Modelling coral calcification accounting for the impacts of coral bleaching and ocean acidification

Abstract. Coral reefs are diverse ecosystems that are threatened by rising CO2 levels through increases in sea surface temperature and ocean acidification. Here we present a new unified model that links changes in temperature and carbonate chemistry to coral health. Changes in coral health and population are explicitly modelled by linking rates of growth, recovery and calcification to rates of bleaching and temperature-stress-induced mortality. The model is underpinned by four key principles: the Arrhenius equation, thermal specialisation, correlated up- and down-regulation of traits that are consistent with resource allocation trade-offs, and adaption to local environments. These general relationships allow this model to be constructed from a range of experimental and observational data. The performance of the model is assessed against independent data to demonstrate how it can capture the observed response of corals to stress. We also provide new insights into the factors that determine calcification rates and provide a framework based on well-known biological principles to help understand the observed global distribution of calcification rates. Our results suggest that, despite the implicit complexity of the coral reef environment, a simple model based on temperature, carbonate chemistry and different species can give insights into how corals respond to changes in temperature and ocean acidification.

Download Full-text

Modeling coral calcification accounting for the impacts of coral bleaching and ocean acidification

Biogeosciences Discussions ◽

10.5194/bgd-11-187-2014 ◽

2014 ◽

Vol 11 (1) ◽

pp. 187-249 ◽

Cited By ~ 1

Author(s):

C. Evenhuis ◽

A. Lenton ◽

N. E. Cantin ◽

J. M. Lough

Keyword(s):

Ocean Acidification ◽

Arrhenius Equation ◽

Carbonate Chemistry ◽

Reef Environment ◽

Local Environments ◽

Trade Offs ◽

Coral Reef Environment ◽

Coral Health ◽

Different Characteristics ◽

Rates Of Growth

Abstract. Coral reefs are diverse ecosystems threatened by rising CO2 levels that are driving the observed increases in sea surface temperature and ocean acidification. Here we present a new unified model that links changes in temperature and carbonate chemistry to coral health. Changes in coral health and population are able to explicitly modelled by linking the rates of growth, recovery and calcification to the rates of bleaching and temperature stress induced mortality. The model is underpinned by four key principles: the Arrhenius equation, thermal specialisation, resource allocation trade-offs, and adaption to local environments. These general relationships allow this model to be constructed from a range of experimental and observational data. The different characteristics of this model are also assessed against independent data to show that the model captures the observed response of corals. We also provide new insights into the factors that determine calcification rates and provide a framework based on well-known biological principles for understanding the observed global distribution of calcification rates. Our results suggest that, despite the implicit complexity of the coral reef environment, a simple model based on temperature, carbonate chemistry and different species can reproduce much of the observed response of corals to changes in temperature and ocean acidification.

Download Full-text

Benthic buffers and boosters of ocean acidification on coral reefs

Biogeosciences ◽

10.5194/bg-10-4897-2013 ◽

2013 ◽

Vol 10 (7) ◽

pp. 4897-4909 ◽

Cited By ~ 45

Author(s):

K. R. N. Anthony ◽

G. Diaz-Pulido ◽

N. Verlinden ◽

B. Tilbrook ◽

A. J. Andersson

Keyword(s):

Ocean Acidification ◽

Benthic Communities ◽

Time Of Day ◽

High Flow ◽

Net Community Production ◽

Reef Environment ◽

Saturation State ◽

Low Co2 ◽

Coral Reef Environment ◽

Community Production

Abstract. Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (NCP) and calcification (NCC). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in the seawater aragonite saturation state (Ωa). Results of flume studies using intact reef habitats (1.2 m by 0.4 m), showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350–450 μatm), macroalgae (Chnoospora implexa), turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h−1 – normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560–700 μatm) and high flow (35 compared to 8 cm s−1). In contrast, branching corals (Acropora aspera) increased Ωa by 0.25 h−1 at ambient CO2 (350–450 μatm) during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6–0.8 h−1) and exacerbated by acidification. Calcifying macroalgae (Halimeda spp.) raised Ωa by day (by around 0.13 h−1), but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from benthic communities with four different compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water-residence times in neighbouring areas dominated by turfs, macroalgae and carbonate sand.

