Volume Backscattering Strength Estimation of Plankton from Water Column Multibeam Echosounder Data at Alor Strait, East Nusa Tenggara, Indonesia

Plankton support marine lives in significant roles as the main food source and ecological functions. However, marine information regarding plankton abundance is scanty and not distributed equally along Indonesian waters. In general, research in plankton abundance were conducted using conventional methods which unable to identify extensively. Hence, the main objective of this study was to estimate the qualitative volume backscattering strength (A ν ) of plankton abundance in the Alor Strait by utilizing multibeam echosounder water column data. Data acquisition was obtained during Jala Citra 3 - "Flores"2023 expedition held by the Indonesian Navy Hydrographic and Oceanographic Center. The instrument used in this study is the Kongsberg EM302 multibeam echosounder operating at a frequency of 30kHz which acquired both bathymetry and water column data simultaneously. The results show the average value of the volume backscattering strength that varies in the distribution of sample pings at the research site. The largest average Av value is -120.071 dB at sample point 287 which placed in shallow water by the nearest island. Additionally, the smallest value is -142.783 dB at sample point 272 with around 1800 meters depth. It expects the correlation between depth and volume backscatter strength value which can be further investigated.