1 8 NOAA Technical Report NMFS 140 



Distribution oi the annual range (difference between maximum and minimum reported values) in bottom water 

 temperature (in degrees Celsius) in the study area. 



more meaningful zoogeographic boundaries for regulat- 

 ing the distribution of benthic taxa within the region. 



Boundaries of the geographical area considered in 

 this report were purposely selected so that they did not 

 terminate at the margin of a perceived zoogeographi- 

 cal barrier. Cape Cod, lying roughly in the center of the 

 study area, is of course the main physical feature his- 

 torically considered to mark the separation between 

 the Boreal and Trans-Atlantic Provinces. The recent 

 work of Schopf (1968b), Hazel ( 1970), Watling (1979b), 

 Fran/ et al. (1981), and other reports (Wigley and 

 Burns, 1971; Williams and Wigley, 1977; Theroux and 

 Wigley, 1983; and Theroux and Grosslein, 1987) based 

 cm the same data as, and including, the present report 

 corroborate the fact that Cape Cod is indeed a zoogeo- 

 graphic boundary. However, the seaward extension of 

 this boundary, at least as it pertains to benthic animals, 

 does not traverse the continental shelf over Nantucket 

 Shoals and the southwestern terminus of Great South 

 Channel as previously supposed. Rather, the boundary 

 appears to lie along an easterly path across the north- 



ern end of Great South Channel at depths of 50 to 100 

 m and to continue along the northern margin of 

 Georges Bank and thence southeasterly along the west- 

 ern boundary of Northeast Channel. 



In bathyal and abyssal depths there are at least two 

 other zoogeographic provinces. Along the continental 

 slope, at depths between 150 and 2,000 m, is the Atlan- 

 tic Transitional Province (Cutler, 1977), and at depths 

 between 2,000 and 4,000 m is the Atlantic Bathyal- 

 Abyssal Province. Because of the interdigitating distri- 

 butional patterns resulting from the southward sub- 

 mergence of Boreal species and the ascendency of Tran- 

 sitional and Bathyal-Abyssal species in their north- 

 ward extension, the delineation of these provinces is 

 imprecise and only partially aligned with topographic 

 features. 



A great deal more work of a zoogeographic nature on 

 the many remaining unstudied taxa of benthic inverte- 

 brates inhabiting the area needs to be performed be- 

 fore precise zoogeographic boundaries may be drawn, 

 if at all possible. 



