Spring type influences invertebrate communities at cold spring sources

The invertebrate fauna from 22 lava spring sources throughout Iceland's volcanically active zone was studied to investigate the role of spring type and environmental variables in shaping invertebrate communities. Springs were selected based on the ability to identify a discrete source, which was discharging water that appeared to be geothermally unaffected. Spring type, temperature, and pH significantly influenced invertebrate community structure. When looking only at chironomid community structure, the same variables were significant. Limnocrene spring sources were characterized by greater abundances of crustaceans, especially cladocerans. Rheocrene sources were characterized primarily by lotic taxa, such as Diamesa spp. Temperature was most strongly related to four species of Diamesa in the study, with the Diamesa being associated with the coldest sites. We conclude that associated habitat (i.e., spring type) structures invertebrate communities at spring sources, which are discrete habitats sensitive to change.