Analysis of long time series of ADCP backscatter data in the Ligurian Sea to investigate the zooplankton variability

Three years of 300 kHz Acoustic Current Doppler Profiler ancillary data collected in the Central Ligurian Sea are analyzed to investigate the zooplankton diel vertical migration in the upper thermocline. After a pre-processing aimed at avoiding the slant range attenuation, hourly volume backscattering strength time series were obtained. Despite the lack of concurrent net samples collection, different migration patterns were identified and their seasonal variability examined by means of time-frequency analysis. Relationships with environmental conditions and lunar phase were also evidenced.