Ultrasound backscattered power from Cochlodinium polykrikoides, the main red tide species in the Southern Sea of Korea

Abstract

The acoustic integrated backscattered power (IBP) of the phytoplankton Cochlodinium polykrikoides, which causes red tides in Korean waters, was measured in the laboratory and in the sea in situ to investigate the feasibility of observing red tides using high frequency ultrasound at 5 and 10 MHz. The IBP was measured with cultured C. polykrikoides at abundance levels of 90, 110, 200, 260, 300, 340, 360, 600, 700 and 850 cells/mL in the laboratory. Using the same high frequency acoustic transducers that were attached to the side of a research vessel, the IBP was measured in situ over a 9 km ship track near the Gumo Islands in Yeosu in the Southern Sea of Korea during the red tide season. The IBP was also measured simultaneously with positional information obtained from global positioning system data and by sampling the seawater in which C. polykrikoides was counted to survey the C. polykrikoides distribution in the study area. The IBP in situ was in agreement with that in the laboratory depending on the C. polykrikoides abundance. Consequently, we suggest that it is feasible to use underwater ultrasonic methodology for the observation of red tides in real time in situ.