The infaunal filter feeder Mulinia lateralis accumulated about five 

 times more l09 Cd than the deposit feeder N. proximo. Evidence pre- 

 sented indicated that early uptake rates might be indicative of sub- 

 sequent acquired body burdens after long-term exposure. 



Astarte castanea (Say, 1822) 



DESCRIPTION: Commonly called the smooth Astarte; 2.5 cm 

 in length and height, trigonal in shape, quite compressed. Shell 

 almost smooth, except for weak, low concentric lines. Color a 

 glossy light brown (Abbott 1974). 



DISTRIBUTION: Nova Scotia to off New Jersey (Abbott 1974). 

 Miner (1950) and Gosner (1971) recorded the range to Cape Hat- 

 teras. 



HABITAT: Characteristic of coarse sand (Franz 1976); in mud, 

 in fairly shallow water to 30 m (Abbott 1968). Gosner (1971) 

 reported it in depths to 119 m. 



Astarte castanea was collected in depths up to 25 m in the New 

 York Bight apex. It occurred in all grades of sand but was most 

 abundant in coarse sands. It was found only in low organic areas 

 (Fig. 17; Table 1). 



FEEDING ECOLOGY: A. castanea has no siphons and is a sus- 

 pension feeder (Sanders 1956; Abbott 1968). 



Astarte castanea is eaten especially by haddock, other ground- 

 fishes, and predator snails. According to Wigley and Theroux 



(1965), Astarte sp. is the third most important mollusk, behind 

 Nucitla tennis and Cerastoderma pinnulatwn. as food for haddock. 



REPRODUCTION AND GROWTH: Sexes are separate, with 

 male and female clams occurring in equal numbers (Abbott 1968). 

 Astarte castanea begins producing mature viable gametes when 

 15-16 mm in length. Production of gametes is neither seasonal nor 

 cyclic since mature gametes have been found in abundance in these 

 animals throughout the year (Ruddell 1977). 



Arctica islandica (Linne', 1767) 



DESCRIPTION: The ocean quahog or mahogany clam; 8-13 cm 

 in length, almost circular in outline, with a rather strong, porcela- 

 neous shell which is commonly chalky. Arctica islandica is the only 

 living species in its family (Arcticidae); there are numerous fossil 

 species. Superficially, A. islandica resembles the hard clam, Mer- 

 cenaria mercenaria, however, the dark brown to black periostra- 

 cum (horny external covering) of A. islandica is the most obvious 

 distinguishing characteristic (Abbott 1974). 



DISTRIBUTION: Newfoundland to off North Carolina, north- 

 ern Europe. Iceland (Pratt 1973; Abbott 1974). 



HABITAT: The ocean quahog is a common, commercially 

 dredged species, most abundant on silty sand and stable fine sand 

 (Turner 1949; Parker and McRae 1970), but occasionally found on 

 silt-clay bottoms (Arcisz and Sandholzer 1947; Bureau of 

 Commercial Fisheries 1970"). Results of National Marine Fisheries 

 Service surveys show that it is found at depths from 18-27 m to the 

 shelf edge off New Jersey and the Delmarva Peninsula, and in scat- 

 tered patches from 37 m off Virginia; it is also landed in small quan- 

 tities in southern New England. While the shoreward boundary has 

 been well established, distribution and abundance offshore is not 

 well known. High temperatures limit the shoreward distribution of 

 A. islandica; in the southern part of its range it is rarely found 

 within the 17.5°C maximum isotherm as drawn by Walford and 

 Wicklund (1968). In the laboratory, the upper lethal limit for fully 

 acclimated Rhode Island animals is about 24°C; the ocean quahog 

 is active at temperatures as low as 0°C. but activity decreases 

 above 18°C (Saila and Pratt 1973). 



Almost all A. islandica collected in New York Bight apex grab 

 samples were juveniles. They were taken from depths between 23 

 and 37 m. Arctica islandica were most common in fine sands but 

 occurred in low numbers in silt. Highest total numbers were in high 

 organic sediments with fewer in medium and low organic areas 

 (Fig. 18: Table 1). 



FEEDING ECOLOGY: A. islandica has very short siphons and 

 is a shallow burrower (Saleuddin 1964). It is a filter feeder with the 

 capacity to filter large and variable amounts of water (Winter 

 1969). Merrill et al. (1969) stated that many dredged quahog shells 

 have been found drilled by predatory, naticid gastropods. 



Caloric values of Canadian specimens follow a seasonal trend, 

 with a summer maximum and winter minimum (4,276 to 3,684 cal/ 

 g dry weight) (Tyler 1973). 



REPRODUCTION AND GROWTH: The reproduction of an 

 ocean quahog population off Rhode Island was studied by 



Figure 17.— Distribution and abundance of Astarte castanea in the New York 

 Bight apex. 



'■Bureau of Commercial Fisheries. 1970. Ocean quahog survey. Cruise Report. 

 Delaware //Cruise 70-5. National Marine Fisheries Service, Exploratory Fishing 

 and Gear Research Base. Woods Hole, Mass., 6 p. 



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