Groundwater Ecology Ireland
Reasons for groundwater ecology research
The purpose of this EPA funded research project was to provide baseline data on the biogeography of Irish crustacean groundwater fauna and its ecology. With the exception of an earlier pilot investigation this research represents the first systematic and detailed attempt of an island wide survey and thus represents a significant step towards filling the knowledge gap identified by the European Groundwater Directive (2006/118/EC) with regard to groundwater ecology.
Obligate groundwater fauna in Ireland
Currently seven crustacean species are classified as obligate groundwater fauna in Ireland. One of them was discovered during this survey and is a species new to science (Moraria sp.). There were also the first record of a blind Gammarus specimen (G. lacustris) from streambed sediments and the first record of the harpacticoid Parastenocaris vicesima. In addition, there is evidence for the existence of several cryptic species among groundwater amphipods and copepods in Ireland.
Biogeography of Irish groundwater fauna
The biogeographic distribution of Irish groundwater fauna reflects the island’s hydrogeological setting. Poorly productive aquifers appear to set boundaries for the biogeographic range of obligate groundwater animals. Associations with bedrock geology varied between different species of the same taxonomic order.
Importance of water exchange with surface environments
Crustaceans in groundwater displayed strong correlations with hydrology related parameters, such as water table dynamics and electrical conductivity, which can be used as a proxy for hydrologic exchange with surface water. The most promising application of groundwater fauna monitoring would therefore be in bioindication of surface water intrusion (i.e. groundwater vulnerability).
Tolerance towards water chemistry parameters
Obligate groundwater crustaceans tolerated a low oxygen environment, but did not occur in environments with saturation levels of 5% or lower. The most frequently encountered species Niphargus k. irlandicus displayed a low tolerance of elevated salt concentration and is therefore unlikely to inhabit coastal margins that are exposed to saline intrusions.
How unique is Irish groundwater fauna?
Genetic investigations for one species revealed that this endemic and therefore uniquely Irish crustacean was separated from other European species several million years ago and must have survived all Quaternary glaciations in Ireland. Based on this genetic assessment, it needs to be elevated from subspecies to species level under the new name Niphargus irlandicus.
Did groundwater fauna survive glaciations in Ireland?
The existence of old genetic lineages and their respective biogeographic ranges indicate that Niphargus irlandicus has indeed survived quaternary glaciations in Ireland most likely under the ice.