title: Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica.
abstract: Ocean acidification, caused by elevated seawater carbon dioxide levels, may have a deleterious impact on energetic processes in animals. Here we show that high PCO(2) can suppress metabolism, measured as oxygen consumption, in the pteropod, L. helicina forma antarctica, by ∼20%. The rates measured at 180-380 µatm (MO(2)  =  1.25 M(-0.25), p  =  0.007) were significantly higher (ANCOVA, p  =  0.004) than those measured at elevated target CO(2) levels in 2007 (789-1000 µatm,  =  0.78 M(-0.32), p  =  0.0008; Fig. 1). However, we further demonstrate metabolic plasticity in response to regional phytoplankton concentration and that the response to CO(2) is dependent on the baseline level of metabolism. We hypothesize that reduced regional Chl a levels in 2008 suppressed metabolism and masked the effect of ocean acidification. This effect of food limitation was not, we postulate, merely a result of gut clearance and specific dynamic action, but rather represents a sustained metabolic response to regional conditions. Thus, pteropod populations may be compromised by climate change, both directly via CO(2)-induced metabolic suppression, and indirectly via quantitative and qualitative changes to the phytoplankton community. Without the context provided by long-term observations (four seasons) and a multi-faceted laboratory analysis of the parameters affecting energetics, the complex response of polar pteropods to ocean acidification may be masked or misinterpreted.
authors.affiliation: Biological Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America. seibel@uri.edu
authors.forename: Brad A
authors.initials: BA
authors.lastname: Seibel
authors.forename: Amy E
authors.initials: AE
authors.lastname: Maas
authors.forename: Heidi M
authors.initials: HM
authors.lastname: Dierssen
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D001835:Body Weight; D002245:Carbon Dioxide / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D004734:Energy Metabolism; D049851:Gastropoda / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009792:Oceans and Seas; D010101:Oxygen Consumption; D012623:Seawater / Q000737:chemistry*
chemical_list: D002254:Carbonates; D002245:Carbon Dioxide