A new CO2 vent for the study of ocean acidification in the Atlantic

•A new underwater CO2 vent has been discovered in the South East coast of La Palma Island.•Annual CO2 emission is around 900 ppm reducing pH values to an annual average of 7.86 ± 0.16.•The pH reduction found at the vent site is predicted for world oceans to occur over the next 70 years.•Nutrients analysis performed at the vent site shows higher levels of Si-SO4 compared to other studied sites.

Natural CO2 vents are considered the gold standard of ocean acidification (OA) studies. In coastal areas these rare vents have only been investigated at the Mediterranean temperate rocky reefs and at Indo-Pacific coral reefs, although there should be more at other volcanic shores around the world. Substantial scientific efforts on investigating OA effects have been mostly performed by laboratory experiments. However, there is a debate on how acute this kind of approach truly represents the responses to OA scenarios, since it generally involves short-term, rapid perturbation and single variable and species experiments. Due to these limitations, world areas with natural CO2 vents are essential to understand long-term marine ecosystem responses to rising human derived atmospheric CO2 concentrations. Here, we presented a new vent found in the subtropical North East Atlantic reefs (28°N, La Palma Island) that shows moderate CO2 emission (900 ppm), reducing pH values to an annual average of 7.86 ± 0.16.

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