242 EISLER 



This paper considers recent material on mercury effects in saline 

 waters and recommends useful criteria and promising research 

 approaches for incorporating mercury contamination standards that 

 will protect marine products of commerce, their food organisms, and 

 their predators, including man. 



HISTORICAL REVIEW 

 Laboratory Studies 



Comparative Toxicity, Survival, and Biotic and Abiotic Modifiers 



In general, salts of mercury and its organic compounds have been 

 shown in short-term bioassays to be more toxic to marine organisms 

 than are salts of other heavy metals. To oyster embryos, for example, 

 mercury salts were more toxic than were Ag, Cu, Zn, Ni, Pb, Cd, As, 

 Cr"^*", Mn, or Al (Calabrese et al., 1973); to clam embryos, mercury 

 was the most toxic metal tested, followed by Ag, Zn, Ni, and Pb, in 

 that order (Calabrese and Nelson, 1974). Toxicity bioassays of 168 hr 

 duration with salts of Hg, Cd, Cr"^^, Ni, and Zn on adults of 

 representative marine fishes, crustaceans, bivalve and gastropod 

 molluscs, annelids, and echinoderms confirmed that mercury was 

 consistently the most toxic metal in this series (Eisler and Hennekey, 

 1977). Similar results are reported for marine algae (Berland et al., 

 1976); marine fungi (Schneider, 1972); sea urchin eggs (Kobayashi, 

 1971); larvae of marine molluscs and crustaceans (Connor, 1972); 

 some species of marine polychaete worms (Reish et al., 1976); 

 freshwater annelids, insects, and gastropods (Rehwoldt et al., 1972); 

 crustaceans (Cabejszek and Stasiak, 1960); and fish (Weir and Hine, 

 1970). 



Acute toxicity values of mercury compounds for various marine 

 species are summarized in Table 1. These values are similar to those 

 reported for freshwater groups (McKim, 1977). Differences in species 

 resistance to mercury compounds (Hendrick and Everett, 1965; 

 Schweiger, 1957; Wisely and Blick, 1967) may account for some of 

 the variability in test results shown in Table 1, but many additional 

 factors are known to affect or modify the survival time of 

 mercury -stressed marine biota, sometimes by one order of magnitude 

 or more. Abiotic modifiers include the chemical form of mercury 

 administered (Boetius, 1960; Boney, 1971; Boney and Corner, 1959; 

 Boney, Corner, and Sparrow, 1959; Corner and Sparrow, 1957; Ellis, 

 1947; Fang, 1973; MacLeod and Pessali, 1973; Middaugh and Rose, 

 1974); cations other than mercury present in the medium (Barnes 



