pounds of meats (Hutchison see footnote 1), how- 

 ever, represents a small fraction of an estimated 

 sustained yield of 86 million pounds of meats an- 

 nually (Rinaldo-^). 



Since surf clams and ocean quahogs have re- 

 placed many traditional species, studies are 

 needed that reflect their economic importance. It 

 is well documented that many molluscs, including 

 surf clams and ocean quahogs, concentrate heavy 

 metals (Brooks and Rumsby 1965; Pringle et al. 

 1968; Waldichuk 1974). Boyden ( 1973) stated that 

 one of the nutritious qualities of shellfish may be 

 their high metal content. However, heavy metals 

 exhibit toxic effects that affect all life stages of 

 shellfish, especially development stages (Cala- 

 brese et al. 1973; Calabrese and Nelson 1974; 

 Thurberg et al. 1975). Considerable research has 

 been done on effects of heavy metals on more popu- 

 lar species of bivalve molluscs, especially the 

 American oyster, Crassostrea virginica, hard 

 clams, and soft-shell clams (Calabrese et al. 1973; 

 Calabrese and Nelson 1974; Thurberg etal. 1974). 

 However, until recently, there has been little in- 

 terest in surf clams or ocean quahogs. Concentra- 

 tions and concentration factors for a number of 

 metals, including cadmium, chromium, copper, 

 lead, nickel, and zinc, have been given by Pringle 

 et al. (1968) and Pringle and Shuster^ for surf 

 clams taken from Atlantic coast waters (Maine 

 through North Carolina). Thurberg et al. (1975) 

 exposed larval, juvenile, and adult surf clams to 

 sublethal doses of silver and measured both 

 physiological responses and bioaccumulation. Re- 

 searchers at the U.S. Environmental Protection 

 Agency (EPA), Narragansett, R.I., have exposed 

 ocean quahogs to low concentrations of cadmium 

 and monitored toxicological, biological, and his- 

 topathological effects, as well as bioaccumulation 

 (Zaroogian''). Bioaccumulation distribution pat- 

 terns associated with industrial and sewage 

 sludge dumpsites southeast of Delaware Bay have 

 been monitored in ocean quahogs by scientists at 

 the EPA, Annapolis, Md. (Lear and Pesch 1975). 

 Awareness, then, of the importance of these 



^Rinaldo. R. G. 1977. Atlantic clam fishery management 

 plan. Environmental impact statement: Mid-Atlantic and New 

 England Regional Fisheries Management Councils. Available 

 Fisheries Management Division, National Marine Fisheries 

 Service, NOAA, State Fisheries Pier, Gloucester. MA 019:30. 



■'Pringle, B. H.. and C. N, .Shuster, Jr. 1967. A guide to 

 trace metal levels in shellfish. USDHEW, Public Health Serv.. 

 Shellfish Sanit. Tech. Rep., 18 p. 



■* Gerald E. Zaroogian. U.S. Environmental Protection Agency. 

 Environmental Research Laboratoi-y. Narragansett, RI 02882, 

 pers. commun. February 1976. 



species is developing, but clearly more research is 

 needed for such an important commercial 

 shellfishery. 



Nine metals were chosen for analysis: arsenic, 

 cadmium, chromium, copper, lead, mercury, nick- 

 el, silver, and zinc. Based upon estimates of global 

 metal production and oceanic sedimentation 

 rates, Bowen (1966) divided 38 metals into their 

 pollution potentials. He categorized cadmium, 

 chromium, copper, lead, mercury, silver, and zinc 

 as very high potential pollutants and arsenic and 

 nickel as moderate. Goldberg (1972) emphasized 

 the need for measurement in benthic organisms of 

 the most potentially hazardous trace metals. 



MatcriaU and Methods 



Sampling 



The area of this survey extended from approxi- 

 mately Montauk Point, N.Y., to Cape Hatteras, 

 N.C., and seaward to approximately the 20- 

 fathom contour. The survey encompassed the 

 southern distribution of both surf clams and ocean 

 quahogs in the United States. Samples were col- 

 lected at 151 stations for chemical analysis (Fig- 

 ure Din June and August 1974, aboard the NOAA 

 ship Delaware II (MARMAP'^). A small hydraulic 

 surf clam dredge, modeled closely after larger 

 commercial dredges, was used throughout the 

 survey. At each station 4-6 clams of marketable 

 size were dissected, using stainless steel equip- 

 ment. The foot was removed from each animal, 

 drained, then combined and frozen in plastic bags. 

 At the laboratory the tissues were homogenized in 

 an electric blender equipped with a glass jar and 

 stainless steel blades then stored for analysis in 

 plastic ointment jars. All containers and equip- 

 ment were acid-washed prior to use. 



Analysis 



Mercury analysis was performed on a Perkin- 

 Elmer Model 305" atomic absorption spectropho- 

 tometer fitted with a 25 X 150 mm absorption cell 

 with silica end windows, using the flameless 

 method of Greig et al. (1975). 



Arsenic analysis, performed on a Perkin-Elmer 

 Model 403 atomic absorption spectrophotometer. 



=MARMAP 1974. Surf clam survey, cruise report, NOAA 

 ship Delaware II. 1.3-28 June 1974 and "5-10 August 1974, 9 p. 



•^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



281 



