title: Calcareous nannoplankton response to surface-water acidification around Oceanic Anoxic Event 1a.
abstract: Ocean acidification induced by atmospheric CO2 may be a major threat to marine ecosystems, particularly to calcareous nannoplankton. We show that, during the Aptian (approximately 120 million years ago) Oceanic Anoxic Event 1a, which resulted from a massive addition of volcanic CO2, the morphological features of calcareous nannofossils traced the biological response to acidified surface waters. We observe the demise of heavily calcified nannoconids and reduced calcite paleofluxes at the beginning of a pre-anoxia calcification crisis. Ephemeral coccolith dwarfism and malformation represent species-specific adjustments to survive lower pH, whereas later, abundance peaks indicate intermittent alkalinity recovery. Deepwater acidification occurred with a delay of 25,000 to 30,000 years. After the dissolution climax, nannoplankton and carbonate recovery developed over approximately 160,000 years under persisting global dysoxia-anoxia.
authors.affiliation: Dipartimento di Scienze della Terra Ardito Desio, Università degli Studi di Milano, via Mangiagalli 34, 20133 Milano, Italy. elisabetta.erba@unimi.it
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Erba
authors.forename: Cinzia
authors.initials: C
authors.lastname: Bottini
authors.forename: Helmut J
authors.initials: HJ
authors.lastname: Weissert
authors.forename: Christina E
authors.initials: CE
authors.lastname: Keller
mesh_terms: D000222:Adaptation, Physiological; D001272:Atmosphere; D002113:Calcification, Physiologic; D002119:Calcium Carbonate; D002245:Carbon Dioxide; D017753:Ecosystem; D005580:Fossils; D019015:Geologic Sediments; D006863:Hydrogen-Ion Concentration; D009792:Oceans and Seas; D010100:Oxygen; D010933:Plankton / Q000166:cytology / Q000502:physiology; D011157:Population Dynamics; D012623:Seawater / Q000737:chemistry*; D013995:Time
chemical_list: D002245:Carbon Dioxide; D002119:Calcium Carbonate; D010100:Oxygen