Fatty acids in surface sediment at the Hebridean shelf edge, west of Scotland

Sediment samples were taken by multicorer from a site at 1000 m water depth on the Hebridean shelf edge, west of Scotland, nine times during the period April 1995 to July 1996, and the surface 1 cm was analysed for lipids. The aims of the study were to (a) determine the seasonal sources of the lipid inputs, and (b) assess the contribution of lipids of terrestrial origin to the lipid budget of surface sediments. The results indicate seasonal variation in the total fatty acid content, with highest concentrations in May, August and September consistent with phytoplankton blooms in spring and autumn. Bacterial biomass appears to increase in abundance in August and then slowly decreases until April. However, sediment fatty acid profiles did not accurately reflect the known species succession within the spring and summer phytoplankton bloom. The general lack of longer chain fatty acids is consistent with a predominantly marine input.