Evidence of zooplankton vertical migration from continuous Southern Adriatic buoy current-meter records. (October 2018)

• Record Type: Journal Article
• Authors: Ursella, Laura; Cardin, Vanessa; Batistić, Mirna; Garić, Rade; Gačić, Miroslav
• Is Part Of: Progress in oceanography. Volume 167(2018)
• Page Start: 78
• Page End: 96
• Publication Date: 2018-10
• Subjects: ADCP backscatter -- Zooplankton vertical migration -- Mixed layer depth -- Diel and seasonal cycles -- Net primary production -- Mixing process -- Eastern Mediterranean -- Southern Adriatic Pit; Oceanography -- Periodicals; 551.4605
• DOI: 10.1016/j.pocean.2018.07.004
• Languages: English
• ISSNs: 0079-6611

Abstract

Highlights: Good agreement between meso-zooplankton DVM and ADCP backscattering strength (Sv). Zooplankton migration is highly conditioned by environmental conditions. MLD, NPP and light (solar and lunar) influence vertical position of zooplankton. Sv and ADCP vertical velocity highlight different types/ranges of DVM. DVM is not mandatory behaviour but depends on food availability in deeper layers. Abstract: From the eleven-year data record at the Southern Adriatic Observatory (E2M3A), we study for the first time in the Adriatic Sea the strength of the backscatter signal from an Acoustic Doppler Current Profiler (ADCP) in relation to zooplankton vertical movement. The signal represents well the general behaviour of the zooplankton to sink at dawn and to emerge at the sunset. The modulation of the signal along the year is linked in particular to the different environmental conditions and the presence of different zooplankton groups. The correlation between the backscatter signal and distinct zooplankton groups (copepods, euphausiids, ostracods, appendicularians, salps) shows that in different seasons and environmental conditions, different groups are responsible for the strength of the signal. Furthermore, the backscatter signal, interpreted in terms of the qualitative composition of the zooplankton community, provides important information on the behaviour and habits of zooplankton in the southern Adriatic. Poorly known aspects of zooplankton behaviour are described in more detail, such as: recovery of zooplankton vertical distribution after mixing events, vertical migration in conditions of increased food availability at depth due to vertical mixing, modulation of vertical migration in dependence of the lunar phase and vertical migration in relation to deep chlorophyll maximum position. In addition, the present study emphasizes the possible influence of gelatinous zooplankton at the open sea on high backscatter values during the warmer part of the year.