High‐resolution carbon budgets on a Palau back‐reef modulated by interactions between hydrodynamics and reef metabolism

Diel trends in carbon chemistry and hydrodynamic regimes were measured on a coral‐dominated back‐reef community in the Republic of Palau, western Pacific. Observed diel ranges over 5 d were pH 7.92–8.09, partial pressure of carbon dioxide 33.4–52.7 Pa, measured total alkalinity 2080–2272 µmol kg−1, total dissolved inorganic carbon 1763–1939 µmol kg−1, aragonite saturation state 2.84–3.98, and calcite saturation state 4.44–5.67. The combination of reef metabolism and hydrodynamic regimes drives this variability. We report net community calcification (NCC) and net community production (NCP) rates of −20.4 (± 7.8) to 41.2 (± 37.7) mmol CaCO3 m−2 h−1 and 77.3 (± 95) to 64 (± 22) mmol C m−2 h−1, respectively. Using a control volume approach, we show that NCC and NCP rate estimates are quite sensitive to the effective control volume dimensions. At this site, tracking vertical mixing of water masses within the control volume shows that active water mixing is often confined to a region 2–3 m above the corals. Vertical carbon mass fluxes into and out of the benthic environment were unexpectedly large for the slow current flow rates observed, suggesting that coral morphology or reef rugosity may affect mass transport of carbon and nutrients. The ranges of NCC and NCP values highlight the need for additional field work on various reefs to tune and optimize the control volume approach to achieve its full potential for reef metabolism monitoring.

[1]  C. Langdon,et al.  Coral Reefs and Changing Seawater Carbonate Chemistry , 2013 .

[2]  Ryan J. Lowe,et al.  Physical and Biological Controls on the Carbonate Chemistry of Coral Reef Waters: Effects of Metabolism, Wave Forcing, Sea Level, and Geomorphology , 2013, PloS one.

[3]  S. Monismith,et al.  Comparison of mixing efficiency and vertical diffusivity models from temperature microstructure , 2012 .

[4]  K. Caldeira,et al.  Carbon turnover rates in the One Tree Island reef: A 40-year perspective , 2012 .

[5]  J. Smith,et al.  Diel Variability in Seawater pH Relates to Calcification and Benthic Community Structure on Coral Reefs , 2012, PloS one.

[6]  Paolo Montagna,et al.  Coral resilience to ocean acidification and global warming through pH up-regulation , 2012 .

[7]  D. Gledhill,et al.  Ocean Acidification Refugia of the Florida Reef Tract , 2012, PloS one.

[8]  Ken Caldeira,et al.  A short-term in situ CO2 enrichment experiment on Heron Island (GBR) , 2012, Scientific Reports.

[9]  Ryan J. Lowe,et al.  Seasonal coupling and de‐coupling of net calcification rates from coral reef metabolism and carbonate chemistry at Ningaloo Reef, Western Australia , 2012 .

[10]  Ryan J. Lowe,et al.  The combined influence of hydrodynamic forcing and calcification on the spatial distribution of alkalinity in a coral reef system , 2012 .

[11]  B. Tilbrook,et al.  Impacts of ocean acidification in naturally variable coral reef flat ecosystems , 2012 .

[12]  R. Feely,et al.  Calcification and organic production on a Hawaiian coral reef , 2011 .

[13]  J. Gattuso,et al.  Coral reefs modify their seawater carbon chemistry – implications for impacts of ocean acidification , 2011 .

[14]  S. Monismith,et al.  The modification of bottom boundary layer turbulence and mixing by internal waves shoaling on a barrier reef , 2011 .

[15]  M. Long,et al.  Vertical structure, seasonal drawdown, and net community production in the Ross Sea, Antarctica , 2011 .

[16]  F. Micheli,et al.  Divergent ecosystem responses within a benthic marine community to ocean acidification , 2011, Proceedings of the National Academy of Sciences.

[17]  J. Ries.  A physicochemical framework for interpreting the biological calcification response to CO 2 -induced ocean acidification , 2011 .

[18]  G. De’ath,et al.  Losers and winners in coral reefs acclimatized to elevated carbon dioxide concentrations , 2011 .

[19]  D. Allemand,et al.  Live Tissue Imaging Shows Reef Corals Elevate pH under Their Calcifying Tissue Relative to Seawater , 2011, PloS one.

[20]  B. Eyre,et al.  Diel coral reef acidification driven by porewater advection in permeable carbonate sands, Heron Island, Great Barrier Reef , 2011 .

[21]  Ryan J. Lowe,et al.  Short-term coherency between gross primary production and community respiration in an algal-dominated reef flat , 2011, Coral Reefs.

[22]  James L. Hench,et al.  Flow effects on benthic grazing on phytoplankton by a Caribbean reef , 2010 .

[23]  N. Bates,et al.  Feedbacks and responses of coral calcification on the Bermuda reef system to seasonal changes in biological processes and ocean acidification , 2010 .

[24]  D. Manzello.  Ocean acidification hotspots: Spatiotemporal dynamics of the seawater CO2 system of eastern Pacific coral reefs , 2010 .

