15 



rains and the spring freshet of the Royal River presumably combined to 

 temporarily depress the salinity at these stations. 



No long-term temperature and salinity records are available for 

 Casco Bay. Long-term records taken since 1906 at Boothbay Harbor, 30 

 kilometers to the east, however, are closely representative of Casco Bay 

 (N. Garfield, personal communication). The annual temperature-salinity 

 cycle based on monthly means of Boothbay Harbor is presented in Fig. 6. 

 During the period of 1950 to the present, surface water temperature at 

 Boothbay Harbor varied between the extremes of -2.3 C and 23.0 C, while 

 salinity ranged from 25.0 to 33.6 °/oo (W.R. Welch, personal 

 communication) . 

 Sediments 



The sediments of Casco Bay are predominantly fine (Table 2) . 

 Graphic mean grain size (Folk, 1974) ranges from -0.305 to 8.471 on the 

 phi scale although the grand mean is in the fine silt range at 6.345. 

 Only 8 stations have mean grain sizes in the sand range while 34 are in 

 the silt range and 13 can be classified as clay. The sand stations are 

 in areas of tidally scoured bottoms, such as the main approach to Casco 

 Bay, or in areas recently dredged. Generally, coarser sediments are 

 found offshore and in outer Portland Harbor, whereas fine sediments are 

 characteristic of the central and upper part of the Bay (Fig. 7). 



Regression of mean grain size in phi units against bottom depth in 

 feet demonstrates that a significant relationship exists between the two 

 (Fig. 8). The correlation coefficient of -0.3317 is significant at the 

 98% level. Remembering, in this and subsequent regressions, that since 

 the phi scale is an inverse measure, this regression indicates that 

 coarser sediments may be expected in the deeper portions of the sampling 



