Understanding Florida s Stream Condition Index Russ Frydenborg FDEP Bureau of Laboratories
Factors Affecting Aquatic Biological Communities Light penetration Temperature Habitat structure Sediment/substrate Conductivity/Salinity Hydrology/flow 2 Dessication Consumers: Fish, wildlife, humans 1 Consumers: Benthic invertebrates, zooplankton, some fish Biota Producers: Algae, macrophytes, terrestrial plant leaf litter, bacteria/detritus Physical factors ph Water quality factors Major ions Introduction of exotics, Harvesting game species Hydrological modifications Dissolved Oxygen Human factors Consumptive use Impounding Ditching/draining Habitat disruption: Physical destruction Siltation/Sedimentation Organic carbon Degradation of water quality: Toxic substances Organic enrichment Nutrient enrichment Nutrients
Defining Ecological Expectations Absent human interference, ecological communities have evolved in response to: physical, chemical, and bio-geographic processes Expectations are set by studying reference condition (and its variability) in each community type.
Adverse Human Factors Hydrologic modifications (consumptive use, impounding, ditching/draining) Habitat disturbance (physical removal, sedimentation) Degradation of water quality (toxic substances, nutrient and organic enrichment) Introduction of invasive exotic taxa Harvesting biomass
Biological Integrity The ability of an aquatic ecosystem to support and maintain a balanced, adaptive community of organisms having: species composition, diversity, and functional organization comparable to that of natural habitats within a region.
Procedure to Develop Biologically-Based Criteria Classify aquatic systems into meaningful units Sample biota across human disturbance gradient (define expectations) Select relevant biological attributes that provide a reliable signal about human effects (nutrient imbalances) Extract and interpret patterns in the data Develop reasonable policy to protect designated aquatic life use
Florida s Stream Condition Index: 1990 s Multimetric Approach Established reference condition in various sub-ecoregions Best professional judgment Surrounding land use, in-stream habitat Sampled known impaired sites Point source discharge studies Toxicity, low DO, poor habitat
Florida s Stream Condition Index: 1990 s Multimetric Approach (cont.) Selected 7 metrics Box and whisker plots determined discrimination power Aggregated by summing metrics 5, 3, 1 point, depending on departure from reference condition
Florida s SCI Re-calibration Develop human disturbance gradient Test disturbance gradient for each Bioregion Evaluate metric response to disturbance gradient (new thresholds, new metrics) Determination of metric variability Power analysis for trend detection Develop consistency with EPA Tiered Aquatic Life Use Support guidance (TALUS)
To Ensure Scientifically Defensible Metrics: Develop criteria, independent from biology, to determine which sites are impaired by humans vs. those that are not (the fabled x axis ) Reference vs. Degraded Sites Human Disturbance Gradient
leaves and twigs Energy source domestic wastes natural Chemical variables excess nutrients, toxins natural flows Flow regime extreme flows pools and riffles Habitat structure uniform native taxa Biotic factors exotic taxa Karr & Rossano
Human Disturbance Factor Analysis Landscape level Landscape Development Intensity Index Habitat alteration Habitat assessment data Hydrologic modification Hydrologic scoring process Chemical Pollution Ammonia, etc.
Summary of the Landscape Development Intensity* Coefficients Category Coefficient Natural System 1 Pine Plantation 1.6 Pasture 3.4 Row Crops 4.5 Residential (low) 6.8 Residential (high) 7.6 Commercial 8.0 Industrial 8.3 Commercial (high) 9.2 Business District 10.0 *Developed by Mark Brown, University of Florida, based on non-renewable Energy inputs, Odom s Embodied Energy concept.
