Copepod Grazing Influences Diatom Aggregation and Particle Dynamics

• Published in: Frontiers in Marine Science
• Main Authors: Toullec, Jordan, Vincent, Dorothee, Frohn, Laura, Miner, Philippe, Le Goff, Manon, Devesa, Jeremy, Moriceau, Brivaëla
• 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 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), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Agence Française pour la Biodiversité (AFB), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-16-CE01-0002,BioPSis,La pompe biologique de carbone: 2 silicifiés essentiels(2016)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: ACL; organic-matter; marine snow; feeding-behavior; calanus-helgolandicus; sinking velocity; zooplankton fecal pellets; copepod; diatom aggregate; diel vertical migration; euterpina-acutifrons; fluorescence analysis; grazing experiment; particle dynamics; Rolling tank; sinking rates; transparent exopolymeric particles; envir; geo; Calanus hyperboreus; Copepods
• Online Access: https://doi.org/10.3389/fmars.2019.00751; https://hal.archives-ouvertes.fr/hal-02920512/file/Toullec_etal_FiMS_2019.pdf; https://hal.archives-ouvertes.fr/hal-02920512

WOS:000502962100001 International audience In marine ecosystems, carbon export is driven by particle flux which is modulated by aggregation, remineralization, and grazing processes. Zooplankton contribute to the sinking flux through the egestion of fast sinking fecal pellets but may also attenuate the flux by tearing apart phytoplankton aggregates into small pieces through swimming activity or direct ingestion. Freely suspended cells, artificial monospecific aggregates from two different diatom species (Chaetoceros neogracile and Skeletonema merinol) and natural aggregates of Melosira sp. were independently incubated with five different copepod species (Acadia clausi, Temora longicomis, Calanus helgolandicus, Euterpina acutifrons, and Calanus hyperboreus). During the grazing experiments initiated with free diatoms, E. acutifrons feeding activity evidenced by ingestion rates of 157 +/- 155 ng Chl a ind(-1) d(-1), induced a significant increase of S. marinoi aggregation. Transparent exopolymeric particles (TEP) production was only slightly boosted by the presence of grazers and turbulences created by swimming may be the main trigger of the aggregation processes. All copepods studied were able to graze on aggregates and quantitative estimates led to chlorophyll a ingestion rates (expressed in Chla a equivalent, i.e., the sum of chlorophyll a and pheopigments in their guts) ranging from 4 to 23 ng Chl a(eq) ind(-1) d(-1). The relation between equivalent spherical diameters (ESDs) and sinking velocities of the aggregates did not significantly change after grazing, suggesting that copepod grazing did not affect aggregate density as also shown by Si:C and C:N ratios. Three main trends in particle dynamics could be identified and further linked to the copepod feeding behavior and the size ratio between prey and predators: (1) Fragmentation of S. marinoi aggregates by the cruise feeder T. longicomis and of Melosira sp. aggregates by C. hyperboreus at prey to predator size ratios larger than 15; (2) no change of ...