628 BXJLLETIir OF THE BUREAU OF FISHERIES 



greater than 80 meters. These differences may have been due to differences in verti- 

 cal cii'culation around Cashes Ledge, however, as may the fact that the water was 

 coldest here on bottom in 1915. 



In the western side of the eastern arm of the basin the differences in tempera- 

 ture between the four summers were less than 1°. On German Bank the temperature 

 was about 1° higher in 1914 than in 1913, but about the same as in 1915 (allowing 

 for seasonal differences, due to the difference in date of the observations) . 



The temperature along the northeastern coast of Maine, in the one side of the gulf, 

 and in the deep bowl off Gloucester, in the other, have varied but little from siunmer 

 to summer; but the deep water was 1° to 2° colder next the land west of Penobscot 

 Bay and off Cape Elizabeth in 1914 than either in 1912 or in 1913. This also applies 

 at depths greater than about 75 meters to the trough between Jeffreys Ledge and 

 the coast. 



In the deep strata of the Bay of Fundy the bottom water ranged about 2° warmer 

 in August, 1914 (Craigie, 1916a), than in the summers of 1915 (Craigie and Chase, 

 1918) or 1916 (Vachon, 1918), and slightly warmer than Mavor (1923) records it for 

 1917 or 1919. 



These annual differences may be summarized as follows: Except for the imme- 

 diate surface, the upper 150 meters was slightly colder in the western, central, and 

 northern parts of the gulf in 1914 than in either of the two preceding years, but the 

 bottom water of the western, northern, and eastern parts of the basin were warmer, 

 with still higher temperatures in the western side in 1915. 



More or less fluctuation in summer temperature is to be expected in any partially 

 inclosed basin as subject to violent climatic changes as is the Gulf of Maine, and 

 where waters of different temperatures meet. What reaUy deserves emphasis is that 

 the yearly changes have been very small during the period of record; certainly not 

 enough seriously to affect the waters of the gulf as a biologic environment, except 

 perhaps in 1916. 



During that year vernal warming proceeded so slowly in the sea, after an almost 

 Arctic winter and a tardy spring, that the temperature of the central part of Massa- 

 chusetts Bay was only 3.67° to 3.9° at 50 to 80 meters depth on July 19 (station 

 10341), though the immediate surface was about as warm as the expectation for 

 that date (16° to 17°). In fact, the deep readings were hardly wai-mer than read- 

 ings taken in May of the preceding year, only about 1 .5° warmer than the mnter 

 minimum for that level during 1913, and 2° warmer than the early March tempera- 

 ture of 1920 (p. 522). The water off Northern Cape Cod (stations 10344 and 

 10345) ^* was likewise decidedly colder in 1916 than in the summers of 1913 to 1915, 

 with the 20 to 40 meter lever 2° to 3° colder than in 1913 and 6° to 9° colder than in the 

 same month of 1914. The suprisingly low surface temperatures of 10° off Chatham and 

 7.2° in the southwestern part of the basin on July 22, 1916, contrast with 16° to 17° 

 for this part of the gulf as a whole at about that same date in 1913 and 1914. It 

 is clear that such cold surface water reflected some temporarily and locally active 

 vertical circulation, because the vertical range of temperature was less than 1° between 

 the surface and 30 meters at the coldest of these two stations (10346), instead of a 

 range of about 9°, which previous experience suggests as normal for the western side 



" About 4.1° at SO meters, 3.85° at 100 meters, and warming fractionally belQ.w that level to 4.06 at 150 meters. 



