MEASUREMENTS OF PHYTOPLANKTON PRIMARY PRODUCTION BY MEANS OF THE ACIDIFICATION AND BUBBLING METHOD

We examined the possibility of using the acidification and bubbling method (ABM) to determine phytoplankton primary production in coastal marine environments. Our results from a number of laboratory and field experiments, suggested that (i) incubations of samples can be carried out in glass vials instead of using the normal incubation bottles, and (ii) storage of samples fixed with formalin or glutaraldehyde can be carried out for at least 8 weeks without a change in radioactivity. In the course of our work, we designed a new manifold removing excess C-14 via ABM. A linear correlation between the G24-max values obtained by the two techniques (r = 0.93) was found. On average the ABM gave values 1.8 times higher than those yielded by the particulate filtration procedure. On a square metre basis, the ABM gave values 1.4 times higher than those yielded by the particulate filtration procedure. The annual production at six marine locations was 57% higher when using the ABM. The ABM is superior to the traditional filtration procedure, because filtration artefacts are avoided, precision is improved, the dissolved primary production is included in the measurement, and the immediate amount of field work is considerably reduced.