RICE ET AL.: EFFECTS OF COPPER ON NORTHERN ANCHOVY 



of previous studies examining the sensitivity to 

 copper of marine fishes' early life history stages 

 (Engleet al. 1976; Blaxter 1977; Rice and Harrison 

 1978). In contrast, studies examining the copper 

 sensitivity of various life stages of freshwater 

 fishes revealed that the larval stages are the most 

 sensitive to copper ( Hazel and Meith 1970; McKim 

 and Benoit 1971; Gardner and LaRoche 1973; Be- 

 noit 1975; McKim et al. 1978; 0'Rear>M. This dif- 

 ference in comparative sensitivity between em- 

 bryos and larvae of freshwater and marine fishes 

 suggests that caution should be exercised in apply- 

 ing the extensive results of toxicity tests on fresh- 

 water fishes to marine fishes. 



The adult northern anchovy and Pacific herring 

 are similar in form and in behavior, but their re- 

 productive strategies are quite different. The 

 northern anchovy spawns pelagic eggs into 

 offshore waters; the 1.0 x 0.5 mm diameter egg is 

 covered by an elliptical, transparent chorion. 

 Northern anchovy eggs hatch in about 48 h at 17° 

 or 18° C into fragile, unpigmented larvae, 2.5-3.0 

 mm long (Ahlstrom 1956). The Pacific herring 

 spawns demersal, adhesive eggs on shallow inter- 

 tidal substrates; the 1.3-1.6 mm diameter egg is 

 covered by a thick, three-layered, chorion (Blaxter 

 and Holliday 1963). Herring eggs hatch in 7-9 d at 

 14° C into pigmented larvae 5.0-6.0 mm long ( Al- 

 derdice and Velsen 1971). Comparisons of the sen- 

 sitivities of the early life stages of these two fish 

 may prove useful for predicting the impact of cop- 

 per on broad groups of fishes. For comparisons 

 between the copper sensitivity of northern an- 

 chovy and Pacific herring embryos and larvae, the 

 data on herring sensitivity are taken from our 

 earlier study (Rice and Harrison 1978). 



It might be expected that the fragile northern 

 anchovy embryo would be more sensitive to copper 

 than the larger, tougher Pacific herring embryo; in 

 fact, however, the opposite appears to be the case. 

 The ILC50 for northern anchovy embryos was ap- 

 proximately six times higher than that for Pacific 

 herring embryos. The results of Engel and Sunda 

 (1979) showed a similar pattern; relatively tough 

 benthic spawned eggs of the silverside, Menidia 

 menidia, were found to be more sensitive to copper 

 than the more fragile pelagic eggs of the spot. 



The differences in sensitivity seen in the two 

 embryos may be the result of differences in the 

 chorionic structure and the developmental period 

 during copper exposure. The chorion of Atlantic 

 herring, C. h. harengus (Rosenthal and Sperling 

 1974), and another demersal adhesive egg, the 

 Baltic garpike, Belone belone (Dethlefsen et al. 

 1975), have been shown to concentrate cadmium. 

 The chorion of the Pacific herring may be the site 

 of mechanisms to accumulate metals, mechanisms 

 that may be reduced or lacking in the northern 

 anchovy. Changes in sensitivity during develop- 

 ment were seen in both the northern anchovy and 

 Pacific herring embryos. The high percentage of 

 northern anchovy mortalities during epiboly indi- 

 cates that this period of development might be 

 more sensitive to copper than the later devel- 

 opmental periods. Increased copper sensitivity 

 during this period also was found for winter floun- 

 der, Pseudopleuronectes americanus, (Cardin^^). 

 The sensitive period for the Pacific herring embryo 

 appeared to be about 96 h after fertilization, well 

 beyond epiboly. 



Differences in sensitivity were also seen be- 

 tween the two larvae. The fragile northern an- 

 chovy larvae were about three times more sensi- 

 tive to copper than the Pacific herring larvae. 



Both northern anchovy and Pacific herring lar- 

 vae displayed spasms before death at the higher 

 copper concentrations to which they were exposed. 

 Such spasms during copper poisoning have been 

 suggested to be similar to those seen in Wilson's 

 Disease (Baker 1969). 



ACKNOWLEDGMENTS 



The authors thank Revelle Davis, John Dawson, 

 and Rose Carrillo for their assistance in the collec- 

 tion, handling, and observation of the test or- 

 ganisms. 



This work was supported by the U.S. Nuclear 

 Regulatory Commission under a Memorandum of 

 Understanding with the U.S. Department of 

 Energy. 



LITERATURE CITED 



Ahlstrom, E. H. 



1943. Appendix. In Studies on the Pacific pilchard or sar- 

 dine {Sardinops caerulea). 4. — bifluence of temperature 



"O'Rear, C. W, Jr. 1972. The toxicity of zinc and copper to 

 striped bass eggs and fry with methods for providing confidence 

 limits. Southeast. Assoc. Game Fish Comm., 26th Annu. Conf , 

 p. 484. 



i^Cardin, J. 1976. In Annual Report, January-December 

 1976. U.S. Environ. Prot. Agency, Environ. Res. Lab., Narragan- 

 sett, R.I., 42 p. 



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