Margaret Passmore, Amy Bergdale, Greg Pond, Louis Reynolds, Kelly Krock and Frank Borsuk

US EPA R3, Wheeling, WV

An evaluation of the Ceriodaphnia dubia chronic

toxicity test as an indicator of instream effects from mountaintop coal mining

Jones BranchMiddle Fork WatershedMartin Co., KY

Background

•

Alkaline coal mining effluent •

Elevated Total Dissolved Solids (dominated by Ca2+, Mg2+, HCO3

-

and SO4

2-), Fe, Mn, Ni, Zn, Se and NO3-

• Mined streams have increased base flow•

Adverse effects to water quality and benthic macroinvertebrates

Background

•

NPDES permit limits require pH, Fe and TSS

•

Some WQBELs for Mn, Al, Se•

No limits for TDS/conductivity/ions

•

Whole Effluent Toxicity (WET) testing has been proposed for NPDES permits

•

Would WET protect native biota?

Objectives

•

What level of water quality degradation is associated with lethal or sublethal effects to C. dubia ?

•

What’s causing the observed toxicity?•

How do WET results compare to macroinvertebrate results?

•

Can

C. dubia chronic tests indicate instream aquatic life condition?

Site Criteria•

Central Appalachians

•

Headwater streams downstream valley fills•

pH circum neutral or alkaline

•

Cond > 1000 uS/cm•

Sampling reach upstream of residences

•

Impaired aquatic life•

Physical habitat “sufficient”

•

18 headwater streams, 1 pond, 1 ditch •

1 VA, 7 KY, 12 WV

Site Locations

Methods•

WVDEP macroinvertebrates–

WVSCI, genus level metrics

–

All sites impaired for macroinvertebrates•

RPB habitat

•

C. dubia 7-day chronic testing–

IC25: dilution that resulted in a 25% decrease in reproduction compared to control

–

IC25 > 100%, no toxicity; as IC25 decreases, more toxicity

•

Field and lab chems•

Ion Toxicity Model (Mount et al 1997): Acute 48-hr mortality, relative measure of ion toxicity

K+ > HCO3-

= Mg2+ > Cl-

> SO42-

Habitat not a confounding factor:

UNT to Cow CreekIsland Creek watershedLogan Co., WVRBP 165Optimal

Habitat a slight confoundingfactor:

Upper Dempsey BranchPigeon Creek WatershedLogan Co., WVRBP 146Marginal to suboptimal

Habitat a severeconfoundingFactor? Severe mineral precipitation caused by poor water quality.

UNT Leatherwood CreekLeatherwood CreekClay Co., WVRBP 111Marginal -

poor

Mineral precipitation on substratesUNT Leatherwood CreekWVA single Hydropsyche was collected.

C. dubia Results•

Lethal and sublethal toxicity at 2 sites

•

Sublethal toxicity at 15 sites•

No toxicity at 3 sites (IC25 > 100%)

•

Mean IC25 of toxic samples was 21%•

Conductivity of ambient sample was a good predictor of toxicity

Conductivity and IC 25

R 2 = 0.8012

0

10

20

30

40

50

60

70

80

90

100

0 500 1000 1500 2000 2500 3000

Spec. Cond. Of Ambient Sample (uS/cm)

IC25

Rep

rodu

ctio

n Increasing Toxicity

0

500

1000

1500

2000

2500

Lab Conductivity100%

Hardness (bycalc.mg/l)

Sulfate (mg/l)

No reproductive effectReproductive effect

0

50

100

150

200

250

Calcium (mg/l) Magnesium (mg/l) Potassium (mg/l) Nickel (ug/l)

Conductivity, hardness, calcium, magnesium, potassium, nickel and sulfate were significantly higher in sites that exhibited reproductive effects (n=17) compared to those that did not (n=3).

All [Metals] < chronicCriteria.

Estimated Chemical Means @ IC 25•

Potential Toxicants–

546 µS/cm conductivity

–

203 mg/l sulfate–

108 mg/l HCO3

-

alkalinity

–

35 mg/l magnesium –

3 mg/l potassium

–

5.0 µg/l

nickel

•

Potential Ameliorating Factors–

291 mg/l hardness

–

59 mg/l calcium

Observed and Predicted Mortality

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

C. dubia mortality (observed)

48 h

r mor

talit

y (p

redi

cted

)

7 day observed mortality48 hr observed mortality

The solid line indicatescomplete agreementbetween 48 hr and 7 daymortality.

Observed IC25 and Predicted Survival

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 10 20 30 40 50 60 70 80 90 100

C. dubia IC25 Reproduction (observed)

C. d

ubia 4

8 hr

sur

viva

l (p

redict

ed)

mortality lowrepro high

mortality medrepro high

mortality lowrepro med

mortality lowrepro low

Increasing Toxicity

Increasing Toxicity

Conclusions

•

17 of 20 sites toxic•

Effect is chronic and sublethal

•

Ions are causing some toxicity•

Metals < chronic criteria

•

Additional toxicants present at some sites?

•

Conductivity correlated well to toxicity

Conclusions

•

C. dubia more tolerant than natives•

Habitat confounding at some sites

•

WET will not fully protect aquatic life, but

•

WET tests and TIEs still a good idea•

Instream biomonitoring also needed to:–

fully protect aquatic life

–

evaluate success of permits