FlowCAM® is an imaging flow cytometer originally designed to characterize particles ranging from 20–200 µm. It provides an image-collage of captured particles and various numerical morpho-characters of each particle. This unique instrument is now widely used in planktology, especially in phytoplankton studies, aiming to reduce microscopy efforts and obtain detailed morphological data on planktonic particles. Because it can provide a continuous record of plankton occurrence and allows detection of rare plankton in its trigger modes, the application of FlowCAM in field research is of interest, especially for red-tide surveys. During our trials for wide-range surveys over the entirety of Tachibana Bay and the Ariake Sea (Nagasaki, Japan), FlowCAM was set onboard the research vessel Yumetobi (19 GT) and continuously monitored the occurrence of notorious red-tide causative raphidophytes Chattonella spp. along a total 148 km cruise line. FlowCAM detected dense occurrences of Chattonella antiqua at the mouth of Tachibana Bay, which continuously appeared to flow into the Ariake Sea. Even during a single cruise, numerous data on Chattonella occurrences were obtained–enough to analyze the water mass transporting the population from the Ariake Sea to Tachibana Bay. In the inner part of Tachibana Bay, on the contrary, no cells were detected over the 13 km cruise line, suggesting the area was tentatively free from red-tide risk; such judgment was not possible with regular on-station samplings. Prior to applying FlowCAM for such surveys, researchers must be careful to select the objective lens (×4 or ×10) and carefully calibrate the system for each target species, because the magnification that is chosen affects processing fluid volume and focal depth, which further affects the minimum detection limit and quantitativity.
抄録全体を表示