This presentation covers some of the approaches that have been used to assess the effects of ocean acidification and ocean-based carbon dioxide removal as well as other stressors using areas acidified by CO2 from underwater volcanoes.  A major advantage of such work is it shows which marine organisms can survive and what coastal habitats might look like in the coming years. These systems can also be used to assess effects on ecosystem services and how people might be affected by the consequences. As carbon dioxide levels increase this benefits some organisms but it causes an overall loss of marine biodiversity, both in temperate and in tropical systems. Key groups, like hard corals, sea urchins and coralline algae, are often lost and the diversity of fish and their reproduction are impacted. The talk highlights the diverse methods used to quantify the abundance and diversity of biota along these natural gradients in carbonate chemistry, the use of settlement substrata, reciprocal transplants, physiological studies as well as molecular and ‘omics approaches. The UN Ocean Decade program ICONA provides a great opportunity to replicate studies worldwide using natural analogues.

CO2 seep, underwater volcanoes, diversity, biota, natural analogues