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

Sampling Locations

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

Gather Data Step 1:

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

Define the Disturbance Gradient (preliminary) Step 2: Variable Least Disturbed Most Disturbed % natural LU (watershed)>50, >25<10% % natural LU (buffer)>50%<10% % imperviousness <3%>5% DONA<3mg/L Habitat score>110<80 LD: Score +1 for each MD: score (-1) for each

Disturbance Gradient Disturbance Gradient Score Longitude Latitude Map Bluff Inter.

NMS Ordination Core Bluff

Natural Gradient % AlluviumFlow Rate

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 Step 3:

Redefine the Disturbance Gradient Interior DeltaBluff Hills Variable Least Disturbed Most Disturbed Least Disturbed Most Disturbed % natural land cover in the whole catchment > 15< 5> 80< 55 % natural land cover in the 200 m buffer > 15< 5n/a Habitat Index Score > 110< 80> 120< 100 Road density (miles/acre) < > 0.005n/a Dissolved oxygen (mg/L) n/a < 5

Metric Responses Step 4: 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

Disturbance Gradient Score Bluff Sites Interior Sites

Metric Response among Classes EPT Taxa LDMDOtherRef Other MD Bluff Hills Interior Delta

Disturbance Gradient Score Bluff Sites Interior Sites

Disturbance Gradient Score Bluff Sites Interior Sites

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 5 th and 95 th %iles

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 Metric nameDE / ZScoring formula a Percent of taxa in the POET orders b 54 / 0.9X/8 Percent of taxa as non-insect46 / -0.5(46-X)/32 Percent EPT individuals62 / 0.7X/47 Percent intolerant individuals69 / 0.5X/12 Percent of taxa as swimmers8 / 0.4X/11 Percent shredder individuals54 / 0.5X/42

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 Metric nameDE / ZScoring formula a EPT taxa75 / 1.3X/12 Percent of taxa as non-insects100 / -2.1(37-X)/33 Percent Tanytarsini of Chironomidae100 / 8.5X/52 Intolerant taxa75 / 1.0X/10 Percent filterer individuals100 / 3.1X/38 Percent clinger individuals100 / 3.3X/57

Index Performance DE: 100% Ref 25 th : 75 90% CI: ±6.2 Bluff Hills DrainageInterior Delta DE: 92% Ref 25 th : 43 90% CI: ±14.9

Biological Condition Gradient Observable Delta Sites (?) LDLD MDMD MDMD LDLD Bluff Hills Interior Delta

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

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