16 



NOAA Technical Report NMFS 140 



subjected. Charts were constructed to illustrate the iso- 

 therms of maximum bottom water temperature (Fig. 9) 

 minimum bottom water temperature (Fig. 10), and 

 annual range in bottom water temperature (Fig. 11). 

 Data for these charts were extracted from temperature 

 records taken during the sampling period when bio- 

 logical data were collected, August 1956 through Au- 

 gust 1965, and from the literature (see above citations). 

 Temperature patterns depicted in these charts are in- 

 tended to provide a general scheme of annual tempera- 

 ture change. Higher or lower temperatures may have 

 existed for short periods in some areas and may have 

 been missed because of the opportunistic nature of the 

 sampling. Extremes of this kind, however, are not con- 

 sidered usual or of great magnitude. 



These charts disclose a wide annual temperature range 

 in coastal bays and in shallow offshore areas, such as 

 Georges Bank and Nantucket Shoals. Very little change 

 occurs in deep water. At depths below 500 meters the 

 annual variation in temperature is roughly 0-3. 9°C. 

 Bottom water in the Gulf of Maine is relatively cold, 4 to 

 8°C and changes very little throughout the year. Bot- 



tom water on the Scotian Shelf and Browns Bank is 

 particularly cold in the spring and warms up only to 

 moderate levels in the fall and early winter. Annual 

 average temperature of bottom water for some of the 

 major areas calculated by Schopf and Colton (1966) 

 and Schopf (1967) are: Georges Bank 8.6°C, Nantucket 

 Shoals 7.8°C, Gulf of Maine 5.7°C, Browns Bank 5.0°C, 

 and the Nova Scotian Shelf 4.6°C. 



Zoogeography 



The topographic, hydrographic, climatic, and fauna! 

 complexities of the sublittoral portion of the study area 

 cause considerable difficulty in the definition of defini- 

 tive zoogeographic boundaries in the Northwest Atlan- 

 tic. Until recently, the traditional view among biogeog- 

 raphers was that the region embraced portions of two 

 major zoogeographic provinces: 1 ) The Boreal Prov- 

 ince, sometimes referred to as Acadian or Nova Scotian, 

 which extends from Newfoundland to Cape Cod, and 

 2) The Trans-Atlantic or (Warm Temperate) Province 



Figure 9 

 Distribution of maximum reported bottom water temperatures (in degrees Celsius) in the study area. 



