Journal of the Marine Biological Association of India

Effects of Carbon dioxide and Phosphate supplied during growth on phosphorus content and photosynthetic rates of some unicellular marine alage.

Volume 16 Issue 2

G. F. Humphrey

Abstract

Amphidinium carterae, Cyllndrotlieca closterium, Dunaliella tertiolecta, and Phaeodactylum tricornutum were grown under acid and alkaline conditions produced by varying the CO₂ supply. Increasing the phosphate in the growth medium from 2 to 20 µg P. ml^-1 had only small effects on the rates of photosynthesis and respiration and on the pholosynlhesis: respiration ratio, unless inocula were so large that the subsequent cell concentrations used more than 2 µg P. ml^-1 culture medium in the 48 hour growth period. Such a rate of phosphorus utilization was not found for Amphidinium. With the other algae, such high utilization gave calls of greatly decreased phosphorus content, with small decreases in the photosynthetic rates of Cylindrotheca and Dunaliella and reduction to half with Phaedactylum. When inocula were smaller so that less than 2 µg, P. ml^-1 culture medium were used, tenfold phosphate increased cell phosphorus only with Amphidinium.

The msan content of cell phosphorus as µg P. µl cell volume was: Amphidinium 1,4, Cylindrothica 5.3, Dunaliella 14.0, and Phaeodactylum 8.3 when grown in media containing 2 µg P. ml^-1. In tenfold phosphate, corresponding figures were 1.7, .5.2, T4.1, and 8.5.

Date : 30-08-1974