Download Full-text

Benthic buffers and boosters of ocean acidification on coral reefs

Biogeosciences Discussions ◽

10.5194/bgd-10-1831-2013 ◽

2013 ◽

Vol 10 (2) ◽

pp. 1831-1865 ◽

Cited By ~ 6

Author(s):

K. R. N. Anthony ◽

G. Diaz-Pulido ◽

N. Verlinden ◽

B. Tilbrook ◽

A. J. Andersson

Keyword(s):

Ocean Acidification ◽

Time Of Day ◽

High Flow ◽

Net Community Production ◽

Reef Environment ◽

Saturation State ◽

Low Co2 ◽

Coral Reef Environment ◽

Co2 Level ◽

Community Production

Abstract. Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (pn) and calcification (gn). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in seawater aragonite saturation state (Ωa). Results of flume studies showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350–450 μatm), macroalgae (Chnoospora implexa), turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h−1 – normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560–700 μatm) and high flow (35 compared to 8 cm s−1). In contrast, branching corals (Acropora aspera) increased Ωa by 0.25 h−1 at ambient CO2 (350–450 μatm) during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6–0.8 h−1) and exacerbated by acidification. Calcifying macroalgae (Halimeda spp.) raised Ωa by day (by around 0.13 h−1), but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from four different benthic compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water residence times in neighbouring areas dominated by turfs, macroalgae and potentially sand.

Download Full-text

Cembranoids of Soft Coral Sarcophyton from Acidified Coral Reef Environment at Shallow Water CO2 vents in Volcano Island, Banda Neira, Indonesia

SQUALEN Bulletin of Marine and Fisheries Postharvest and Biotechnology ◽

10.15578/squalen.v12i1.276 ◽

2017 ◽

Vol 12 (1) ◽

Cited By ~ 2

Author(s):

Hedi Indra Januar ◽

Neviaty Putri Zamani ◽

Dedi Soedharma ◽

Ekowati Chasanah

Keyword(s):

Climate Change ◽

Genetic Diversity ◽

Ocean Acidification ◽

High Performance ◽

Soft Coral ◽

Future Climate Change ◽

Isolation And Identification ◽

Reef Environment ◽

Low Genetic Diversity ◽

Coral Reef Environment

Cembranoid content in soft coral is known as a chemotype that relate with genotype and environment. This research aimed to characterize the cembranoid Sarcophyton soft coral from the reef that acidified by CO2 volcanic vents (pHT 7.8) at Volcano Islands waters, Banda-Neira (Indonesia), as a means of predicting the future impact of ocean acidification to the genetic diversity of Sarcophyton soft coral. 30 random colonies were taken, combined, and extracted with ethanol. Cembranoid isolation and identification had been done by high performance liquid chromatography and spectrometry techniques. Results of the study found sarcophytol derivatives (sarcophytol A, 11,12-epoxy sarcophytol A, sarcophytol B, and sarcophytol M) as the only chemotype in the sample. This may suggest low genetic diversity in the observed Sarcophyton sample. Therefore, it may suggest that even soft coral is known to be resilient to future acidification pressures, the genetic diversity or the production of diverse cytotoxic metabolite may be hampered due to ocean acidification in future climate change adaptation.

Download Full-text

Calcification of an estuarine coccolithophore increases with ocean acidification when subjected to diurnally fluctuating carbonate chemistry

Marine Ecology Progress Series ◽

10.3354/meps12639 ◽

2018 ◽

Vol 601 ◽

pp. 59-76

Author(s):

MM White ◽

DT Drapeau ◽

LC Lubelczyk ◽

VC Abel ◽

BC Bowler ◽

...

