Mesozooplankton structure and functioning during the onset of the Kerguelen phytoplankton bloom during the KEOPS2 survey

• Published in: Biogeosciences
• Main Authors: Carlotti, F, Jouandet, M.-P, Nowaczyk, A, Harmelin-Vivien, Mireille L., Lefèvre, Dominique, Richard, P, Zhu, Y, Zhou, M
• Other Authors: Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Department of Environmental, Earth and Ocean Sciences Boston (EEOS), University of Massachusetts Boston (UMass Boston), University of Massachusetts System (UMASS)-University of Massachusetts System (UMASS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: NATURAL IRON FERTILIZATION; STABLE-ISOTOPE RATIOS; SOUTHERN-OCEAN SOUTH; PELAGIC FOOD-WEB; MEDITERRANEAN SEA; SEASONAL SUCCESSION; NITROGEN ISOTOPE; ZOOPLANKTON; CARBON; COPEPODS; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDE.ES]Environmental Sciences/Environmental and Society; [SDE.MCG]Environmental Sciences/Global Changes; Kerguelen; Kerguelen Islands; Southern Ocean; Mesozooplankton; Copepods
• Online Access: https://hal-amu.archives-ouvertes.fr/hal-01231387; https://hal-amu.archives-ouvertes.fr/hal-01231387/document; https://hal-amu.archives-ouvertes.fr/hal-01231387/file/bg-12-4543-2015.pdf; https://doi.org/10.5194/bg-12-4543-2015

International audience This paper presents results on the spatial and temporal distribution patterns of mesozooplankton in the naturally fertilized region to the east of the Kerguelen Islands (Southern Ocean) visited at early bloom stage during the KEOPS2 survey (15 October to 20 November 2011). The aim of this study was to compare the zooplankton response in contrasted environments localized over the Kergue-len Plateau in waters of the east shelf and shelf edge and in productive oceanic deep waters characterized by conditions of complex circulation and rapidly changing phytoplankton biomass. The mesozooplankton community responded to the spring bloom earlier on the plateau than in the oceanic waters, where complex mesoscale circulation stimulated initial more or less ephemeral blooms before a broader bloom extension. Taxonomic compositions showed a high degree of similarity across the whole region, and the populations initially responded to spring bloom with a large production of lar-val forms increasing abundances, without biomass changes. Taxonomic composition and stable isotope ratios of size-fractionated zooplankton indicated the strong domination of herbivores, and the total zooplankton biomass values over the survey presented a significant correlation with the integrated chlorophyll concentrations in the mixed layer. The biomass stocks observed at the beginning of the KEOPS2 cruise were around 1.7 g C m −2 above the plateau and 1.2 g C m −2 in oceanic waters. Zooplankton biomass in oceanic waters remained on average below 2 g C m −2 over the study period, except for one station in the Polar Front zone (F-L), whereas zooplankton biomasses were around 4 g C m −2 on the plateau at the end of the survey. The most remarkable feature during the sampling period was the stronger increase in abundance in the oceanic waters (25 × 10 3 to 160 × 10 3 ind m −2) than on the plateau (25 × 10 3 to 90 × 10 3 ind m −2). The size structure and tax-onomic distribution patterns revealed a cumulative contribution of various ...