Table 6. --Total monthly discharge (in cubic 

 feet per second) of the major rivers empty- 

 ing into the Gulf of Maine, March, April, 

 and May (spring) 1965 and 1966 



■'■ Data from the U.S. Geological Survey, 

 Water Resources Division, Augusta, Maine, and 

 Boston, Mass. 



the lower salinities in the western and cen- 

 tral areas in the spring an<i summer of 1966. 

 The dominant zooplankter, C. finmarchicus , 

 was more numerous in the western Gulf in 

 1965 than in 1966. Between-year differences 

 in the abundance of C. finmarchicus , and 

 consequently in volunnes of zooplankton as 

 well, appear to be related to variations in 

 developnnent of the dominant nontidal drift 

 along the coast. In periods of low runoff, cir- 

 culation along the western north Atlantic coast 

 is weak; less water is lost to the offshore 

 system, and less water is drawn into the 

 coastal system (Bumpus, 1966^). Inlate spring 

 and sunnmer the dominant drift from Cape 

 Elizabeth to Cape Ann is southwesterly 

 (Bunnpus and Lauzier, 1965), The lower runoff 

 in 1965 than in 1966 weakened the flow of 

 nontidal drift. The resulting decreased loss 

 of C, finmarchicus from the western area 

 in 1965 most probably contributed to the 

 between-year differences in zooplankton abun- 

 dance, A similar difference in the abundance 

 of C, finmarchicus occurred in 1963 and 1964; 

 C, finmarchicus was more nunnerous in 1964, 

 when spring runoff was lower than in 1963 

 (Sherman, 1966). 



Bumpus, Dean F. 1966. Investigations of climate and 

 oceanographic factors influencing the environment offish. 

 Woods Hole Oceanographic Institution. Technical Report 

 66-59, 7 pp. Unpublished manuscript. 



Distributions of copepod species in 1965 and 

 1966 generally decreased from west to east 

 along the coast (fig, 4). The concentrations 

 of C^. finmarchicus in the central area in the 

 spring of 1966 may have resulted from an 

 indraft of offshore water to compensate for 

 water displaced by the spring increase in 

 runoff of the Penobscot, Sheepscot, and Kenne- 

 bec Rivers. Incursions of C. finmarchicus and 

 other copepods fronn offshore to inshore areas 

 are known to occur periodically in the Gulf 

 (Bigelow, 1926; Fish, 1936a, 1936b, 1936c), 

 and one of the chief centers of abundance of 

 C, finmarchicus is in the eastern basin of 

 the Gulf beyond the 100-m, isobath in the 

 offing of Penobscot Bay (Bigelow, 1926). In- 

 cursions of zooplankters to the central region 

 could contribute to the standing-crop values 

 of the western area if the plankters are car- 

 ried along the coast in the dominant nontidal 

 drift. The constancy and magnitude of this 

 contribution to the coastal zooplankton of the 

 Gulf, however, is not presently known. 



LITERATURE CITED 



BIGELOW, HENRY B. 



1914. Explorations in the Gulf of Maine, 

 July and August, 1912, by the United 

 States fisheries schooner Grampus . 

 Oceanography and notes on the plankton. 

 Mus. Comp. Zool., Bull. 58: 29-147. 



1915. Exploration of the coastbetween Nova 

 Scotia and Chesapeake Bay, July and 

 August, 1913, by the United States fish- 

 eries schooner Grampus . Oceanography 

 and plankton. Mus. Comp. Zool., Bull. 

 59: 152-359. 



1917. Explorations of the coast water be- 

 tween Cape Cod and Halifax in 1914 and 

 1915 by the United States fisheries 

 schooner Grampus . Oceanography and 

 plankton. Mus. Comp. Zool., Bull. 61: 

 164-357. 



1926. Plankton of the offshore waters of 

 the Gulf of Maine. U.S. Bur. Fish., 

 Bull. 40: 1-509. 



1927. Physical oceanography of the Gulf of 

 Maine. U.S. Bur. Fish., Bull. 40: 

 511-1027. 



BUMPUS, DEAN F. 



1960. Sources of water contributed to the 

 Bay of Fundy by surface circulation. 

 J. Fish. Res. Bd. Can. 17: 181-197. 

 BUMPUS, DEAN F., and LOUIS M. LAUZIER. 

 1965. Surface circulation on the continental 

 shelf off eastern North America be- 

 tween Newfoundland and Florida, In 

 Serial atlas of the marine environment. 

 Folio 7, Amer, Geogr, Soc, 24 pp. 

 FISH, CHARLES J. 



1936a. The biology of Calanus finmarchicus 

 in the Gulf of Maine and Bay of Fundy. 

 Biol. Bull. (Woods Hole) 70: 118-141. 



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