Rapid assessments of Pacific Ocean net coral reef carbonate budgets and net calcification following the 2014–2017 global coral bleaching event

The 2014–2017 global coral bleaching event caused widespread coral mortality; however, its impact on the capacity for coral reefs to maintain calcium carbonate structures has not been determined. Here, we quantified remotely sensed maximum heat stress during the 2014–2017 bleaching event, census‐based net carbonate budgets from benthic imagery and fish survey data, and net reef calcification from salinity normalized seawater total alkalinity anomalies collected from 2017–2019 for 56 Pacific coral reef sites (Mariana Islands, Northwestern Hawaiian Islands, Pacific Remote Island Areas, and American Samoa). We incorporated the census‐based and chemistry‐based metrics to determine a calcification vulnerability index for each site to maintain calcium carbonate balance to provide accessible information to managers and policy makers. Most coral reef sites likely experienced ecologically severe (79%, n = 44) or significant (9%, n = 7) heat stress during the 2014–2017 coral bleaching event. Census‐based net carbonate budgets (mean ± 95% = 2.1 ± 0.6 kg CaCO3 m−2 yr−1) were positive for 77% of sites (n = 43), neutral for 16% of sites (n = 9), and negative for 7% of sites (n = 4). Chemistry‐based relative net reef calcification (mean ± 95% = 22 ± 10 μmol kg−1) was positive for 84% of sites (n = 47), neutral for 11% of sites (n = 6), and negative for 5% of sites (n = 3). The calcification vulnerability index suggested the Pacific Ocean reef sites surveyed were of minimal (68%, n = 38) to moderate (32%, n = 18) concern for maintaining calcium carbonate balance following the bleaching event. This suggests that many reefs maintained positive calcium carbonate balance, but that a large number of reefs may be approaching a potential threshold for maintaining their calcium carbonate balance under the climate crisis.

[1]  A. Andersson,et al.  Implications of salinity normalization of seawater total alkalinity in coral reef metabolism studies , 2021, PloS one.

[2]  Michael V. W. Cuttler,et al.  Predicting Responses of Geo-ecological Carbonate Reef Systems to Climate Change: A Conceptual Model and Review , 2021, Oceanography and Marine Biology.

[3]  David J. Kriegman,et al.  Area-normalized scaling of ReefBudget calcification, macrobioerosion, and microbioerosion rates for use with CoralNet Version 1.0 , 2021 .

[4]  Gang Liu,et al.  CoralTemp and the Coral Reef Watch Coral Bleaching Heat Stress Product Suite Version 3.1 , 2020, Remote. Sens..

[5]  N. Graham,et al.  Site-Level Variation in Parrotfish Grazing and Bioerosion as a Function of Species-Specific Feeding Metrics , 2020, Diversity.

[6]  K. Gross,et al.  Disturbances drive changes in coral community assemblages and coral calcification capacity , 2020, Ecosphere.

[7]  C. Perry,et al.  Carbonate budgets as indicators of functional reef “health”: A critical review of data underpinning census-based methods and current knowledge gaps , 2020, Ecological Indicators.

[8]  A. Andersson,et al.  Evaluating measurements of coral reef net ecosystem calcification rates , 2019, Coral Reefs.

[9]  Estradivari,et al.  Social–environmental drivers inform strategic management of coral reefs in the Anthropocene , 2019, Nature Ecology & Evolution.

[10]  C. Eakin,et al.  The 2014–2017 global-scale coral bleaching event: insights and impacts , 2019, Coral Reefs.

[11]  T. Oliver,et al.  El Niño-associated catastrophic coral mortality at Jarvis Island, central Equatorial Pacific , 2019, Coral Reefs.

[12]  W. Skirving,et al.  The relentless march of mass coral bleaching: a global perspective of changing heat stress , 2019, Coral Reefs.

[13]  Christina C. Hicks,et al.  Coral reef ecosystem services in the Anthropocene , 2019, Functional Ecology.

[14]  C. Perry,et al.  Changing geo‐ecological functions of coral reefs in the Anthropocene , 2018, Functional Ecology.

[15]  R. Steneck,et al.  Loss of coral reef growth capacity to track future increases in sea level , 2018, Nature.

[16]  B. Eyre,et al.  Coral reefs will transition to net dissolving before end of century , 2018, Science.

[17]  H. Page,et al.  Recovery of reef‐scale calcification following a bleaching event in Kāne'ohe Bay, Hawai'i , 2018 .

[18]  D. Gledhill,et al.  Taking the metabolic pulse of the world’s coral reefs , 2018, PloS one.

[19]  A. DesRochers,et al.  Long-term monitoring of coral reef fish assemblages in the Western central pacific , 2017, Scientific Data.

[20]  J. H. Burns,et al.  Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands) , 2017, PloS one.

[21]  R. van Woesik,et al.  Some coral diseases track climate oscillations in the Caribbean , 2017, Scientific Reports.