Keyword(s):

Ocean Acidification ◽

Carbonate Chemistry

Download Full-text

Thermal stress reduces pocilloporid coral resilience to ocean acidification by impairing control over calcifying fluid chemistry

Science Advances ◽

10.1126/sciadv.aba9958 ◽

2021 ◽

Vol 7 (2) ◽

pp. eaba9958

Author(s):

Maxence Guillermic ◽

Louise P. Cameron ◽

Ilian De Corte ◽

Sambuddha Misra ◽

Jelle Bijma ◽

...

Keyword(s):

Thermal Stress ◽

Ocean Acidification ◽

Pocillopora Damicornis ◽

Carbonate Chemistry ◽

Negative Interaction ◽

Saturation State ◽

Stylophora Pistillata ◽

Coral Calcification ◽

Influence Of Temperature On ◽

Different Time Scales

The combination of thermal stress and ocean acidification (OA) can more negatively affect coral calcification than an individual stressors, but the mechanism behind this interaction is unknown. We used two independent methods (microelectrode and boron geochemistry) to measure calcifying fluid pH (pHcf) and carbonate chemistry of the corals Pocillopora damicornis and Stylophora pistillata grown under various temperature and pCO2 conditions. Although these approaches demonstrate that they record pHcf over different time scales, they reveal that both species can cope with OA under optimal temperatures (28°C) by elevating pHcf and aragonite saturation state (Ωcf) in support of calcification. At 31°C, neither species elevated these parameters as they did at 28°C and, likewise, could not maintain substantially positive calcification rates under any pH treatment. These results reveal a previously uncharacterized influence of temperature on coral pHcf regulation—the apparent mechanism behind the negative interaction between thermal stress and OA on coral calcification.

Download Full-text

Evaluating the feasibility and advantage of a multi-purpose submerged breakwater for harbor protection and benthic habitat enhancement at Kahului Commercial Harbor, Hawai‘i: case study

SN Applied Sciences ◽

10.1007/s42452-020-04072-4 ◽

2021 ◽

Vol 3 (2) ◽

Author(s):

Yuko Stender ◽

Michael Foley ◽

Ku’ulei Rodgers ◽

Paul Jokiel ◽

Amarjit Singh

Keyword(s):

Coral Reef ◽

Coral Cover ◽

Ecological Impact ◽

Coastal Protection ◽

Benthic Habitat ◽

Engineering Structures ◽

Camera System ◽

Reef Environment ◽

Submerged Breakwater ◽

Coral Reef Environment

AbstractConstruction of breakwaters provides an engineering solution for coastal protection. However, little effort has been made toward understanding the ecological impact on local coral reef ecosystems and developing engineering structures that would enhance the coral reef environment. A submerged breakwater proposed for Kahului Commercial Harbor, Hawai‘i, provided an opportunity to design a multi-purpose ‘reef structure’ to mitigate wave impacts while providing new coral reef habitat. This design involved ecological and environmental considerations alongside engineering principles, serving as a model for environmentally sound harbor development. This field study evaluated environmental conditions and reef community composition at the proposed site in a gradient extending outward from the harbor, using in situ data with multivariate analyses. Benthic and topographic features in the area were assessed using a towed drop camera system to relate to biological factors. Results that support breakwater topography should follow the natural spur and groove and depth of the adjacent reef and orient with wave direction. A deep area characterized by unconsolidated substrata and low coral cover would be replaced with the shallow, sloping hard bottom of the breakwater, and provide an exemplary area for corals to flourish while protecting the harbor from large ocean swells. Surfaces on shallow sloping hard bottoms receive higher levels of irradiance that benefits coral growth. Optimal levels of water motion facilitate sediment removal and promote coral recruitment and growth. The design of the Kahului Harbor submerged multi-purpose structure serves as a model for design of shoreline modification that enhances, rather than degrades, the local coral reef environment.

