Diatoms of the Middle Fork of the Salmon River drainage, with notes on their relative abundance and distribution

A total of 145 species of diatoms was collected from 13 sites in the Middle Fork of the Salmon River drainage, Idaho, USA. Achnanthes minutissima was the prevalent species with an importance index of 19.25. Cluster analysis revealed 2 main site groupings, sites above the entrance of Loon Creek and sites below. The entrance of Loon Creek (6th order) increases the Middle Fork of the Salmon River to a 7th order stream. Shannon-Weiner diversity values were generally high.