Mesozoic methane seep communities from the polar regions

by Crispin Little (University of Leeds)

Naturhistoriska riksmuseet

Naturhistoriska riksmuseet

Lilla hörsalen (mittemot restaurangen)
Modern hydrocarbon seeps host 'sister' communities to those found at hydrothermal vents, with a number of shared species, genera and families. Molecular biological studies suggest that many hydrothermal vent animals are derived from seep taxa. As at hydrothermal vents the ultimate energy source for hydrocarbon seep communities is hydrogen sulphide, although at seep sites the hydrogen sulphide is the result of the anaerobic oxidation of methane (AOM) by a sub-surface dwelling consortium of sulphate-reducing bacteria and methanotrophic archaea. Carbonate formation is induced by AOM and is consequently restricted to anoxic environments. The methane-derived carbonates show characteristic negative carbon isotope values <delta>13C as low as -60‰ PDB). The fossil record of hydrocarbon seep communities is increasingly well known and is proving to be richer than that of hydrothermal vent communities. By studying the hydrocarbon seep record we may get important insights into the observed temporal distribution pattern of hydrothermal vent taxa.