Method and apparatus for calculating abundance of specific species of phytoplankton, and method and apparatus for detecting sign of red tide occurrence caused by specific species of phytoplankton

An apparatus for calculating an abundance of the specific species of the phytoplankton, the apparatus comprising:

• an excitation light generation unit that irradiates a reference sample containing a phytoplankton group with excitation light, the phytoplankton group containing a plurality of kinds of phytoplankton, the plurality of kinds of phytoplankton possibly including the specific species of the phytoplankton, and the specific species of the phytoplankton emitting fluorescence by absorbing the excitation light;
• a fluorescence intensity measurement unit that measures a reference sample wavelength band fluorescence intensity that is an intensity in each of two wavelength bands and a reference sample total fluorescence intensity that is an intensity in a substantially entire wavelength band;
• and
• a calculation unit that calculates a reference sample intensity ratio that is a ratio of the two reference sample wavelength band fluorescence intensities and calculates an other species plankton intensity ratio that is a ratio of intensities in each of the two wavelength bands of the fluorescence emitted from other species of phytoplankton other than the specific species of the phytoplankton in the phytoplankton group based on the reference sample intensity ratio, the reference sample total fluorescence intensity, and a reference abundance counted in advance in the specific species of the phytoplankton contained in the reference sample, wherein
• the excitation light generation unit irradiates an analysis sample, which is expected to have similarity with the reference sample with respect to composition of the phytoplankton group, with excitation light,
• the fluorescence intensity measurement unit measures a wavelength band fluorescence intensity that is an intensity in each of the two wavelength bands of the fluorescence emitted from the analysis sample and a total fluorescence intensity that is an intensity in a substantially entire wavelength band of the fluorescence emitted from the analysis sample, and
• the calculation unit calculates an intensity ratio that is a ratio of two of the wavelength band fluorescence intensities, and calculates an abundance of the specific species of the phytoplankton that may be contained in the analysis sample based on the other species plankton intensity ratio, the intensity ratio, and the total fluorescence intensity.