Combined effects of ocean acidification and warming

A new study focused on the responses of marine trophic levels to the combined effects of ocean acidification

by Lorenzo Ciotti
Combined effects of ocean acidification and warming
© Sean Gallup / Staff Getty Images Sport

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; resulting in the dissolution of the calcareous shells of shells, molluscs and calcareous plankton, made up of calcium carbonate. 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. Although many organisms are affected by this increasing acidification, some photosynthetic organisms benefit from it. One case is represented by diatoms. Microscopic algae belonging to the phytoplankton. For these organisms, the increase in CO2 in water increases their ability to carry out their photosynthesis processes. These processes can be carried out if certain environmental conditions are present.

Ocean acidification
Ocean acidification© Sean Gallup / Staff Getty Images Sport

The researchers, in the study Responses of marine trophic levels to the combined effects of ocean acidification and warming, published in the Nature communications, told:

"Marine organisms are simultaneously exposed to anthropogenic stressors associated with ocean acidification and ocean warming, with expected interactive effects. Species from different trophic levels with dissimilar characteristics and evolutionary histories are likely to respond differently. Here, we perform a meta-analysis of controlled experiments including both ocean acidification and ocean warming factors to investigate single and interactive effects of these stressors on marine species.

Contrary to expectations, we find that synergistic interactions are less common (16%) than additive (40%) and antagonistic (44%) interactions. overall and their proportion decreases with increasing trophic level. We also identify climate region-specific patterns, with interactive effects ranging from synergistic in temperate regions to compensatory in subtropical regions, to positive in tropical regions. Our findings improve understanding of how ocean warming, and acidification affect marine trophic levels and highlight the need for deeper consideration of multiple stressors in conservation efforts."