%0 Conference Proceedings
%9 ACTI : Communications avec actes dans un congrès international
%A Tiedemann, M.
%A Brehmer, Patrice
%A Mouget, Anne
%A El Ayoubi, S.
%A Behagle, Nolwenn
%A Perrot, Yannick
%A Charouki, N.
%A Migayrou, C.
%A Uanivi, U.
%A Jeyid, M.A.
%A Mbye, E.M.
%A Rodriguez, E.
%A Sarré, A.
%T Comparative analysis of Diel Vertical migration between three Atlantic African large marine ecosystems [résumé de poster]
%S International conference ICAWA 2017 and 2018 : extended book of abstract : the AWA project : ecosystem approach to the management of fisheries and the marine environment in West African waters
%C [s.l.]
%D 2019
%E Brehmer, Patrice
%E Diogoul, N.
%E Zenk, C.
%E Vareilles, M. de
%E Keenlyside, N.
%E Nascimento, J.M.
%E Ramos, V. M.
%E Sow, B.A.
%E Fock, H.
%E Schmidt, J.
%E Ekau, W.
%E Mbaye, A.
%E Fall. A.
%E Monteiro, I.
%E Kouassi, A.M.
%E Silva, O.
%E Brochier, Timothée
%E Sall. M.
%E Mayif, M.
%E Koné, V.
%E Gorgues, Thomas
%E Ferreira Santos, C.
%E Bamy, I.L.
%E Barry, I.
%E Sidibe, M.
%E Diadhou, H.
%L fdi:010078281
%G ENG
%I SRFC/CSRP ; IRD
%@ 978-9553602-0-06
%K AFRIQUE DE L'OUEST ; ATLANTIQUE
%P 153
%U https://www.documentation.ird.fr/hor/fdi:010078281
%> https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers20-05/010078281.pdf
%W Horizon (IRD)
%X 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.
%B ICAWA : International Conference AWA
%8 2018/04/17-20
%$ 020 ; 021 ; 036 ; 032