Water level fluctuations in lacustrine systems: ecological impacts and prospects of future climate change - Konstanz,, December 11^th-13th, 2005.

Oral presentation : Potential changes in eulittoral invertebrate composition following water level fluctuations in North-German lowland lakes. Brauns M, Garcia XF, Pusch M.

Abstract

Lakes in North-East Germany are highly sensitive to climatic changes, as precipitation is low and higher temperatures in the future are forecasted. Especially the many lakes fed by groundwater will suffer a substantial lowering of their water level. This will probably be accompanied by a change of the riparian vegetation from trees to reed, which is able to follow the receding shoreline more quickly. As tree roots constitute the most important habitat for eulittoral macroinvertebrates in North-German lowland lakes, severe effects can be expected. Hence, we examined if that loss in the eulittoral zone can be compensated by the availability of the major infralittoral habitat types. For that purpose, we examined differences in the faunal characteristics between the habitat-specific communities in terms of species richness, species composition, densities of major groups, and functional feeding groups. We collected 43 macroinvertebrate samples from the five major habitat types sand, stones, reed, CWD, and roots in seven North-German lowland lakes. Species richness did not significantly differ between the five habitats, while species composition on roots significantly differed from those of sand and stones. The densities of Odonata and Coleoptera, as well as the density of predators, were significantly lower on sand than in roots. The macroinvertebrate community in reed, stone and CWD habitats did not show pronounced differences to the community of root habitats. We conclude that the loss of root habitats in the eulittoral zone can be substituted in the infralittoral zone provided that reed, stone and CWD habitats are present there.

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