Effect of in situ acidification on the boring microflora of aragonitic substrates

• Main Author: Grange, J. S.
• Other Authors: Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), IRD, UPMC
• Format: Report
• Language: French
• Published: HAL CCSD 2012
• Subjects: Italia; Ischia; bioerosion; aragonitic substrates; boring microflora; acidification; envir; geo; Ocean acidification
• Online Access: https://hal.ird.fr/ird-01080744/file/M2julieGrange.compressed.pdf; https://hal.ird.fr/ird-01080744

Up to now, the impact of acidification on the boring microflora of calcifying organisms has only been addressed by Tribollet et al. (2009), in a short-term laboratory experiment. The study by Tribollet et al. (2009) is the first to show an accelerated weathering of limestone substrates by boring microflora when exposed to high partial pressure of carbon dioxide (750 ppm). The present study aims to investigate the impact of acidification on the microflora of two aragonitic substrates in volcanic carbon dioxide vents in Ischia in Italy. Three sites were selected along a gradient of pH and other environmental data (reported by Rodolpho-Metalpa et al. (2011)): a control site (C; pH = 8.02, close to current seawater pH), a S1 site (pH = 7.24) and a S2 site (pH = 7.44). To highlight the impact of ocean acidification on these micro-organimes, their species diversity was determined and several biological parameters were measured. These data were obtained through the realization of thin sections, which were observed under an optical microscope, and selected observations made with scanning electron microscopy. The results of this study are contradictory to the reference study. Indeed, for low pH rate of carbonate dissolution seems slow. To explain the opposition of the two main studies we hypothesize that there is a pH threshold at which bioerosion by boring microflora is slowed. A study on a pH gradient ranging from 8.1 to 7 with increments of 0.1 or 0.2 pH units would help to better understand the influence of ocean acidification on boring microflora L’impact de l’acidification sur les microperforants des organismes calcifiants n’a été abordé pour le moment que par Tribollet et al. (2009) lors d’une expérience réalisée à court terme et en aquarium. Cette étude a montré une accélération de l’altération des substrats calcaires par la microflore perforante lors d’une exposition à une forte pression partielle en dioxyde de carbone (750 ppm). L’étude présentée ici a pour objectif d’étudier l’impact de l’acidification sur ...