OXYGEN BALANCE IN SOME REEF CORALS

Abstract

Oxygen exchange is reported for 14 species of Florida reef corals in the dark and at different light intensities. Oxygen tension was monitored with a recording polarographic electrode. Results are given as grams of carbon fixed per square meter of coral surface per day, and compensation light intensities were given for each species. Maximum ratios of photosynthesis to respiration varied from 1.9 to 5.8. Boring, filamentous green algae living in the skeleton of Dichocoenia stokesii were not observed to change their rate of oxygen consumption from dark conditions up to 5000 footcandles of light. It is concluded that reef corals are among the most productive organisms known and that, in Florida corals, the boring green algae contribute very little indeed to this productivity. Some data are given on the light impinging on Florida reefs and the light penetrating coral skeleton. Reasons for believing boring green algae are of minor importance are given in the discussion.