observed that Mya activity (measured by physical 

 criteria: extension of siphon, response to tactile 

 stimuli) increased in direct proportion to an in- 

 crease in temperature. Other investigators have 

 reported that Mya arenaria pumps as effectively at 

 all temperatures (Belding 1930; Marston 1931; 

 Arcisz and Kelly 1955). If this were true in our 

 studies, Mya would be expected to acclimate to a 

 dilution as quickly at 3°C as at 16°C. Clearly, in 

 the case of Parker Head clams, our findings do not 

 agree with these authors. 



In the case of Seafair, Inc., it is apparent that 

 depuration took longer because the Parker Head 

 clams first had to acclimate to unaccustomed 

 salinity before they could actively pump and 

 cleanse themselves. Low water temperature 

 would, of course, tend to lengthen this acclimation 

 period. Our findings are consistent with Furfari's 

 (1966) statements, "Time taken by shellfish to 

 acclimate to the stress of a change in salinity, is 

 time lost in depuration." 



In addition to establishing the time required for 

 Mya to acclimate to dilutions at ambient tem- 

 perature ranges, this study demonstrates the need 

 for appraising the response of clams from the 

 harvest area to the environmental conditions 

 existing at the depuration site. Acclimation times 

 recorded in this paper are specific for Parker Head 

 clams. Mya dug from other locations may respond 

 differently. 



Acknowledgments 



We extend our appreciation to Philip L. Goggins 

 and John W. Hurst, Jr. for their advice and as- 

 sistance in various aspects of this research, and to 

 James A. Rollins for photographic services. 



This research was conducted by the Maine 

 Department of Marine Resources Research 

 Laboratory, West Boothbay Harbor, Maine, in 

 cooperation with the U.S. Public Health Service, 

 under Contract No. 86-64-78. 



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EDWIN P. CREASER, JR. 



David A. Clifford 



Maine Department of Marine Resources 



Research Laboratory 



West Boothbay Harbor, ME 04575 



229 



