An Experimental Study of Vertical Habitat Use and Habitat Shifts in ...

Introductions of non-native fishes have increased dramatically within the past
century (Courtenay and Hensley 1980). Drainages with naturally low species diversity,
such as the New River drainage of North Carolina, Virginia, and West Virginia, have
typically incurred the largest numbers of introduced species (Jenkins and Burkhead
1994). The New River drainage not only has a high proportion of non-native fishes (over
50% nonnative, Wellman 2004), but also includes a diverse endemic fish fauna
(bigmouth chub Nocomis platyrhynchus, New River shiner Notropis scabriceps,
Kanawha minnow Phenacobius teretulus, Kanawha sculpin Cottus kanawhae, Bluestone
sculpin Cottus sp., albino cave sculpin Cottus sp., Appalachia darter Percina
gymnocephala, Kanawha darter Etheostoma kanawhae, and candy darter Etheostoma
osburni). Within the last half century, range distributions have decreased for many of
these New River endemics (Chipps 1993b, Cincotta et al. 1999, Burns 2007), but few
research efforts have focused on the relationship or non-relationship between a
concurrent increase in nonnative diversity (number of species and population sizes) and a
decrease in population sizes and range distributions of native species.
Many non-native fishes have recently expanded their distributional ranges within
the lower New River drainage and tributaries, such as the 4000 km 2 Greenbrier River
watershed of West Virginia, including whitetail shiner Cyprinella galactura, telescope
shiner Notropis telescopus, Roanoke darter Percina roanoka, rainbow darter Etheostoma
caeruleum, and variegate darter Etheostoma variatum (Wellman 2004). The fish fauna of
the Greenbrier River drainage includes seven of the nine New River endemics (excluding
Kanawha darter and Bluestone sculpin) and has relative high population sizes of two nonnative
minnows, telescope and whitetail shiner. The ecological influences of these non-
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