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TITLE Development of Monitoring Technology of Oceanic Plankton Abundance
(Joint Program to Promote Technological Development with the Private Sectors)

in Alec Electronics Co.,Ltd


The purpose of this research to develop technologies those allow us to identify species of zooplanktons and phytoplankton as well as to count and to measure its size. The principle of one of our developing technologies is to classify phytoplankton based on its spectral characteristics of fluorescence. Another approach to distinguish phytoplankton from other suspended particulate matters is fluorescent imaging of phytoplankton.

We have developed a prototype of sensor that can classify phytoplankton into major taxonomic unit via characteristics of excitation spectrum. As excitation, 12  LEDs with different wavelength have been employed. To detect chlorophyll specific fluorescence, we use a photomultiplier tube. It has been demonstrated that discrimination is possible with this configuration.

To measure size of phytoplankton and to know the species, automatic imaging system has also developed. We can take image of plankton whose size is larger than 10 micro-meters. We have also developed fluorescent imaging of phytoplankton. This fluorescent imaging of particle allows us to distinguish phytoplankton from other non-fluorescent suspended particulate matter.

For zooplankton measurement, we have imaged plankton without any lens. Plankton flowing in a cuvette was imaged as a silhouette with laser beam. Compared to conventional imaging system with lens, this system enables us to take image more efficiently. Thus automatic counting of zooplankton is feasible

When these technologies are applied in the field of ocean, changes of carbon amount fixed by phytoplankton can be quantitatively estimated, and then absorption of carbon dioxide in the ocean can be estimated more precisely. Therefore, environmental assessment is believed to be performed more quantitatively.