Community calcification in Lizard Island, Great Barrier Reef: A 33 year perspective

Silverman, Jacob; Schneider, K.J.; Kline, David I.; Rivlin, Tanya; Rivlin, Asaph; Hamylton, Sarah; Lazar, Boáz; Erez, Jonathan; Caldeira, Ken

doi:10.1016/j.gca.2014.09.011

Cited by 45 publications

(64 citation statements)

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“…The present experiments demonstrate the importance of living organisms on benthic surfaces in maintaining a positive balance between precipitation and dissolution of calcium carbonate. Whereas several reefs around the world are already at the threshold between precipitation and dissolution of calcium carbonate (Silverman et al, 2009(Silverman et al, , 2014, the susceptibility of coral reefs to net dissolution in the future likely will be linked directly to the proportion of the reef covered by macrocalcifiers and sediments. In addition to dissolution, it also is possible that coral reefs will be exposed to increased bioerosion at high pCO 2 (Wisshak et al, 2012;Crook et al, 2013) that will decrease the integrity of the carbonate framework.…”

Section: Discussionmentioning

confidence: 99%

Ocean acidification accelerates dissolution of experimental coral reef communities

et al. 2015

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Abstract. Ocean acidification (OA) poses a severe threat to tropical coral reefs, yet much of what is know about these effects comes from individual corals and algae incubated in isolation under high pCO 2 . Studies of similar effects on coral reef communities are scarce. To investigate the response of coral reef communities to OA, we used large outdoor flumes in which communities composed of calcified algae, corals, and sediment were combined to match the percentage cover of benthic communities in the shallow back reef of Moorea, French Polynesia. Reef communities in the flumes were exposed to ambient (∼ 400 µatm) and high pCO 2 (∼ 1300 µatm) for 8 weeks, and calcification rates measured for the constructed communities including the sediments. Community calcification was reduced by 59 % under high pCO 2 , with sediment dissolution explaining ∼ 50 % of this decrease; net calcification of corals and calcified algae remained positive but was reduced by 29 % under elevated pCO 2 . These results show that, despite the capacity of coral reef calcifiers to maintain positive net accretion of calcium carbonate under OA conditions, reef communities might transition to net dissolution as pCO 2 increases, particularly at night, due to enhanced sediment dissolution.

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Section: Discussionmentioning

confidence: 99%

Ocean acidification accelerates dissolution of experimental coral reef communities

et al. 2015

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“…For the latter, sustained observations of contemporaneous chemical and ecological conditions in reef and coastal environments provide important data sets to test our understanding of variability and response over time (e.g., Juranek et al, 2009;Alin et al, 2012Alin et al, , 2015Breitburg et al, 2015;Kline et al, 2015), but most time-series datasets do not extend beyond 5 years. Longer-term studies of reef chemistry and ecology are few in number (e.g., Silverman et al, 2012Silverman et al, , 2014 and often characterized by large gaps in time between repeat sampling.…”

Section: Introductionmentioning

confidence: 99%

Twenty Years of Marine Carbon Cycle Observations at Devils Hole Bermuda Provide Insights into Seasonal Hypoxia, Coral Reef Calcification, and Ocean Acidification

Bates

2017

Front. Mar. Sci.

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Open-ocean observations have revealed gradual changes in seawater carbon dioxide (CO 2 ) chemistry resulting from uptake of atmospheric CO 2 and ocean acidification (OA), but, with few long-term records (>5 years) of the coastal ocean that can reveal the pace and direction of environmental change. In this paper, observations collected from 1996 to 2016 at Harrington Sound, Bermuda, constitute one of the longest time-series of coastal ocean inorganic carbon chemistry. Uniquely, such changes can be placed into the context of contemporaneous offshore changes observed at the nearby Bermuda Atlantic Time-series Study (BATS) site. Onshore, surface dissolved inorganic carbon (DIC) and partial pressure of CO 2 (pCO 2 ; >10% change per decade) have increased and OA indicators such as pH and calcium carbonate (CaCO 3 ) saturation state ( ) decreased from 1996 to 2016 at a rate of two to three times that observed offshore at BATS. Such changes, combined with reduction of total alkalinity over time, reveal a complex interplay of biogeochemical processes influencing Bermuda reef metabolism, including net ecosystem production (NEP = gross primary production-autotrophic and heterotrophic respiration) and net ecosystem calcification (NEC = gross calcification-gross CaCO 3 dissolution). These long-term data show a seasonal shift between wintertime net heterotrophy and summertime net autotrophy for the entire Bermuda reef system. Over annual time-scales, the Bermuda reef system does not appear to be in trophic balance, but rather slightly net heterotrophic. In addition, the reef system is net accretive (i.e., gross calcification > gross CaCO 3 dissolution), but there were occasional periods when the entire reef system appears to transiently shift to net dissolution. A previous 5-year study of the Bermuda reef suggested that net calcification and net heterotrophy have both increased. Over the past 20 years, rates of net calcification and net heterotrophy determined for the Bermuda reef system have increased by ∼30%, most likely due to increased coral nutrition occurring in concert with increased offshore productivity in the surrounding subtropical North Atlantic Ocean. Importantly, this long-term study reveals that other environmental factors (such as coral feeding) can mitigate against the effects of ocean acidification on coral reef calcification, at least over the past couple of decades.

