ACUTE TOXICITY OF CADMIUM TO BLUEGILL
(Lepomis macrochirus), RAINBOW TROUT
(Salmo gairdneri), AND PINK SHRIMP
(Penaeus duorarum).
BIONOMICS

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ACUTE TOXICITY OF CADMIUM TO BLUEGILL
(Lepomis macrochirus), RAINBOW TROUT
(Salmo gairdneri), AND PINK SHRIMP
(Penaeus duorarum).
BY
ROBERT. E. BENTLEY
TOM HEITMULLER
BEVIER H. SLEIGHT, III
PATRICK R. PARRISH
ORDER NUMBER: WA-6-99-1414-B
PROJECT OFFICER: MR. WILLIAM FOX
ENVIRONMENTAL PROTECTION AGENCY
CRITERIA BRANCH (WH-585)
ROOM 1013 EAST TOWER
4 01 M STREET, S.W.
WASHINGTON, D.C. 20460

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INTRODUCTION
The current concern regarding the protection of aquatic
life in surface waters has prompted the evaluation of the
effects of exposure to chemicals on aquatic organisms.
The primary objective of these studies was to provide the
Environmental Protection Agency with information to evaluate
the relative susceptibility of aquatic organisms to acute
exposure to cadmium- The acute toxicity of cadmium to
bluegill and rainbow trout in both a soft and a hard
water> and to pink shrimp in sea water was estimated during
static bioassays.
The bioassays with fishes were conducted at the Aquatic
Toxicology Laboratory of E G & G, Bionomics, Wareham,
Massachusetts. The shrimp bioassay was conducted at the
Marine Research Laboratory of E G & G, Bionomics, Pensacola,
Florida.

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Page two
MATERIALS AND METHODS
The methodology for acute toxicity testing of fishes
and shrimp closely followed the recommended bioassay
procedures except for certain conditions described below.
The chemical evaluated in these bioassays was cadmium,
as cadmium chloride (CdC^/ 61.25% cadmium), a white
anhydrous powder manufactured by Matheson, Coleman &
Bell (lot #Z27 3). Results for all tests were expressed
as the median lethal concentration (LC50), the nominal
concentration of the test compound in water causing 50
percent mortality of test animals. The LC50 value and its
95% confidence interval were calculated by converting the
test concentrations and the corresponding observed percent
response to logs and probits, respectively. These values
were then utilized in a least squares regression analysis,
and the LC50 value and its confidence interval were estimated
from the calculated regression equation.
The animals used in these tests were bluegill (Lepomis
macrochirus), rainbow trout (Salmo gairdneri) and pink
shrimp (Penaeus duorarum). The bluegill were acquired from

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Page three
a commercial fish hatchery in Nebraska, and had a mean wet
weight of 1.1 g and a mean standard length of 37 mm. The
rainbow trout were obtained from a commercial fish farmer
in Washington, and had a mean wet weight of 1.0 g and a
mean standard length of 32 mm. The shrimp were collected
by laboratory personnel from"Big Lagoon in Pensacola,
Florida and had rostrum-telson lengths of 35-50 mm.
The bluegill and rainbow trout were held in 1700-1 concrete
raceways which are coated with an epoxy resin paint to
prevent leaching of materials into the water. Flow of
well water (having a temperature of 21 + 1.0°C for the
bluegill, and 12 + 1.0°C for the rainbow trout) into these
raceways was at a minimum flow of 4 1/minute, providing
an adequate rate of turnover for holding these species.
This water had a hardness of 35 mg/1 as CaC03, a pH of
7.1 andxa dissolved oxygen concentration of at least 6.0
mg/1 (60% of saturation). These species were maintained in
the laboratory hatchery facilities for at least 30 days
prior to testing. During the 30 day period, mortality was
<2%; no mortality was observed during the 48 hours immediately
prior to testing, and these fish were judged to be in ex-
cellent condition. The shrimp were held in 1100-1 fiber-
glass tanks in constantly flowing filtered (10 micrometers)

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Page four
natural sea water. The salinity of this water was 25
parts per thousand (o/oo) and the temperature was 20 + 1.0°C.
The static bioassays were conducted in 19.6-1 wide-mouth
soft-glass bottles containing 15 liters of test solution.
Exposure mixtures for the bluegill bioassays were maintained
in water baths at 21 + 1.0°C by immersion coil heaters and
mercury column thermoregulators. Test solutions for the
rainbow trout and shrimp were maintained in water baths at
12 + 1.0°C and 20 + 1.0°C, respectively, by use of commercial
refrigeration units. Each species was from the same year
class, and the standard length of the longest fish or shrimp
was no more than two times that of the shortest fish or
shrimp. The bluegill and rainbow trout were acclimated to
test conditions of temperature and water quality over a 96-
hour period prior to testing. These species were not fed
during the 48 hours immediately prior to testing or during
the tests. The shrimp were acclimated to test conditions of
water quality and temperature for at least seven days prior
to testing. Water in the test vessels was not aerated.- The
test compound dissolved in distilled water was added to each"
jar in the bluegill and rainbow trout bioassays. In the shrimp
bioassays, the test material was introduced into each jar directly.
Animals were introduced into the test vessel within 30 minutes