[22]  K. Yates,et al.  Divergence of seafloor elevation and sea level rise in coral reef ecosystems , 2017 .

[23]  A. Cohen,et al.  Mass coral mortality under local amplification of 2 °C ocean warming , 2017, Scientific Reports.

[24]  S. Jennings,et al.  Drivers and predictions of coral reef carbonate budget trajectories , 2017, Proceedings of the Royal Society B: Biological Sciences.

[25]  S. Planes,et al.  Local-scale projections of coral reef futures and implications of the Paris Agreement , 2016, Scientific Reports.

[26]  C. Sabine,et al.  Comparing Chemistry and Census-Based Estimates of Net Ecosystem Calcification on a Rim Reef in Bermuda , 2016, Front. Mar. Sci..

[27]  Timothy F. R. Burgess,et al.  Validation of Reef-Scale Thermal Stress Satellite Products for Coral Bleaching Monitoring , 2016, Remote. Sens..

[28]  Holly K. East,et al.  Remote coral reefs can sustain high growth potential and may match future sea-level trends , 2015, Scientific Reports.

[29]  N. Bates,et al.  Shifts in coral reef biogeochemistry and resulting acidification linked to offshore productivity , 2015, Proceedings of the National Academy of Sciences.

[30]  Chris Roelfsema,et al.  Towards Automated Annotation of Benthic Survey Images: Variability of Human Experts and Operational Modes of Automation , 2015, PloS one.

[31]  R. Dunbar,et al.  Environmental and ecological controls of coral community metabolism on Palmyra Atoll , 2015, Coral Reefs.

[32]  Ryan J. Lowe,et al.  Oceanic forcing of coral reefs. , 2015, Annual review of marine science.

[33]  L. Raymundo,et al.  Unprecedented coral bleaching across the Marianas Archipelago , 2014, Coral Reefs.

[34]  B. Eyre,et al.  Permeable coral reef sediment dissolution driven by elevated pCO2 and pore water advection , 2013 .

[35]  R. Steneck,et al.  Caribbean-wide decline in carbonate production threatens coral reef growth , 2013, Nature Communications.

[36]  D. Kadko,et al.  A multi‐tracer model approach to estimate reef water residence times , 2012 .

[37]  G. De’ath,et al.  The 27–year decline of coral cover on the Great Barrier Reef and its causes , 2012, Proceedings of the National Academy of Sciences.

[38]  David R. Bellwood,et al.  The Roles of Dimensionality, Canopies and Complexity in Ecosystem Monitoring , 2011, PloS one.

[39]  Scott F. Heron,et al.  Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005 , 2010, PloS one.

[40]  F. Mackenzie,et al.  Net Loss of CaCO 3 from a subtropical calcifying community due to seawater acidification: mesocosm-scale experimental evidence , 2009 .

[41]  J. Bruno,et al.  Regional Decline of Coral Cover in the Indo-Pacific: Timing, Extent, and Subregional Comparisons , 2007, PloS one.

[42]  P. Berg,et al.  Eddy correlation flux measurements: The sediment surface area that contributes to the flux , 2007 .

[43]  Akira Negishi,et al.  Seasonal and bleaching‐induced changes in coral reef metabolism and CO2 flux , 2005 .

[44]  A. Grant,et al.  Long-Term Region-Wide Declines in Caribbean Corals , 2003, Science.

[45]  R. Aronson,et al.  White-band disease and the changing face of Caribbean coral reefs , 2001, Hydrobiologia.

[46]  R. W. Buddemeier,et al.  The future of coral reefs in an age of global change , 2001 .

[47]  J. Gattuso,et al.  Validation of the alkalinity anomaly technique for investigating calcification of photosynthesis in coral reef communities , 1991 .

[48]  Stephen V. Smith,et al.  Stoichiometric modeling of carbon diagenesis within a coral reef framework , 1990 .

[49]  Arnold I. Miller,et al.  Production and Cycling of Calcium Carbonate in a Shelf-Edge Reef System (St. Croix, U.S. Virgin Islands): Applications to the Nature of Reef Systems in the Fossil Record , 1990 .

[50]  S. V. Smith,et al.  Carbon dioxide and metabolism in marine environments1 , 1975 .

[51]  Stephen V. Smith,et al.  Carbonate production by coral reefs , 1972 .

[52]  Taro Takahashi,et al.  Calcium carbonate precipitation on the Bahama Banks , 1966 .

[53]  Oscar Beijbom,et al.  Leveraging Automated Image Analysis Tools to Transform Our Capacity to Assess Status and Trends of Coral Reefs , 2019, Front. Mar. Sci..

[54]  Brett Schumacher,et al.  Analysis of benthic survey images via CoralNet : a summary of standard operating procedures and guidelines. , 2017 .

[55]  A. Heenan,et al.  Coral Reef Ecosystem Division standard operating procedures data collection for rapid ecological assessment fish surveys , 2011 .

[56]  THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. , 1931, Science.