engleski

Glacier meltwater inputs affect feeding habits of alpine stream macroinvertebrates

Shifts in glacier meltwater inputs and vegetation gradients substantially change energy supply and trophic interactions within alpine stream food webs. Our goal was to enhance understanding of food resource changes and dietary niches of macroinvertebrates inhabiting alpine stream types contrasting in glacier meltwater inputs. We measured a range of physico-chemical stream attributes and carbon and nitrogen isotope ratios (δ13C, δ15N) of stream macroinvertebrates and their potential food sources at seven sites accessible throughout a year (2013/2014) within a Swiss Alpine glacial floodplain (Val Roseg) undergoing rapid glacier retreat. The range in macroinvertebrate δ13C (-33.5 to -18.4 ‰) and δ15N (-6.9 to 6.7 ‰) values corresponded to values measured in a previous (1997/1998) study within the same alpine catchment, suggesting that macroinvertebrates inhabiting Val Roseg stream network generally have not changed feeding behavior during the period of rapid glacier retreat. Feeding niche differences across differing stream types and alpine stream taxa were not significant, indicating that most alpine stream macroinvertebrates are plastic in their feeding behavior, relying on food resources available in a particular stream. Macroinvertebrate δ13C seasonal trends followed the respective periphyton patterns, suggesting that autochthonous resources are the main energy source within this alpine catchment. A significant correlation among physico-chemical proxies of glacier meltwater inputs (P-PO43-, TIC, conductivity and turbidity), δ13C and δ15N values, and isotope niche parameter SEAc (a proxy for feeding niche width) indicated that glacier meltwater plays an important role in shaping the energy base within alpine stream ecosystems.

alpine streams ; glaciers ; global warming ; macroinvertebrates ; stable isotopes ; food webs

nije evidentirano