Effects of Spatial Scale on Assessment of Dissolved Oxygen Dynamics in the Atchafalaya River Basin, Louisiana |
PRESENTATION
M. D. Kaller, W. E. Kelso, and D. A. Rutherford mkalle1@lsu.edu
School of Renewable Natural Resources, LSU Agricultural Center, Baton Rouge, LA 70803
Abstract
Low levels of dissolved oxygen (DO) are potential stressors of fishes and invertebrates in freshwater and marine systems. Because of the incredibly productive nature of the Atchafalaya Basin (ARB), microbial decomposition in backwater areas with limited flow often results in potentially stressful, if not lethal, DO levels throughout much of the ARB during and after the annual flood pulse. In order to better guide the development of water management projects, we investigated the relationship between dissolved oxygen and a suite of potential structuring variables. Considerable research suggests that for many ecological phenomena, spatial scale is critical to properly interpreting ecological relationships. Therefore, using continuous monitoring data collected from 2000‐2007, we used a variable selection procedure to construct statistical models to describe the relationship between dissolved oxygen level and several potentially important predictor variables at three spatial scales; the entire sampled area of the ARB, individual water management subunits (WMSs), and individual sampling sites. Goodness of fit statistics suggested that our analyses best described the relationship between dissolved oxygen and structuring variables at the WMS scale. Further, at the WMS scale, water temperature, stage height, and, to a lesser extent current velocity, appear to be the most important variables in setting dissolved oxygen levels. We suggest that management decisions at the WMS scale will offer the greatest potential benefits for improvement of DO conditions in the ARB.
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