When bottom trawls are dragged across the seafloor, they stir up sediments. This not only releases previously stored organic carbon, but also intensifies the oxidation of pyrite, a mineral present in marine sediments, leading to additional emissions of carbon dioxide (CO2).
The resuspension of sediments from the seabed, caused by bottom trawling or by storms and tides, can significantly increase the release of CO2 into the atmosphere.