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 242. 

 Wallack. R a . AND K Selman 



1981. Cellular and dynamic aspects of oocyte growth in 

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Waltz. C W . W A Roumillat. and C A Wenner 



1982. Biology of the whitebone porgy. Calamus leucos- 

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Wenner, C A , W A Roumillat, and W Waltz 



1986. Contributions to the life history of black sea bass. 

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Mark R Collin.s 



C Wayne Waltz 



William A Roumillat 



Daryl L Stubbs 



South Carolina Wildlife am! Marine Resources Department 

 Marine Resources Research Institute 

 P.O. Box 125.59 

 Charleston, SC 29412 



AGE AND GROWTH, REPRODUCTIVE CYCLE, 



AND HISTOCHEMICAL TESTS EOR HEAVY 



METALS IN HARD CLAMS, MERCENARIA 



MERCEXARIA, FROM RARITAN BAY, 



1974-75. 



Raritan Bay has historically supported an abun- 

 dant hard clam, Mercenaria mercenaria L., re- 

 source. It was considered the most important com- 

 mercial species in the bay with an estimated total 

 value of 34 million dollars in 1963 (Jacobsen and 

 Gharrett 19671. Campbell (1967) reported a total 

 standing crop of 4.8 million bushels of clams for 

 the Bay for the same year (3.4 million bushels in 

 New York waters and 1.4 million bushels off New 

 Jersey). More recent estimates are unavailable. 

 Raritan Bay waters have historically received 

 various domestic and industrial wastes, some of 

 which have had adverse effects on its shellfish 

 resources and fisheries. Raritan Bay was closed to 

 harvesting of hard clams on 1 May 1961, after an 

 epidemic of human infectious hepatitis was 

 traced to the consumption of raw clams from the 

 bay (Campbell 1967). The closure remains in ef- 



fect to the present time. Zoellner (1977) reviewed 

 the nationwide water quality problems related to 

 shellfish and included Raritan Bay as one of the 

 case studies in the report. 



Bivalves accumulate various biological and 

 chemical contaminants by mechanisms related to 

 their filter-feeding habits and transport across 

 their mucous-covered, semipermeable soft body 

 tissues (Goldberg 1957; George 1982). The accu- 

 mulation of heavy metals, pesticides, polychlori- 

 nated biphenyls (PCB's), oil and dispersants, dis- 

 ease causing bacteria, viruses, fungi, parasites, 

 and toxic phytoplankton have serious public 

 health implications and may also adversely affect 

 bivalve resources. Zoellner (1977) has reviewed 

 natural and manmade conditions affecting 

 bivalve populations, including specific studies of 

 the effects of heavy metals, pesticides, and PCB's. 

 McCormick et al. (1984) reviewed physical and 

 sediment characteristics of Raritan Bay, studies 

 of benthic organisms, plankton, and fish, and im- 

 pact of pollution from sewage, organic chemicals, 

 and heavy metals. 



The present study was undertaken to assess 

 potential impacts of contaminants in Raritan Bay 

 on the spawning potential of hard clams. Monthly 

 samples were collected from three study areas 

 within the bay to obtain measurements of the 

 shells, soft body tissues for observations of gen- 

 eral condition, and gonadal tissues for observa- 

 tions of the reproductive cycle. Selected speci- 

 mens were chosen to determine age and growth, 

 and special tissue samples were collected for his- 

 tochemical tests of certain metals. Published hy- 

 drographic conditions and assessment of pollu- 

 tants in Raritan Bay are discussed in relation to 

 sample results. 



Methods 



Campbell (1967) described the distribution of 

 hard clams in Raritan Bay and, based on his find- 

 ings, sites were chosen for repeated collections. 

 The sites were Ward Point, New Dorp Beach, and 

 Horseshoe Cove (Fig. 1). Each was sampled at 

 about monthly intervals beginning on 21 f^ebru- 

 ary 1974 and ending on 7 April 1975. The clams 

 were collected by towing a drag-type, non- 

 hydraulic dredge with a 12-in (30 cm) wide knife 

 from the U.S. National Marine Fisheries Service 

 (NMFS) RV Rorqual. Tows were made at each 

 site until 30 or more clams larger than 50 mm in 

 shell length were caught. Special collections were 

 made at Ward Point and New Dorp Beach on 

 1 November 1978 to obtain tissues for histochem- 



FISHERY BULLETIN VOL 8.5. NO .3, 1987. 



653 



