Sea Water, The Natural Medium of Phytoplankton I. General Features

Abstract

Preliminary culture assays were made using marine algae to elucidate the ‘quality’ of sea waters from the North Sea and North Atlantic Ocean for phytoplankton growth. Assays with (a) bacteria-free Skeletonema costatum, (b) unialgal Skeletonema and Peridinium trochoideum and (c) mixed phytoplankton organisms indicated change of quality according to location, depth and season. Assay results correlated best with zooplankton indicator quality and to a lesser extent with phytoplankton abundance. Assay results were also compared with the distributions of temperature, salinity, oxygen, phosphate, U.V. fluorescence, phytoplankton dominants, zooplankton dominants and abundance. Assessment of sea-water quality was biased for the assay organism used. Factors which altered sea-water quality were added thiamine and B12 (40% improved), IAA (25% improved) and EDTA (almost invariable manyfold improvement). Destructive chemical treatments removed almost completely any good qualities for growth of Skeletonema but seldom for that of Peridinium.