Aquatic fungi in rivers, their distribution and response to pollutants

Two lotic habitats in the vicinity of Blacksburg, Virginia were selected for field investigations. The New River represented a river with a high nutrient load. Little Stony Creek, a tributary of the New River, has no sources of man-made effluent which might contribute nutrients to the stream. Collecting sites on the New River were located above, just below, and some distance farther downstream from the effluent outfall of a munitions plant. The effect of this effluent on the number of taxa was not conspicuous. However, there was a reduction in the number of taxa per collection at the station near the effluent when compared with the other stations.

Filamentous aquatic Phycomycetes such as Achlya, Sapro/egnia, and Pythium were commonly found in both habitats. However, a greater diversity of the chytrid type of aquatic Phycomycete was found in Little Stony Creek as compared to the New River. Twelve chytrid taxa were found in Little Stony Creek and two in the New River.

Two fungi, Achlya caroliniana from the New River and Rhizidium sp. from Little Stony Creek, were studied in pure culture in terms of the effect of common pollutants on their growth and reproduction. The A. caroliniana had higher tolerances to zinc, cyanide, and mannitol as compared to the

Rhizidium sp. The Rhizidium was more tolerant to higher concentrations of detergents than the Achlya.