The Biology of the Zooplankton Population in the Bay of Fundy and Gulf of Maine with Special Reference to Production and Distribution.

Abstract

Analyses in the gulf of Maine and bay of Fundy show the zooplankton population to be dominated by a relatively few species of boreal endemic crustaceans. Calanus finmarchicus, the most abundant form, averaged 39.9 per cent by number in the total region during the period, April to September in 1932, and 35.5 per cent for the year in the bay of Fundy. Fluctuations in the volume of zooplankton reflect to a large extent numerical changes in the stock of this species. The vernal rise in 1932 occurred following propagation of Calanus, and the rapid downward trend in June coincided with the critical period of maturation and subsequent mortality of adults after spawning. Due to differences in the time of spawning in different parts of the region, two, and in some cases three, breeding stocks of boreal plankton animals can usually be distinguished. The distinct spawning periods are continued in subsequent generations that year no matter where distributed. Productivity was found to be closely correlated with temperature and stability of the water mass, and dispersal with the nontidal circulation in the region. The vernal crop of boreal plankton species appears to be derived largely from adults maturing in the western or outer gulf. With the advance of the season the centre of production moves to the eastern basin. The turbulent New Brunswick-eastern Maine coastal zone as far west as Mount Desert is relatively unproductive, and characterized by small zooplankton volumes.