Each unique basins fauna exists in one of the most hostile areas to life known to exist.  The communities could last as long as the high saline anoxic environment can be maintained (van der Wielen et al. 2005).  With that being said, age estimates of these communities are very hard to hypothesize.  However, Parkes et al. (2000) report live bacteria in 4.7 million year old sapropels from the Mediterranean.  

           The bacteria contribute to biogeochemical cycling of sulfur and carbon (van der Wielen et al. 2005) , but it a mystery how these bacteria would leave traces in the sediment.  Maybe higher concentrations of methane than an average would indicate the presence of life.  The discovery of deep anoxic hypersaline bacteria is just beginning, so hopeful in the future we will know more about the bacteria themselves and how they impact their environment.