Natural ocean acidification at Papagayo upwelling system (north Pacific Costa Rica): implications for reef development

摘要: Abstract. Numerous experiments have shown that ocean acidification impedes coral calcification, but knowledge about in situ reef ecosystem response to is still scarce. Bahia Culebra, situated at the northern Pacific coast of Costa Rica, a location naturally exposed acidic conditions due Papagayo seasonal upwelling. We measured pH and pCO2 during two non-upwelling seasons (June 2012, May–June 2013), with high temporal resolution every 15 30 min, respectively, using Submersible Autonomous Moored Instruments (SAMI-pH, SAMI-CO2). These results were compared published data from 2009 upwelling season. Findings revealed carbonate system Culebra shows variability. Incoming offshore waters drive intra- interseasonal changes. Lowest (7.8) highest (658.3 µatm) values cold-water intrusion event season similar those minimum reported (pH  =  7.8, pCO2  =  643.5 µatm), unveiling natural also occurs sporadically This affects interaction photosynthesis, respiration, calcification dissolution resulting diel cycle reefs Culebra. During season, aragonite saturation state (Ωa) rises  >  3.3 falls below 2.5. The Ωa threshold for growth derived correlation between linear extension rates which obtained literature suggest future will threaten continued contribute building better understanding dynamics reefs' key (e.g., growth) low-pH conditions, areas eastern tropical beyond.