Seasonal and Areal Distribution of Zooplanlcton in 

 Coastal Waters of the Gulf of Maine, 1964 



By 



KENNETH SHERMAN, Fishery Biologist (Research) 



Bureau of Commercial Fisheries Biological Laboratory 

 Boothbay Harbor, Maine 



ABSTRACT 



A description is given of the composition and seasonal variations of zooplankton 

 in coastal waters of the Gulf of Maine during 1964, and comparisons are made 

 between 1963 and 1964. Twelve zooplankton groups (major taxa) were represented 

 in the samples. Five occurred as holoplanktonic forms and seven were mero- 

 planktonic. Copepods were the donninant zooplankters during all seasons. Zoo- 

 plankton volumes for both years followed similar areal trends. Mean annual volumes 

 were highest in the western area (Cape Ann, Mass., to Cape Elizabeth, Maine); 

 moderate in the central area (Cape Elizabeth to Mt. Desert Island, Maine); and 

 low in the eastern sector (Mt. Desert Island to Machias Bay, Maine). Zooplankton 

 volumes were generally lower in 1964 than in 1963. Seasonal and annual variations 

 in abundance of zooplankters are discussed in relation to hydrography. Local 

 hydrography appears to influence the abundance and distribution of coastal zoo- 

 plankters more directly then does the cyclonic- eddy system of the Gulf proper. 



INTRODUCTION 



An expanded program of biological and en- 

 vironmental sampling of Gulf of Maine coastal 

 waters was begun in 1963 by the Bureau of 

 Commercial Fisheries Biological Laboratory, 

 Boothbay Harbor, Maine. The program was 

 designed to provide information on the rela- 

 tions between the environment and the availa- 

 bility and abundance of immature herring, 

 Clupea harengus L. This rt jrt is the second 

 of a series describing the zooplankton as- 

 semblage in Gulf of Maine coastal waters. The 



relative abundance, composition, and areal 

 distribution of the zooplankton in 1963 was 

 described previously (Sherman, 1965). 

 Sampling in 1964 was directed at determining 

 seasonal, annual, and areal variations of the 

 larger zooplankters, particularly calanoid 

 copepods and herring larvae. This report pre- 

 sents results of the 1964 coastal survey and a 

 description of between-year differences (1963- 

 1964). 



METHODS 



Four stations in each of three Gulf of Maine 

 coastal areas--western (Cape Ann to Cape 

 Elizabeth), central (Cape Elizabeth to Mt. 

 Desert Island), and eastern (Mt. Desert Island 

 to Machias Bay)- -were sampled seasonally on 

 single quasi- synoptic cruises of the research 

 vessel Rorqual : winter, January 21-February 

 14; spring. May 21-28; summer, August 10- 

 20; and fall, October 1-13 (fig, 1). As in 1963, 

 samples were collected with a Gulf III sampler, 

 fitted with a 20.4- cm. nose cone and monel 

 netting (aperture width, 0.37 mm.). Step-oblique 

 tows from 20 m. to the surface lasting 30 min- 

 utes each were tciken during daylight. The net 



was towed for approximately 10 minutes at each 

 tow--at the surface, at 10 m., and at 20 m. The 

 amount of water strained was determined from a 

 calibrated flow meter mounted on the tail 

 section of the Gulf III. The average 30-minute 

 tow covered 3 nautical miles and filtered about 

 200 m.-^ of water. Towing speed was 6 knots. 



In the laboratory, displacement volumes 

 were determined by the mercury-immersion 

 method (Yentsch and Hebard, 1957). Cten- 

 ophores, large coelenterate remains (>2 cm. 

 long), and all fish larvae were removed in 

 advance of the volume determinations. Zoo- 

 plankton samples were split into aliquot s 



