Water flow and ocean acidification effects on oxygen

The study Effects of water flow and ocean acidification on oxygen and pH gradients in coral boundary layer, published on the Scientific reports, made an interesting retrospective on the issue

by Lorenzo Ciotti
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Water flow and ocean acidification effects on oxygen
© Sean Gallup / Staff Getty Images

The process of continuous acidification of ocean waters undoubtedly leads to effects on the food chain and, in particular, can influence the lysocline and the carbonate compensation depth. With consequent dissolution of the calcareous shells of shells, molluscs and calcareous plankton, made up of calcium carbonate.

Continuing with this regime of greenhouse emissions, it is thought that in 2100 the oceans will lower by another 0.43 pH units, with inevitable effects for both human beings and ecosystems. Marine organisms sensitive to pH variations, in fact, could reproduce and thrive with increasing difficulty in the future, with a clear decrease in the food available in our markets. The fishing sector would be seriously affected and the populations that exploit fishing as a primary source of food would find themselves in serious situations of famine. Due to ocean acidification, marine wildlife is put in serious danger. The lowering of marine pH creates the phenomenon of coral bleaching; the calcium carbonate that makes up shells, molluscs, crustaceans and even coral decreases in relation to the increase in acidity, thus losing the algae that live on the surface of the organism, leading to its death.

Ocean acidification
Ocean acidification© Sean Gallup / Staff Getty Images
 

The study Effects of water flow and ocean acidification on oxygen and pH gradients in coral boundary layer, published on the Scientific reports, made an interesting retrospective on the issue.

The researchers explained: "Reef-building corals live in highly hydrodynamic environments, where water flow largely controls the complex chemical microenvironments surrounding them-the concentration boundary layer. The CBL may be key to alleviate ocean acidification effects on coral colonies by partially isolating them However, OA effects on coral CBL remain poorly understood, particularly under different flow velocities. Here, we investigated these effects on the reef-building corals Acropora cytherea, Pocillopora verrucosa, and Porites cylindrica four months and tested how low flow and moderate flow affected OA, traits remained generally stable across flows, except surface pH all species, the H+ CBL was thin and led to lower surface pH Still, low flow thickened H+ CBLs and increased light elevation of surface pH. In general, our findings reveal a weak to null OA modulation of the CBL. Moreover, the OA-buffering capacity by the H+ CBL may be limited in coral species, though low flow could enhance CBL sheltering."