The Research About Laws Of NO Effect On The Growth Of Marine Phytoplankton

Although nitric oxide (NO) is toxic but it is colorless and odorless. Due to its broad existence and special actions in the atmosphere and the diversity of its physiological functions in organism and high plants, NO has attracted a great deal of attention from biologist, physiologist, and chemist. NO is intituled as "Molecular of year" in 1992. The Nobel Prize of Physiology & Medicine in 1998 is awarded jointly to Robert F. Furchgott, Louis J. Ignarro and Ferid Murad for their discoveries concerning nitric oxide as a signalling molecule in the cardiovascular system. However, no research about NO in oceanological field has been reported. No research about the laws of NO effect on the growth of marine phytoplankton has been reported yet. So on one hand, this paper chooses four algae namely Platymonas halgolandica var. tsingtaoensis, Platymonas subcordiformis, Skeletonema costatum and Nitzschia closterium farma minutissima to discuss the laws of the NO effect on the growth of marine phytoplankton from chemical point of view for the first time. During the cultivation process, nitric oxide of different concentrations is added one or twice a day. On the other hand, this paper also discusses the variation of nitric oxide in Skeletonema costatum solution through ISO-NOPMC NO microsensors. The conclusions are as follows:(1) Nitric oxide is added into the medium when the four algae are growing. We found in f/2 medium or f/50 medium, the growth of these four algae are obviously promoted or inhibited when nitric oxide of different concentrations is added one or twice a day during the cultivation process.(2) The NO effect on the growth of marine phytoplankton is kurtosis. Different phytoplankton has different optimum NO concentration, which is consistent with the influence of NO on the growth of high plants.3(3) The effect of NO on Platymonas halgolandica var. tsingtaoensi and Platymonas subcordiformis, which is food algae, is different from that on the red tide algae Skeletonema costatum and Nitzschia closterium farma minutissima. First, the respond of the red tide algae to NO is more sensitive than that on the food algae. Second, the optimum NO concentration on the red tide is far lower than that on the food algae.(4) Put forward a new opinion, that is every algae has two kinds of NO threshold concentration. One can promote the growth of phytoplankton, and this value is about nmol or lower. The other can inhibit the phytoplankton growth, which is about u mol or higher.(5) The change of NO in the algae solution is complicated. It doesn't change into nutrient. Moreover, the relationship between the speed of NO variation in the algae solution and its concentration is nonlinear. The higher the NO concentration is, the higher speed of NO variation is.The above conclusions show that the effects of NO on the growth of marine phytoplankton are unassailable. The laws of the NO effect on the growth of marine phytoplankton may provide new clues to explain the formative and vanishing mechanism of red tide. These results are the experimental basis of further study on the nitrogen cycle in oceanic ecological system from chemical and biological points of view, which is important to the marine chemistry and marine biogeochemistry.