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Article by Calvin R. Fremling regarding mayflies as river toxicity and water quality monitors. Fremling is credited as "professor in the Department of Biology at Winona State University, Winona, MN." Abstract: "Analysis of Hexagenia mayfly distribution patterns has proven to be a simple, inexpensive method of monitoring water quality in the Upper Mississippi River. Burrowing Hexagenia nymphs live at the mud-water interface intimately associated with organically enriched sediments that have a strong affinity for contaminants. By their presence or absence in silted habitats, they assess the synergistic effects of hypoxia, toxins, and other stresses throughout the year. Adults are large and easily collected, providing inexpensive water quality monitoring on a river so large that comprehensive chemical, physical, and biological analyses are not logistically feasible or affordable. Pollution abatement in metropolitan Minneapolis-St. Paul allowed a recurrence of Hexagenia in formerly denuded areas of Pool 2 and Lake Pepin during the early 1980s, but the drought of 1988 caused a population crash in both areas, demonstrating that the environment at the mud-water interface was intolerable to Hexagenia during low flow conditions." Article originally from Journal of the Minnesota Academy of Science, volume 55, number 1, 1989. 5 pages. Part of the Cal R. Fremling Collection.

Publication Date


Item Type





Winona, Minnesota


Biologists; Mayflies; Pollution; Upper Mississippi River


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


Hexagenia mayflies: biological monitors of water quality in the Upper Mississippi River



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