Studies of Uptake and Turnover of Glycollic Acid in the Menai Straits, North Wales

Abstract

Measurements were made of the concentrations of glycollic acid, photosynthetic pigments and mineral nutrients (N, P and Si), of the cell numbers and species-composition of the phytoplankton, of the rates of photosynthesis and release of extracellular products, and of the salinity, tidal height, temperature and light intensity over two 24-h periods in the Menai Straits, North Wales (21-22 February and 17-18 April 1975). A less complete study was made on 5 August 1975. In addition the kinetic characteristics of glycollate uptake (turnover-time, affinity constant and maximum velocity of uptake) were determined in the laboratory for a sample of water collected from the Menai Straits on 5 August 1975; three sets of conditions were used: darkness, and light with and without a specific inhibitor for diatom growth (germanium dioxide). The level of glycollate varied diurnally in all three study periods; it was maximal (15-25 pg I-') during the morning on all three occasions. In the first study period glycollate level was significantly correlated with the rate of release of extracellular products, but not with any of the other properties measured. No significant correlations were found in the later studies. Diatoms appeared to play no part in the uptake of glycollate under the conditions used.