Quantification of Floating Algae in a Small Reservoir Using a Multicopter

The landscape of a small pond in Fukuoka prefecture has been ruined by floating algae. Basic information, such as the type of algae, location of occurrence, and the amount of generated floating algae, was required to take action. In this study, we identified the floating algae by polarizing microscope observation and microbial community analysis. Additionally, we conducted aerial investigations using a multicopter equipped with a visual and near-infrared camera, and we quantified floating algae areas using images obtained from aerial observation. The results revealed that the floating algae were primarily made up of filamentous cyanobacteria from the family Pseudanabaenaceae. They mainly grow in the shallow area of the pond and peel off from the shallow bottom of the pond because of proliferation-related bubbles in summer. In addition, there was a relationship between the increase and decrease in algae carbon calculated using water temperature and solar radiation and the fluctuation in aerially observed algae area, suggesting that measures to limit solar radiation may be effective as a means of controlling algae proliferation.