Ionic Stress in Appalachian Headwater StreamsIonic Stress in Appalachian Headwater StreamsAre Total Dissolved Solids Toxic?Are Total Dissolved Solids Toxic?

Ionic Stress in Appalachian Headwater StreamsIonic Stress in Appalachian Headwater StreamsAre Total Dissolved Solids Toxic?Are Total Dissolved Solids Toxic?

Conductivity

Reference

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Residential

Mined/Residential

MB

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Scatterplot of MBI Scores Versus Conductivity (S/cm)by Land Use Category

R2 = 0.60 (for log-transformed data)

Conductivity

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Mined/Residential

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Mined/Residential

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Scatterplot of MBI Scores Versus Conductivity (S/cm)by Land Use Category

R2 = 0.60 (for log-transformed data)

Scatterplot of O/E Scores Versus Conductivity (S/cm)by Land Use Category

Conductivity

Reference

Residential

Mined

Mined/Residential

O/E

>0.

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R2 = 0.59 (for log-transformed data)

Scatterplot of O/E Scores Versus Conductivity (S/cm)by Land Use Category

Conductivity

Reference

Residential

Mined

Mined/Residential

O/E

>0.

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0.0

0.2

0.4

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R2 = 0.59 (for log-transformed data)

Scatterplot of O/E Scores Versus Conductivity (S/cm)by Land Use Category

Conductivity

Reference

Residential

Mined

Mined/Residential

O/E

>0.

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0.2

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R2 = 0.59 (for log-transformed data)

Conductivity

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Residential

Mined

Mined/Residential

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Residential

Mined

Mined/Residential

O/E

>0.

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R2 = 0.59 (for log-transformed data)

10th percentile=impairment threshold

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KY Mayflies vs. Conductivity

Taxon Cond Type IV Mean SD p-value

Ephemerella <150 82.5 34 4.69 0.001

Ameletus <150 74.8 33.3 4.87 0.001

Epeorus <150 73.4 31.3 4.98 0.001

Neophylax <150 69.9 30.5 4.92 0.001

Rhyacophila <150 63.4 29.4 4.4 0.001

Amphinemura <150 61.7 46.2 5.04 0.005

Cinygmula <150 60.9 26.5 4.81 0.001

Leuctra <150 60.8 29.9 4.46 0.001

Diplectrona <150 57.9 31.6 4.81 0.001

Prosimulium <150 54.7 32.9 5.45 0.003

Acentrella <150 47.9 27.7 5.68 0.001

Helichus <150 44.9 22.8 4.13 0.001

Psephenus <150 44.7 24 4.68 0.002

Acroneuria <150 44.6 21.1 4.04 0.001

Hexatoma <150 44.2 20.7 4.31 0.001

Paraleptophlebia <150 43.7 20.9 4.77 0.001

Drunella <150 42.2 19.2 4.16 0.001

Simulium <150 39.7 26.1 5.54 0.02

Stenonema <150 39.1 18.1 4.15 0.003

Ectopria <150 35.9 17 4.18 0.001

Lepidostoma <150 34.4 16.2 4.05 0.002

Sweltsa <150 31.2 15.1 3.85 0.004

Eurylophella <150 31.1 15.9 3.79 0.005

Wormaldia <150 28.1 13.6 3.44 0.003

Haplopera <150 25 12.6 3.57 0.006Yugus <150 25 13.1 3.76 0.009

Taxon Cond Type IV Mean SD p-value

Parametriocnemus >500 55 35.5 5.65 0.003

Cheumatopsyce >500 49.7 23.9 4.53 0.001

Cricotop/Orthocladius >500 45.2 18 4.06 0.001

Cricotopus >500 37.4 14.7 4.22 0.001

Lumbriculidae >500 34.4 22 4.86 0.018

Hydropsyche >500 33 16.8 4.16 0.001

Chimarra >500 31.6 10.3 3.41 0.001

Diamesa >500 30.8 16 4.19 0.009

Orthocladius >500 27.6 12.3 3.54 0.002

Eukiefferiella >500 27.5 13 3.66 0.003

Hemerodromia >500 21.5 11.4 3.42 0.019

Allocapnia >500 19.4 5.9 2.45 0.001

Prostoia >500 12.9 4.7 1.99 0.007Limnodrilus >500 9.7 3.7 1.82 0.03

Kentucky Indicator TaxaLow Conductivity

High Conductivity

West Virginia Indicator TaxaLow Conductivity

High Conductivity

N=59 N=25 N=21 N=18

<150

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400-750>750

CONDUCTIVITY

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Indicator Species Analysis (Headwater/Spring Season)

Gregory J. Pond and Margaret E. Passmore, U.S. EPA Region 3, Wheeling, WV 26003Teresa Norberg-King, U.S. EPA ORD, Duluth, MN

Gregory J. Pond and Margaret E. Passmore, U.S. EPA Region 3, Wheeling, WV 26003Teresa Norberg-King, U.S. EPA ORD, Duluth, MN

CONCLUSIONS

Response to Conductivity (KY & WV headwater streams)

This analysis found many taxa significantly related to high or low conductivity. The KY and WV datasets yielded similar taxa lists, but some differences were noted. The tables below are sorted by highest Indicator Value (IV). Two metrics were created from these lists and boxpots showing their relation to conductivity are shown below.

