I want to know how corals can affect the pH and other nutrients concentration of ambient seawater? I overheard someone talking about how corals could lower down the ambient pH. But I don't know why. Currently I am dealing with a sponge which can encrust on corals. If corals do affect the pH, there would be more factors for me to consider.
Everything that does photosynthesis in the sea, takes inorganic carbon out of the water, raising the pH. Likewise, anything which is giving off dissolved inorganic carbon as product of cellular respiration will be lowering the pH. The degree to which the pH changes in a given location depends on the intensity of the biological activity and water flow in the area.
Adding to the point of photosynthesis that the symbiotic algae in corals as example do and change the Ph. In addition, the time the corals are in stress either by anthropogenic or natural factors, they will lose energy and shows mucus which contribute to the Ph level and allow bacteria attack corals and causing necrosis affect and disease (black or white band) appears.
Dear Fang
Loved the question that you have raised here. Recently, an article came out in the journal called Nature Climate Change wherein the authors discussed over - how the biogeochemical responses of coral reef communities can partially offset changes in seawater pH and Ωa by an average of 12–24% and 15–31%, respectively! I am sending you the link. Please read on.
http://www.nature.com/nclimate/journal/v4/n1/full/nclimate2050.html
Yes. when corals are actively growing they will use more CO2 and pH may increase. When they are stressed and inactive, they respire more than they produce, release exudates facilitating bacterial activity and cause high respiration and decrease of pH.
as I mentioned before corals do change the pH of the ambient water which isinfluenced by their growth rate. during active phase of the growth of corals there will be temporal change in the p|H towards alkaline side as there will be a faster rate of CO2 use. similarly during this phase the nutrient use will be high and the ambient water surrounding the coral will be comparatively nutrient poor. the reverse will occur when the corals are stressed or are dying. I suppose there would be an increase in pH when the coral are encrusted by sponge. Please check from other sources.
Although you might expect that corals lower the CO2 in the surrounding sea water by accumulating it in their skeletons the reverse in true! When calcium carbonate is precipitated CO2 is generated rather than consumed (Arrhenius 1896) so this will lower the pH.
Ca2+ + 2 HCO3- CaCO3 + H2O + CO2
see Ware et al . 1991, link below
http://link.springer.com/article/10.1007%2FBF00255465#page-1
The short answer is yes but whether it increases or decreases pH and nutrient concentration and HOW they do can be complex. It depends on factors such as whether the corals have symbiotic algae and what the light, temperature and other ambient conditions are.
Coral records of reef-water pH across the central Great Barrier ...
https://pdfs.semanticscholar.org › ...
by JP D’Olivo .....
Also you can consult this book.. Best Wishes
Corals and Chemistry - Climate Change Lesson Plan - EPA
https://www3.epa.gov › climatechange › kids › documents › corals
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