Landscape Development Intensity Index
Hydrologic Modification Scoring Best, 1-2 points Flow regime as naturally occurs (slow and fairly continual release of water after rains), few impervious surfaces in watershed; high connectivity with ground water and surface features delivering water (e.g., sandhills, wetlands; no ditches, berms, etc.) Very poor, 9-10 points Flow regime entirely human controlled; hydrograph very flashy (scouring after rain events with subsequent reductions in flow, leading to stagnant or dry conditions, related to impervious surfaces and ditching throughout watershed); water withdrawals & impoundments fundamentally alter the nature of the ecosystem
Florida s HDG: Combination of other Disturbance Measures Scores 1 2 3 4 Measure NH3 <0.1 >0.1 >2 Habitat >65 >50 and <50 <65 Hydro <6 6-7 8-9 10 LDI <200 200-350 >350 (buffer) LDI (ws) <200 200-350 >350
Evaluating Metrics 23 Total Taxa Discrimination Efficiency Redundancy 12 EPT Taxa 13% Ephemeroptera Scoring Metrics Reference 72% Chironomids Precision 10% Collector-Filterers
Metric Selection Criteria Meaningful measure of ecological structure or function Strong and consistent correlation with human disturbance Statistically robust, low measurement error Represent multiple categories of biological organization Cost-effective to measure Not redundant with other metrics Exception: response signature metrics
Attribute Groups INDIVIDUAL CONDITION TAXONOMIC COMPOSITION COMMUNITY STRUCTURE LIFE HISTORY ATTRIBUTES SYSTEM PROCESSES DISEASE ANOMALIES CONTAMINANT LEVELS DEATH METABOLIC RATE IDENTITY TOLERANCE RARE OR ENDANGERED KEY TAXA TAXA RICHNESS RELATIVE ABUNDANCE DOMINANCE FEEDING GROUPS HABIT VOLTINISM TROPHIC DYNAMICS PRODUCTIVITY MATERIAL: CYCLES PREDATION RECRUITMENT TOXICITY TESTS RIVPACS INVERTEBRATE IBI FISH IBI INTEGRATED BIOASSESSMENT
Desirable Metric Qualities Ecologically Justified Discriminating Represent Integrity Precise Sufficient range of values
Florida Sites Ranked According to HDG 3.5 3.0 2.5 HDG 2.0 1.5 1.0 0.5 0 20 40 60 80 100 HDG_rank (%) Consistent loss of species beyond this point 40% of sites undisturbed
Example of a Sensitive Mayfly Genus (Stenonema) TX1082=Stenonema smithae2 0.14 0.10 0.06 0.02-0.02-20 20 60 100 140 180 220 HDG_rnk TX1078=Stenonema 0.022 0.018 0.014 0.010 0.006 0.002-0.002-20 20 60 100 140 180 220 HDG_rnk TX1079=Stenonema exiguum2 0.07 0.05 0.03 0.01-0.01-20 20 60 100 140 180 220 HDG_rnk Increasing disturbance
Example of a Tolerant Clam Species 0.18 TX216_Corbicula fluminea 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00-0.02-20 20 60 100 140 180 220 HDG_rnk Increasing disturbance
Incorporating Integrity Include Robust, Discriminating Metrics from a Variety of Categories: Richness Composition Tolerance Feeding Functions Habit Voltinism
Richness Measures Total taxa EPT taxa Ephemeroptera taxa Plecoptera taxa Trichoptera taxa Diptera taxa Chironomidae taxa Coleoptera taxa Oligochaeta taxa Insect taxa Non-insect taxa Shannon-Wiener Index Composition Measures % EPT % EPT (no Baetidae or Hydropsychidae) % Ephemeroptera % Ephemeroptera (no Baetidae) % Plecoptera % Trichoptera % Trichoptera (no Hydropsychidae) % Diptera % Diptera (no Chironomidae) % Chironomidae % Coleoptera % Oligochaeta % non-insects % 5 dominant % 10 dominant
Feeding Measures % Collectors % Scrapers % Shredders % Filterers % Predators Collectors taxa Scrapers taxa Shredders taxa Filterers taxa Predators taxa Tolerance and Other Measures HBI BCI CTQa Beck's Biotic Index Intolerant taxa % tolerant % Clingers Clingers taxa % Semivoltine Semivoltine taxa
Two Approaches to Assessing Metrics Compare extremes reference vs. impaired Compare across contiuum of disturbance Human Disturbance Gradient
Works for extremes, but what about TALUS axis? REF Impaired Biological response
Noise on both axes! Human disturbance Biological response
Human disturbance Refine human disturbance scale, select best biological metrics Biological response
Index with Ideal Response Multimetric index Human disturbance gradient
Chironomid Taxa : 26 Reference vs. Impaired Numer of chironomid taxa 22 18 14 10 6 2-2 Reference Impaired
26 Chironomid taxa vs. HDG Numer of chironomid taxa 22 18 14 10 6 2 R = 0.38 (Discard metric) -2 <= 1.5 (1.5,2] (2,2.5] (2.5,3] > 3 Human Disturbance Gradient
% Diptera : Reference vs. 110 Impaired 90 % Diptera 70 50 30 10-10 Reference Impaired
% Diptera vs. HDG 110 90 r = 0.01 (Discard metric) % Diptera 70 50 30 10-10 <= 1.5 (1.5,2] (2,2.5] (2.5,3] > 3 Human Disturbance Gradient
