抄録
Indigenous phytoplankton assemblage was used in algal assay procedure to estimate limiting nutrient for phytoplankton growth in marine water. Algal assays were also conducted using size-fractionated indigenous phytoplankton, i.e., microphytoplankton, nanophytoplankton, and picophytoplankton to identify the difference in limiting nutrient among phytoplankton species of different size. Specific conclusions derived from this study are as follows;
1) Indigenous phytoplankton assemblage could be used for algal assay to estimate limiting nutrient for phytoplankton growth.
2) There was the difference in limiting nutrient for phytoplankton growth between conventional algal assay procedure with Heterosigma akashiwo and the present method with indigenous phytoplankton community.
3) Growth of both microphytoplankton and nanophytoplankton was limited by nitrogen, whereas picophytoplankton was limited by phosphorus despite the same seawater sample.
4) It was possible to estimate the limiting nutrient for microphytoplankton, nanophytoplankton and picophytoplankton even in case of inoculation density equivalent to Kuroshio water or conventional algal assay procedure.
