Applying acoustic scattering layer descriptors to depict mid-trophic pelagic organisation : the case of Atlantic African Large marine ecosystems continental shelf [résumé de poster]
Résumé
Hydroacoustic is a reliable and often used tool to monitor and study marine ecosystems. This study focus on acoustic scattered layers, which are the echosounder detection of pelagic marine organism of low trophic level, important in ecosystems functioning. Data have been recorded at 38 kHz in the three Atlantic African Large Marine Ecosystems (AA LME). To describe parsi-moniously ecosystems, compare them and understand the difference, 14 descriptors have been used. Some of them are based on already used descriptors and others are new. The aim of this study is to ensure that these descriptors are relevant to monitor and compare systems. So, we first explore spatial (intra- and inter-LME comparisons) and then temporal dimension (interannual variability). For such purpose, we use a large acoustic database collected over 15 years in the three AA LME: Canary Current LME, Guinea Current LME and Benguela Current LME. Our methodology is innovative, introducing original new descriptors to monitor pelagic com-partment of each LME and should be efficiently used for environmental monitoring in case of perturbation as overfishing, climate change or marine pollution. Indeed the acoustic scattered layer are mainly composed of macrozooplankton and ichtyoplankton which are sensitive to en-vironmental change.