Patchiness in a large floodplain river: Associations among hydrology, nutrients, and fish communities

River Research and Applications
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Abstract

Large floodplain rivers have internal structures shaped by directions and rates of water movement. In a previous study, we showed that spatial variation in local current velocities and degrees of hydrological exchange creates a patch-work mosaic of nitrogen and phosphorus concentrations and ratios in the Upper Mississippi River. Here, we used long-term fish and limnological data sets to test the hypothesis that fish communities differ between the previously identified patches defined by high or low nitrogen to phosphorus ratios (TN:TP) and to determine the extent to which select limnological covariates might explain those differences. Species considered as habitat generalists were common in both patch types but were at least 2 times as abundant in low TN:TP patches. Dominance by these species resulted in lower diversity in low TN:TP patches, whereas an increased relative abundance of a number of rheophilic (flow-dependent) species resulted in higher diversity and a more even species distribution in high TN:TP patches. Of the limnological variables considered, the strongest predictor of fish species assemblage and diversity was water flow velocity, indicating that spatial patterns in water-mediated connectivity may act as the main driver of both local nutrient concentrations and fish community composition in these reaches. The coupling among hydrology, biogeochemistry, and biodiversity in these river reaches suggests that landscape-scale restoration projects that manipulate hydrogeomorphic patterns may also modify the spatial mosaic of nutrients and fish communities. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Patchiness in a large floodplain river: Associations among hydrology, nutrients, and fish communities
Series title River Research and Applications
DOI 10.1002/rra.3026
Volume 32
Issue 9
Year Published 2016
Language English
Publisher Wiley
Contributing office(s) Upper Midwest Environmental Sciences Center
Description 12 p.
First page 1915
Last page 1926
Online Only (Y/N) N
Additional Online Files (Y/N) N