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Case StudyDevelopment 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 SitesAbout 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
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
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 non-indigenous 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 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)
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