Apparent Microfloral Response to Organic Degradation on Bathyal ­Seafloor: An Analysis Based on Sediment Fatty Acids

. Abyssal microfloral succession induced by experimental organic degradation was investigated. Notable changes in amounts and compositions of short‐chain (C9‐20) sediment fatty acids were observed, which indicated the shift of sediment microflora. Biomarker fatty acids for methanotrophs and sulfate‐reducing bacteria dominated. Resultant fatty acid compositions were most closely related to those from a nearby methane seep harboring a dense Calyptogena colony; the clams were also seen in close vicinity of the deployed organic mass. These observations suggest that the organic degradation on the bathyal seafloor stimulates the formation of methanotrophic and thio­trophic microflora, resulting in the formation of a methane‐seep‐type benthic community.