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 Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl^–, NO₃^–, SO₄^2–, and SiO₂) 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/mm³]^*10⁶) 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 SO₄^2– 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.