Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster E10
Jónína Herdís Ólafsdóttir, Jón S. Ólafsson og Bjarni Kristófer Kristjánsson
Hólar University College.
Kynnir / Presenter: Jónína Herdís Ólafsdóttir
Tengiliður / Corresponding author: Jónína Herdís Ólafsdóttir (jonina109@gmail.com)
The location of Iceland on two diverging tectonic plates results in the formation of numerous fissures paralleling the fault line. In some areas these fissures penetrate far underground and expose the groundwater aquifer within the bedrock. The main objective of the project was to describe the biological diversity within groundwater fissures in Iceland. A special emphasis was put on invertebrate fauna while presence or absence of fish was also noted. Assemblages were studied in three fissures: Silfra and Flosagjá in SW Iceland and Stekkjagjá in NE Iceland. All the fissures contain cold oligotrophic groundwater and all samples and measurements were acquired by scuba diving. Invertebrates were sorted and 4 of the most common groups (Chironomidae, Cladocera, Copepoda and Ostracoda) were identified to the species level or the lowest taxonomic level possible. Assemblages were found to vary significantly on a landscape scale in regards to taxa richness, density and diversity while fissure communities in the same region showed no significant difference except in mean densities of cladocerans. Within fissures Shannon diversity was greatest on the deepest sampling stations on horizontal bottom. Chironomids in Flosagjá and Stekkjagjá had significant differences in mean densities on horizontal bottom in response to depth. A significant difference in mean density in response to angle of rock substrate was only found for ostracods within Flosagjá. Flosagjá was also the only fissure that had a significant difference in Shannon diversity in response to angle of rock face. Invertebrates were living within and around benthic mats that are mostly made out of Cyanobacteria and benthic diatoms. During the project a new fissure was found in Þingvellir National park and is currently the only known underground fissure in Iceland. This fissure which was named Huldugjá (The Hidden fissure) is home to a cave adapted groundwater amphipod, Crangonyx islandicus.