Diatom Indicators of Climate Change in Glacier National Park

Abstract

Permanent slides in the Montana Diatom ollection representing periphyton samples collected during the 2007 field season and samples collected in prior years were examined to determme the distribution and abundance in and near Glacier National Park of two diatom species: Didymosphenia geminata and Distrionella incognito (Kingdom Plantae, Phylum Bacdlariophyta). Didymosphenia geminata ("didymo", "rock snot") is becoming a nuisance in the v.,est and will probably increase in abundance in response to global wanning and reduced stream flows. Distrionella incognito ("glacier gold") is a rare glacial relict species and will probably decrease in abundance in response to predicted climate change. Didymosphenia has been widely distnhutcd and locally abundant in the Park since 1976. Large populations of this diatom have been recorded in all three of the Park's major drainage basins: Pacific, Atlantic, and Hudson Bay. Samples collected in 2007 from Duck Lake, Kintla Lake, and St. Mary Lake document the first large populations of Distrionella to be recorded in North America. The genus Distrionella is known only from cold, mountainous, and glaciated regions of the world.