Research Projects


ABYSS – Assessment of bacterial life and matter cycling in deep-sea surface sediments

Within the ERC Advanced Investigator Grant ABYSS, we want to develop a systematic understanding of abyssal sediment bacterial community distribution, diversity, function and interactions. Our goals in the project include the identification of key bacterial types in deep-sea sediments and the characterization of their role in organic matter remineralization at the seafloor, as well as developing a better understanding of links between the pelagic and benthic realms. The long-term observatory HAUSGARTEN will present a cornerstone of our work in the Arctic deep sea. During yearly research cruises we will use the site for in situ and ex situ experimental work, in order to better characterize deep-sea bacterial diversity and function in a changing Arctic Ocean.

Also see our recent publication on the export of algal biomass in the central Arctic Ocean.

Bacterial diversity patterns in deep-sea sediments

The deep seafloor below 200 m water depth covers approximately 65% of the Earth’s surface and therefore presents the largest continuous ecosystem on Earth, but also one of the least understood. Bacterial communities play an essential role for carbon and nutrient cycling in deep-sea sediments, and are thus an important component not only of benthic deep-sea ecosystems, but also of the global carbon cycle. Nevertheless, bacterial diversity and its distribution in deep-sea sediments of the world’s oceans remain largely unknown. My studies aim at developing a better understanding of bacterial diversity patterns and ecosystem functioning at the deep seafloor.
I specifically investigate patterns of bacterial community structure in an environmental and spatial context. Recently, we could evidence distinct energy-diversity relationships for bacterial communities in Arctic deep-sea sediments (Bienhold et al., 2012). I am currently expanding analyses to a set of globally distributed deep-sea surface sediments to understand which contextual parameters are important drivers for changes in bacterial communities at the global scale.

Ecology of wood falls in the deep sea

Chemosynthetic ecosystems in the deep sea (e.g., hydrothermal vents and cold seeps) present oases of life in an otherwise largely oligotrophic environment. Large organic food falls such as whale carcasses, wood and kelp can lead to the development of chemosynthetic environments in the deep sea which may act as stepping stones in the evolution and distribution of chemoautotrophic communities. Considerable effort has been spent on the exploration of hydrothermal vent and cold seep ecosystems as well as whale falls, but the role of wood falls as localized boosts of organic material to the deep seafloor remains largely unstudied. In the framework of the ESF EUROCORES EuroDEEP Project “Colonization processes in chemosynthetic ecosystems – CHEMECO” and the MPG-CNRS GDRE „Diversity, establishment and function of organisms associated with marine wood falls – DIWOOD”, we carried out wood colonization experiments in the Eastern Mediterranean deep sea to investigate the succession of colonization and the establishment of biogeochemical gradients at deep-sea wood falls (Figure 1). The aim of this study was to contribute to a better understanding of the microbial ecology and biogeochemistry of wood fall ecosystems and their role as biological and biochemical hotspots in the deep sea.

Wood colonization experiment in the Eastern Mediterranean deep sea. Picture taken by ROV Quest 4000 (Marum, Bremen, Germany) shortly after deployment during the Bionil cruise in 2006 (RV Meteor M76/2b).


2014 RV Polarstern, ARKXXVIII/2, Fram Strait, Arctic Ocean
2013 RV Maria S. Merian, MSM-29, HAUSGARTEN, Fram Strait, Arctic Ocean
2012 RV Polarstern, ARK 27-3, IceArc, Central Arctic
2009 RV Maria S. Merian, MSM 13-3, Eastern Mediterranean (wood colonization experiments)
2008 RV Meteor, M 76/3B, Congo fan (cold seeps)
2007 RV Pourquoi Pas?, MEDECO-2, Eastern Mediterranean (wood colonization experiments)
2007 RV Polarstern, ANT XXIII/9, Prydz Bay, Antarctic (Geophysics)
2004 RV Heincke, North Sea, student course, University of Bremen
2003 RV Heincke, North Sea, University of Hamburg


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