DOI: 10.5061/dryad.j3tx95xbj
title: Data from: Does rapid glacial recession affect feeding habits of alpine stream insects?

description: 1. Glacial retreat, accompanied by shifts in riparian vegetation and
 glacier meltwater inputs, alters the energy supply and trophic structure
 of alpine stream food webs. Our goal in this study was to enhance
 understanding of dietary niches of macroinvertebrates inhabiting different
 alpine streams with contrasting glacial and non-glacial (groundwater,
 precipitation, snowmelt) water inputs in conjunction with seasonal and
 habitat-specific variation in basal resource availability.   2.
 We measured a range of stream physico-chemical attributes as well as
 carbon and nitrogen isotopes (δ13C, δ15N) of macroinvertebrates and
 primary food sources at seven sites across seasons within a Swiss
 glaciated catchment (Val Roseg) undergoing rapid glacial retreat (1-2 km
 between years 1997–2014). Sampling sites corresponded to streams used in a
 previous (1997/1998) study within the same alpine catchment. 3.
 Physico-chemical attributes showed wide variation in environmental
 conditions across streams and seasons. Significant correlation among
 physico-chemical proxies of glacier meltwater (P-PO43-, TIC, conductivity,
 turbidity) and macroinvertebrate δ13C, δ15N and SEAc (a proxy for feeding
 niche width) values showed that the extent of glacial water input shapes
 the energy base among alpine streams. Feeding niche differences among
 common alpine stream insect taxa (Chironomidae, Baetidae, Heptageniidae)
 were not significant, indicating that these organisms likely are plastic
 in feeding behaviour, opportunistically relying on food resources
 available in a particular stream and season. 4. Seasonal trends in
 macroinvertebrate δ13C largely followed patterns in periphyton δ13C
 values, indicating that autochthonous resources were the main consumer
 energy source within the stream network, as shown previously. The overall
 range in macroinvertebrate δ13C (-33.5 to -18.4 ‰) and δ15N (-6.9 to 6.7
 ‰) values also corresponded to values measured in the previous study,
 suggesting that macroinvertebrates altered diets in line with changes in
 environmental conditions and food resources during a period of rapid
 glacial retreat. Our results suggest that environmental changes brought on
 by rapid glacial retreat have not yet caused a profound change in the
 trophic structure within these fluvial networks.
description: <b>INVERTS</b> Excel file showing bulk delta13C
 and delta15N isotope values from macroinvertebrates collected in different
 channel types (lake outlet, main channel, proglacial and tributary) within
 the Val Roseg glacial floodplain (Switzerland), during November 2013 –
 July 2014. Other columns include taxonomic and functional information
 about each sample that was analysed for isotopes, and the site name,
 channel type, sampling date, month and season.
 <b>SOURCES</b> Excel file showing bulk delta13C
 and delta15N isotope values from food source materials collected in
 different channel types (lake outlet, main channel, proglacial and
 tributary) within the Val Roseg glacial floodplain (Switzerland), during
 November 2013 – July 2014. Other columns include the detailed description
 of the resource, the classification of the resource in terms of CPOM,
 FPOM, periphyton and riparian vegetation, and the site name, channel type,
 sampling date, month and season.