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Simulation shows trawling and dredging impact the processes behind natural ocean alkalinity production

A pair of marine scientists at the University of Antwerp, in Belgium, working with a colleague from the University of Otago, in New Zealand, have found that simulations they created showed that trawling and dredging impact the processes behind natural ocean alkalinity production.

In their paper in the journal Science Advances, Astrid Hylén, Filip Meysman and Sebastiaan van de Velde, note that such changes can prevent the sea from sequestering as much carbon dioxide as it would otherwise, reducing its impact on mitigating climate change.

Prior research has suggested that approximately 30% of the carbon dioxide released into the atmosphere by humans is absorbed by the world's oceans. The result has been an increase in acidification, which has led to damage to coral reefs and possibly other ecosystems.

In this new study, the research team noted that little research has been done regarding the ability of the sea to absorb carbon dioxide in places where the seafloor is being disturbed by human activities, such as trawling or dredging to increase water depth. To learn more about such an impact, the researchers built a computer simulation.

The team first collected real-world data describing seafloor carbon flux and pH and oxygen levels over time in places where trawling and dredging has occurred. They then calculated the results of chemical reactions that occur when such activities take place. They then added data containing information about global dredging and trawling to calculate the global impact of these activities.

The research team found that the simulation showed approximately 2 to 8 teragrams of carbon dioxide being released into the sea, much of which makes its way back into the atmosphere—approximately equivalent to emissions from 1 million homes.

The researchers acknowledge that the amount of carbon dioxide being released by trawling and dredging is rather tiny compared to much bigger sources, such as cars or coal-burning factories, but also note that any reductions could help reduce global warming. They suggest new types of equipment be developed to catch marine life on the bottom of the sea or change where trawling and dredging are conducted to reduce carbon emissions from the seafloor in the coming years.