Stability of the Wabash River fish assemblages from 1974 to 1998

Abstract

1. We measured temporal variability of the fish assemblage in the Wabash River using a 25-year electrofishing dataset through a combination of a time-lag analysis and multivariate analysis. 2. The fish assemblage had substantial year-to-year variation, but the overall abundance pattern did not change. Based on time-lag analyses and ordinations, there was only weak predictable directional change at individual sites. At the scale of the entire reach, however, the overall combined data had a statistically significant directionality with the time-lag analysis. 3. These results support the hypothesis that the middle Wabash River stream fish assemblage has undergone change over a time period of 25 years, although at the scale of individual sites this change was not detectable.

Temporal and spatial variation in an index of biological integrity for the middle Wabash River, Indiana

“…However, our impression is that even though raw IBI scores may vary substantially, the resulting integrity class scores (i.e., poor, good, excellent ranks) are robust to this variation. Spatial patterns that we observed using these Wabash River data were consistent with Gammon (1998), Gammon & Simon (2000), and Pyron et al (2006) using subsets of the same collections, and Pyron & Lauer (2004) using collections from 2001 to 2002: sites upstream of river km 500 resulted in higher IBI scores than downstream sites. This pattern was present in nearly every year.…”

“…However, detection of improvements is likely scale and context-dependent. For example, Pyron et al (2006) found directional changes in the fish assemblages during this 25-year period, but only at the scale of the entire reach, not at individual stations. Directional changes were only significant at the scale of the entire reach.…”

Interannual variations of the fish assemblage in the transitional zone of the Three Gorges Reservoir: persistence and stability

“…The test for directional change was performed by first calculating Bray-Curtis dissimilarity matrix for the species× time data matrix. Bray-Curtis dissimilarity measures were used because they result in more normal frequency distributions than Euclidean distance (Pyron et al 2006). The dissimilarity values were then regressed against time lags in years, which could produce three theoretical patterns (Collins et al 2000).…”

“…Persistence and stability of fish assemblages structure across temporal scales have been investigated in many aquatic ecosystems (Ross et al 1985;Meffe and Minckley 1987;Matthews et al 1988;Oberdorff et al 2001;Pyron et al 2006;Hued et al 2010). For example, in the middle Wabash River, USA, Pyron et al (2006) found that the fish assemblage was unstable over a period of 25 years. In Suquía River Basin, Argentina, Hued et al (2010) identified a persistent and stable fish assemblage, even though the deterioration of water quality was recorded.…”

“…Although theses terms have often been confused and used interchangeably, both should be considered separately when evaluating temporal change in natural assemblages (Meffe and Minckley 1987). Persistence and stability of fish assemblages structure across temporal scales have been investigated in many aquatic ecosystems (Ross et al 1985;Meffe and Minckley 1987;Matthews et al 1988;Oberdorff et al 2001;Pyron et al 2006;Hued et al 2010). For example, in the middle Wabash River, USA, Pyron et al (2006) found that the fish assemblage was unstable over a period of 25 years.…”