Skip Navigation



Journal Molluscan Studies Advance Access published online on September 29, 2009
Journal of Molluscan Studies, doi:10.1093/mollus/eyp045
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplementary Data
Right arrow All Versions of this Article:
76/1/67    most recent
eyp045v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Bartsch, M. R.
Right arrow Articles by Sauer, J. S.
PubMed
Right arrow Articles by Bartsch, M. R.
Right arrow Articles by Sauer, J. S.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© Published by Oxford University Press on behalf of The Malacological Society of London, 2009.

INFLUENCE OF SHELL MORPHOLOGY ON DISTRIBUTIONS OF UNIONIDS IN THE UPPER MISSISSIPPI RIVER

Michelle R. Bartsch, Steve J. Zigler, Teresa J. Newton and Jennifer S. Sauer

U.S. Geological Survey, Upper Midwest Environmental Sciences Center, 2630 Fanta Reed Road, La Crosse, WI 54603, USA

Correspondence: M.R. Bartsch; e-mail: mbartsch{at}usgs.gov


  Abstract

Attempts to predict the distribution of unionids from readily measurable microhabitat descriptors (i.e. water depth, current velocity, stream size, sediment type) have been largely unsuccessful, but certain biological and calculated hydraulic variables have recently shown some predictive power. We used historic and recent data on unionids (from 1987 to 2003) and hydraulic conditions at 438 sample locations over a 38-km reach of the Upper Mississippi River (Navigation Pool 8) to compare the distribution of unionids with different shell morphologies. We evaluated whether sculptured, thick-shelled (STK) species would be found in areas with higher velocity and shear stress, compared to nonsculptured, thin-shelled (NSTN) species. We used classification trees to model the presence and absence of STK and NSTN species to determine which variables were most likely to predict their distribution. Candidate predictor variables included sampling gear, field substrate, water depth (bathymetry), slope, velocity, shear stress and Froude number under low, moderate and high discharges. Our models predicted that STK mussels would occupy a larger portion of the total aquatic area in this reach of the river than NSTN mussels. However, our data demonstrated that NSTN species used areas of higher shear stress and velocity than STK species, but were also present in backwaters with low energy, thus rejecting our hypothesis. The presence of NSTN species over a wide range of shear stress and velocity was probably due to the wide array of life histories displayed within this guild. Overall, these results are consistent with the flow refuge concept in which unionids are more prevalent in areas with low to moderate hydraulic stresses, regardless of shell morphology, and demonstrate the importance of incorporating abiotic and biotic variables into predictive models.

(Received 6 June 2008; accepted 5 August 2009)


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.