High-resolution vertical profiles of pelagic tunicates

Abstract

The objectives of our research were to obtain high-resolution vertical profiles of the abundance of pelagic tunicates and to relate their distribution to physical and biological variables. The abundance of doholids (Tunicata: Thaliacea) from near the surface to near the seafloor was determined by obtaining continuous videotape recording from a descending submersible. These vertical profiles, accompanied by temperature and fluorescence measurements, revealed (i) pronounced changes in dololiolid concentration within 2 m depth intervals, and (ii) two general modes of vertical distribution, one characterized by a peak in abundance in the thennocline and the second by a more or less even distribution throughout much of the water column. This in situ approach can provide estimates of zooplankton abundance in near real-time © 1991 Oxford University Press.