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