Distribution, Morphometry, and Seasonal Biology of the Planktonic Copepods, Calanus tenuicornis and C. lighti, in the Pacific Ocean

Abstract

The ecology of sympatric, congeneric species has been extensively studied on the supposition that such species require rather similar resources and are therefore potential competitors when they co-occur. The pelagic environment is of great areal extent, low faunal diversity, and high physical homogeneity in comparison with terrestrial environments, and hence the nature of the niches of closely related, oceanic species of zooplankton is of some interest (Mullin, 1967). The present investigation concerns the geographical and vertical distribution of two such species, the question of character displacement in size of body and mouthparts, and the extent to which the two species have different breeding seasons.