Prokaryotic, protozoan and metazoan processing of organic matter in the sediments: a tracer approach

Abstract

Bacteria, protists and eukaryotes are the key actors in organic matter (OM) procesing but the knowledge on their relative importance and impact on the composition of sediment OM is still limited. Research approaches so far have been generally monodisciplinary, providing a biased view of sedimentary OM processing. This work attempts to approach the topic in an integrative and comprehensive way. We focussed on the effect of oxygen and organic matter form on isotopically enriched algal tracers OM degradation and transformation by deep-sea biota, trying to identify their role in the food web. Furthermore, to assess the carbon metabolic pathways and tissue storage of the main biochemical compounds (phospholipid fatty acids and amino acids) in megafauna, we selected a shallow-water species of bivalve as an analogue for deep-sea megafauna and subjected it to feeding experiments with live isotopically enriched algae.