Project: Toward Predicting the Impact of Ocean Acidification on Net Calcification by a Broad Range of Coral Reef Ecosystems: Identifying Patterns and Underlying Causes

Acronym/Short Name:Coral Reef Ecosystem OA Impact
Project Duration:2012-09 - 2015-08
Geolocation:Republic of Palau, Caroline Islands, Micronesia, western Pacific Ocean; Dongsha Atoll, Pratas Islands, South China Sea; Kingman Reef, US Northern Line Islands, 6 deg. 23 N, 162 deg. 25 W

Description

text copied from the NSF award abstract:

Much of our understanding of the impact of ocean acidification on coral reef calcification comes from laboratory manipulation experiments in which reef organisms are removed from their natural habitat and reared under conditions of calcium carbonate saturation (Omega) predicted for the tropical oceans at the end of this century. By comparison, there is a paucity of in situ data describing the sensitivity of coral reef ecosystems to changes in calcium carbonate saturation. Yet emerging evidence suggests there may be critical differences between the calcification response of organisms in culture and the net calcification response of a coral reef ecosystem, to the same degree of change in calcium carbonate saturation. In the majority of cases, the sensitivity of net reef calcification to changing calcium carbonate saturation is more severe than laboratory manipulation experiments predict. Clearly, accurate predictions of the response of coral reef ecosystems to 21st century ocean acidification will depend on a robust characterization of ecosystem-scale responses and an understanding of the fundamental processes that shape them. Using existing data, the investigators show that the sensitivity of coral reef ecosystem calcification to Delta calcium carbonate saturation conforms to the empirical rate equation R=k(Aragonite saturation state -1)n, which also describes the relationship between the rate of net abiogenic CaCO3 precipitation (R) and the degree of Aragonite supersaturation (Aragonite saturation state-1). By implication, the net ecosystem calcification (NEC) response to ocean acidification is governed by fundamental laws of physical chemistry and is potentially predictable across space and time. When viewed this way, the existing, albeit sparse, dataset of NEC reveals distinct patterns that, if verified, have important implications for how different coral reef ecosystems will respond to 21st century ocean acidification. The investigators have outlined a research program designed to build on this proposition. The project expands the currently sparse dataset of ecosystem-scale observations at four strategically placed reef sites: 2 sites in the Republic of Palau, Caroline Islands, Micronesia, western Pacific Ocean; a third at Dongsha Atoll, Pratas Islands, South China Sea; and the fourth at Kingman Reef, US Northern Line Islands, 6 deg. 23 N, 162 deg. 25 W.  The four selected sites will allow investigators to test the following hypotheses: (1) The sensitivity ("n" in the rate equation) of coral reef ecosystem calcification to Delta Aragonite saturation state decreases with decreasing Aragonite saturation state. By implication, the rate at which reef calcification declines will slow as ocean acidification progresses over the course of this century. (2) The energetic status of the calcifying community is a key determinant of absolute rates of net ecosystem calcification ("k" in the rate equation), which, combined with n, defines the Aragonite saturation state value at which NEC approaches zero. By implication, the shift from net calcification to net dissolution will be delayed in healthy, energetically replete coral reef ecosystems and accelerated in perturbed, energetically depleted ecosystems. and (3) The calcification response of individual colonies of dominant reef calcifiers (corals and algae) is weaker than the measured ecosystem-scale response to the same change in Aragonite saturation state. By implication, processes not adequately captured in laboratory experiments, such as bioerosion and dissolution, will play an important role in the coral reef response to ocean acidification.

Broader Impacts: Ocean acidification threatens the livelihoods of 500 million people worldwide who depend on coral reefs to provide habitable and agricultural land, food, building materials, coastal protection and income from tourism. Yet data emerging from ocean acidification (OA) studies point to critical gaps in our knowledge of reef ecosystem-scale responses to OA that currently limit our ability to predict the timing and severity of its impact on different reefs in different parts of the world. Using existing data generated by the investigators and others, this project will address a series of related hypotheses, which, if verified by the research, will have an immediate, direct impact on predictions of coral reef resilience in a high CO2 world. This project brings together expertise in coral reef biogeochemistry, chemical oceanography and physical oceanography to focus on a problem that has enormous societal, economic and conservation relevance. In addition to sharing the resultant data via BCO-DMO, project data will also be contributed to the Ocean Acidification International Coordination Centre (OA-ICC) data collection hosted at the PANGAEA Open Access library (http://www.pangaea.de).


DatasetLatest Version DateCurrent State
Porites coral calcification responses to declining Ωar in a CO2 manipulation experiment in Palau versus the calcification responses observed in ten other studies of massive Porites corals2017-06-30Final no updates expected
Weekly coral calcification rates in the CO2 manipulation experiment conducted on Porites corals from Palau2017-06-27Final no updates expected
Calcification rates of Porites corals collected from a naturally high-Ωar reef and a naturally low-Ωar reef in Palau incubated at three experimental Ωar conditions2017-06-26Final no updates expected
Data from reciprocal transplant experiments conducted on Porites coral collected on Palau in December 20122017-06-23Final no updates expected
Porites macrobioerosion study: individual calcification rates, skeleton density, and the volume of borings in the tropical Pacific from 2011-2012 (Coral Reef Ecosystem OA Impact project)2017-04-21Final no updates expected
Seawater chemistry measurements for Porites macrobioerosion experiments collected from reefs from across the Pacific Basin (Coral Reef Ecosystem OA Impact project)2017-04-20Final no updates expected
Temperature on Dongsha Atoll measured from June 2013 to August 20152017-04-18Final no updates expected
Coral extension, density, calcification, and bioerosion from corals collected at Palau from small boats from 2011-20132015-06-25Final no updates expected
Coral and algae cover, coral richness, and coral diversity from coral reef sites sampled by small boats in the Palauan archipelago from 2011-20132015-06-23Final no updates expected
Seawater carbonate chemistry from 13 sites in Palau collected from small boats in the Palauan archipelago from 2011-20132015-06-23Final no updates expected
Reef locations, macrobioerosion rates, and nitrate concentrations in the tropical Pacific from 2011-2012 (Coral Reef Ecosystem OA Impact project, Thermal Thresholds and Projections project)2014-12-10Final with updates expected

People

Lead Principal Investigator: Anne L. Cohen
Woods Hole Oceanographic Institution (WHOI)

Co-Principal Investigator: Steven J. Lentz
Woods Hole Oceanographic Institution (WHOI)

Co-Principal Investigator: Kathryn E.F. Shamberger
Texas A&M University (TAMU)


Programs

Science, Engineering and Education for Sustainability NSF-Wide Investment (SEES): Ocean Acidification (formerly CRI-OA) [SEES-OA]

Ocean Carbon and Biogeochemistry [OCB]