Survey of selenium requirements in marine phytoplankton

Abstract

A survey of 27 species of marine phytoplankters, representing 4 algal classes, was conducted to determine if selenium was required for growth. The species were grown in natural and artificial seawater media to which 1 0 ~ M Na,SeO, was added (controls) and in artifical seawater with no Se addition. Fifteen out of 20 species of diatoms tested required Se for growth. Eight out of 9 oceanlc diatoms showed an apparent Se requirement. Only 1 (Scrippsiella trochoidea) of the 4 dinoflagellates tested exhibited a similar SE requirement. Two Chrysochromulina spp. and the one Synecl~ococcus p. grew normally in the artifical seawater medium without added Se. For the species that did not require a Se addition to the artificial seawater medium, it was not possible to determine whether these species have a very low Se requirement that is met by the background Se contamination in the artificial seawater or they actually have no Se requirement. The effect of various Se concentrations (10-l0 to 10-' M) on growth rates of 4 diatom species (3 coastal and 1 ocednic) were examined. The half saturation constant for growth (K,,) was approximately 10-' M Se for all 4 species.