title: Six Month In Situ High-Resolution Carbonate Chemistry and Temperature Study on a Coral Reef Flat Reveals Asynchronous pH and Temperature Anomalies.
abstract: Understanding the temporal dynamics of present thermal and pH exposure on coral reefs is crucial for elucidating reef response to future global change. Diel ranges in temperature and carbonate chemistry parameters coupled with seasonal changes in the mean conditions define periods during the year when a reef habitat is exposed to anomalous thermal and/or pH exposure. Anomalous conditions are defined as values that exceed an empirically estimated threshold for each variable. We present a 200-day time series from June through December 2010 of carbonate chemistry and environmental parameters measured on the Heron Island reef flat. These data reveal that aragonite saturation state, pH, and pCO2 were primarily modulated by biologically-driven changes in dissolved organic carbon (DIC) and total alkalinity (TA), rather than salinity and temperature. The largest diel temperature ranges occurred in austral spring, in October (1.5 - 6.6°C) and lowest diel ranges (0.9 - 3.2°C) were observed in July, at the peak of winter. We observed large diel total pH variability, with a maximum range of 7.7 - 8.5 total pH units, with minimum diel average pH values occurring during spring and maximum during fall. As with many other reefs, the nighttime pH minima on the reef flat were far lower than pH values predicted for the open ocean by 2100. DIC and TA both increased from June (end of Fall) to December (end of Spring). Using this high-resolution dataset, we developed exposure metrics of pH and temperature individually for intensity, duration, and severity of low pH and high temperature events, as well as a combined metric. Periods of anomalous temperature and pH exposure were asynchronous on the Heron Island reef flat, which underlines the importance of understanding the dynamics of co-occurrence of multiple stressors on coastal ecosystems.
authors.affiliation: Scripps Institution of Oceanography, Integrative Oceanography Division, University of California San Diego, San Diego, California, United States of America; Global Change Institute, The University of Queensland, Brisbane, Australia; Coral Reef Ecosystems Laboratory, School of Biological Sciences, The University of Queensland, Brisbane, Australia.
authors.forename: David I
authors.initials: DI
authors.lastname: Kline
authors.affiliation: Stanford University, Environmental Earth System Science, Stanford, CA, United States of America; Conservation International, Betty and Gordon Moore Center for Science and Oceans, Honolulu, HI, 96825, United States of America.
authors.forename: Lida
authors.initials: L
authors.lastname: Teneva
authors.affiliation: International Pacific Research Centre, University of Hawaii, Honolulu, HI, United States of America; Institute of Marine Science, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, United States of America.
authors.forename: Claudine
authors.initials: C
authors.lastname: Hauri
authors.affiliation: Stanford University, Environmental Earth System Science, Stanford, CA, United States of America; Carnegie Institution, Department of Global Ecology, Stanford, CA, United States of America.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Schneider
authors.affiliation: Coral Reef Ecosystems Laboratory, School of Biological Sciences, The University of Queensland, Brisbane, Australia; Institut Océanographique Paul Ricard, Ile des Embiez- Le Brusc, 83140, Six-Fours-Les-Plages, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Miard
authors.affiliation: Coral Reef Ecosystems Laboratory, School of Biological Sciences, The University of Queensland, Brisbane, Australia.
authors.forename: Aaron
authors.initials: A
authors.lastname: Chai
authors.affiliation: The University of Queensland, Faculty of Engineering, Architecture and Information Technology, Brisbane, Australia.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Marker
authors.affiliation: Stanford University, Environmental Earth System Science, Stanford, CA, United States of America.
authors.forename: Rob
authors.initials: R
authors.lastname: Dunbar
authors.affiliation: Carnegie Institution, Department of Global Ecology, Stanford, CA, United States of America.
authors.forename: Ken
authors.initials: K
authors.lastname: Caldeira
authors.affiliation: The Interuniversity Institute for Marine Sciences, The H. Steinitz Marine Biology Laboratory, The Hebrew University of Jerusalem, Eilat, Israel.
authors.forename: Boaz
authors.initials: B
authors.lastname: Lazar
authors.affiliation: The Interuniversity Institute for Marine Sciences, The H. Steinitz Marine Biology Laboratory, The Hebrew University of Jerusalem, Eilat, Israel.
authors.forename: Tanya
authors.initials: T
authors.lastname: Rivlin
authors.affiliation: Scripps Institution of Oceanography, Integrative Oceanography Division, University of California San Diego, San Diego, California, United States of America.
authors.forename: Brian Gregory
authors.initials: BG
authors.lastname: Mitchell
authors.affiliation: Global Change Institute, The University of Queensland, Brisbane, Australia; Coral Reef Ecosystems Laboratory, School of Biological Sciences, The University of Queensland, Brisbane, Australia; The ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Australia.
authors.forename: Sophie
authors.initials: S
authors.lastname: Dove
authors.affiliation: Global Change Institute, The University of Queensland, Brisbane, Australia; Coral Reef Ecosystems Laboratory, School of Biological Sciences, The University of Queensland, Brisbane, Australia; The ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Australia.
authors.forename: Ove
authors.initials: O
authors.lastname: Hoegh-Guldberg
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D057894:Coral Reefs; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D002119:Calcium Carbonate