Assessing the influence of watershed- and reach-scale environmental variables on the speciose darter (Percidae: Etheostoma, Percina) assemblage of a central Kentucky (USA) landscape

Abstract

Darters are a speciose group of small fishes belonging to the family Percidae and endemic to the eastern Nearctic region (ETNIER & STARNES 1993, PAGE 1983). Most species are assigned to the genera Etheostoma and Percina, with a third genus (Ammocrypta) having relatively few species. Most Etheostoma and Percina is centered in (l) the In teri o r Plateau region that encompasses the Ouachita Mountains of western Arkansas and eastern Oklahoma, (2) the Ozark uplift area of northern Arkansas and southern Missouri, and (3) Kentucky south through central Tennessee and northern Alabama, and east North Carolina and Virginia. The southeastern United States harbors an impressive diversity of stream fishes (MAYDEN 1988, WARREN et al. 2000). Kentucky's Green River is one ofthe top 4 rivers in the United States according to fish and mussel diversity (ThE NATURE CoNSERVANCY 2005). The Upper Green River Basin, in particular, is the subject of a Nature Conservancy landscape-scale conservation effort and in 200 l was established as Kentucky's USDA Conservation Reserve Enhancement Program (CREP). A primary goal of the 40 000 ha Kentucky CREP is to reduce non-point source pollution loading (e.g., sediment, fertilizer) into the mainstem ofthe Green River and main tributaries by recruiting landowners into incentive-based l 0--15 yr. cooperative agreements. We assessed the relationship between abundance patterns of a speciose darter assemblage in Kentucky's Upper Green River Basin in relation to watershedand reach-scale environmental variables. Intensive biological sampling was initiated in 2001, and we considered this data as a pre-manipulative, basin-wide control because through 2001 only 516 ha ( 1.3 %) had been incorporated into CREP practices, with only 234 ha as riparian buffer. Additionally, because landuse data were not quantified prior to the start of biological sampling we did not have preconceived assumptions regarding fish assemblage response to environmental variables indicative of anthropogenic perturbation (e. g., row cropping).