Biodiversity and plankton-benthos coupling: an integrated ecosystem analysis from the Late Cretaceous Chalk

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The structure of marine fossil food chains in pre-Cenozoic oceans is poorly understood due to a bias of integrated palaeobiological studies towards the reconstruction of past geological environments. Despite an often good knowledge of the taxonomic and palaeoecologic affinities of individual groups of organisms (e.g. calcareous nannofossils, foraminifera, bivalves, etc.), hardly any approaches exist which integrate quantitative and qualitative palaeobiological data from taxonomically different macroand microfossils in order to reconstruct food chains, feeding patterns and nutrient fluxes of the past. We aim at reconstructing the structure and composition of a Cretaceous food chain by deciphering coupling patterns of primary producers and consumers. By studying plankton and benthos from the same samples of Lower Maastrichtian Chalk, attributed to a stable oligotrophic phase, we want to answer the following questions: a) How did the pelagic-benthic coupling and nutrient flow operate under oligotrophic conditions in a large epicontinental shelf area? b) What are the effects of low vertical Corg fluxes for benthic associations? c) Are minor productivity changes across orbitally forced cycles reflected by palaeontological and geochemical proxies? d) What is the palaeoecologic and palaeooceanographic significance of specific macrofossil-rich horizons? Ultimately, the combined data set will result in an integrated ecosystem analysis of the Late Cretaceous Chalk Sea.