Middelburg, J. J.. Netherlands Institute of Ecology, Middelburg@cemo.nioo.knaw.nl
Herman, P. J.. Netherlands Institute of Ecology, herman@cemo.nioo.knaw.nl
Boschker, E. Netherlands Institute of Ecology, boschker@cemo.nioo.knaw.nl
Barranguet, C. Dept. of Ecotoxicology, Univ. of Amsterdam, barranguet@bio.vu.nl

At two intertidal sites (one sandy and one more silty in the Schelde estuary, The Netherlands) the fate of microphytobenthos was studied through an in situ 13C labelling approach. Label was added at the beginning of low tide and uptake of 13C by algae, and its transfer to bacteria and a variety of benthic animals was followed. Uptake was linear during the whole period of tidal exposure. About halve of the initially labelled organic matter was recovered after four days, but the labelled organic matter was displaced towards deeper sediment layers, in particular at the dynamic, sandy site. The incorporation of 13C into bacterial biomass was quantified by carbon-isotope analyses of polar lipid derived fatty acids (PLFA) specific for bacteria. The PLFA i15:0, a characteristic biomarker for heterotrophic bacteria, showed significant transfer from the benthic algae to the bacteria and a maximum labelling after 48 hours. The assimilation of 13C-enriched algal carbon by benthic animals was studied by separating the animals and subsequent analysis of their isotopic composition. Animals feeding at the sediment surface (e.g., Nereis succinea, Macoma balthica) were strongly labelled, whereas deep-deposit feeders such as Heteromastus filiformis showed limited labelling.
Day: Tuesday, Feb. 2
Time: 12:15 - 12:30pm
Location: Eldorado Hotel
Code: SS32TU1215E