Long-term history of chemoautotrophic clam-dominated faunas of petroleum seeps in the Northwestern Gulf of Mexico

摘要: Chemoautotrophic clam-dominated assemblages are commonly associated with petroleum seepage on the continental slope of Gulf Mexico. We examine persistence and resilence these communities by evaluating downcore trends in abundance, biomass, trophodynamics from four separate seep sites Louisiana slope. Some retained optimal habitat for some species continuously over geologically-relevant periods time. More commonly, however, optimality varied substantially time scales hundreds years. Thus, one important characteristic was degree chemoautotrophic biota. A fauna typically persistent a span few hundred years, but not longer span. The mechanisms producing local extinction remain unclear, however temporal variations juvenile survivorship seem to be larger than larval settlement, extent that heavily taphonomically-biased record individuals permits such conclusion. When extinctions occurred biota, biota replaced normal or mixture juveniles failed survive adulthood. only faunal transitions were between specific faunas non-chemoautotrophic fauna. Not distinctive transition two observed. Accordingly, each discrete resilient long scales; geological importance.