Benthic studies at HAUSGARTEN focus on small- and large-scale distribution and diversity patterns of sediment-inhabiting organisms from bacteria to the epi-/megabenthos. Sampling at HAUSGARTEN is conducted on an annual base since 1999 to detect and track the impact of environmental changes on the deep-sea benthos. Furthermore, we carry out a number of biological short- and long-term experiments to determine the factors controlling deep-sea benthic biodiversity.

To study the impact of abiotic and biotic changes in environmental variables on the small biota, virtually undisturbed sediments are taken with a video-guided multiple corer (MUC). We analyse distribution and activity patterns of sediment-inhabiting bacteria and try to follow bacterial community shifts by means of microbiological and biochemical methods. Spatial and temporal distribution patterns of meiofauna organisms (size range: 32 - 1.000 µm) are analysed with special focus on foraminiferans (unicellular protists) and nematodes (“roundworms”). Foraminiferans are grouped into morphological classes; nematodes are identified up to species level and classified in functional groups.

Surface sediments, sampled with a giant box corer, are analysed for patterns of standing stock, composition, and diversity of macrofauna organisms (size range: 0.1 - 2 cm). Organisms were identified to the lowest possible taxonomic level and become weighed for biomass estimations. Large-scale distribution patterns of megafaunal assemblages at HAUSGARTEN are assessed by means of towed and remotely-controlled photo/video systems. To rapidly analyse large quantities of images, we developed computer algorithms that can be trained to automatically detect organisms on seafloor images. Sporadic sampling of megafauna for taxonomic identification and for ground-truthing of the photo and video footage is carried out using epibenthic sleds, Agassiz trawls, and occasionally the suction system (‘slurp gun’) of a Remotely Operated vehicle (ROV).

Contact: T. Soltwedel, M. Jacob, C. Hasemann, I. Schewe, M. Bergmann

Literature: 

Quéric, N., Soltwedel, T. & W.E. Arntz (2004). Application of a rapid direct viable count method to deep-sea sediment bacteria, Journal of Microbiological Methods 57 (3): 351-367.

Hoste, E., Vanhove, S., Schewe, I., Soltwedel, T. & A. Vanreusel (2007). Spatial and temporal variations in deep-sea meiofauna assemblages in the Marginal Ice Zone of the Arctic Ocean, Deep-Sea Research I 54 (1): 109-129.

Wlodarska-Kowalczuk, M., Kendall, M. A., Weslawski, J.-M., Klages, M. & T. Soltwedel (2004). Depth gradients of benthic standing stock and on the continental margin at a high latitude ice-free site (off West Spitsbergen, 79°N), Deep-Sea Research I 51: 1903-1914.

Soltwedel, T., Jaeckisch, N., Ritter, N., Hasemann, C., Bergmann, M. & M. Klages (2009). Bathymetric patterns of megafaunal assemblages from the arctic deep-sea observatory HAUSGARTEN, Deep-Sea Research I 56 (10): 1856-1872.

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