title: Effect of carbonate chemistry alteration on the early embryonic development of the Pacific oyster (Crassostrea gigas).
abstract: Ocean acidification, due to anthropogenic CO₂ absorption by the ocean, may have profound impacts on marine biota. Calcareous organisms are expected to be particularly sensitive due to the decreasing availability of carbonate ions driven by decreasing pH levels. Recently, some studies focused on the early life stages of mollusks that are supposedly more sensitive to environmental disturbances than adult stages. Although these studies have shown decreased growth rates and increased proportions of abnormal development under low pH conditions, they did not allow attribution to pH induced changes in physiology or changes due to a decrease in aragonite saturation state. This study aims to assess the impact of several carbonate-system perturbations on the growth of Pacific oyster (Crassostrea gigas) larvae during the first 3 days of development (until shelled D-veliger larvae). Seawater with five different chemistries was obtained by separately manipulating pH, total alkalinity and aragonite saturation state (calcium addition). Results showed that the developmental success and growth rates were not directly affected by changes in pH or aragonite saturation state but were highly correlated with the availability of carbonate ions. In contrast to previous studies, both developmental success into viable D-shaped larvae and growth rates were not significantly altered as long as carbonate ion concentrations were above aragonite saturation levels, but they strongly decreased below saturation levels. These results suggest that the mechanisms used by these organisms to regulate calcification rates are not efficient enough to compensate for the low availability of carbonate ions under corrosive conditions.
authors.affiliation: Centre National de la Recherche Scientifique-Institut National des Sciences de l'Univers, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-Mer, France. f.gazeau@obs-vlfr.fr
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gazeau
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gattuso
authors.forename: Mervyn
authors.initials: M
authors.lastname: Greaves
authors.forename: Henry
authors.initials: H
authors.lastname: Elderfield
authors.forename: Jan
authors.initials: J
authors.lastname: Peene
authors.forename: Carlo H R
authors.initials: CH
authors.lastname: Heip
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Middelburg
mesh_terms: D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry / Q000494:pharmacology; D002254:Carbonates / Q000737:chemistry* / Q000494:pharmacology*; D049896:Crassostrea / Q000187:drug effects* / Q000196:embryology*; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D012623:Seawater / Q000737:chemistry; D013997:Time Factors
chemical_list: D002254:Carbonates; D002119:Calcium Carbonate