Florida Index: Reference vs. 35 Impaired Florida Index 25 15 5-5 Reference Impaired
Florida Index vs. HDG Florida Index 35 25 15 Good metric, but substitute stronger Florida Sensitive Taxa R = 0.72 5-5 <= 1.5 (1.5,2] (2,2.5] (2.5,3] > 3 Human Disturbance Gradient
Correlation for Metrics and HDG Chironomid taxa Long lived % voltinism Tanytarsini taxa Diptera taxa Tanytarsini % Filter-feeder % Dominant % Filter-feeder no Chuemat. Tanytarsini % Total Taxa feeding structure composition richness Attribute Trichop % Eph % Clinger % Very tolerant taxa Eph taxa Trichop taxa All Tolerant % Very Tolerant % Clinger taxa richness richness tolerance habit Florida Index EPT taxa Sensitive taxa tolerance 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Absolute Spearmans r
Total number of taxa 60 50 40 30 20 10 Median 25%-75% Non-Outlier Range Outliers Taxa Richness 0 Human disturbance gradient
7 Number of Eph. taxa 6 5 4 3 2 1 Ephemeroptera Taxa 0 Human disturbance gradient
Number of Trichoptera taxa 8 6 4 2 0 0.8 2.4 4 5.6 7.2 Human disturbance gradient Trichoptera Taxa
40 % Tanytarsini 30 20 10 % Tanytarsini (Sensitive midges) 0 0.8 2.4 4 5.6 7.2 Human disturbance gradient
60 % Filterer 40 20 % Filterers 0 Human disturbance gradient
6 5 4 3 2 1 0-1 Human disturbance gradient Long-lived Taxa Number of long-lived taxa
Number of clinger taxa 10 5 0 Clinger Taxa 0.8 2.4 4 5.6 7.2 Human disturbance gradient
80 % Dominance 60 40 % Dominance 20 Human disturbance gradient
15 10 5 0 Human disturbance gradient Sensitive Taxa Number of sensitive taxa
% Very tolerant individuals 90 60 30 0 0.8 2.4 4 5.6 7.2 Human disturbance gradient % Very Tolerant Taxa
SCI vs. Human Disturbance Gradient 100 80 60 Median 25%-75% Non-Outlier Range Outliers r = 0.72 SCI 40 20 0 1.2 1.6 2.0 2.4 2.8 Human disturbance gradient
SCI from 1992 to 2001 100 80 60 SCI 40 20 0 0 2 4 6 8 10 Human disturbance gradient
Bio-regions of Florida 65f 65g 65h 75e 75f 75a Northeast Panhandle 75c Southeastern Plains Ecoregion (#65) 65f Southern Pine Plains and Hills 65g Dougherty/Marianna Plains 65h Tifton Upland/Tallahassee Hills 75d Peninsula Southern Coastal Plains Ecoregion (#75) 75a Gulf Coast Flatwoods 75b Southwestern Florida Flatwoods 75c Central Florida Ridges and Uplands 75d Eastern Florida Flatwoods 75e Okeefenokee Swamps and Plains 75f Sea Island Flatwoods Southern Florida Coastal Plains Ecoregion (#76) 76a Everglades 76b Big Cypress 76c Miami Ridge/Atlantic Coastal Strip 76d Southern Coast and Islands 75b 76b 76d 76a 76c
Florida Mayfly Taxa vs. HDG Mayfly Taxa 7 6 5 4 3 2 1 0-1 -2 0.6 1.2 1.8 2.4 3.0 0.6 1.2 1.8 2.4 3.0 0.6 1.2 1.8 2.4 3.0 NE Ecoregion Peninsula Ecoregion Panhandle Ecoregion HDG
Florida Sensitive Taxa vs. HDG Sensitive Taxa 20 18 16 14 12 10 8 6 4 2 0-2 -4-6 0.6 1.2 1.8 2.4 3.0 0.6 1.2 1.8 2.4 3.0 0.6 1.2 1.8 2.4 3.0 NE Ecoregion Peninsular Ecoregion Panhandle Ecoregion HDG
Florida Clinger Taxa vs. HDG 14 12 10 Clingers 8 6 4 2 0-2 0.6 1.2 1.8 2.4 3.0 NE Ecoregion 0.6 1.2 1.8 2.4 3.0 Peninsula Ecoregion HDG 0.6 1.2 1.8 2.4 3.0 Panhandle Ecoregion
90% Confidence Interval: SCI =/- 15 points SCI 100 90 80 70 60 50 40 30 20 10 0 Data from Repeat Visits Site
SCI can reliably detect 3 categories based on 1 sample Number of categories: ~ 15 points x 2 = 30 points 100 / 30 = 3 categories SCI 70-100 40-69 0-39 Description Good Fair Poor
SCI Can Reliably Detect 5 Categories Based on 2 Samples SCI 80-100 60-79 40-59 20-39 0-19 Description Excellent Good Fair Poor Very poor
Number of sites Test sites Reference sites SCI Impairment
Number of sites Test sites Reference sites Poor Fair V. Poor Good Outstanding SCI
SCI Categories and TALUS Axis Condition of the Biotic Community [Specific to Ecotype] 1 LOW Natural structure and function of biotic community maintained Excellent 2 Good 3 Fair Poor Very Poor Minimal changes in structure & function 4 Evident changes in structure and minimal changes in function Human Disturbance Gradient Moderate changes in structure and minimal changes in function 5 Major changes in structure & moderate changes in function 6 Severe changes in structure & function HIGH
Existing Applications of SCI Ambient Monitoring Impaired Waters Rule (TMDLs) Point Source Permitting Watershed (NPS) Studies BMP Effectiveness Studies
Conclusions The SCI is effective in regulatory programs Discriminatory power of metrics Comparing extremes identifies strong metrics, but includes some noisy metrics Human Disturbance Gradient improves metric selection and provides an independent measure for comparing biological response