COMPARATIVE GROWTH OF <i>Isochrysis galbana</i> PARKE AND <i>Isochrysis</i> aff. <i>galbana</i>, CLONE T‐ISO AT POUR TEMPERATURES AND THREE LIGHT INTENSITIES

Abstract

Abstract The growth of a temperate and a tropical strain of Isochrysis was studied at four temperatures and three light intensity levels. All algal cultures were grown in an enriched artificial seawater medium under constant illumination and were bubbled with air enriched with 0.1% CO 2 . Culture density (cells/ml) was measured periodically during exponential growth. Average growth rates for each combination of temperature and light intensity are presented as doublings/day. Observations of growth under the various culture conditions indicate that T‐ISO (tropical strain) grows rapidly over a much broader range of temperatures than does I. galbana. Variations in growth at different light intensity levels suggest that the optimum light level increases as a function of temperature for T‐ISO and that the growth of I. galbana is inhibited by high levels of light (1500 μW/cm 2 ). The relative value of both strains as food for larval and juvenile oysters and the advantages and limitations of large scale culture are discussed.