title: CO2-induced ocean acidification increases anxiety in rockfish via alteration of GABAA receptor functioning.
abstract: The average surface pH of the ocean is dropping at a rapid rate due to the dissolution of anthropogenic CO2, raising concerns for marine life. Additionally, some coastal areas periodically experience upwelling of CO2-enriched water with reduced pH. Previous research has demonstrated ocean acidification (OA)-induced changes in behavioural and sensory systems including olfaction, which is due to altered function of neural gamma-aminobutyric acid type A (GABAA) receptors. Here, we used a camera-based tracking software system to examine whether OA-dependent changes in GABAA receptors affect anxiety in juvenile Californian rockfish (Sebastes diploproa). Anxiety was estimated using behavioural tests that measure light/dark preference (scototaxis) and proximity to an object. After one week in OA conditions projected for the next century in the California shore (1125 ± 100 µatm, pH 7.75), anxiety was significantly increased relative to controls (483 ± 40 µatm CO2, pH 8.1). The GABAA-receptor agonist muscimol, but not the antagonist gabazine, caused a significant increase in anxiety consistent with altered Cl(-) flux in OA-exposed fish. OA-exposed fish remained more anxious even after 7 days back in control seawater; however, they resumed their normal behaviour by day 12. These results show that OA could severely alter rockfish behaviour; however, this effect is reversible.
authors.affiliation: Department of Psychology, MacEwan University, , Edmonton, Alberta, Canada, Marine Biology Research Division, Scripps Institution of Oceanography, University of California, , San Diego, CA, USA.
authors.forename: Trevor James
authors.initials: TJ
authors.lastname: Hamilton
authors.forename: Adam
authors.initials: A
authors.lastname: Holcombe
authors.forename: Martin
authors.initials: M
authors.lastname: Tresguerres
mesh_terms: D000818:Animals; D001007:Anxiety / Q000139:chemically induced; D001522:Behavior, Animal / Q000187:drug effects*; D002245:Carbon Dioxide / Q000032:analysis*; D004781:Environmental Exposure; D029941:Fish Proteins / Q000502:physiology*; D018756:GABA Antagonists / Q000494:pharmacology; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D009118:Muscimol / Q000494:pharmacology; D009792:Oceans and Seas; D010473:Perciformes / Q000378:metabolism / Q000502:physiology*; D011724:Pyridazines / Q000494:pharmacology; D011963:Receptors, GABA-A / Q000502:physiology*; D012623:Seawater / Q000737:chemistry*
chemical_list: D029941:Fish Proteins; D018756:GABA Antagonists; D058785:GABA-A Receptor Agonists; D011724:Pyridazines; D011963:Receptors, GABA-A; D002245:Carbon Dioxide; D009118:Muscimol; C049853:gabazine
keywords: Sebastes; gabazine; muscimol; upwelling