Assessing the Impact of Ocean Acidification on Coral Calcification: Investigating pH Induced Stress Responses in Coral Species

Coral reefs rank among the most critical ecosystems on Earth due to their exceptional biodiversity. These structures not only act as habitats for countless marine species but also safeguard shorelines and sustain global livelihoods through fisheries and tourism. Nevertheless, escalating levels of atmospheric CO₂ linked to climate change present a significant risk to their continued existence. When carbon dioxide (CO₂) dissolves in seawater, it reacts with water to form carbonic acid, which lowers pH levels and reduces the concentration of carbonate ions needed for coral skeleton formation. This study investigates how different pH levels (8.1, 7.8, and 7.6) influence coral calcification rates and overall health. We tracked their growth and stress responses over four weeks using Red Cap Montipora, Hispita Montipora, Toadstool Leather Coral, and Brown Sympodium as model species. The results indicate a significant correlation between decreasing pH levels and reduced coral growth, with up to a 50% reduction at pH 7.6. Corals exposed to more acidic conditions exhibited increased bleaching, tissue loss, and reduced polyp extension. These findings underscore the urgency of addressing rising CO₂ emissions to prevent irreversible damage to coral reefs, mainly as NOAA confirms we are experiencing the fourth global coral bleaching event since early 2023, unprecedentedly impacting reef systems worldwide.