Influence of eastern hemlock (Tsuga canadensis L.) on fish community structure and function in headwater streams of the Delaware River basin

摘要: Abstract –  Hemlock (Tsuga canadensis) forests of the eastern U.S. are in decline due to invasion by exotic insect hemlock woolly adelgid (Adelges tsugae). Aquatic biodiversity ecosystems has not been documented; thus true impact infestation cannot be assessed. We compared ichthyofaunal assemblages and trophic structure streams draining hardwood sampling first- second-order 14 paired stands during base flows July 1997 at Delaware Water Gap National Recreation Area Pennsylvania New Jersey. Over 1400 fish 15 species 7 families were collected, but individually harbored only one four species. Brook trout (Salvelinus fontinalis) brown (Salmo trutta) two three times as prevalent than streams. Insectivorous fishes occurred significantly higher proportion (0.90) (0.46) stands, while piscivores more often (0.85) (0.54) stands. Functional (trophic) diversity was numerically greater that first-order Species composition also differed stream order terrain type. Biodiversity is threatened several levels within risk forests.