FN Archimer Export Format
PT J
TI Deep particle stocks following the summer bloom around the Kerguelen islands: Insights into diatoms physiological state, community structure and mortality modes
BT 
AF Leblanc, Karine
   Lafond, Augustin
   Cornet, Veronique
   Legras, Justine
   Marie, Barbara
   Queguiner, Bernard
AS 1:1;2:1;3:1;4:1;5:2;6:1;
FF 1:;2:;3:;4:;5:;6:;
C1 Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288 Marseille, France
   Sorbonne Université, CNRS, Laboratoire d'Océanographie Microbienne, LOMIC, F-66650 Banyuls/mer, France
C2 UNIV AIX MARSEILLE, FRANCE
   UNIV SORBONNE, FRANCE
IF 3.01
TC 1
UR https://archimer.ifremer.fr/doc/00704/81648/97811.pdf
LA English
DT Article
CR MOBYDICK-THEMISTO
BO Marion Dufresne
DE ;Biological carbon pump;Diatoms;Mortality modes;Southern Ocean;Diversity;Deep particle stocks
AB Particles located at the interface between the surface ocean layer and the top of the mesopelagic domain are the initial vector of the biological pump yet, their nature is still largely unknown. During the MOBYDICK cruise in the vicinity of the Kerguelen Islands (Indian sector of the Southern Ocean) we deployed a recently available device that concentrates and collects deep particles over a predetermined layer of water. In this paper, we present a detailed description of the collected particles and individual planktonic cells, including their taxonomy, carbon and lipid content, as well as cell viability, in order to characterize the particle stocks present at depth. The cruise was carried out at the end of the summer bloom, a period characterized by declining stocks of biogenic material associated with various mortality processes of planktonic organisms. Unexpectedly, the majority of the collected particles consisted of single empty diatom frustules, while fecal pellets and aggregates accounted for only a minor fraction. Distinct mortality processes, from parasitic infection to mesozooplankton grazing, and distinct silicification degrees as well as different life stages could be identified in relation to diatom taxa suggesting the occurrence of several export modes to intermediate and deep layers within the diatom community. We observed a dominant contribution of single cell diatoms (93 ± 6%) to the deep particle stocks but a very small contribution of intact diatom cells (~0.3%) to C content in the intermediate layer (125–500 m), together with a very small fecal pellet contribution, that was dominated by the minipellet size-class. Taxonomical analyses revealed distinct communities west of Kerguelen in the HNLC area compared to the island's fertilized plateau and its eastern flank. Differences in silicification degrees as well as distinct mortality/export processes linked to surface nutrient depletion and trophic interactions (such as parasitic infection or grazing by phaeodarians) were identified in the upper layer, leading to distinct contributions of major diatom taxa to deep suspended particles. 
PY 2021
PD OCT
SO Journal Of Marine Systems
SN 0924-7963
PU Elsevier BV
VL 222
UT 000691515600002
DI 10.1016/j.jmarsys.2021.103609
ID 81648
ER

EF