Some results of artificially induced red tide in 4 mesocosm experiments, reported natural red tide processes in Western Xiamen Harbour, the relationship between the occurrence and distribution scale of diatom red tide, and relevant physical and chemical factors, are analysised and discussed in this paper. Present some results are summarized below.

There was little influences on diatom red tide occurrence by stirring the water column. Close relationship existed between nutrient concentrations and red tide formation in especially the concentration of active phosphates, which might be a inducing and controlling factor for diatom bloom in Western Xiamen Harbour. The (3 - 4) μg/L dissolved Mn, in the water was enough to support the phytoplanktonic proliferation. The unusual increase of dissolved Fe concentration in this region might stimulate the occurrence of diatom red tide. Vitamin B₁₂ can promote the division rate of some diatom, and so induce red tide occurrence or enlarging the distribution scale.