Download Full-text

Estimation of Sand Distribution in Coral Reef Environment using Colour Segmentation and Colour Thresholding Methods

Universiti Malaysia Terengganu Journal of Undergraduate Research ◽

10.46754/umtjur.v1i3.83 ◽

2019 ◽

Vol 1 (3) ◽

pp. 96-104

Author(s):

Pauleen Ong ◽

Muhammad Suzuri Hitam ◽

Zainuddin Bachok ◽

Mohd Safuan Che Din

Keyword(s):

Coral Reef ◽

Extraction Methods ◽

Colour Difference ◽

Reef Environment ◽

Still Images ◽

Point Count ◽

Automatic Computer ◽

Computer Based ◽

Coral Reef Environment ◽

Colour Segmentation

At present, marine scientists employ manual method to estimate the components in coral reef environment, where Coral Point Count with Excel extensions (CPCe) software is used to determine the coral reef components and substrate coverage. This manual process is laborious and time consuming, and needs experts to conduct the survey. In this paper, a prototype for estimating the distribution of sand cover in coral reef environment from still images by using colour extraction methods was introduced. The colour segmentation called delta E was used to calculate the colour difference between two colour samples. Another method used was colour threshold by setting the range of sand colour pixels. The system was developed by using a MATLAB software with image processing toolbox. The developed system was semi-automatic computer-based system that can be used by researchers even with little knowledge and experience to estimate the percentage of sand coverage in coral reef still images.

Download Full-text

Change Detection in Coral Reef Environment Using High-Resolution Images: Comparison of Object-Based and Pixel-Based Paradigms

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi7110441 ◽

2018 ◽

Vol 7 (11) ◽

pp. 441 ◽

Cited By ~ 11

Author(s):

Zhenjin Zhou ◽

Lei Ma ◽

Tengyu Fu ◽

Ge Zhang ◽

Mengru Yao ◽

...

Keyword(s):

Coral Reef ◽

Change Detection ◽

Accuracy Assessment ◽

Detection Accuracy ◽

Reef Environment ◽

Object Based ◽

Coral Reef Environment ◽

Study Sites ◽

Object Area ◽

Segmentation Image

Despite increases in the spatial resolution of satellite imagery prompting interest in object-based image analysis, few studies have used object-based methods for monitoring changes in coral reefs. This study proposes a high accuracy object-based change detection (OBCD) method intended for coral reef environment, which uses QuickBird and WorldView-2 images. The proposed methodological framework includes image fusion, multi-temporal image segmentation, image differencing, random forests models, and object-area-based accuracy assessment. For validation, we applied the method to images of four coral reef study sites in the South China Sea. We compared the proposed OBCD method with a conventional pixel-based change detection (PBCD) method by implementing both methods under the same conditions. The average overall accuracy of OBCD exceeded 90%, which was approximately 20% higher than PBCD. The OBCD method was free from salt-and-pepper effects and was less prone to images misregistration in terms of change detection accuracy and mapping results. The object-area-based accuracy assessment reached a higher overall accuracy and per-class accuracy than the object-number-based and pixel-number-based accuracy assessment.

Download Full-text

A short history of ocean acidification science in the 20th century: a chemist's view

Biogeosciences ◽

10.5194/bg-10-7411-2013 ◽

2013 ◽

Vol 10 (11) ◽

pp. 7411-7422 ◽

Cited By ~ 7

Author(s):

P. G. Brewer

Keyword(s):

Ocean Acidification ◽

20Th Century ◽

Fossil Fuel ◽

Trade Offs ◽

History Of ◽

Chemical Knowledge ◽

The Creation ◽

Ph Scale ◽

The Impact

Abstract. This review covers the development of ocean acidification science, with an emphasis on the creation of ocean chemical knowledge, through the course of the 20th century. This begins with the creation of the pH scale by Sørensen in 1909 and ends with the widespread knowledge of the impact of the "High CO2 Ocean" by then well underway as the trajectory along the IPCC scenario pathways continues. By mid-century the massive role of the ocean in absorbing fossil fuel CO2 was known to specialists, but not appreciated by the greater scientific community. By the end of the century the trade-offs between the beneficial role of the ocean in absorbing some 90% of all heat created, and the accumulation of some 50% of all fossil fuel CO2 emitted, and the impacts on marine life were becoming more clear. This paper documents the evolution of knowledge throughout this period.

Download Full-text