Distribution and abundance of pelagic copepods in the Drake Passage and off the coast of Argentina, with special reference to hydrology of these areas

The distribution of pelagic copepods with relation to the hydrology of the Drake Passage and off the coast of Argentina was studied in the plankton samples collected from four cruises made between February 1963 and July 1964. Hydrological studies made in the Drake Passage indicated that the position of the Antarctic Convergence does not show appreciable displacement from its mean position between 58° and 59°S lat in the Passage. Lower temperatures, higher dissolved oxygen content, and substantial increase in silicate values were noted as the Antarctic Convergence was crossed from north to south. During the October 1963 cruise the Sub-tropical Convergence was located at approximately 40°S lat off the Argentine continental shelf. Areas of upwelling were located between 40° and 43°S lat close to the border of the shelf. The distribution and composition of the pelagic copepods showed remarkable conformity with the hydrology of the areas under investigation. Based on the plankton samples studied, it was possible to divide the areas investigated into four regions: Antarctic, sub-Antarctic, transitional, and sub-tropical. The Antarctic region is characterized by the occurrence of Calanus propinquus, Calanoides acutus, Haloptilus ocellatus, Metridia gerlachei, Racovitzanus antarcticus, and Saphocalanus subbrevicornis. ..