Chemosynthetic habitats and biogeochemical processes at the Chilean methane seepage area – preliminary results from the SO210 expedition

The Chilean methane seepage area (CMSA) is characterized by patchy islands of chemosynthetic communities embedded in carbonate outcrops or plain sediment areas. The communities were often found to be dominated by one type of chemosynthetic organism: bacterial mat (Beggiatoa Sp.), clam fields (Calyptogena Sp., Archivesica Sp.), tubeworms (Lamellibrachia), and pogonophorans. Some samples revealed chemosynthetic organisms below the surface such as the clam Tyosira Sp. and the sulfur bacteria Thioploca. Other sites revealed indications of successions from a less to a more active seepage site (e.g., high-sulfidic sediments containing clam shells) or vice versa (e.g., sulfide-free sediments containing clam shells). This presentation will provide a preliminary overview of chemosynthetic communities and geochemical profiles at the CMSA and their implications for methane seepage and consumption activity in sediments.