Seasonal variability in glacial influence affects macroinvertebrates assemblage in North-Andean Patagonian glacier-fed streams

MARTYNIUK, N.; MODENUTTI, B.; BALSEIRO, E.

Inland Waters

Taylor & Francis

Lugar: Londres; Año: 2019

2044-2041

Macroinvertebrate communities of glacial streams are affected by mountain glaciers melting that, in turn, is influenced by landscape and local and global climate change. Here, we analyzed macroinvertebrate communities in two North-Andean Patagonian glacier-fed streams. The two streams showed significant differences in glacial influence due to differences in glacier flow velocity and to the presence of a proglacial lake in one of them. Our main aim was to analyze whether temporal variations in physical and chemical parameters of meltwater, produced shifts in macroinvertebrate taxon richness and community composition. We applied the glaciality index (GI) to consider the combined effect of suspended solids, mean water temperature, conductivity and streambed stability. On each stream we established one sampling station and we sampled during the melting season (spring-summer) of consecutive 3 years on 12 occasions. Macroinvertebrate taxon richness, diversity and evenness increased as glacial influence decreased. Scrappers were the dominant functional feeding group in the stream with the lower glacial influence while detritivores-gathers dominated under high glacial influence. We further analyzed how temporal changes in glaciality index (GI) affected compositional differences among communities using Bray-Curtis dissimilarities. Under stable GI, communities did not show substantial compositional changes (low Bray-Curtis), while under change in glacial influence (ΔGI different from 0) the communities decrease in similarity.