Title

Abstract

abstract

Time-course measurements of water-column fluorescence, zooplankton gut pigment and phytoplankton concentration were made at the Prince Edward Islands during April/May 1985 and 1986. Fluorescence records showed a decrease in pigment levels during the night. This is particularly marked in the pico- and nanosize fractions. This coupled with the zooplankton total gut pigments suggests that grazing is responsible. The netsize plankton, however, did not show any general trend of diurnal variations and only very few species in this size class showed a significant night decrease in the water-column. As the persistent phytoplankton blooms in the area are mostly composed of netplankton, it is suggested that this rich food source is scarcely exploited by the pelagic grazers. The possible direct transfer of primary biomass from the pelagic to the benthic subsystems is also discussed.