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Report by Calvin R. Fremling regarding mayflies and their utility as biological indicators, mayfly distribution factors, future distribution projection questions, toxicity tolerance, and laboratory procedures. Introduction: "Three species of burrowing mayflies (Hexagenia bilineata, Hexagenia limbata, and Pentagenia vittigera) are sufficiently abundant to cause nuisance problems along portions of the Mississippi River. Mayfly distribution, as determined by collections made by ship captains and other cooperators over a 13-year period, has proven to be an excellent index of general water quality on a river which is so large that it cannot be monitored effectively or economically by standard methods. Pollutants have severely reduced the numbers of all three species for 30 miles below Minneapolis, Minnesota, and for over 300 miles below St. Louis, Missouri. P. vittigera is able to emerge only in early and late summer in the St. Louis area when cool water temperatures lessen toxic effects in the zone of degradation. Impoundment and enrichment of the Upper Mississippi River has temporarily increased the carrying capacity of the river for H. bilineata which now dominates areas formerly dominated by H. limbata. The total productivity of the Upper Mississippi is being reduced by pollution, man's encroachment into the flood plain and by the filling of navigation pools by sand. Methods have been developed to rear large numbers of Hexagenia nymphs in the laboratory. Bioassay tests utilizing artificial, burrow-containing substrates reveal that H. bilineata nymphs can survive anaerobic conditions for as long as 11 hours. TLm values for hydrogen sulfide varied from 0.42 ppm at 48 hr to 0.17 ppm at 96 hr. Of several heavy metals (Cr, Ni, Zn, Cu) tested, copper was the most toxic to H. bilineata nymphs. TLm values for copper ranged from 0.54 ppm at 12 hr to 0.22 ppm at 48 hr. This report was submitted in fulfillment of project WP00987(1603DQH)11/70 under the sponsorship of the Federal Water Pollution Control Administration." Article is part of the Water Pollution Control Research Series of reports, and is reviewed by the Water Quality office of the Environmental Protection Agency of the United States. 44 pages. Part of the Cal R. Fremling Collection.

Publication Date


Item Type





Winona, Minnesota


Biologists; Upper Mississippi River; Ecology; Mayflies; Laboratory; Pollution


Special Collections-Library



Rights Management

Requests to reproduce this image must be granted by the Winona County Historical Society.

Contributing Institution

Winona County History Center

Master File Format


Fiscal Sponsor

This project has been financed in part with funds provided by the State of Minnesota from the Arts and Cultural Heritage Fund through the Minnesota Historical Society.

Scanning Responsibility

Northern Micrographics

Date Digital

2019-06-24 00:00

Metadata Creation Responsibility

Anna Gaffey

Unique Identifier


Mayfly distribution as a water quality index



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