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

[26]  T. Nakamura,et al.  Estimation of photosynthesis and calcification rates at a fringing reef by accounting for diurnal variations and the zonation of coral reef communities on reef flat and slope: a case study for the Shiraho reef, Ishigaki Island, southwest Japan , 2009, Coral Reefs.

[27]  Ryan J. Lowe,et al.  Continuous measurements of net production over a shallow reef community using a modified Eulerian approach , 2008 .

[28]  F. Mackenzie,et al.  Ocean acidification and calcifying reef organisms: a mesocosm investigation , 2008, Coral Reefs.

[29]  J. Erez,et al.  Effect of aragonite saturation, temperature, and nutrients on the community calcification rate of a coral reef , 2007 .

[30]  Ryan J. Lowe,et al.  Effects of nonlocal turbulence on the mass transfer of dissolved species to reef corals , 2007 .

[31]  S. Monismith.  Hydrodynamics of Coral Reefs , 2007 .

[32]  S. Monismith,et al.  Boundary layer turbulence and flow structure over a fringing coral reef , 2006 .

[33]  Kimberly K. Yates,et al.  CO 3 2− concentration and pCO 2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii , 2006 .

[34]  H. Kayanne,et al.  Analysis of the seawater CO2 system in the barrier reef‐lagoon system of Palau using total alkalinity‐dissolved inorganic carbon diagrams , 2006 .

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

[36]  Chris Langdon,et al.  Effect of elevated pCO2 on photosynthesis and calcification of corals and interactions with seasonal change in temperature/irradiance and nutrient enrichment , 2005 .

[37]  Joel H. Ferziger,et al.  Parameterization of turbulent fluxes and scales using homogeneous sheared stably stratified turbulence simulations , 2005, Journal of Fluid Mechanics.

[38]  M. Merrifield,et al.  Mass‐transfer limitation of nutrient uptake by a wave‐dominated reef flat community , 2004 .

[39]  S. G. Nelson,et al.  Effect of elevated CO2 on the community metabolism of an experimental coral reef , 2003 .

[40]  A. Dickson,et al.  Reference materials for oceanic CO2 analysis: a method for the certification of total alkalinity , 2003 .

[41]  H. Kayanne,et al.  Salinity records for the 1997–98 El Niño from Western Pacific corals , 2002 .

[42]  J. Jaubert,et al.  Primary production, respiration, and calcification of a coral reef mesocosm under increased CO2 partial pressure , 2002 .

[43]  S. Monismith,et al.  BPJ AKIN H/AVE£ Intense Benthic Grazing on Phytoplankton in Coral Reefs Revealed Using the Control Volume Approach , 2002 .

[44]  S. V. Smith,et al.  Measurement of community metabolism and significance in the coral reef CO2 source-sink debate. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[45]  Denis Allemand,et al.  Photosynthesis and Calcification at Cellular, Organismal and Community Levels in Coral Reefs: A Review on Interactions and Control by Carbonate Chemistry , 1999 .

[46]  R. Woesik,et al.  Carbon dioxide flux and metabolic processes of a coral reef, Okinawa , 1999 .

[47]  H. Kawahata,et al.  Coral reef ecosystems as a source of atmospheric CO2: evidence from PCO2 measurements of surface waters , 1997, Coral Reefs.

[48]  J. Gattuso,et al.  PRIMARY PRODUCTION, CALCIFICATION, AND AIR‐SEA CO2 FLUXES OF A MACROALGAL‐DOMINATED CORAL REEF COMMUNITY (MOOREA, FRENCH POLYNESIA) 1 , 1997 .

[49]  A. Al-shooshan.  Estimation of photosynthetically active radiation under an arid climate , 1997 .

[50]  J. Gattuso,et al.  Carbon fluxes in coral reefs. II. Eulerian study of inorganic carbon dynamics and measurement of air-sea CO2 exchanges , 1996 .

[51]  J. Gattuso,et al.  Carbon fluxes in coral reefs. I. Lagrangian measurement of community metabolism and resulting air-sea CO2 disequilibrium , 1996 .

[52]  D. J. Barnesa,et al.  Metabolic performance of a shallow reef patch near Eilat on the Red Sea , 1993 .

[53]  J. Gattuso,et al.  Community metabolism and air-sea C02 fluxes in a coral reef ecosystem (Moorea, French Polynesia) , 1993 .

[54]  R. Wanninkhof.  Relationship between wind speed and gas exchange over the ocean , 1992 .

[55]  R. Bilger,et al.  Effects of water velocity on phosphate uptake in coral reef-hat communities , 1992 .

[56]  D. Kinsey.  Metabolism, calcification and carbon production. I. System level studies , 1985 .

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

[58]  R. Weiss.  Carbon dioxide in water and seawater: the solubility of a non-ideal gas , 1974 .

[59]  C. Culberson,et al.  MEASUREMENT OF THE APPARENT DISSOCIATION CONSTANTS OF CARBONIC ACID IN SEAWATER AT ATMOSPHERIC PRESSURE1 , 1973 .

[60]  John King Vennard,et al.  Elementary Fluid Mechanics , 1940 .