On Some Planktonic Protozoa Taken from the Track of the Drift Station ARLIS I, 1960-61

Twenty-six species of protozoans identified from ARLIS I plankton collections are discussed with respect to their geographic and depth distribution. Diversity of species and abundance of organisms were both greater in the eastern than in the western collections. Plankton was generally sparse in the upper 30 m. of water. The greatest abundance of plankton was at depths of about 70 m. and about 400 m., both regions of temperature maxima. The common protozoa were present in both depth zones. It is suggested that some of the phytoplankton are maintained through the dark season by heterotrophic means. The luminescence of Noctiluca was noted to be of a shade of blue different from that of the metazoans collected.