525. 



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