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North Atlantic Oscillation (NAO) is the dominant signal of interannual variability in the atmospheric circulation of the North Atlantic region. The NAO Index is an indication of the position and strength of weather systems across the North Atlantic, which in turn determine precipitation, sea surface temperature, direction and flow of marine currents, height of waves, and the stability of the water column in the North Sea. A high index is associated with strong and a low one with weak westerly winds. Consequently, during high NAO winters the moderating influence of the ocean results in unusually warm winter temperatures in the North Sea. In contrast to earlier decades, the NAOI increased to the highest consistently positive values of the century after 1987. Biological long-term studies in the North Sea reveal a significant correlation between the variability of species number, abundance and biomass and the NAOI. In the late 1980s a “regime shift” was related to the significant NAOI increase.

Within this project we study the decadal variability of epifaunal communities in the south-eastern and northern North Sea in relation to environmental and climate factors. Multivariate and geo-statistical analyses will be used to study a) climate-induced changes in community structure and function of epifaunal communities, b) the role of water temperature in mediating these changes and c) the role of neozoa in present and future community structure and function. Model approaches will be used to predict changes in communities due to increasing water temperature.


Dippner, J.W., Junker, K.& Kröncke, I. (2010) : Biological regime shifts and changes in predictability. Geophysical Research Letters 37:

Junker, K., Sovilj, D., Kröncke, I. & J.W. Dippner (2012) : Climate induced changes in benthic macrofauna-A non-linear model approach. - Journal of Marine Systems 96-97: 90-94.

Kröncke, I., Reiss, H., Eggleton, J.D., Aldridge, J., Bergman, M.J.N., Cochrane, S., Craeymeersch, J., Degraer, S., Desroy, N., Dewarumez, J.-M., Duineveld, G., Essink, K., Hillewaert, H., Lavaleye, M.S.S., Moll, A., Nehring, S., Newell, J., Oug, E., Pohlmann, T., Rachor, E., Robertson, M., Rumohr, H., Schratzberger, M., Smith, R., Vanden Berghe, E., van Dalfsen, J., van Hoey, G., Vincx, M., Willems, W., Rees, H.L. (2011) : Changes in North Sea macrofauna communities and species distribution between 1986 and 2000. - Estuarine, Coastal and Shelf Science 94: 1-15.

Kröncke, I. (2011) : Changes in Dogger Bank macrofauna communities in the 20th century caused by fishing and climate. - Estuarine, Coastal and Shelf Science 94 (3): 234-245.

Neumann, H., Kröncke I. & S. Ehrich (2010) : Establishment of the angular crab Goneplax rhomboides (Linnaeus, 1758) (Crustacea, Decapoda, Brachyura) in the southern North Sea. - Aquatic Invasion 5: S27 - S30.

Neumann, H., Kröncke, I. (2011) : Long-term effects of sea surface temperature on the ecological functioning of epifauna in the German Bight. - Marine Ecology 32 (Suppl. 1): 49-57.

Neumann, H., Reiss, H., Ehrich, S., Sell, A., Panten, K., Kloppmann, M., Wilhelms, I. & I. Kröncke (2013) : Benthos and demersal fish habitats in the German Exclusive Economic Zone (EEZ) of the North Sea. - Helgoland Marine Research 67: 445-459.

Neumann, H. & H. Reiss (2010) : Die Nordsee wird wärmer und beeinflusst damit das Leben am Boden. Natur und Museum 140 (5/6).

Neumann, H., deBoois, I., Kröncke, I. & H. Reiss (2013) : Climate change facilitated range expansion of the non-native angular crab Goneplax rhomboides into the North Sea. - Marine Ecology Progress Series 484: 143-153.

Neumann, H., Ehrich, S. & I. Kröncke (2009) : Variability of epifauna and temperature in the northern North Sea. - Marine Biology 156: 1817-1826.

Neumann, H., Reiss, H., Rakers, S., Ehrich, S. & I. Kröncke (2009) : Temporal variability of southern North Sea epifauna communities after the cold winter 1995/1996. - ICES Journal of Marine Science, 66: 2233-2243.
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Reiss, H., Cunze, S., König, K., Neumann, H. & I. Kröncke (2011) : Species distribution modelling of marine benthos: a North Sea case study. - Marine Ecology Progress Series, Vol. 442: 71–86; doi: 10.3354/meps09391
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