GILMARTIN and REVELANTE. CONCENTRATION OF METALS IN TWO ADRIATIC FISH 



Table 10. — Mean elemental concentrations in Engraulis 

 mordax collected from Monterey Bay, Calif. (Pacific) from 

 Knauer (1972) and in E. encrasicholus from Rovinj, Yugoslavia 

 (Adriatic) (mercury: ng g-i wet weight: other elements: /ig g~i 

 wet weight). 



The calculated concentrations of mercury in 

 the whole sardine range from 100 to 645 ng g^ 

 dry weight, with a seasonal mean of 320. These 

 values compare favorably with the 580 ng g^^dry 

 weight reported by Ui (1971) for sardine collected 

 in coastal waters 2 to 3 km north of Porto 

 Corsini, on the Italian side of the northern 

 Adriatic. Levels of mercury found in the northern 

 Adriatic anchovy were relatively high when com- 

 pared with levels in the same or similar species 

 in other parts of the world. Mean concentrations 

 of 140 ng g'^wet weight were found in muscle 

 tissue, and values in excess of 200 ng g^ were 

 observed (Table 4). The same species from the 

 Gulf of Cadiz and off northwestern Africa con- 

 tained 60 and 50 ng g"^ wet weight respectively 

 (Establier 1972); and the northern anchovy, En- 

 graulis mordax, occupying the same ecological 

 niche (see Baxter 1967), contained concentra- 

 tions in muscle tissue averaging 40 ng g'^ wet 

 weight (Knauer and Martin 1972). These last data 

 are directly comparable, since the analyses were 

 conducted in the same laboratory using the same 

 techniques and equipment. 



Short-lived, low trophic level fish such as the 

 anchovy have a tendency to concentrate low 

 levels of mercury relative to longer-lived higher 

 order carnivores, e.g. tunas and billfishes (Rivers 

 et al. 1972), yet the higher concentrations of 

 mercury in internal tissues indicate an accumu- 

 lation in the Adriatic anchovy as well. However, 

 it should be noted that the source of such mercury 

 is not necessarily lower trophic level organisms. 

 On entering the sea, mercury is immediately 

 bound to proteinaceous materials, and if not 

 adsorbed or absorbed by organisms, is often 

 present in detritus/matrixlike suspended matter 



(see Keckes and Miettinen 1972, for review). 

 Since massive amounts of suspended matter are 

 found in feeding areas, filter feeders cannot 

 avoid ingesting it (Leong and O'Connell 1969). 



While mercury input to the sea results from a 

 combination of natural processes, such as wea- 

 thering and atmospheric fallout, and from various 

 anthropogenic processes, a number of recent 

 studies have focused on the pollution resulting 

 from increasing urbanization and industrializa- 

 tion along the northern Adriatic coast, in partic- 

 ular within the Po River watershed (Stirn 

 1965, 1970; Majori, Morelli, Diana, and Rausa 

 1967; Majori, Rausa, Morelli, and Diana 1967; 

 Majori et al. 1968; Majori 1968; Panella 

 1968a, b, 1970; Cescon and Grancini 1971; 

 General Fisheries Council for the Mediterranean 

 1972). Three factories in northern Italy use the 

 same acetaldehyde process as the Japanese 

 Minimata plant (Ui and Kitamura 1971), and two 

 of these are located on the coast at Ravenna 

 and Venice, offshore of which are the spring 

 spawning grounds of the anchovy (Stirn 1969). 

 In addition, the wintering grounds of the anchovy 

 lie to the south, in an area influenced by the 

 Po River (Stirn 1969; Piccinetti 1970). 



The rate of mercury elimination by fish is slow, 

 e.g. 267-700 days (Keckes and Miettinen 1972). 

 This time scale easily spans annual migrations 

 encompassing the northern Adriatic and empha- 

 sizes the necessity for international considera- 

 tion of the potential pollution of the region. 

 Although the levels of mercury observed in this 

 study are well within the tolerances established 

 by most countries (e.g. 200 ng g"^ muscle wet 

 weight in Switzerland, 500 ng g * in the United 

 States, and 1,000 ng g ^ in Italy and Japan), 

 it is likely that with increasing anthropogenic 

 input to the northern Adriatic, concentrations 

 will increase, perhaps to prohibitory levels. Thus 

 it is essential that monitoring continue, espe- 

 cially of the clupeid Engraulis encrasicholus, 

 which not only concentrates mercury to a greater 

 degree than the sardine, but which may repre- 

 sent one of the few significantly underutilized 

 fish resources of the northern Adriatic Sea. 



ACKNOWLEDGMENTS 



Support for this study was provided through 

 U.S. National Science Foundation grants GF 

 31947X and GA 3 127 IX. The authors gratefully 



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