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WV EPT vs. Conductivity

Tracheal Gills – used in

respiration and ion regulation

Concentrated Hemolymph(insect blood)

Urine and Frass --

active H2O and salt loss

Eating and Drinking --

active H2O and salt intake

passive H20 intake

passive salt loss

Dilute Freshwate

r

Courtesy WVDEP

Tracheal Gills and Active Ion UptakeGill surfaces are covered in chloride

cells, the site of ion exchange↘

1. Certain species can regulate the number of active cells

2. Within a species, the number of active cells is inversely related to the salinity of the medium

3. Species with abundant chloride cells appear vulnerable due to overexposure to various ions

Courtesy WVDEP

Possible Physiological MechanismsVulnerable/Specialists Tolerant/

GeneralistsHigh Chloride Cell Densit

y

Low Chloride Cell Densit

y

Courtesy WVDEP

Does coal mine effluent cause acute mortality to, or interfere with molting in sensitive mayfly taxon (Epeorus ) or sensitive stonefly taxon (Peltoperla ) since these taxa are not found in high conductivity streams? An Ecoregion 69 example.

Test (toxicity of mine effluent to adjacent stream Epeorus mayfly and Peltoperla stonefly)

4/1/2006

1. Control water 10% Perrier mineral water and MilliQ+ (little/no chloride)2. Mine Effluent/Stream water (Boardtree Br. of Twentymile Cr., WV). Known Benthic ImpairmentThis mine treats for Mn, black precipitant observed on riffle substrate

Water allowed to aerate and stabilize in incubator for 24 hrCond pH DO Temp

Control 120 7.2 12.3 10.1Mine effluent 2621 8.81 11.1 10.2

mid- to late-instar Epeorus mayflies collected from 2nd order stream with conductivity of 37, pH of 6.7mid- to late-instar Peltoperla stoneflies collected from 1st order stream (low conductivity and neutral pH)

3 replicates of 4 specimens each in 100 ml water, aerated with glass pipette, no feeding Held at 10° C with 12hr:12hr light/dark periodicity; organisms acclimated to temp, placed directly into test media.

Results: 144 hr (6 d)

Survival (%) ± SD Control Mine Effluent StreamEpeorus 100±0.0 100±0.0 2 mayflies emerged as adults by day 4 (late instar)Peltoperla 100±0.0 91±14.41 in controls.

Total # Exuviae (Molts) Control Mine Effluent StreamEpeorus 8 7Peltoperla 1 1Ending Conductivity 188 2910

1 1 specimen died after 1d, no more died from day 2-6

Conclusion-No acute effects on Epeorus or Peltoperla survival or molting after 6d exposure

Not an Acute Effect? Most Sensitive Life Stage?Backgrou

ndRegion 3 and our component states are currently struggling to develop Total Maximum Daily Loads (TMDLs) for total dissolved solids (TDS). The toxicity testing literature indicates that changes in the concentrations and types of major cations and anions can be both acutely and chronically toxic to aquatic life, in the absence of any other toxicant. These tests are typically conducted using synthetic salt solutions. Some of these tests mimic the makeup of various types of effluents, but lack other toxicants found in the effluents. Adverse endpoints include death, and effects on reproduction and growth.

In the southern coal fields of Region 3, where alkaline coal mine drainage is common, TDS and/or elevated conductivity have been identified as a primary stressor to aquatic life in many biologically-impaired streams. These streams are naturally very dilute with conductivities measured at < 40 uS/cm. However, alkaline coal mine drainage routinely increases conductivity to 500-2000 uS/cm due to increased mineralization of the mine overburden on the mined areas and in associated valley fills. The elevated conductivity and ionic changes are thought to interfere with normal osmoregulation in invertebrates.

Field studies of macroinvertebrate communities from Kentucky, Virginia, and West Virginia coal fields have shown that conductivity explains the most variance in commonly used benthic assessment metrics. Because macroinvertebrates have evolved in and are adapted to very dilute streams in the region, ionic imbalance is a probable physiological mechanism of impairment. Empirical data from the West Virginia and Kentucky coalfields suggest that 90-100% of macroinvertebrate IBI’s score below established impairment thresholds (based on the reference condition) when conductivity is greater than 500 uS/cm. Mayflies (Ephemeroptera) appear to be highly sensitive to TDS in the region. Acute and chronic endpoints of particular ions have been established for commonly used test organisms such as Ceriodaphnia; however, few toxicological studies have been carried out using sensitive Appalachian macroinvertebrates. Furthermore, the toxicity testing literature indicates No Observed Effects Concentrations (NOECs) that are typically 2—3 times higher than the TDS thresholds suggested by the empirical data.

Our research interests include testing organisms that are more representative of the native Appalachian fauna, taking into account various life stages, temperatures, and other variables that may define the critical exposures.

Region 3 has been awarded a grant to work with ORD-Duluth and USGS to conduct laboratory experiments to determine toxicity of various ions or total dissolved solids to indigenous aquatic life.

