High prey-predator size ratios and unselective feeding in copepods: A seasonal comparison of five species with contrasting feeding modes

• Published in: Progress in Oceanography
• Main Authors: Djeghri, Nicolas, Atkinson, Angus, Fileman, Elaine S., Harmer, Rachel A., Widdicombe, Claire E., Mcevoy, Andrea J., Cornwell, Louise, Mayor, Daniel J.
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Plymouth Marine Laboratory (PML), Universität Hamburg (UHH), National Oceanography Centre Southampton (NOC), University of Southampton
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: ACL; Feeding; community; calanus-finmarchicus; Copepod; acartia-clausi; centropages-typicus; ecological research; egg-production; food selectivity; Intraguild predation; marine planktonic copepod; oithona-similis; Predator-prey size ratio; Selectivity; Sloppy feeding; Western Channel Observatory; Zooplankton biomass; helgolandicus; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Calanus finmarchicus; Copepods
• Online Access: https://hal.science/hal-02619265; https://hal.science/hal-02619265/document; https://hal.science/hal-02619265/file/Djeghri_etal_PiO_2018.pdf; https://doi.org/10.1016/j.pocean.2018.04.013

WOS:000441489600006 International audience There has been an upsurge of interest in trait-based approaches to zooplankton, modelling the seasonal changes in the feeding modes of zooplankton in relation to phytoplankton traits such as size or motility. We examined this link at two English Channel plankton monitoring sites south of Plymouth (L4 and El). At L4 there was a general transition from diatoms in spring to motile microplankton in summer and autumn, but this was not mirrored in the succession of copepod feeding traits; for example the ambushing Oithona similis dominated during the spring diatom bloom. At nearby El we measured seasonality of food and grazers, finding strong variation between 2014 and 2015 but overall low mesozooplankton biomass (median 4.5 mg C m(-3)). We also made a seasonal grazing study of five copepods with contrasting feeding modes (Calculus helgolandicus, Centropages typicus, Acartia clausi, Pseudocalanus elongatus and Oithona similis), counting the larger prey items from the natural seston. All species of copepod fed on all food types and differences between their diets were only subtle; the overriding driver of diet was the composition of the prey field. Even the smaller copepods fed on copepod nauplii at significant rates, supporting previous suggestions of the importance of intra-guild predation. All copepods, including O. similis, were capable of tackling extremely long ( \textgreater 500 mu m) diatom chains at clearance rates comparable to those on ciliates. Maximum observed prey:predator length ratios ranged from 0.12 (C. helgolandicus) up to 0.52 (O. similis). Unselective feeding behaviour and the ability to remove highly elongated cells have implications for how copepod feeding is represented in ecological and biogeochemical models.