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Case Study

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

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Case Study

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  1. Case Study Development of an Index of Biotic Integrity for the Mid-Atlantic Highland Region McCormick et al. 2001

  2. 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

  3. Methods

  4. MAHA Sites About 450 sites were selected based on a probabilistic sampling (randomly selected within cells)

  5. Ecoregions McCormick et al. 2000; found no effect of ecoregion on fish communities. Journal of the North American Benthological Society 19(3):385-404

  6. 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

  7. MAHA Stressors

  8. Ecoregion Impairments

  9. Reference Selection • Used three reference definitions for selection and setting scoring thresholds • Least restrictive • Water chemistry and RVHA • Moderately restrictive • Water chemistry, land use, road density, and quantitative habitat filters • Highly restrictive • Moderately restrictive criteria and watershed condition class

  10. Metric Screening • Combined habitat variable and fish data to identify suitable metrics • MAHA IBI screened 58 candidate metrics • Scoring range • Variability • Responsiveness • Redundancy

  11. Results

  12. Mid-Atlantic IBI Metrics • 9 were selected (to include at least 2 in each metric category)

  13. 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

  14. # Native Cyprinid Species • Positive scoring metric • Declines with increasing watershed impairment • Exclude tolerant species • Scaled by log drainage basin

  15. # 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

  16. 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

  17. 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)

  18. Proportion Tolerant Individuals • Negative scoring metric • Increases with degraded water quality, physical habitat, and watershed condition • Indicative of physical or chemical impairment

  19. Proportion Non-Indigenous Individuals • Negative scoring metric • Not associated with physico-chemical impairment • Measures biological pollution • Increased non-indigenous individuals means decreased “integrity” Telescope Shiner

  20. 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

  21. Proportion of Macro-Omnivores • 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)

  22. 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

  23. 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

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