Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification
The equilibration of rising atmospheric ${\mathrm{CO}}_{2}$ with the ocean is lowering $\mathrm{pH}$ in tropical waters by about 0.01 every decade. Coral reefs and the ecosystems they support are regarded as one of the most vulnerable ecosystems to ocean acidification, threatening their long-term vi...
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ftdoajarticles:oai:doaj.org/article:4dd7d39bc81148d4afab82e36577dfe9 2023-09-05T13:22:08+02:00 Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification Mathieu Mongin Mark E Baird Scott Hadley Andrew Lenton 2016-01-01T00:00:00Z https://doi.org/10.1088/1748-9326/11/3/034023 https://doaj.org/article/4dd7d39bc81148d4afab82e36577dfe9 EN eng IOP Publishing https://doi.org/10.1088/1748-9326/11/3/034023 https://doaj.org/toc/1748-9326 doi:10.1088/1748-9326/11/3/034023 1748-9326 https://doaj.org/article/4dd7d39bc81148d4afab82e36577dfe9 Environmental Research Letters, Vol 11, Iss 3, p 034023 (2016) ocean acidfication carbonate chemistry marine management coral reef Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 article 2016 ftdoajarticles https://doi.org/10.1088/1748-9326/11/3/034023 2023-08-13T00:37:50Z The equilibration of rising atmospheric ${\mathrm{CO}}_{2}$ with the ocean is lowering $\mathrm{pH}$ in tropical waters by about 0.01 every decade. Coral reefs and the ecosystems they support are regarded as one of the most vulnerable ecosystems to ocean acidification, threatening their long-term viability. In response to this threat, different strategies for buffering the impact of ocean acidification have been proposed. As the $\mathrm{pH}$ experienced by individual corals on a natural reef system depends on many processes over different time scales, the efficacy of these buffering strategies remains largely unknown. Here we assess the feasibility and potential efficacy of a reef-scale (a few kilometers) carbon removal strategy, through the addition of seaweed (fleshy multicellular algae) farms within the Great Barrier Reef at the Heron Island reef. First, using diagnostic time-dependent age tracers in a hydrodynamic model, we determine the optimal location and size of the seaweed farm. Secondly, we analytically calculate the optimal density of the seaweed and harvesting strategy, finding, for the seaweed growth parameters used, a biomass of 42 g N m ^−2 with a harvesting rate of up 3.2 g N m ^−2 d ^−1 maximises the carbon sequestration and removal. Numerical experiments show that an optimally located 1.9 km ^2 farm and optimally harvested seaweed (removing biomass above 42 g N m ^−2 every 7 d) increased aragonite saturation by 0.1 over 24 km ^2 of the Heron Island reef. Thus, the most effective seaweed farm can only delay the impacts of global ocean acidification at the reef scale by 7–21 years, depending on future global carbon emissions. Our results highlight that only a kilometer-scale farm can partially mitigate global ocean acidification for a particular reef. Article in Journal/Newspaper Ocean acidification Directory of Open Access Journals: DOAJ Articles Heron Island ENVELOPE(-112.719,-112.719,58.384,58.384) Environmental Research Letters 11 3 034023 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
ocean acidfication carbonate chemistry marine management coral reef Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 |
spellingShingle |
ocean acidfication carbonate chemistry marine management coral reef Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 Mathieu Mongin Mark E Baird Scott Hadley Andrew Lenton Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification |
topic_facet |
ocean acidfication carbonate chemistry marine management coral reef Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 |
description |
The equilibration of rising atmospheric ${\mathrm{CO}}_{2}$ with the ocean is lowering $\mathrm{pH}$ in tropical waters by about 0.01 every decade. Coral reefs and the ecosystems they support are regarded as one of the most vulnerable ecosystems to ocean acidification, threatening their long-term viability. In response to this threat, different strategies for buffering the impact of ocean acidification have been proposed. As the $\mathrm{pH}$ experienced by individual corals on a natural reef system depends on many processes over different time scales, the efficacy of these buffering strategies remains largely unknown. Here we assess the feasibility and potential efficacy of a reef-scale (a few kilometers) carbon removal strategy, through the addition of seaweed (fleshy multicellular algae) farms within the Great Barrier Reef at the Heron Island reef. First, using diagnostic time-dependent age tracers in a hydrodynamic model, we determine the optimal location and size of the seaweed farm. Secondly, we analytically calculate the optimal density of the seaweed and harvesting strategy, finding, for the seaweed growth parameters used, a biomass of 42 g N m ^−2 with a harvesting rate of up 3.2 g N m ^−2 d ^−1 maximises the carbon sequestration and removal. Numerical experiments show that an optimally located 1.9 km ^2 farm and optimally harvested seaweed (removing biomass above 42 g N m ^−2 every 7 d) increased aragonite saturation by 0.1 over 24 km ^2 of the Heron Island reef. Thus, the most effective seaweed farm can only delay the impacts of global ocean acidification at the reef scale by 7–21 years, depending on future global carbon emissions. Our results highlight that only a kilometer-scale farm can partially mitigate global ocean acidification for a particular reef. |
format |
Article in Journal/Newspaper |
author |
Mathieu Mongin Mark E Baird Scott Hadley Andrew Lenton |
author_facet |
Mathieu Mongin Mark E Baird Scott Hadley Andrew Lenton |
author_sort |
Mathieu Mongin |
title |
Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification |
title_short |
Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification |
title_full |
Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification |
title_fullStr |
Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification |
title_full_unstemmed |
Optimising reef-scale CO2 removal by seaweed to buffer ocean acidification |
title_sort |
optimising reef-scale co2 removal by seaweed to buffer ocean acidification |
publisher |
IOP Publishing |
publishDate |
2016 |
url |
https://doi.org/10.1088/1748-9326/11/3/034023 https://doaj.org/article/4dd7d39bc81148d4afab82e36577dfe9 |
long_lat |
ENVELOPE(-112.719,-112.719,58.384,58.384) |
geographic |
Heron Island |
geographic_facet |
Heron Island |
genre |
Ocean acidification |
genre_facet |
Ocean acidification |
op_source |
Environmental Research Letters, Vol 11, Iss 3, p 034023 (2016) |
op_relation |
https://doi.org/10.1088/1748-9326/11/3/034023 https://doaj.org/toc/1748-9326 doi:10.1088/1748-9326/11/3/034023 1748-9326 https://doaj.org/article/4dd7d39bc81148d4afab82e36577dfe9 |
op_doi |
https://doi.org/10.1088/1748-9326/11/3/034023 |
container_title |
Environmental Research Letters |
container_volume |
11 |
container_issue |
3 |
container_start_page |
034023 |
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1776202657979957248 |