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PRODUCTIVITY AND SPECIES RICHNESS IN SMALL HIGHLAND STREAMS: THE INTERACTION OF HABITAT AND LAND USE HISTORY
Citation:
McCormick, F H. PRODUCTIVITY AND SPECIES RICHNESS IN SMALL HIGHLAND STREAMS: THE INTERACTION OF HABITAT AND LAND USE HISTORY. Presented at American Society of Ichthyologists and Herpetologists, La Paz, B.C.S., Mexico, June 14-20, 2000.
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
Small, upland, coldwater streams are an important resource for watershed management. In the Mid-Atlantic region, these streams are affected by acid deposition, mountaintop removal and valley fill for mineral extraction, and the effects of historical timber harvests. Small streams may be naturally unproductive, making the assessment of their condition based on fish species richness and biomass difficult to interpret. Fish assemblages in upland, coldwater systems were more depauperate, with fewer individuals, and represented by "pioneering" species such as blacknose dace (Rhinichthys atratulus) than valley and plateau streams of comparable size (50km2). Mean species richness, mean water column species richness, and mean number of trophic and reproductive guilds were significantly greater in lowland streams. However, mean number of sensitive species were greater in upland systems while the proportion of tolerant individuals were lower. Species richness variables (number of native species, families, species representing habitat preferences, or specific taxonomic groups) were higher at sites with abiotic characteristics (chemistry, land use, and habitat) indicative of human disturbance than for "reference" sites that had passed screens for those characteristics. While land use and its accompanying habitat degradation may account for low species richness in streams that would otherwise be expected to support greater native species diversity, differentiating impaired streams from naturally depauperate ones required evaluation on case by case, and often variable by variable, bases.