BOTTOM-WATER TEMPERATURES ON THE 



CONTINENTAL SHELF, 



NOVA SCOTIA TO NEW JERSEY 



JOHN B. COLTON, JR. and RUTH R. STODDARD' 



INTRODUCTION 



It is not easy to generalize and to designate 

 any one physical factor as having greater eco- 

 logical influence than any other in the complex 

 environment of continental shelf waters. Howr- 

 ever, both laboratory and field observations have 

 shown that temperature is a factor of prime im- 

 portance because of its action (1) directly upon 

 physiological processes such as metabolic rate 

 and reproductive cycle and (2) indirectly 

 through its influence on other environmental 

 factors such as dissolved gases, viscosity, and 

 density. 



There is good evidence to the eff"ect that the 

 distribution of benthic organisms in continental 

 shelf waters in temperate latitudes is controlled 

 to a large extent by seasonal temperature con- 

 ditions (Fritz, 1965; Haynes and Wigley, 1969; 

 Hutchins, 1947; Schopf, 1967; Taylor, Bigelow, 

 and Graham, 1957). Temperatures exert a di- 

 rect control over distribution in cases where 

 they become too extreme for survival or do not 

 attain or maintain critical values necessary for 

 reproduction or completion of life cycles. In 

 addition, temperature also indirectly controls 

 the distribution of higher trophic level organ- 

 isms such as fish by regulating the dispersal of 

 primary prey organisms. 



Although an appreciable number of hydro- 

 graphic surveys have been made on the conti- 

 nental shelf off New England and the Maritime 

 Provinces since the early 1900's, the coverage 

 has been sporadic. Up to the present time it 

 has been only possible to summarize in detail 

 the distribution of bottom-water temperatures 



^ National Marine Fisheries Service Narragansett 

 Laboratory, Narragansett, RI 02882. 



for limited areas and time periods. Bigelow 

 (1927, 1933) described the seasonal cycles and 

 ranges in bottom-water temperatures in various 

 physiographic areas in the Gulf of Maine and 

 on the continental shelf between Cape Cod and 

 Chesapeake Bay based on observations made 

 during the periods 1912-26 and 1927-32. A 

 brief description and a plot of the distribution 

 of bottom-water temperatures on the continental 

 shelf between Nova Scotia and New Jersey 

 based on average values determined from bathy- 

 thermograph observations made during Sep- 

 tember-November 1955-61 are given by Fritz 

 (1965). Schopf (1967) presents data on the 

 range and seasonal cycle of bottom-water tem- 

 peratures on Nantucket Shoals, Georges Bank, 

 Scotian Shelf, and in the Gulf of Maine and 

 shows contour charts of average bottom-water 

 temperatures for the coldest (February-March) 

 and warmest (September-October) parts of the 

 year in the area between Nova Scotia to Hudson 

 Canyon. Schopf's data are based on bathyther- 

 mograph observations obtained during the pe- 

 riod 1955-66. Walford and Wicklund (1968) 

 constructed monthly bottom-water temperature 

 contour charts based on estimated values from 

 a series of 38 monthly temperature profiles 

 across the continental shelf between Cape Cod 

 and the Florida Keys. These temperature pro- 

 files were drawn on a basis of average values 

 determined from a selected sample of hydro- 

 graphic station and bathythermograph data col- 

 lected during the period 1914-64. 



In studies being undertaken at the NMFS 

 Northeast Fisheries Center, Woods Hole. Mass., 

 on the distribution and ecology of groundfish 

 and benthic food organisms, we have long felt 

 the need for a more comprehensive and detailed 

 summary of the long-term seasonal distribution 



