The association of water chemistry variables and fish condition in streams of Shenandoah National Park (USA)
As part of the “Shenandoah National Park: Fish in Sensitive Habitats” (SNP:FISH) project, the blacknose dace ( Rhinichthys atratulus ) was utilized as an indicator species to assess the susceptibility of the ichthyofaunal community of Shenandoah National Park (USA) to acidification. Water chemistry (ANC, conductivity, pH, and concentrations of Ca 2+ , Mg 2+ , Na + , K + , Cl − , NO 3 − , SO 4 2− , and SiO 2 ) was sampled every three months over the course of 3 1/4 years which represents the probable maximum lifetime of R atratulus. Condition factors (K=[g/mm 3 ] * 10 6 ) were calculated for samples of fish (age class 2+ yr; n=370) from nine montane, second/third order streams representing a range of ANCs. A principle components regression was performed on factor scores from a principle components analysis of the water chemistry variables and fish condition factor. Two factors, one associated with stream water ANC and ion concentrations, and another associated with SO 4 2− concentration, collectively explained 84% of the variance in condition factor. The influence of variables other than water chemistry upon R atratulus K is addressed. The results show that environmental chemistry is highly associated with the K of R atratulus.