until equilibrium was reached, proportional to the concentration introduced. 

 Mercenaria meraenaria and Crassostrea virginiaa continually increased in 

 concentration. The algae were the principal source of accumulation in the 

 aquaculture system. Safe levels of Cd for human consumption of shellfishes 

 were calculated from known human body burden and natural accumulation and 

 transfer of Cd from phytoplankton to bivalves. The critical concentration in 

 municipal effluent for culture of plankton as food for clams would be 0.003- 

 0.005 ug/ml. This points up the importance of quality of effluent and 

 dilution seawater for an aquacultural system using nutrients from treated 

 sewage. - J.L.M. 



992 



Kerkut, G. A., C. B. Sedden,and R. J. Walker. 1966. 



The effect of DOPA, a-methyl DOPA and reserpine on the dopamine content of 

 the brain of the snail, Helix aspersa. Comp. Biochem. Physiol. 18(4) : 

 921-930. 



Dopamine was the only catecholamine found in Mercenaria mercenaria cerebral, 

 visceral, and pedal ganglia. Concentration was 22 yg/g wet tissue, which was 

 only 10% of the value reported by Sweeney (1963), abstracted elsewhere in 

 this bibliography. The discrepancy is not explained. - J.L.M. 



993 



Kerr, N. M. 1970. 



Harvesting of marine biological resources by dredging. Proc . Inst. Mar, 

 Eng. Symposium, Ocean Eng . Section, Glasgow: 14-23. 



This is an interesting paper, although it does not deal with hard clam 

 harvesting. Essentially it describes development of a hydraulic suction 

 dredge, which has the advantage of continuous dredging, rather than 

 frequent lifts to empty the bag. Considerable effort was devoted to 

 obtaining the best catch per unit time, and to reducing breakage. The 

 paper is liberally illustrated by diagrams, and might be worth study by 

 clam dredgers. - J.L.M. 



994 



Kerswill, Charles J. 1941. 



Some environmental factors limiting growth and distribution of the quahog 

 Venus mercenaria L. Ph.D. Thesis, Univ. Toronto, 104 p., 18 fig., 2 

 appendices. (Also cited under same title and date as a Manuscript Report, 

 Fish. Res. Bd. Canada, Atl. Biol. Sta. 187, 104 p. - this ms rept. was not 

 seenj 



Kellogg (1903) and Belding (1912) did extensive work on rapidly diminishing 

 abundance of hard clam in N.Y. and Mass. Their recommendations apparently 

 were adequate, and no more research was done on quahog for over 2 yrs until 

 resumed in 1935 by Loosanoff. In Canada, quahaug is a warm-water form at 

 the northern limit of its range. It occurs only where seawater temp reaches 

 high levels early in summer. Malpeque Bay is one of the most important 

 centers of production. There the stocks were reduced in 1916 by improperly 

 controlled harvesting and by disease, as oyster was. The Prince Edward Island 

 Biological Station was established in 1930 on the Bideford River near the 

 center of production to develop cultural methods to restore the oyster 

 resource. The Kerswill study began in 1938. Limited funds restricted 

 research to only one outside area, Tatamagouche Bay, N.S., where environmental 

 conditions are much different from Malpeque Bay: tidal range is much greater. 

 Natural habitat of quahaug is Gulf of St.' Lawrence to Gulf of Mexico. Its 

 occurrence on the Pacific coast is attributed to accidental planting with 

 eastern oysters. In the northern part of its natural range hard clam is 



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