Real-time detection of the red tide dinoflagellate Akashiwo sanguinea using a newly developed ultrasonic acoustic technique

Abstract

Red tide, known as harmful algal bloom, is caused by the proliferation of a toxic or nuisance algae species and has been the focus of worldwide research communities for several decades. Until recently, the techniques available for red tide detection were mainly microscopic and molecular techniques. However, these techniques are unable to detect in real time. Here, we have developed a technique for real-time detection of harmful algal blooms (HABs), focusing on ultrasonic acoustic backscattering properties. The developed detection system is mainly composed of a pulser-receiver board, signal processor board, control board, network board, power board, ultrasonic sensors (3.5 MHz), and environmental sensors. To evaluate the performance of the system, trails were performed in laboratory and field experiments. In the laboratory, the acoustic signal agreed with various levels of Akashiwo sanguinea (one of the HABs) densities. In field experiments (in Jangmok-Bay, South Korea), acoustic signals were not detected before blooms of A. sanguinea appeared. However, when A. sanguinea blooms appeared at density of over 3,000 cells mL-1, the acoustic signals varied with red tide occurrence density and there was a good correlation between the acoustic signal and A. sanguinea densities. Therefore, the developed ultrasonic acoustic detection system for early detection of HABs was shown to be an effective system to monitor the occurrencdetection were mainly microscopic and molecular techniques. However, these techniques are unable to detect in real time. Here, we have developed a technique for real-time detection of harmful algal blooms (HABs), focusing on ultrasonic acoustic backscattering properties. The developed detection system is mainly composed of a pulser-receiver board, signal processor board, control board, network board, power board, ultrasonic sensors (3.5 MHz), and environmental sensors. To evaluate the performance of the system, trails were performed in laboratory and field experiments. In the laboratory, the acoustic signal agreed with various levels of Akashiwo sanguinea (one of the HABs) densities. In field experiments (in Jangmok-Bay, South Korea), acoustic signals were not detected before blooms of A. sanguinea appeared. However, when A. sanguinea blooms appeared at density of over 3,000 cells mL-1, the acoustic signals varied with red tide occurrence density and there was a good correlation between the acoustic signal and A. sanguinea densities. Therefore, the developed ultrasonic acoustic detection system for early detection of HABs was shown to be an effective system to monitor the occurrenc