Longitudinal patterns of fish assemblages in small unregulated subbasins: evaluating reach- and watershed-scale parameters

Abstract

Fish assemblage relationships with environmental parameters were studied in four small unregulated subbasins in the speciose Upper Green River Basin of central Kentucky, USA. One subbasin drains into a tributary of the Green River and produced the lowest species (28) richness. The three other subbasins drain directly into the Green River and supported 41-59 species. Parameters were partitioned into watershed-and reach-scale spatial categories. Watershed area per stream segment and stream-size related environmental parameters at the reach scale produced the highest loadings of a principle components analysis (PCA), and both PCA Axes 1 and 2 for all subbasins were reflective either of watershed area or stream-size parameters. Small loadings were produced by all watershed-scale land-use parameters and all reachscale water chemistry parameters. Fish richness and diversity were positively correlated with watershed area for the two largest subbasins and for the three Upper Green River subbasins combined. The lack of a linear relationship, however, between the residuals of multiple linear regression models between richness and diversity versus stream width, percent bedrock, percent pool and percent fine substrates indicated that a simple species area relationship was not operating. A detrended correspondence analysis (DCA) performed for each subbasin showed that several fish species were associated mainly either with small, upland segments or conversely the largest, deeper segments, and each subbasin yielded significant correlations between the environmental PCA loadings and fish assemblage DCA site scores. These results indicated that within the regional scale, and in absence of steep disturbance gradients, stream fish assemblages can reflect natural hydrologic and geomorphic gradients.

Local and ecoregion effects on fish assemblage structure in tributaries of the Rio Paraíba do Sul, Brazil

“…, 2004; Pinto et al. , 2006; Grubbs, Meier & Meier, 2007). Similarly, increased agriculture was correlated with low index of biotic integrity scores for fish assemblages, where the gradient was from natural vegetation to arable land (rowcrops) or pasture (Roth, Allan & Erickson, 1996; Wang et al.…”

“…This is probably because higher altitude ecoregions are less accessible to humans and less suited for agriculture and urbanisation than valley ecoregions. Urban land-use was associated with low values of the index of biotic integrity for fish assemblages in streams along a forest-urban gradient (Steedman, 1988;Wang et al, 2001;Snyder et al, 2003;Van Sickle et al, 2004;Pinto et al, 2006;Grubbs, Meier & Meier, 2007). Similarly, increased Environmental effects on fish assemblages in tributaries 2609 agriculture was correlated with low index of biotic integrity scores for fish assemblages, where the gradient was from natural vegetation to arable land (rowcrops) or pasture (Roth, Allan & Erickson, 1996;Wang et al, 1997;Fitzpatrick et al, 2001;Mebane, Maret & Hughes, 2003;Meador et al, 2008).…”

Predicting assemblages and species richness of endemic fish in the upper Yangtze River

“…The upstream-downstream gradient is probably the most well-known large-scale pattern in stream fish assemblages, and correspondingly the flow regime, temperature, food availability and substrate conditions of the river also vary from upstream to downstream areas (Rahel and Hubert, 1991;Belliard et al, 1997;Marchetti and Moyle, 2001;Grubbs et al, 2007). Any change in expected assemblages could indicate environmental changes in the area (Hughes et al, 1986), which can provide a useful framework for studying and managing streams in different subgeographic areas of certain drainage basins (Céréghino et al, 2001;Oberdorff et al, 2001).…”

Relationships between Crayfish Abundance Patterns and Environmental Variables across Two Spatial Scales in a Central Kentucky River Basin, USA

“…The highest density of 0. rusticus occurred in stream reaches with the greatest proportion of this land-use type. Previous studies of upper Green River basin fish assemblages similarly revealed no relationship to either agriculture or forest land-use patterns (Grubbs et al 2007), yet small streams influenced by urban land-use possessed darter (e.g., Etheostoma zonale) faunas typical of larger streams (Grubbs et al 2010).…”

“…Watershed area above each sampling reach was determined using an online tool for Kentucky streams (USGS 2004). Land use was quantified according to the methods outlined in Grubbs et al (2007). (Helsel 1990).…”