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Case Study Development of an Index of Biotic Integrity for the Mid-Atlantic Highland Region McCormick et al. 2001 Mid-Atlantic Highlands Assessment (MAHA) Many believe that IBIs must be watershed and or ecoregion specific Several IBIs have been developed for specific ecoregions of the Mid-Atlantic Highlands McCormick et al. used a widespread sampling regime of 1st to 3rd order streams throughout the upland ecoregions of the mid-Atlantic Highlands attempting to develop a single IBI for assessing fish assemblages within the region Methods MAHA Sites About 450 sites were selected based on a probabilistic sampling (randomly selected within cells) Ecoregions McCormick et al. 2000; found no effect of ecoregion on fish communities. Journal of the North American Benthological Society 19(3):385-404 Fish and Habitat Sampling Fish communities were sampled during spring low flow conditions over three years Water chemistry, physical habitat, and landscape variables known to be responsive to a variety of anthropogenic impairments were sampled at selected site MAHA Stressors Ecoregion Impairments Reference Selection Used three reference definitions for selection and setting scoring thresholds Least restrictive Moderately restrictive Water chemistry and RVHA Water chemistry, land use, road density, and quantitative habitat filters Highly restrictive Moderately restrictive criteria and watershed condition class Metric Screening Combined habitat variable and fish data to identify suitable metrics MAHA IBI screened 58 candidate metrics Scoring range Variability Responsiveness Redundancy Results Mid-Atlantic IBI Metrics 9 were selected (to include at least 2 in each metric category) Mid-Atlantic IBI Metrics • • • • • • • • • Number of native Cyprinid species ^ (Log) Number of native benthic species ^ (Log) Proportion of individuals in the family Cottidae Sensitive species richness (Log) Proportion of tolerant individuals * Proportion of non-indigenous individuals * Proportion of invertivore - piscivore individuals Proportion of macro-omnivores * Proportion of (clean) gravel spawning species * = negative scoring metric ^ = Exclude tolerant species (Log) = Scaled # Native Cyprinid Species Positive scoring metric Declines with increasing watershed impairment Exclude tolerant species Scaled by log drainage basin # Native Benthic Species Positive scoring metric Decreases with increasing sedimentation and loss of quality benthic habitat Linked to benthic macroinvertebrates and sediment supply and transport Exclude tolerant species Scaled by log drainage basin Proportion Cottidae Positive scoring metric Declines with degradation of all habitat measures and increasing nutrient loading Linked to human activity in watershed Found to be dominant in all reference streams w/in the Cheat basin Sensitive Species Richness Positive scoring metric Declines with increasing human activity in the watershed, turbidity, and AMD High scores indicate intact watershed with minimal impairment Scaled by log (drainage basin) Proportion Tolerant Individuals Negative scoring metric Increases with degraded water quality, physical habitat, and watershed condition Indicative of physical or chemical impairment Proportion Non-Indigenous Individuals Negative scoring metric Not associated with physico-chemical impairment Measures biological pollution Increased nonindigenous individuals means decreased “integrity” Telescope Shiner Proportion Invertivore / Piscivore Species Positive scoring metric Declines with increased habitat degradation Linked to habitat quality (particularly pools) and stability Speaks toward a systems ability to support long lived top predators Brown Trout Proportion of MacroOmnivores Negative scoring metric Increases with increasing nutrient loading and habitat alteration leading to shifts in food availability Dominant in impaired streams & those with missing links in food web (i.e. Unbalanced) Proportion Clean Gravel Spawning Species Positive scoring metric Declines with sedimentation, reduced substrate quality, and channel degradation These fishes rely upon interstitial spaces within clean gravel for egg development and reproductive success Indicates that sediment deposition and transport ability is not limiting River Chub Discussion Fish assemblage variable were found to be highly correlated to wide-ranging disturbance gradients Standardized consistent fish-assemblage sampling methods, coupled with quantitative physical, chemical, and landscape data, allowed for the development of a sensitive and regionally applicable index of fish assemblage integrity