Long-term evaluation of Harmful Algal Bloom’s real time acoustic detection system installed on the buoy

Abstract

The toxic, Harmful Algal Blooms (HABs, called red tide) caused by the Cochlodinium polykrikoides has serious impact annually in coastal waters of Korea and its impact is a tendency to increase in the world ocean. Considering rapidly dispersive speed and massive damage of the species, various methods for real-time detection are absolutely necessary.During the last 3 years, Korea Institute of Ocean Science & Technology has been developed real-time acoustic detection system, based on the acoustic scattering properties of C. polykrikoides. The acoustic detection system was comprised of mainly two components; (1) detection and process parts, (2) remote control & monitoring parts. Firstly, the detection and process parts were made up transducers (3.5 and 5.0 MHz), pulser/receiver board, signal processor board, control board, network board, power board, GPS, and environmental sensors, respectively. Secondly, remote control & monitoring parts were consisted of data receiver from the system/sending various commands into the system through the wireless network, and display using a developed user application program.After successfully stability evaluation under various conditions (no red-tide and red-tide) in laboratory, we operated and evaluated the two integrated systems to be installed on the buoy system during two months in summer season, Korea. From the results of a long term evaluation, although need to some modifications, the developed acoustic red tide detection system was well worked for a long term and a long distance, and acoustic data for deciding absent/present red tide were good correlated with directly sampling data, especially cell number of C. polykrikoides and other phytoplankton.From this study, the developed real-time acoustic detection system has shown a useful utility to early monitor and manages red tide in the coastal regions. Additionally, the system could be adapted to ship board type or hull-mounted type.