ORGANIC AND TRACE METAL LEVELS IN 



OCEAN QUAHOG, ARCTICA ISLANDICA LINNE, 



FROM THE NORTHWESTERN ATLANTIC 



Frank W. Steimle, 1 Paul D. Boehm, 2 Vincent S. Zdanowicz, 1 

 and Ralph A. Bruno 1 



ABSTRACT 



Chemical contamination of biological resources is an important problem for resource managers. This study 

 reports on body burden levels of several contaminants of concern: polychlorinated biphenyls (PCB), poly- 

 nuclear aromatic hydrocarbons (PAH) of both petroleum and combustion sources, total petroleum hydrocar- 

 bons, and seven trace metals (Ag, Cd, Cr, Cu, Ni, Pb, and Zn) in a resource species, the ocean quahog, 

 collected between Virginia and Nova Scotia. Organic and trace metal contaminants were detected, at low 

 levels, in all samples examined, with highest levels being generally found in samples from the inner New 

 York Bight and Rhode Island Sound. The highest PCB and PAH values were 27 and 55 ppb, respectively; 

 Ag, Cd, and Cr values were generally <5 ^g/g dry weight; Cu, Ni, and Pb generally <15 ^g/g dry weight 

 with a few exceptions; and Zn ranged from 50 to 153 uglg dry weight. 



The ocean quahog, Arctica islandica Linne, is a 

 large, bivalve mollusc found on both sides of the 

 North Atlantic In the northwestern Atlantic, it oc- 

 curs from just north of Cape Hatteras, NC, to New- 

 foundland, Nova Scotia, being most abundant on the 

 middle to outer continental shelf at depths between 

 about 30 and 150 m (Merrill et al. 1969). The species 

 is edible and some commercial harvesting has oc- 

 curred since 1943 in the Rhode Island area; however, 

 intensive fishing for this species did not begin until 

 the 1970s when surf clam, Spisula solidissima (Dill- 

 wyn), stocks, an inshore species, were drastically 

 reduced by overfishing (Ropes 1979). 



Arctica islandica generally inhabit silty sand sedi- 

 ments of the middle to outer continental shelf that 

 are less influenced by waves and strong currents 

 than shallower areas. Areas of silty sand are thought 

 to be at least partially depositional in nature, i.e, fine 

 organic-rich particles tend to accumulata It is gen- 

 erally agreed that many chemical pollutants, intro- 

 duced to the marine environment via impacted estu- 

 aries and coastal areas, ocean dumping, and atmo- 

 spheric sources, often are bound to and associated 

 with fine organic and inorganic particle aggregates, 

 both in the water column and at the sediment sur- 

 face These aggregates ultimately can accumulate 

 in these natural depositional areas as the results of 

 some recent studies show that contaminants ap- 



'Northeast Fisheries Center Sandy Hook Laboratory, National 

 Marine Fisheries Service, NOAA, Highlands, NJ 07732. 



2 Battelle, New England Marine Research Laboratory, 397 Wash- 

 ington Street, Duxbury, MA 02332. 



parently are accumulating in silty areas relatively 

 remote from most possible sources, eg., organic con- 

 taminants found south of Cape Cod, MA, in the mid- 

 dle to outer continental shelf (Boehm 1983a). Some 

 authors have also reported a trend of increasing sedi- 

 ment trace metal levels with depth on the Middle 

 Atlantic shelf (Harris et al. 1977), but the specific 

 sources of these contaminants are still unknown. 



Because A. islandica is a common, sedentary, long- 

 lived (Thompson et al. 1980) inhabitant of these sil- 

 ty sands that frequently contain higher levels of con- 

 taminants than coarser sands, the species may be 

 particularly susceptible to contamination. Wenzloff 

 et al. (1979) reported "greater average concentration 

 of silver, arsenic, cadmium, copper, and zinc 

 ... in ocean quahogs than in surf clams" for the Mid- 

 dle Atlantic Surf clams are generally found in 

 shallower, medium sand areas. Thus, A. islandica 

 may be a good offshore "indicator" species to moni- 

 tor for trends in marine chemical pollution. Although 

 some studies on contaminant body burdens of A. 

 islandica have been reported (ERCO 1978 3 ; Sick 

 1978, 1981; Wenzloff et al. 1979; Reynolds 1979; 

 Payne et al. 1982), these studies have been limited 

 generally to a particular restricted area, have not 

 examined both types of contaminants or only a few 

 components of each contaminant class, or have ex- 

 amined only certain tissues, not whole body levels. 



The present study provides body burden data over 



Manuscript accepted April 1985. 



FTSHF.RY RTTT.T.F.TTN- VDT, 84 NO 1 IftSfi 



3 ERCO (Energy Resources Company). 1978. New England 

 OCS Environmental Benchmark. Draft Final Rep., Vol. II, to U.S. 

 Dep. Inter., Bur. Land Manage, Miner. Manage Serv., 628 p. 



133 



