Citizen science request – UK watercraft duty cycles survey

[RunAgroundHard]

So the carbon is safely stored in perpetuity but it can be released by a yacht anchor? Anybody else find that hard to believe?

No, it's not hard to believe. Deep water tends to produce a stable seabed sediment that contains rotted organic matter. It remains there until it is disturbed e.g. by an anchor or trawling over the seabed. No idea if the quantity released by leisure sailors is a serious volume. In popular anchorages like Puilladobhrain south of Oban, it is probably so much churned up by anchoring that there is no carbon left to be released.

Disturbing the seabed could make climate change worse - British Antarctic Survey

Edit
This report, section 4.5 Risks to carbon stocks is worth reading if interested.

https://www.bluemarinefoundation.com/wp-content/uploads/2021/11/SAMS-03745-BCNSea-Report.pdf