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“…Yet these projections do not eq kg −1 and 707 mol kg −1 respectively ( Fig. 5-2), greater than those measured in water flowing across other coral reefs where CO 2 with similar residence times and bathymetry (Shamberger et al, 2011;Shaw et al, 2014;Silverman et al, 2014;Kline et al, 2015).…”

Section: Carbonate Chemistry and Community Metabolismmentioning

confidence: 66%

“…These studies consistently report correlations between NEC and reef-water Ω , and these relationships are used to forecast when ocean acidification will shift reefs from net accretion to net dissolution (Ohde and van Woesik, 1999;Shamberger et al, 2011;Shaw et al, 2012;Bernstein et al, 2016;Muehllehner et al, 2016). Multi-decade declines of NEC have already been observed on the Great Barrier Reef and attributed primarily to ocean acidification (Silverman et al, 2012(Silverman et al, , 2014. Supporting this assertion, Albright et al (2016) artificially manipulated reef-water pH to levels of the pre-industrial open ocean, and found that NEC increased.…”

Section: Introductionmentioning

confidence: 77%

Coral biomineralization, climate proxies and the sensitivity of coral reefs to CO2-driven climate change

DeCarlo¹

2017

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Scleractinian corals extract calcium (Ca 2+ ) and carbonate (CO 2−3 ) ions from seawater to construct their calcium carbonate (CaCO 3 ) skeletons. Key to the coral biomineralization process is the active elevation of the CO 2− 3 concentration of the calcifying fluid to achieve rapid nucleation and growth of CaCO 3 crystals. Coral skeletons contain valuable records of past climate variability and contribute to the formation of coral reefs. However, limitations in our understanding of coral biomineralization hinder the accuracy of (1) coral-based reconstructions of past climate, and (2) predictions of coral reef futures as anthropogenic CO 2 emissions drive declines in seawater CO 2− 3 concentration.In this thesis, I investigate the mechanism of coral biomineralization and evaluate the sensitivity of coral reef CaCO 3 production to seawater carbonate chemistry. First, I conducted abiogenic CaCO 3 precipitation experiments that identified the U/Ca ratio as a proxy for fluid CO 2− 3 concentration. Based on these experimental results, I developed a quantitative coral biomineralization model that predicts temperature can be reconstructed from coral skeletons by combining Sr/Ca -which is sensitive to both temperature and CO 2− 3-with U/Ca into a new proxy called "Sr-U". I tested this prediction with 14 corals from the Pacific Ocean and the Red Sea spanning mean annual temperatures of 25.7-30.1 ∘ C and found that Sr-U has uncertainty of only 0.5 ∘ C, twice as accurate as conventional coral-based thermometers. Second, I investigated the processes that differentiate reef-water and open-ocean carbonate chemistry, and the sensitivity of ecosystem-scale calcification to these changes. On Dongsha Atoll in the northern South China Sea, metabolic activity of resident organisms elevates reef-water CO 2− 3 twice as high as the surrounding open ocean, driving rates of ecosystem calcification higher than any other coral reef studied to date. When high temperatures stressed the resident coral community, metabolic activity slowed, with dramatic effects on reef-water chemistry and ecosystem calcification. Overall, my thesis highlights how the modulation of CO 2− 3 , by benthic communities on the reef and individual coral polyps in the colony, controls the sensitivity of coral reefs to future ocean acidification and influences the climate records contained in the skeleton.

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Community calcification in Lizard Island, Great Barrier Reef: A 33 year perspective

Cited by 45 publications

References 45 publications

Ocean acidification accelerates dissolution of experimental coral reef communities

Ocean acidification accelerates dissolution of experimental coral reef communities

Twenty Years of Marine Carbon Cycle Observations at Devils Hole Bermuda Provide Insights into Seasonal Hypoxia, Coral Reef Calcification, and Ocean Acidification

Coral biomineralization, climate proxies and the sensitivity of coral reefs to CO2-driven climate change

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