AN INCUBATOR DESIGNED FOR EXTENSIVE AND SENSITIVE MEASUREMENTS OF PHYTOPLANKTON PHOTOSYNTHETIC PARAMETERS

An improved incubator for the determination of the photosynthesis rate -irradiance curve is described. It allows measurements of carbon fixat ion in waters with low chlorophyll a concentration by using rather lar ge seawater volume. The irradiance gradient inside the incubation cham bers is reproducible and can be accurately determined. With the capabi lity of simultaneous measurements on 10 water samples, extensive deter mination of vertical profiles of photosynthetic parameters is achievab le. Examples of photosynthetic parameters are given for waters collect ed in eutrophic, mesotrophic, and oligotrophic sites of the tropical A tlantic Ocean.