RELATIONSHIP BETWEEN BIOOPTICAL CHARACTERISTICS AND PHOTOINHIBITION OF PHYTOPLANKTON

The relationship between the bio-optical properties of different micro algae and photoinhibition after shea-term exposure (15 and 30 min) to solar radiation was analyzed, Photoinhibition was determined as the de crease in oxygen production and in the in vivo-induced chlorophyll flu orescence. Microalgae with different chlorophyll concentrations, cell size and volume were used. Both photoinhibition and recovery of oxygen production and quantum yield were higher after 30 than after 15 min e xposure to solar radiation. Photoinhibition was reduced when UV-A and UV-B radiations were eliminated from the solar radiation, The decrease of effective quantum yield and oxygen production was not dependent on cell size, biovolume or chlorophyll concentration in the algal cultur es, It was, however, related to the bio-optical property of the cultur es, manifested as the specific attenuation coefficient (K-c). As a gen eral response, the inhibition of effective quantum yield slightly decr eased with the increase in K-c. Recovery of yield and oxygen productio n in darkness after exposure to solar radiation was also clearly relat ed to k(c). The relation between the recovery of the yield and K-c fol lowed a parabolic function. It was also found that the recovery of the inhibition of the yield was higher in phytoplankton with active xanth ophyll cycle but that it was not dependent on the concentration of tot al carotenoids. (C) 1997 Elsevier Science B.V.