Tiedemann M. auteur aut IRD Brehmer Patrice auteur aut IRD Mouget Anne auteur aut IRD El Ayoubi S. auteur aut IRD Behagle Nolwenn auteur aut IRD Perrot Yannick auteur aut IRD Charouki N. auteur aut IRD Migayrou C. auteur aut IRD Uanivi U. auteur aut IRD Jeyid M.A. auteur aut IRD Mbye E.M. auteur aut IRD Rodriguez E. auteur aut IRD Sarré A. auteur aut IRD text conferencePaper eng text/pdf reformatted digital access Diel vertical migration (DVM) of micronekton is a behavioural mechanism driven by a trade-off between predator avoidance and access to prey. This trade-off is controlled by environmental forcing that can lead to changes of DVM pattern under changing environmental conditions. Time series of hydro acoustic surveys between 1995 - 2015 of three large Atlantic ecosystems (Canary Current - CCLME, Guinea Current - GCLME, and Benguela Current - BCLME) were analysed to calculate DVM patterns based on volume backscattering strength (Sv). DVM related descriptors (n=15) were calculated for areas according to bathymetric definitions (shelf = 10 - 150 m bottom depth, slope = 150 - 500 m bottom depth, and plain > 500 m bottom depth). Typical DVM I pattern, with micronekton descending during daytime and ascending during night-time, were observed on the slope and plain in all three ecosystems, but not on the shelf with only negative day-night values in the CCLME and BCLME. Lower daytime Sv values during the day compared to night-time suggest either less dense patches of micronekton leading to negative day-night differences in the CCLME and GCLME or insufficient measurements of certain depth strata (e.g., 0 - 10 m surface). Only a few significant and different DVM descriptors suggest a change in the CCLME and the GCLME in the last 20 years. All other insignificant descriptors assume natural variability in large Atlantic ecosystems. Our results provide insight into inter-annual variability in micronekton DVM patterns. specialized AFRIQUE DE L'OUEST ATLANTIQUE 020 021 036 032 ICAWA : International Conference AWA, 5., Lanzarote (ESP), 2018/04/17-20 153 Brehmer Patrice ed. edt IRD Diogoul N. collab. clb IRD Zenk C. collab. clb IRD Vareilles M. de collab. clb IRD Keenlyside N. collab. clb IRD Nascimento J.M. collab. clb IRD Ramos V. M. collab. clb IRD Sow B.A. collab. clb IRD Fock H. collab. clb IRD Schmidt J. collab. clb IRD Ekau W. collab. clb IRD Mbaye A. collab. clb IRD Fall. A. collab. clb IRD Monteiro I. collab. clb IRD Kouassi A.M. collab. clb IRD Silva O. collab. clb IRD Brochier Timothée collab. clb IRD Sall. M. collab. clb IRD Mayif M. collab. clb IRD Koné V. collab. clb IRD Gorgues Thomas collab. clb IRD Ferreira Santos C. collab. clb IRD Bamy I.L. collab. clb IRD Barry I. collab. clb IRD Sidibe M. collab. clb IRD Diadhou H. collab. clb IRD Dakar (SEN) SRFC/CSRP Marseille IRD 2019 https://www.documentation.ird.fr/hor/fdi:010078281 978-9553602-0-06 [F A010078243] https://www.documentation.ird.fr/hor/fdi:010078281 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers20-05/010078281.pdf IRD - Base Horizon / Pleins textes 2020-05-05 2025-12-10 fdi:010078281 fre