Abstract: | A study of plankton samples collected in the Western Sargasso Sea during nine cruises has shown discontinuity between samples from different latitudes as regards their percentage, abundance, and number of species of Acantharia. Limits separating zones rich in Acantharia from those poor in Acantharia were singled out. The latitude at which the difference in abundance occurs can vary. This is in accord with differences in primary production, phytoplankton, and mesopelagic fishes noted by other workers who believe that the points of these faunal changes correspond to a temperature change indicated as “thermal fronts.” |