ZOOPLANKTON AND HYDROGRAPHY 



Variations of temperature and salinity 



Hydrographic data showed seasonal and an- 

 nual variations along the coast. The curves of 

 mean seasonal surface temperature and 

 salinity for each of the Gulf areas are given in 

 figure 9, A-C. Curves for 1963 and 1964 were 

 similar; tennperatures increased fronn a winter 

 minimum to a summer maximum, and then de- 

 clined in the fall. Salinities rose to a fall- winter 

 maximum from a spring low. Similar seasonal 

 variations of temperature and salinity have 

 been reported for Gulf waters by Bigelow 

 (1927), Gran and Braarud (1935), and Graham 

 and Boyar (1965). 



Ranges of temperature and salinity among the 

 three coastal areas differed seasonally and 

 annually. Temperatures were cooler and salin- 

 ities higher in the eastern area for spring, 

 summer, and fall. Winter conditions of low 

 temperature and high salinity were similar in 

 all areas. The greatest between-year tempera- 



ture difference occurred in the western area 

 during spring, where temperatures were 

 4.8° C. lower in 1964 than in the preceding 

 year. Salinity values werehigher in 1964 during 

 all seasons. Seasonal changes of salinity were 

 similar in the central and eastern areas dur- 

 ing both years, increasing from a spring mini- 

 mum to a fall maximum. In the western area 

 salinity reached a maximum in the fall in 1963, 

 but the maximum was in winter in 1964. Spring 

 runoff for major rivers emptying into the Gulf 

 was much reduced in 1964 (table 4); this de- 

 creased river drainage apparently was respon- 

 sible for the higher salinities of 1964. The 

 importance of river discharge on the salinity 

 and circulation characteristics of the Gulf has 

 been reported by Bigelow (1914, 1927), Bumpus 

 (I960), and Bumpus and Lauzier (1965). 



Areal differences in surface temperature and 

 salinity in coastal waters of the Gulf of Maine 

 have been shown to reflect local conditions 

 rather than advection of waters (Bigelow, 1914). 



TEMPERATURE 



SALINITY 



33.0 



!/ 



V j 



WINTER SPRING SUMMER FALL WINTER SPRING SUMMER FALL WINTER SPR'ING SUMMER FALL 



A^EST 



CENTRAL 



EAST 



Figure 9. — Mean seasonal surface temperature and salinity for the western, central, and eastern areas of the coastal 



Gulf of Maine in 1963 (broken line) and 1964 (soUd line). 



