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Climate Change Will Enhance Hypercapnic Hypoxia Threatening Mangrove Habitats
Journal article   Open access   Peer reviewed

Climate Change Will Enhance Hypercapnic Hypoxia Threatening Mangrove Habitats

Gloria M.S. Reithmaier, Ariel K. Pezner, Adam Ulfsbo, Frank Melzner and Isaac R. Santos
Geophysical research letters, Vol.53(4), pp.1-10
28/02/2026
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Abstract

Mangroves host many marine species and support fisheries in developing (sub)tropical countries. The suitability of mangrove habitats depends strongly thier the water chemistry. Here, we show how global warming and rising atmospheric CO 2 will reduce dissolved oxygen and increase CO 2 in mangrove waters. Observations from 23 mangrove‐lined estuaries worldwide revealed that most sites already experience mild (34%–43% of the time) or severe (6%–32%) hypercapnic hypoxia, that is, high CO 2 and low oxygen conditions. Hypercapnic hypoxia mostly occurs during low tide, at low‐salinity sites, and in warm tropical regions. Climate change will decrease oxygen concentrations by 5%–35% and increase CO 2 concentrations by 8%–60% in mangrove waters by 2100. Overall, hypercapnic hypoxia events will occur more frequently, last longer, and become more severe. These shifts will reduce mangrove biodiversity and deteriorate habitat quality for commercially valuable fish. The strongest impact is expected in tropical developing countries. Plain Language Summary Mangrove forests are important coastal ecosystems that provide food, nursery grounds, and storm protection for millions of people, especially in tropical developing countries. Their value depends strongly on the chemistry of their surrounding waters. Using observations from 23 mangrove systems around the world, we show that mangrove waters already experience frequent periods of low oxygen and high carbon dioxide, which are stressful for many marine organisms. Climate change will worsen these problems by further reducing oxygen and raising carbon dioxide levels in mangrove waters. Stressful periods will occur more often, last longer, and become more severe. As a result, mangrove habitats will become less suitable for fish and other marine life, potentially reducing biodiversity and threatening coastal fisheries in developing countries.

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