Theme 1 & 2
Project 1081

Prokaryotic and metazoan processing of organic matter in sediments
Project leader: Prof. dr. J.J. Middelburg
Researcher(s): Dr. L. Pozzato
Starting date: 17-apr-08

Most of the organic matter delivered to marine sediments is respired and transformed because heterotrophic organisms inhabiting these sediments depend on it for energy and nutrients. This extensive degradation results in major compositional changes in the tiny fraction that is eventually buried and recorded in the sedimentary archive available for paleoreconstructions. Organic matter processing is due to bacteria, archaea and eukaryotes, but we lack understanding of their relative importance and their impact on the composition of sediment organic matter. The monodisciplinary approaches adopted so far have not only hampered progress, but also provided a biased view of sediment organic matter processing. On the one hand, ecologists and biogeochemists have focused on food-web transfers and respiration, respectively, while ignoring the heterogeneous nature of organic matter. On the other hand, organic geochemists have studied in detail the composition of organic matter, but ignored respiratory losses and the biological actors. In this Darwin project, ecologists of NIOO join forces with organic geochemists of NIOZ, to obtain an integrative and comprehensive view of sediment organic matter processing. Special attention will be given to the effect of oxygen on natural organic matter degradation and transformation by bacteria and archaea. Moreover, we will use isotopically enriched algae to identify the role of archaea, bacteria and animals, study a selection of sediment eukaryotes for their role in sediment organic matter transformation and quantify organic matter degradation using the amino acid based Dauwe-degradation index.

Lara Pozzato (2012). Prokariotic, protozoan and metazoan processing of organic matter in the sediments: a tracer approach.
Darwin Center authors: Pozzato L.

Lara Pozzato, Dick van Oevelen, Leon Moodley, Karline Soetaert, Jack J. Middelburg (2013). Carbon processing at the deep-sea floor of the Arabian Sea oxygen minimum zone: A tracer approach. Journal of Sea Research78: 45-58.
Darwin Center authors: Middelburg J.J., Pozzato L., Soetaert K. E. R.