Corals for Climate Change

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BillTre
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Here is a long Science magazine News article on trying to engineer corals to better deal with climate change.
Two challenges corals face due to climate change:
  • increasing the temperature of the water in which coral lives (A 2˚ C temperature increase is said to be deadly to most coral)
  • as well as increasing the water's pH (higher pH increases the CaCO)3 tendancy to dissolve).

The researchers involved are taking several different approaches:
  • creating hybrids of existing corals
  • genetically modifying coral and it's symbiotic algae
  • manipulating the corals microbiome (bacteria/archaea)
  • raise corals and algae in more extreme environments to select for greater heat resistance
 

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  • #2
Bystander
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increasing the water's pH (higher pH increases the CaCO)3 tendancy to dissolve).
???
 
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Laroxe
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This seems a bit odd really. The Red sea is the warmest area and also has the richest diversity of life, it is also rich in coral species, none of that work is needed. The oceans are and will remain resolutely alkaline, people talk about acidification when what they mean is less alkaline. There are some extreme examples usually caused by pollution but the shear volume of buffers like calcium carbonate in rocks means long term change is virtually impossible.
 
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BillTre
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The oceans are and will remain resolutely alkaline, people talk about acidification when what they mean is less alkaline. There are some extreme examples usually caused by pollution but the shear volume of buffers like calcium carbonate in rocks means long term change is virtually impossible.
This article begs to differ.
 
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Laroxe
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This article begs to differ.
It doesn't disagree much, in fact you have to get to the results before it even mentions the PH and tries to get some wriggle room because of the relative insensitivity to change. Things are generally thought of as acidic when the PH gets below 7, I don't think you would get carbonates dissolving at a PH of around 8.2.
This is from a basic educational exercise at; is it wrong?
http://www.carboeurope.org/education/CS_Materials/CarbonatesAndpH.pdf
The major carbon reservoir in the ocean is in the dissolved inorganic carbon (DIC), which is the total of aqueous CO2, bicarbonate (HCO3) and carbonate (CO3) ions. The pH of seawater is dependent on which of these species is the most predominant. The normal present day pH of seawater is more on the basic side between 7,9 – 9,0. At this pH the HCO3ions predominate. Carbonate ion concentrations increase with increasing pH and when more CO2 dissolves in seawater it becomes more acidic. When CO2 from the atmosphere reacts with seawater, it immediately forms carbonic acid (H2CO3), which in itself is unstable. This further dissociates to form bicarbonate and carbonate ions. The bicarbonate and carbonate ions are responsible for the buffering capacity of seawater, i.e. seawater can resist drastic pH changes even after the addition of weak bases and acids. The carbonate ion can react with calcium ions (Ca), which are in excess in seawater, to form calcium carbonate (CaCO3), the material out of which the shells of mussels, the skeleton of corals and the exoskeleton of some microalgae is made of.
 
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BillTre
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Things are generally thought of as acidic when the PH gets below 7, I don't think you would get carbonates dissolving at a PH of around 8.2.
This is from a basic educational exercise at; is it wrong?
Just like the affect of blood pH on human health, it does not take a pH below 7.0 to start having adverse effects upon sealife. Relatively small pH changes can have strong adverse affects.
Besides things like corals and crustaceans which have obvious calcium carbonate skeletons, pteropods also have calcium carbonate shells. Pteropods are the base of the ocean food chain for many economically important life forms (meaning food for people) and therefore have been well studied.

Abstract from (Proceedings for the Royal Society B): Limacina helicina shell dissolution as an indicator of declining habitat suitability owing to ocean acidification in the California Current Ecosystem:
Few studies to date have demonstrated widespread biological impacts of ocean acidification (OA) under conditions currently found in the natural environment. From a combined survey of physical and chemical water properties and biological sampling along the Washington–Oregon–California coast in August 2011, we show that large portions of the shelf waters are corrosive to pteropods in the natural environment. We show a strong positive correlation between the proportion of pteropod individuals with severe shell dissolution damage and the percentage of undersaturated water in the top 100 m with respect to aragonite. We found 53% of onshore individuals and 24% of offshore individuals on average to have severe dissolution damage. Relative to pre-industrial CO2 concentrations, the extent of undersaturated waters in the top 100 m of the water column has increased over sixfold along the California Current Ecosystem (CCE). We estimate that the incidence of severe pteropod shell dissolution owing to anthropogenic OA has doubled in near shore habitats since pre-industrial conditions across this region and is on track to triple by 2050. These results demonstrate that habitat suitability for pteropods in the coastal CCE is declining. The observed impacts represent a baseline for future observations towards understanding broader scale OA effects.
 
  • #8
Laroxe
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My main problem with the article is that it didn't seem to make much sense and for some very obvious reasons, this sort of paper does little for the credibility of the science and that has become a huge problem. If I was commenting on the second there are some very similar problems. Its well known that there are significant local variations, particularly in coastal waters due to pollution. I'm presuming that OA isnt just a feature of the inshore waters of the west coast of the US.
This is interesting for the chemistry, and suggests that "On time scales shorter than ~103 yrs, the natural reservoirs that exchange carbon with the ocean can be considered essentially constant. They even describe it as a simplification, not for me it isnt. :)
https://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/Publications/ZeebeWolfEnclp07.pdf
 

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