ABSTRACT: Measurements of microphytobenthos primary production were carried out in the German Wadden Sea in order to test the application of a 'Photosynthetic Light Dispensation System', which was originally developed for photosynthetic research of higher plants. A description of the computer-controlled system, consisting mainly of a subunit providing the irradiance (photosynthetically active radiation, PAR), and a subunit equipped with a Clark-type electrode for measuring oxygen production and respiration processes is given. The system allows rapid and reproducible measurements of photosynthesis-irradiance (P-E) curves at light modes predetermined by the computer and simple, rapid data analysis. Additionally, P-E curves obtained by this system were compared to those received by simultaneously conducted ¹⁴C measurements. Primary production measured by the oxygen method was on average 2.00 times higher than the values obtained by the ¹⁴C method. Production rates varied between 1.7 and 4.1 mg C mg chl a^-1 h^-1 with a mean of 2.75 mg C mg chl a^-1 h^-1.

KEY WORDS: Photosynthetic Light Dispensation System · Primary production · Microphytobenthos · German Wadden Sea

Published in MEPS Vol. 166 (1998) on May 28
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1998