Abstract
Rates of calcification and photosynthesis were highest in the apical intergenicular segments of Corallina. Rates were lower in the penultimate segment and fell to steady values in the 5th segment. Differences in the dry weight of the five ultimate segments showed a positive correlation with differences in photosynthetic rate. Calcification rates were variable but showed a positive correlation with photosynthetic rates. In apical segments the mean ratio of photosynthetic 14CO2 uptake to 14CO2 incorporation into calcite (Cr) was 1·03. Calcification in the dark was 30–50% of the light saturated rate and probably resulted from the combination of a delayed light dependent reaction and a physical absorption process.