Research Objectives/Outcomes:1. A literature review of the bioassay research on TDS or conductivity.

2. An analysis and summary of available empirical datasets in Region 3 and surrounding states to develop empirical relationships between TDS/conductivity and the condition of aquatic life.

3. Bioassay results using synthetic salts that mimic typical southern Appalachian coal field ambient samples (but lack other potential stressors like Selenium) and several commonly cultured species to establish both acute and chronic endpoints (eg. LC50s, LOECs and NOECs). Longterm research objectives may include more relevant species of Appalachian mayflies, stoneflies and caddisflies , various life stages (e.g. nymphs and eggs), and various temperatures.

4. Recommendations for defensible TDS/conductivity thresholds that would be protective of the typical Appalachian macroinvertebrate community.

5. We have been also testing for metals associated with periphyton/ aufwuchs scrapings on rocks below valley fills to explore routes of exposure other than the water column. Many of the conductivity intolerant taxa are “scrapers” and eat the periphyton/aufwuchs.

2006-2007 RARE Project

It is obvious, from the empirical data, that elevated conductivity has strong effects on sensitive Appalachian benthic communities. Although TDS may serve as a surrogate to actual toxicants, it is logical to conclude that conductivity can affect osmoregulation or cause dehydration in freshwater taxa. However, preliminary toxicity and growth (molting) tests showed that sensitive Epeorus and Peltoperla were not affected by mine effluent after a 6d exposure period. Because these and other taxa are absent from waters with high TDS, we think there are chronic effects or toxicity to other life stages (eggs, early instar nymphs). Moreover, there is evidence that higher temperatures (e.g., 20˚ C) causes lower toxicity thresholds in Isonychia mayflies (Kennedy 2000). Thus, the effect of temperature will be addressed in the future rounds of bioassay tests.

10th percentile=impairment threshold

Taxon Cond Type IV Mean SD p-value

Ephemerella <150 72.5 40.2 5.23 0.001Leuctra <150 63.9 49.6 4.09 0.001Amphinemura <150 62.8 46.9 4.33 0.005Epeorus <150 59.9 33.5 4.75 0.001Baetis <150 59.6 46.8 4.77 0.013Paraleptophlebia <150 53.6 32.6 4.63 0.001Stenonema <150 48.3 27.1 4.9 0.001Drunella <150 45.4 26.3 5.01 0.004Isoperla <150 44.5 31.1 4.71 0.019Cinygmula <150 43 23.7 4.3 0.003Rhyacophila <150 42.3 28.6 4.47 0.014Dolophilodes <150 41.5 27.8 4.99 0.015Haplopera <150 40.4 24.3 4.64 0.008Leptophlebiidae <150 36.7 22.3 4.77 0.015Stempellinella <150 34.6 22.4 4.63 0.022Oulimnius <150 34.3 21.2 4.43 0.012Heptageniidae <150 31.4 19.7 4.42 0.016Acroneuria <150 30.1 19.6 4.29 0.031Ameletus <150 29.1 18.8 4.5 0.028Pteronarcys <150 28 18.6 4.24 0.034Neophylax <150 25 16 3.73 0.025Yugus <150 24.9 16.5 4.06 0.047Heleniella <150 18 11.7 3.44 0.057

Taxon Cond Type IV Mean SD p-valueParametriocnemus >500 61.8 44.7 5.8 0.008Cheumatopsyche >500 59.9 23.9 5 0.001Cricot/Orthocladius >500 46.5 23.6 5.03 0.001Cricotopus >500 41.1 16.5 4.09 0.003Optioserervus >500 32 27 5.31 0.069Stenelmis >500 31.8 18.6 4.53 0.014Hydropsyche >500 29.1 14.5 4.05 0.009Tvetenia >500 28.6 22.7 4.42 0.100Diamesa >500 25.7 14.9 3.93 0.021Ceratopsyche >500 24.8 9.6 3.08 0.002Tubificidae >500 22.8 4.8 1.86 0.001Psephenus >500 20.8 13.2 3.88 0.052Rheocricotopus >500 20.5 11 3.3 0.021Hydroptila >500 19.2 3.1 1.57 0.001Limnophyes >500 18.2 5.7 2.38 0.002Thienimanniella >500 17.2 8.9 3.15 0.027Perlesta >500 16.3 8.5 2.99 0.031Hydropsychidae >500 16 6.4 2.29 0.007Pagastia >500 15.4 2.7 1.43 0.001Chironomus >500 15.4 2.6 1.52 0.002Sialis >500 15.2 4.3 1.89 0.009Rheotanytarsus >500 14.3 10.1 3.09 0.113Zavrelimyia >500 12.7 7.9 2.81 0.058Chimarra >500 11.4 4.7 2.15 0.015Corydalus >500 11.1 2.8 1.39 0.005Aeshnidae >500 9.2 3.4 1.68 0.029Conchapelopia >500 9.1 6 2.58 0.098Caenis >500 8.7 5 2.28 0.08Caloparyphus >500 7.7 1.8 1.22 0.019Limnodrilus >500 7.7 1.7 1.22 0.02Ochrotrichia >500 7.5 2.3 1.23 0.016