engleski

Macroinvertebrate drift-benthos patterns in glacial streams undergoing rapid environmental change

This study examined seasonal drift-benthos patterns in the Val Roseg catchment (Switzerland) – a glacial-fed stream system undergoing environmental change during the past decade from rapid glacier retreat. Samples were collected monthly from October 2008 to August 2009 in a glacial lake outlet stream, a proglacial (glacier-fed) stream, and their post-confluence stream (main channel), and data compared with the same sites in 1997/1998. Temporal trends in physico-chemical parameters indicated the greatest glacial meltwater influence in the proglacial stream and its lower inflow in 2008/2009 compared to 1997/1998. Drift largely coincided with benthic structure at each site, although drift-benthos patterns were sporadically asynchronous, depending on site, season and flow conditions. Our results indicate that low to moderate flow conditions are most favorable for benthic macroinvertebrates in glacial streams. Drift density was significantly lower in 2008/2009 than in 1997/1998. In 2008/2009, we observed lower chironomid, but higher ephemeropteran and plecopteran drift densities. The observed drift-benthos changes likely reflect behavioral and life history responses of proglacial stream macroinvertebrates to seasonal shifts in environmental conditions in response to glacial retreat.

macroinvertebrate drift; alpine streams; drift-benthos patterns; climate change; glacier retreat

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