which relates surface current speed (V ) to wind 

 speed (W) in terms oflatitude ((/>) and an empirical 

 constant (A = 10 2 ), we obtain an estimate of aver- 

 age wind-driven surface current velocity of 5.7 

 cm/s northward. 



In light of the velocity estimates, it is apparent 

 that locally wind-driven currents are significant 

 for the northward transport of pelagic larvae east 

 of the northern Bahamas only if the larvae spend 

 most of their time near the sea surface. If, instead, 

 they are scattered throughout the upper layer or 

 undergo diurnal vertical migration, their 

 northward progress will be much slower. 



Another possible pathway of larval transport 

 which should be considered, however, is the near- 

 shore band of strong flow mentioned by R. Yager 

 (pers. commun.). If such a band exists as a regular, 

 steady feature of the current field east of the 

 Bahama Banks, then it would be particularly 

 informative to conduct seasonal ichthyoplankton 

 surveys on a scale appropriate to determine the 

 relative abundance of pelagic larvae in and near 

 the current band. 



Literature Cited 



BAKUN, A. 



1973. Coastal upwelling indices, west coast of North 



America, 1946-71. U.S. Dep. Commer., NOAATech. Rep. 



NMFS SSRF-671, 103 p. 

 BOISVERT, W. W. 



1967. Major currents in the North and South Atlantic 

 Oceans between 64°N and 60°S. U.S. Nav. Oceanogr. Off., 

 Tech. Rep. TR-193, 92 p. 



DEFANT, A. 



1961. Physical oceanography, Vol. I. Pergamon Press, N.Y., 

 729 p. 



Ingham, M. C. 



1975. Velocity and transport of the Antilles Current north- 

 east of the Bahama Islands. Fish. Bull., U.S. 73:626-632. 

 ISELIN, C. O. 



1936. A study of the circulation of the western North Atlan- 

 tic. Pap. Phys. Oceanogr. Meteor. 4(4), 101 p. 

 KNAUSS, J. A. 



1969. A note on the transport of the Gulf Stream. Deep-Sea 

 Res. 16 (Suppl.):117-123. 

 MONTGOMERY, R. B. 



1941. Transport of the Florida Current off Habana. J. Mar. 

 Res. 4:198-220. 

 STOMMEL, H. 



1965. The Gulf Stream — A physical and dynamical descrip- 

 tion. Univ. Calif. Press, Berkeley, and Cambridge Univ. 

 Press, Lond., 248 p. 

 STURGES, W. 



1968. Flux of water types in the Gulf Stream. [Abstr.] Trans. 

 Am. Geophys. Union 49:198. 



U.S. NAVAL OCEANOGRAPHIC OFFICE. 



1963. Oceanographic atlas of the North Atlantic Ocean, 



Section IV Sea and Swell. U.S. Nav. Oceanogr. Off, Publ. 



700, 227 p. 

 WORTHINGTON, L. V. 



In press. On the North Atlantic circulation. John Hopkins 



Univ. Press. 

 WUST, G. 



1924. Florida-Und Antillestrom. Verbffentlichungen des 



Instituts fur Meereskunde an der Universitat Berlin. A. 



Geographisch-naturwissenschaftlicke Reiche. Heft 12, 48 



P- 



JOHN T. GUNN 



Merton C. Ingham 



Atlantic Environmental Group 



National Marine Fisheries Service, NOAA 



Narragansett, RI 02882 



SALINITY ACCLIMATION IN 

 THE SOFT-SHELL CLAM, MYA ARENARIA 



A steady increase in sewage pollution followed by 

 the closing of many productive shellfish growing 

 areas has seriously affected the harvesting of the 

 soft-shell clam, Mya arenaria, in the State of 

 Maine. In areas where a large percentage of the 

 population derives its income from harvesting 

 soft-shell clams, these closings have caused severe 

 economic hardships. Beginning in the mid-1950's 

 the Maine Department of Marine Resources (then 

 Maine Department of Sea and Shore Fisheries) 

 accelerated research on clam depuration in an 

 attempt to salvage moderately polluted clams of 

 70-700 most probable number of Escherichia coli 

 bacteria per 100 g. Based upon the design and 

 development of a pilot process (Goggins et al. 

 1964) five commercial depuration plants have 

 been established. The first of these (Seafair, Inc. 1 ), 

 in Phippsburg, Maine, utilized clams dug from 

 Parker Head, Maine. During routine operation of 

 this plant, it was apparent that exposure of clams 

 to certain salinity and temperature conditions 

 increased the time required for depuration. 



Former investigators have revealed that 

 pumping activity and associated shell and ciliary 

 movements are affected when bivalves other than 

 soft-shell clams are immersed in water of a dif- 

 ferent salinity from that to which they are ac- 

 customed (Wells et al. 1940; Medcof 1944; 

 Loosanoff 2 ). In this paper, salinities lower than 



1 Reference to a commercial enterprise does not imply en- 

 dorsement by the National Marine Fisheries Service, NOAA. 



2 Loosanoff, V. L. 1952. Behavior of oysters in water of low 

 salinities. Conv. Address Proc. Natl. Shellfish. Assoc., Atlantic 

 City. 



225 



