PHTSICAL, OCEAlSrOGKAPHY OF THE GULF OF MAINE 



625 



for which the exposure of the neighboring flats to the sun at low tide is no doubt 

 responsible — with 13.2° at 18 meters off Plymouth (station 10642). In winter these 

 same regions cool to 0° or even fractionally colder. Around the more exposed shores 

 of Massachusetts Bay, however, we have found the bottom temperature 12° to 9.8° 

 in 15 to 18 meters depth; 7° to 9.8° at 25 to 30 meters; 7.2° to 5.6° at 40 to 50 

 meters; and 4.5° to 6.2° at 65 to 75 meters in August. 



Compare this with the Bay of Fundy, where even the httoral zone warms 

 only slightly above 10° to 12° off open shores, but where the bottom in 40 to 50 

 meters is almost equally warm by the end of the summer (p. 599). Under these con- 

 ditions cool-water animals, at home in temperatures up to 10°, find no limit to their 

 bathic dispersal short of the surface, instead of being confined to depths greater 

 than 12 to 15 meters, as they are in Massachusetts Bay in summer. On the other 



Stations 



Meter Ok 



Fig. 66.— Temperature profile crossing the mouth of Massachusetts Bay from Gloucester to 

 Cape Cod, August 22, 1922 (stations 10631 to 10633). The broken curve represents the 

 shoalest contour of the bottom along the rim formed by Stellwageu Bank 



hand, any animal restricted physiologically to truly Arctic temperatures would find 

 a more favorable habitat in the deeper parts of Massachusetts Bay and in the still 

 colder trough off the Isles of Shoals than in the Bay of Fundy at any depth. 



The studies on the life history of the cod, on which the Bureau of Fisheries is 

 now engaged, lend special interest to the bottom temperatures on the grounds where 

 most of the fish have been tagged — Nantucket Shoals, Platts Bank, and the vicinity 

 of Mount Desert Island. 



In August, 1925, the Halcyon had bottom readings of 11.2° to 15.56° on the 

 shoals in depths of 20 to 30 meters (p. 1012), and probably this is about the maxi- 

 mum to be expected there in an average summer. On the other hand, the bottom 

 water cools to about 3° to 4° there at the end of winter, so that any fish (or other 



