The length of time that gas hydrates remain outcropped on the surface, or are sufficiently near the surface to create methane plumes. is unknown.  Evidence exists to support the idea that hydrates can catestrophically degas, perhaps killing all communities associated with near-surface hydrates.  The carbonate deposits at the Carolina Rise methane seep were radiocarbon dated to the Pleistocene (Van Dover et al. 2003).  The communities also seem to live and die by the methane plume, as large numbers of dead mussels and clams were found on the periphery.  Dead clams and mussels were of the same sizes, respectively, demonstrating that they all died at about the same stage in their life cycle.  Younger clams and mussels currently residing in the dead fields suggest that the plume fluctuates with time and directly impacts these communities. (Van Dover et al .2003).

Logarythmic scale showing the length of time communties at methane seeps can survive.

Size distribution of mussels at two sites on the Blake  Ridge and Carolina Rise interesection showing distinct spikes, demonstrating the onset and demise of large communities of mussels, rather than a general curve showing mussels at all life stages.  This distribution supports the notion that these communties persist as long as the methane plumes, their energy source, exist (Van Dover et al. 2003).