Characterization of phytoplankton communities by laser induced seawater fluorescence measurements

摘要

The results and methods obtained in one round-the world sea expedition and several north-western Pacific expeditions are presented. Measurements of hydrological and bio-optical parameters of seawater were carried out. It was used method of ship-borne laser-induced fluorescence realized in flowing variant which allow to conduct measurements during ship movement. In some expeditions in-depth fluorescence measurements were obtained with the help of fiber add-on device and in some cases two excitation wavelengths were used (355 and 532 nm). Dissolved organic matter (DOM) fluorescence - chlorophyll-a fluorescence scattering diagrams were investigated in various seawater areas of Oceans in different algae development stage. Procedure of phytoplankton communities characterization were offered, it is based on the data of hydrological measurements and on the parameters of linear regression between chlorophyll-a and DOM fluorescence. It was shown that significant linear correlation between chlorophyll-a fluorescence and DOM fluorescence induced by 532 nm Nd:YAG laser radiation generally observed during algae blooming and for all waters with chlorophyll-a concentration upper then 5 μg/l. The procedure can be used for flowing fluorometers or LIDAR fluorometers which allow to conduct measurements from moving carrier with spatial resolution better then 500 m.