| Summary: | Freshwater springs are thermally stable environments which are largely unaffected by changes in air temperature. They could thus have the potential to buffer rising temperatures and serve as small-scale refugia for aquatic invertebrates in a warming world. To better understand what environmental variables drive invertebrate diversity and community composition, I conducted an extensive field survey on springs in Iceland. Due to rifts in the tectonic plates, large parts of Iceland are of volcanic origin and geothermally active. Thus, a high number of freshwater springs can be found along the edges of the porous lava fields, ranging in temperature from 2°C to boiling hot. Springs also differ in other characteristics, e.g., altitude, spring type, substrate, and vegetation density. I studied the invertebrate community of 49 springs on a spatial scale and followed one of them throughout a year to analyse temporal variability. The most abundant invertebrate groups in Icelandic springs were Chironomidae (Diptera), followed by Ostracoda and Copepoda. One of the main drivers of community composition was temperature, resulting in a distinct species group characteristic for hot springs. Additionally, spring type and geographical position influenced communities. Community composition also differed on a temporal scale within the same spring, with distinctions between summer and winter community. This seasonality in the invertebrate community was unaffected by temperature changes but had implications on the apex predator in the system, Arctic charr. The results of this thesis give some insight into Icelandic spring ecosystems and will contribute to conservation of these unique habitats. Fjölbreytileiki ferskvatnslinda er mikill t.d. hvað hita varðar, allt frá því að vera mjög kaldar og sjóðandi heitar. Þrátt fyrir þennan fjölbreytileika er þó hiti í hverjum og einstökum lindum mjög stöðugur og hafa breytingar í lofthita lítil áhrif á hitastig þeirra. Lindir gætu þannig dregið úr áhrifum af hækkandi hita og þannig myndað ...
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