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BENTHIC INDICATORS FOR THE SUBSTANTIALLY ALTERED LANDSCAPE OF THE MISSISSIPPI ALLUVIAL PLAINS. Ben Jessup – Tetra Tech, Inc. Valerie Alley – Mississippi DEQ Matt Hicks – USGS . SWPBA November 14, 2012 Lake Guntersville State Park.

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benthic indicators for the substantially altered landscape of the mississippi alluvial plains

BENTHIC INDICATORS FOR THESUBSTANTIALLY ALTERED LANDSCAPE OF THEMISSISSIPPI ALLUVIAL PLAINS

Ben Jessup – Tetra Tech, Inc.

Valerie Alley – Mississippi DEQ

Matt Hicks – USGS

SWPBA

November 14, 2012

Lake Guntersville State Park

analytical steps
Analytical Steps
  • Gather and Compile Data
  • Define the Disturbance Gradient
  • Classify Sites by Natural Types
  • Assess Metric Responses to Disturbance
  • Combine Metrics in an Index
slide7

Step 1:

Gather Data

data elements
Data Elements
  • Collected during 2002*, 2007, 2008, and 2010 by MDEQ and the U.S.G.S.
  • Macroinvertebrates, water quality, habitat ratings, general site observations, and GIS.
  • 57 sites (2002 samples eliminated)
  • QC process for lab processes
  • In EDAS for metric calculation
slide9

Step 2:

Define the Disturbance Gradient (preliminary)

LD: Score +1 for each MD: score (-1) for each

disturbance gradient
Disturbance Gradient

Longitude

Latitude

Bluff

Inter.

-5 -4 -3 -2 -1 0 1 2 3 4 5

Disturbance Gradient Score

Map

natural gradient
Natural Gradient

% Alluvium

Flow Rate

site classification

Step 3:

Site Classification
  • All the “best” sites (lower disturbance) have bluff and non-Delta land in their catchments
  • Core Delta sites are essentially different than bluff sites (slope, substrate, flow, soils, etc.)
  • This confounds the “natural” and “anthropogenic” gradients
  • We should not expect bluff-like bug samples in the core of the Delta
  • Two site classes: Bluff Hills and Core Delta
slide15

Step 4:

Metric Responses

  • Screened metrics against the disturbance gradient score using correlation
  • Plotted the most responsive metrics to evaluate responses within site classes
  • Compared reference and stressed within site classes using DE and Z-score
slide16

Bluff Sites

Interior Sites

Disturbance Gradient Score

metric response among classes
Metric Response among Classes

EPT Taxa

LD

Other

MD

Ref

MD

Other

Bluff Hills

Interior Delta

slide18

Bluff Sites

Interior Sites

Disturbance Gradient Score

slide19

Bluff Sites

Interior Sites

Disturbance Gradient Score

metric results
Metric Results
  • In the Interior Delta
    • Only five of 67 potential metrics had DE ≥69%
  • In the Bluff Hills
    • One metric in each category had a DE = 100%
  • Scoring was based on the 5th and 95th %iles
combine metrics in an index interior delta
Combine Metrics in an Index Interior Delta
  • Of several combinations of responsive metrics
  • The best index had a DE of 92%

a ”X” in the formula represents the metric value

  • b POET includes Plecoptera, Odonata, Ephemeroptera, & Trichoptera
combine metrics in an index bluff hills
Combine Metrics in an Index Bluff Hills
  • Several combinations of responsive metrics
  • The best index had a DE of 100%

1”X” in the formula represents the metric value

index performance
Index Performance

Bluff Hills Drainage

Interior Delta

  • DE: 100%
  • Ref 25th: 75
  • 90% CI: ±6.2
  • DE: 92%
  • Ref 25th: 43
  • 90% CI: ±14.9
biological condition gradient
Biological Condition Gradient

LD

MD

MD

LD

Bluff Hills

Interior Delta

(?)

Observable Delta Sites

slide25

Conclusions

  • Metrics responses are related to both the stressor gradient and site classes
  • In this case it is best to find metrics that respond uniquely in each site class
  • Stressor gradients have different meanings in different site classes