the lakes contain arctic char ("salvelinus alpinus" l.), which is usually found much further north in sub-arctic lakes. it's a relict species left behind in the area after the last ice age, and are consequently indicative of pristine environmental conditions. although they were once widespread, they now are confined to isolated populations in inland freshwater lakes that have a suitable habitat. they are isolated in their respective lakes since the last ice age. they are extremely sensitive to environmental changes when they are as far south as ireland, where they are at the southern edge of their species range. the greatest threats to their survival in ireland are introduced fish species, eutrophication, acidification and climate change. the rate of extinction of entire populations in ireland has increased in recent decades.