Free and bound fatty acids and hydroxy fatty acids in the living and decomposing eelgrass Zostera marina L.

Very early diagenetic processes of free, esterified and amide or glycosidically bound fatty acids and hydroxy fatty acids present in well documented samples of living and decomposing eelgrass (Zostera marina L.) were investigated. Free and esterified fatty acids decreased significantly over a period of decay of 12.5 years, although their distribution patterns were largely unchanged. Amide or glycosidically bound α-hydroxy fatty acids and the newly recognized α,β-dihydroxy fatty acids were not degraded. Thus both, but in particular the α,β-dihydroxy fatty acids, may serve as potential biomarkers for the recognition of eelgrasses in palaeoenvironments. The increasing amounts of ω-hydroxy fatty acids and α,ω-dicarboxylic fatty acids upon decay indicate bacterial transformations of eelgrass lipids. This bacterial action was further demonstrated by a substantial increase of amide-bound β-hydroxy fatty acids derived from LPS of gram-negative bacteria.