FISHERY BULLETIN: VOL. 76, NO. 2 



Benoit 1975). Contrary to these findings, we found 

 that embryos of the Pacific herring appear to be 

 the stage that is more sensitive to copper. It should 

 be noted that the fishes examined in previous 

 studies spawn in fresh or brackish waters and 

 cannot be considered true marine species as is the 

 herring. 



Another interesting feature of the toxic re- 

 sponse of the herring embryos and larvae was that 

 the behavior prior to death was similar to that of 

 adult fish exposed to copper. Jerky, uncoordinated, 

 and spontaneous movements were noted by Baker 

 (19691 in the winter founder, Pseudopleuronectes 

 americanus, acutely exposed to 3,200 and 1,000 

 juig/1 copper. Bluegill, Lepom/s macrochirus, 

 chronically exposed to 162 /u,g/l copper showed 

 periodic involuntary spasms several weeks prior 

 to death (Benoit 1975). The spasmodic contrac- 

 tions and quiverings noted in herring embryos and 

 larvae prior to death might be of a similar nature. 

 Baker noted that these symptoms are similar to 

 those of Wilson's disease which also manifests 

 spasmodic muscle contractions and quiverings in 

 mammals. Wilson's disease is the result of an in- 

 born error of metabolism that results in an excess 

 of unbound copper in the blood stream (Adelstein 

 and Vallee 1962). Goldfish, Carassius auratus, 

 subjected to doses of 1,000 /xg/1 copper exhibit se- 

 vere neurotoxic symptoms and accumulate copper 

 in nervous tissues at levels similar to those seen in 

 Wilson's disease (Vogel 1959). 



Some of the toxic effects observed in herring 

 embryos and larvae were similar to those reported 

 for other heavy metals. Striped bass, Morone 

 saxatilis, embryos exposed to copper or zinc 

 (O'Rear 1972) and Baltic needlefish, Belone bel- 

 one, exposed to cadmium (Dethlefsen et al. 1975) 

 developed opaque discoloration of the chorion dur- 

 ing exposure. In the present study, the chorion of 

 the herring embryos became increasingly opaque 

 as exposure to copper continued. Wedemyer (1968) 

 found that in coho salmon, Oncorhynchus kisutch, 

 70% of the total zinc-65 uptake during exposure 

 was firmly bound to the chorion, 26% was bound in 

 the perivitelline space, and only 2% reached the 

 yolk and 1% reached the embryo. Wedemyer 

 (1968) also demonstrated that copper is bound by 

 the salmon embryo's chorion. The opaque discol- 

 oration noted in herring embryos with continued 

 exposure to copper may well be a reaction result- 

 ing from copper uptake by the chorion. 



The observation of a reaction period during 

 bioassays with herring embryos has been noted 



previously. A reaction period for herring embryos 

 continuously exposed to cadmium (Rosenthal and 

 Sperling 1974) and high temperatures and 

 salinities (Alderdice and Velsen 1971) occurred at 

 about the time of the onset of heart beat. The 

 sensitivity of this developmental period in the 

 herring was further borne out by our findings in 

 which 36-h pulses of 100 /xg/1 copper during the 

 reaction period caused higher mortalities than 

 36-h pulses during later developmental periods. 



Pacific herring embryos may be vulnerable to 

 toxic effects from effluents now being discharged 

 into coastal environments. A survey of 108 muni- 

 cipal waste effluents on the Atlantic coast showed 

 that 50% of the waste effluents contained >100 

 H.gl\ copper; some discharges were as high as 5,900 

 /Ltg/1 copper (Mytelka et al. 1973). A survey of six 

 municipal waste discharges along the southern 

 California coast revealed concentrations ranging 

 from 74 to 13,900 ^xgl\ copper with an average 

 annual mass emission rate of 532 t of copper dur- 

 ing 1971-74 (Mitchell and McDermott 1975). 

 While the amount of copper discharged in the ionic 

 form was not reported, the potential for environ- 

 mental exposure levels approaching the incipient 

 LC50 of 33 /x.g/1 copper found for herring embryos in 

 the present study should be considered in estab- 

 lishing water pollution control standards. 



Frequently authors conducting bioassays using 

 copper or other heavy metals have not examined 

 the chemical state of the metal in their bioassay 

 system. Such characterizations are important 

 since different chemical forms of metals may have 

 different toxic effects (Lee 1973). The method out- 

 lined in this work for examining the particulate 

 bound fraction, the ionic fraction, and the com- 

 plexed fraction of metals in seawater provides a 

 means of examining the important chemical forms 

 of copper in aquatic bioassay systems. With the 

 use of appropriate isotopes this method could eas- 

 ily be applied to other metals. In the case of the 

 system used to expose Pacific herring embryos and 

 larvae it appears that the ionic form of copper 

 predominated. In freshwater the ionic form of cop- 

 per seems to be the most toxic (Pagenkopf et al. 

 1974). This is probably also the case for Pacific 

 herring embryos and larvae exposed to copper in 

 seawater. 



ACKNOWLEDGMENTS 



We express our appreciation to Richard E. Tul- 

 lis, California State University, Hayward, for re- 



354 



