Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2025
Erindi/veggspjald / Talk/poster V76
Höfundar / Authors: Alicia Madleen Knauft (1), Gísli Már Gíslason (2), Martin Reiss (3), Jón S. Ólafsson (4), Iris Hansen (4), Ragnhildur Þ. Magnúsdóttir (4), and Peter Chifflard (1)
Starfsvettvangur / Affiliations: 1. Philipps University of Marburg, Geography, 2. University of Iceland, Life and Environmental Sciences 3. Hessische Landgesellschaft mbH 4. Marine and Freshwater Research Institute
Kynnir / Presenter: Alicia Madleen Knauft
Glacier retreat due to climate change is expected to strongly alters hydrological and chemical parameters in glacier-fed streams, with consequences for biodiversity. To assess long-term effects, we revisited the Vestari-Jökulsá river, first studied in 1996/97, and compared historical data with new measurements from 2022. Over the past decades, the glacier terminus has retreated by approximately 541m, accompanied by an increase in minimum daily runoff and changes in water temperature and nutrient concentrations. Our analysis of macroinvertebrate communities reveals a trend that species richness, Shannon diversity and evenness decreased at several sites, while overall density remained relatively stable. Community composition, based on Bray–Curtis dissimilarities, shows higher similarity among sites in 2022 compared to 1996/97, indicating a homogenization of assemblages. Overall, the water temperature and phosphate (PO₄) concentrations significantly influenced the community patterns, highlighting the interaction between changing abiotic conditions and biodiversity. By integrating hydrological, chemical, and ecological perspectives, our study provides new insights into how glacier retreat reshapes arctic stream ecosystems. The results underscore that biodiversity responses involve not only species losses but also community homogenization.