Macroinvertebrate assemblages in 25 high alpine ponds of the Swiss National Park (Cirque of Macun) and relation to environmental variables

Abstract

High-altitude freshwater ecosystems and their biocoenosis are ideal sentinel systems to detect global change. In particular, pond communities are likely to be highly responsive to climate warming. For this reason, the Swiss National Park has included ponds as part of a long-term monitoring programme of the high-alpine Macun cirque. This cirque covers 3.6 km 2 , has a mean altitude of 2,660 m a.s.l., and includes a hydrographic system composed of a stream network and more than 35 temporary and permanent ponds. The first two steps in the programme were to (i) make an inventory of the macroinvertebrates of the waterbodies in the Macun cirque, and (ii) relate the assemblages to local or regional environmental variables. Sampling was conducted in 25 ponds between 2002 and 2004. The number of taxa characterising the region (Macun cirque) was low, represented by 47 lentic taxa. None of them was endemic to the Alps, although several species were cold stenothermal. Average pond richness was low (11.3 taxa). Assemblages were dominated by Chironomidae (Diptera), and Coleoptera and Oligochaeta were also relatively well represented. Other groups, which are frequent in lowland ponds, had particularly poor species richness (Trichoptera, Heteroptera) or were absent (Gastropoda, Odonata, Ephemeroptera). Macroinvertebrate assemblages (composition, richness) were only weakly influenced by local environmental variables. The main structuring processes were those operating at regional level and, namely, the connectivity between ponds, i.e. the presence of a physical connection (tributary) and/or small geographical distance between ponds. The results suggest that during the long-term monitoring of the Macun ponds (started in 2005), two kinds of change will affect macroinvertebrate assemblages. The first change is related to the natural dynamics, with high local-scale turnover, involving the metapopulations characterising the Macun cirque. The second change is related to global warming, leading to higher local and regional richness through an increase in the number of colonisation events resulting from the upward shift of geographical ranges of species. At the same time the cold stenothermal species from Macun will be subject to extinction.

Is there a core set of organisms that structure macroinvertebrate assemblages in freshwater wetlands?

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Dragonflies and climatic change - recent trends in Germany and Europe

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The ecology of European ponds: defining the characteristics of a neglected freshwater habitat

“…Such plans can only be effective if based on a solid knowledge of the factors that affect pond community structure and diversity. In this issue, several studies document clear associations between the communities of organism groups (macrophytes, zooplankton, macroinvertebrates and waterbirds) and a variety of ecologically relevant gradients, such as hydroperiod Della Bella et al, 2007), surface area (Céréghino et al, 2007), salinity and amongpond connectivity Gascón et al, 2007;Oertli et al, 2007). If these associations are causal, it is clear that the conservation of such environmental gradients at the landscape scale is essential for the conservation of among-pond variability (beta diversity) and total landscape biodiversity (gamma diversity).…”