aquatic life criteria developments relevant to coal...
TRANSCRIPT
Aquatic Life CriteriaDevelopments Relevant to
Coal Mining
Charles DelosU.S. EPA, Office of Water
Health & Ecological Criteria DivisionSeptember 6, 2007
Three Topics:
New Copper Criterion
Selenium
Biological Criteria
Views are those of the author, not necessarily those of EPA.
Bioavailability-based Criterionfor Copper
Biotic Ligand Model2007
Compared toprevious hardness-based criterion,
the new BLM-based criterion may have:
– Higher value when Dissolved OrganicCarbon is high,
– Lower value when pH is low.
Selenium Toxicity
&
Aquatic Life Criteria Development
Selenium: bioaccumulationbut little or no biomagnification
• Algae and aquatic plants bioconcentrateselenium. Aquatic animals (further up thefood chain) receive nearly all of theirselenium from their diet, not directly fromwater.
• Exposure concentrations do not usuallychange significantly moving up the foodchain (in contrast to mercury).
Selenium Risk
• Species differences in sensitivity result indifferences in risk.
• In the field, effects have been observed infish and in birds.
• Mammals (including humans) appear to beless sensitive.
• Effects on invertebrates have notgenerally been the object of concern forselenium.
What are the threshold effects in fish?
• Deformities of offspring of excessivelyexposed adults:– Frequently observed in the field and in
combined field-lab tests.• Possible mortality of first year juveniles
over winter in cold climates.– Observed in one laboratory test (simulated
winter).– Not corroborated by field observations.– Subject of new toxicity testing by EPA.
Why did EPA opt for a fish tissuecriterion in its 2004 draft?
• The capacity for selenium bioaccumulationvaries from one water body to anotherbecause of differences in food webs.
• The same water concentration may yielddifferent degrees of fish tissueaccumulation and different degrees of riskin different water bodies.
• During implementation, a tissue criterionallows consideration of site-to-sitevariability in bioaccumulation.
What is the status of EPA criteria?
• Current criterion: 5 µg/L (water).– 1987 criterion relied on field observations of a
North Carolina impoundment.• 2004 draft: 7.9 µg/g (dry wt, fish tissue)
with 5.85 µg/g monitoring trigger value.• Currently re-evaluating to consider public
input and new data.– Due for publication late 2008.– Cannot predict the criterion value.
How much tissue-based datawere available for 2004 draft?
RotiferChinook salmonRainbow troutCutthroat troutBrook troutFathead minnow
Flannelmouth suckerRazorback suckerBluegill sunfishSunfish mixtureStriped bass
Aquatic species with chronic toxicity data:
Bluegill Chronic Toxicity TissueThresholds, parts per million
<5.85 – 7.9Lab> 17Mesocosm8.95Lab
12Mesocosm21 – 28Field
> 13Lab> 5.4Field
> 6.0Lab20 – 44Field
ValueTypeValueType
Site-Specific Effects Testing
• Obtain ripe adults from Se-contaminatedarea and reference area.
• Return to lab and fertilize eggs.• Culture eggs and larvae (further Se
exposure unnecessary).• Observe percentage of larvae with edema
or deformities (e.g., craniofacial and spinalmalformations).
Biological Criteria&
Tiered Aquatic Life Uses
Biological Criteria
• Biological Criteria are narrative or numericexpressions that describe the referencebiological integrity (structure and function)of aquatic communities inhabiting watersof a given designated aquatic life use.Biocriteria are based on the numbers andkinds of organisms present and areregulatory-based biologicalmeasurements.
Bio
logi
cal C
ondi
tion
The Biological Condition Gradient – Tiers
Increasing Levels of Stressors
Natural structure & function of biotic community maintained
Minimal changes in structure & function
Evident changes in structure andminimal changes in function
Moderate changes in structure &minimal changes in function
Major changes in structure &moderate changes in function
Severe changes in structure & function
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33
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Ecological Attributes Evaluated ForEach Tier
Native taxa and non native taxa
Sensitive, intolerant taxa
Tolerant taxa
Condition (e.g. anomalies, parasites)
Ecosystem function (P/R ratios, decomposition,trophic level)
Ecosystem connectedness, temporal and spatialextent of effects
CaddisfliesCaddisflies
MayfliesMayflies
StonefliesStoneflies
Dragonflies and DamselfliesDragonflies and DamselfliesSensitive Organisms in Ohio Streams
Courtesy of Chris Yoder, CABB
MidgesMidgesLeechesLeeches
SnailsSnailsScudsScudsTolerant Organisms in Streams
Courtesy of Chris Yoder, CABB
BiologicalCondition
The Biological Condition Gradient
NaturalVariability
Increasing Level of Stressors
Minimal changes in structure & function
Evident changes in structure andminimal changes in function
Moderate changes in structure &minimal changes in function
Major changes in structure &moderate changes in function
Severe changes in structure & function
11 22
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44
55
66
Natural structural, functional,and taxonomic integrity is
preserved.
A Tier 1 Communityin Maine
MidgesMidges
BeetlesBeetles
Dragonflies,Dragonflies,DamselfliesDamselflies
CaddisfliesCaddisflies
MayfliesMayflies
StonefliesStoneflies
1 inch
Courtesy of Susan Davies, ME DEP
BiologicalCondition
The Biological Condition Gradient
NaturalVariability
Increasing Level of Stressors
Natural structure and function of biotic community maintained
Minimal changes in structure & function
Evident changes in structure andminimal changes in function
Moderate changes in structure &minimal changes in function
Major changes in structure &moderate changes in function
Severe changes in structure & function
1122
3344
55
66
Evident changes instructure due to loss ofsome rare native taxa;shifts in relativeabundance; ecosystemlevel functions fullymaintained throughredundant attributes ofthe system.
CaddisfliesCaddisflies
StonefliesStoneflies
MayfliesMayfliesBlackflies
MidgesMidges
Non-insectsNon-insects
Crane flies
Beetles
A Tier 3 Community
1 inchCourtesy of Susan Davies, ME DEP
BiologicalCondition
The Biological Condition Gradient
NaturalVariability
- - No Effect - -
Natural structure and function of biotic community maintained
Minimal changes in structure & function
Evident changes in structure andminimal changes in function
Moderate changes in structure &minimal changes in function
Major changes in structure &moderate changes in function
Severe changes in structure & function
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33
44
66Extreme changes in structure;
wholesale changes in taxonomiccomposition; extreme alterationsfrom normal densities; organism
condition is often poor; anomaliesmay be frequent; ecosystem
functions are extremely altered.
A Tier 5-6 Community
CaddisfliesCaddisflies
SnailsSnails
MidgesMidges
LeechesLeeches
ScudsScuds
BeetlesBeetlesCranefliesCraneflies
1 inch
Courtesy of Susan Davies, ME DEP
Bio
logi
cal C
ondi
tion
The Biological Condition Gradient – Tiers
Increasing Levels of Stressors
Natural structure & function of biotic community maintained
Minimal changes in structure & function
Evident changes in structure andminimal changes in function
Moderate changes in structure &minimal changes in function
Major changes in structure &moderate changes in function
Severe changes in structure & function
1122
33
44
55
66