E. Marsh-matthews et Wj. Matthews, Spatial variation in relative abundance of a widespread, numerically dominant fish species and its effect on fish assemblage structure, OECOLOGIA, 125(2), 2000, pp. 283-292
Collections of fish assemblages from streams in the midwestern United State
s were used to examine assemblage-level effects of spatial variation in rel
ative abundance of the red shiner, Cyprinella lutrensis, a widespread and h
ighly abundant minnow species. This species has been widely introduced outs
ide its native range and is suspected to have impacted local assemblages wh
ere it has become established. Given its overall dominance of midwest fish
assemblages, and its suspected impact on assemblage structure, we asked if
structure of the residual fish assemblages (red shiners excluded) was a fun
ction of the relative abundance of red shiners throughout the native range
of C. lutrensis in the USA. Although red shiner ranked first in abundance i
n half of the assemblages and numerically dominated 28% of the assemblages,
red shiner relative abundance in an assemblage had no detectable effect on
richness, diversity, evenness, or complexity of other (residual) species i
n the assemblage. Relative abundance of red shiners did have a positive eff
ect on the abundance of benthic minnows in the residual assemblage, but not
on water column minnows that are ecologically most like red shiners. Envir
onmental factors did not explain a significant amount of the variation in r
elative abundance of red shiners, but did explain some variation in residua
l assemblage structure. Although widespread and numerically dominant at man
y localities, red shiners do not appear to have a strong impact on local fi
sh assemblage structure within their native range. This is in sharp contras
t to the reported negative effects of red shiners on fish assemblages where
they have been introduced outside their native range.