Some development patterns of plankton communities in the upwelling areas of the Pacific Ocean

Abstract

The principal trophic levels, each subdivided into groups of organismic elements, are distinguished in the planktonic communities of the Eastern Equatorial and the Peruvian upwellings. Production intensity or metabolism have been determined experimentally for all elements. A scheme is suggested for computing production from data on metabolism for all the elements of a community, as well as for computing net and real production and other functional characteristics for definite trophic levels and the community as a whole. Based on the quantitative estimation of the efficiency of primary production and other functional characteristics, the development of communities is divided into production and destruction periods; they are, in turn, subdivided into steps associated with a certain degree of water trophicity. The balance of net production of the communities in the Peruvian upwelling indicates that the excess production of a community above the shelf is utilized completely in the narrow (100 to 150 sea miles) band of off-shore water. This paper describes an attempt to trace the changes taking place in the functional characteristics of plankton communities and to compare them with the changes observed in the communities of the Peruvian and East-Equatorial upwellings.