Marine organisms in the Southern Ocean may find themselves between a rock and a hard place by the end of the century as ocean acidification creates a shallower zone for life. The new research results forecast that at current carbon dioxide (CO2) emission rates, the depth at which some shelled organisms can survive will shrink from an average of 1,000 meters (3,280 feet) to just 150 meters (492 feet) by the year 2100, a drastic reduction in habitat. The change, which could happen over a period as short as one year in some areas, could significantly impact marine food webs and lead to cascading changes across ocean ecosystems, including disruptions of fisheries. Acidification occurs when oceans absorb atmospheric CO2 created by burning fossil fuels. The absorption alters the water's chemistry, lowering its pH and reducing the amount of available carbonate, which organisms such as corals and pteropods (mollusks) use to construct their calcium carbonate shells. The Southern Ocean is particularly vulnerable to acidification due to colder waters that increase the solubility of CO2 and upwelling that brings carbon-rich water close to the surface.
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