Stable isotopes in deep-sea living (stained) foraminifera from the Mozambique Channel (eastern Africa): multispecies signatures and paleoenvironmental application
|Author(s)||Fontanier Christophe1, 2, 3, 4, Sakai Saburo5, Toyofuku Takashi5, Garnier Eline1, 2, Brandily Christophe6, Eugene Thibaut7, Deflandre Bruno2|
|Affiliation(s)||1 : IFREMER, Lab Geodynam & Enregistements Sedimentaires, Ctr Brest, Technopole Brest Iroise,BP 70, F-29280 Plouzane, France.
2 : Univ Bordeaux, Lab Environm & Paleoenvironm Ocean & Continentaux, UMR 5805, F-33615 Pessac, France.
3 : FORAM, Foraminiferal Study Grp, F-49140 Villeveque, France.
4 : Univ Angers, F-49035 Angers, France.
5 : Japan Agcy Marine Earth Sci & Technol, 2-15 Natsushima Cho, Yokosuka, Kanagawa 2370061, Japan.
6 : IFREMER, Ctr Brest, Lab Environm Profonds, Technopole Brest Iroise,BP 70, F-29280 Plouzane, France.
7 : IFREMER, Ctr Brest, Serv Cartog Traitement Donnees & Instrumentat, Technopole Brest Iroise,BP 70, F-29280 Plouzane, France.
|Source||Journal Of Oceanography (0916-8370) (Springer), 2017-04 , Vol. 73 , N. 2 , P. 259-275|
|WOS© Times Cited||7|
|Keyword(s)||Oxygen and carbon isotopes, Deep-sea foraminifera, Organic matter, Oxygenation, Microhabitat|
|Abstract||Oxygen and carbon isotopes (δ18O and δ13C) have been investigated in carbonate tests of deep-sea foraminifera living in the Mozambique Channel (eastern Africa) to understand how environmental constraints (e.g., organic matter, oxygenation) control the intra- and interspecific variability of isotopic signatures. 197 living individuals, including eight different species, from various microhabitats within the sediment were sorted from sediment samples gathered at two stations on the Malagasy upper slope. Results show that the δ18O values of foraminiferal taxa were not controlled by microhabitat pattern. They presented tremendous and intriguing intraspecific variability that is not explained by the classical ontogenetic effect. The δ13C values of infaunal foraminiferal taxa do not show a 1:1 relationship with the bottom water δ13C DIC and do not present a constant offset from it; instead, they appear to be mainly controlled by a microhabitat effect. The lower δ13C values of shallow, intermediate, and deep infaunal taxa at the deeper station compared to those seen at the shallower station reflect the enhanced exportation of sedimentary organic matter at the sediment–water interface, and its related mineralization within the upper sediments. The ∆δ13C between shallow/very shallow infaunal species (i.e., Hoeglundina elegans, Uvigerina hispida) and intermediate/deep infaunal species (i.e., Melonis barleeanus, Globobulimina barbata) permits insight into (1) the exportation of organic matter to the seafloor and (2) the various degradation pathways for organic detritus in the benthic environments off NW Madagascar.|