Discordant Harmonies in Fingernail Clam Populations (Musculium transversum) of Mississippi River Backwater Lakes

Authors

Jim Eckblad, Luther CollegeFollow

Document Type

Research

Keywords

fingernail clams, population decline, Mississippi River

Abstract

The populations of Musculium transversum from 8 backwater lakes have been studied over a 29-year period based upon over 440 grab samples. These lakes in Navigation Pool 9 of the Upper Mississippi River (UMR) range in size from 2 to 255 hectare surface area, mean depths from 0.2 to 0.9 meters, with mean water exchange times from 0.5 to almost 57 hours. Samples from the 1989-91 period suggested summer Muscu!ium populations had declined to about 9 percent of their mid-1970 levels. Deterministic models have attempted to explain this decline. More recent sampling suggests a substantial recovery of Musculium populations (mid-summer mean of 560 m^{- 2} in 2002). Simple stochastic models, with realistic levels of POISSON and NORMAL variables, may provide a better explanation of population fluctuations than previously used deterministic models.

Publication Date

July-December 2005

Journal Title

Journal of the Iowa Academy of Science

Volume

112

Issue

3-4

First Page

28

Last Page

35

Copyright

© Copyright 2007 by the Iowa Academy of Science, Inc.

Language

EN

File Format

application/pdf

Recommended Citation

Eckblad, Jim (2005) "Discordant Harmonies in Fingernail Clam Populations (Musculium transversum) of Mississippi River Backwater Lakes," Journal of the Iowa Academy of Science: JIAS, 112(3-4), 28-35.
Available at: https://scholarworks.uni.edu/jias/vol112/iss3/4