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Page five
after the compound was added. Ten bluegill or rainbow
trout were randomly assigned to each test vessel. Ten
shrimp (2 replicates, 5 animals/vessel) were exposed
to each concentration.
The dilution water used in the fish bioassays was the same
as previously described for holding these fish. The hard
water for these bioassays was prepared by adding 192 mg
of NaHC03, 120 mg of CaS04, 120 mg of MgS04, and 8 mg'of
KC1 per liter of deionized water. The resulting water had
a pH of 7.6 and a total hardness of 200 mg/1 as CaCO^-
The dilution water for the shrimp bioassays consisted of
filtered (10 micrometers) natural sea water with a salinity
i
of 25 o/oo and a pH of 8.0 + 0.5. Concentrations of dis-
*
solved oxygen were measured with a combination temperature-
oxygen probe and meter in selected concentrations at 24,
48, and 96 hours of exposure.
Two series of concentrations were established within a
bioassay, a series of range-finding (preliminary) con-
centrations and a series of definitive concentrations. The
preliminary test was conducted to determine the approximate
range of concentrations for evaluating the dose-response
relationship. The definitive test, consisting of at least

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five concentrations, evaluated the dose-response relation-
ship to a degree allowing the LC50 to be calculated from
the data with optimum accuracy. A control, which consisted
of the same dilution water, conditions, procedures, and
organisms, was maintained for each species tested.
RESULTS AND DISCUSSION
The estimated LC50 values (95% confidence intervals) for
cadmium and the species tested are presented in Table 1
along with the highest nominal concentration tested at
which there were no discernible effects on test animals due
to exposure to cadmium. A summary of observed mortality
for each individual test concentration at 24, 48 and 96
hours of exposure to cadmium is also presented (Table 2).
The mortality syndrome among fish from those concentrations
where mortality was observed was similar. Fish generally
became dark and lethargic, lost equilibrium, and expired.
Affected shrimp generally lost equilibrium, swam erratically,
and died.
The concentrations of dissolved oxygen, measured at 0, 24,
48 and 96 hours, are presented in Table 3. Final pH was
7.0 + 0.5 for all test concentrations and controls where

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Page seven
bluegill and rainbow trout were exposed in soft water.
Comparable pH's for the test concentrations where bluegill
and rainbow trout were exposed in hard water were 7.5 + 0.5.
Final pH was 8.0 + 0.5 for all test concentrations and the
control for the shrimp bioassay.
Cadmium appeared to be more toxic in soft water than in
hard water, indicating the effect of water quality was on
the toxicant and not on the test species. The bluegill ex-
hibited a 96-hour LC50 value of 6.62 mg/1 in soft water, and
48.2 mg/1 in hard water. A similar situation, was observed
for rainbow trout tested in soft and hard Water. The
96-hour LC50 value was 0.007 mg/1 in soft water, while that
for the hard water bioassay was 0.016 mg/1. The 96-hour
LC50 value for pink shrimp was 4.9 mg/1.

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LITERATURE CITED
A.P.H.A. 1971. Standard Methods for the Examination
of Water and Wastewater. 13th Edition, 874 pp.

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a	i.
Table 1 — Acute toxicity of cadmium to bluegill0 (Lepomis
macrochirus), rainbow troutc (Salmo gairdneri), and
j
pink shrimp (Penaeus duorarum). These data are based
on the results of bioassays conducted at the Aquatic
Toxicology Laboratory of E G & G, Bionomics, Wareham,
Massachusetts and Pensacola, Florida.
Species/
diluent
No discernible
LC50 (mg active ingredient/1)	effect level
24 hour	48 hour 96 hour	(mg/1)
bluegill/
soft water
11.20
7.41
6.62
(6.98-17.80)e (5.43-10.10) (5.45-8.05)
4.20
bluegill/
hard water
76.3	48.2	48.2
(61.1-95.4) (39.6-58.6) (39-6-58.6)
32.0
rainbow trout/
soft water
0.94	0.030	0.007
(0. 32-2.73) (0.016-0.056) (0.005-0.011)
0.0018
rainbow trout/
hard water
>7.50	0.043	0.016
(0.025-0.073)(0.011-0.023)
0.012
pink shrimp/
sea water
17
(13-23)
8.6
(5.6-12)
4.9
(2.9-8.6)
<2.0
Cadmium chloride (CdCl2)t 61.25% cadmium.
5
Bioassays conducted at 21 + 1.0°C, mean wet weight of bluegill, 1.1 g.
Bioassays conducted at 12 + 1.0°C, mean wet weight of rainbow trout,
1.0 g.
I	Q
Bioassays conducted at 20 +1.0 C, rostrum-telson lengths of pink
shrimp, 35-50 mm.
95% confidence interval.

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Table 2 — Concentrations tested and corresponding observed
percentage mortalities at 24, 48 and 96 hours
for bluegill (Lepomis macrochirus), rainbow
trout (Salmo gairdneri) and pink shrimp (Penaeus
duorarum).
Species/
diluent
Nominal
concentration
(mg/1)
% mortality observed
24 hour 48 hour 96 hour
bluegill/
soft water
18.0
10.0
7.5
5.6
4.2
control
100
20
0
0
0
0
100
100
40
0
0
0
100
100
50
10
0
0
bluegill/
hard water
140.0
100.0
75.0
56.0
42.0
32.0
control
100
60
40
0
10
0
0
100
100
100
60
30
0
0
100
100
100
60
30
0
0

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Table 2 — Continued.
Species/
diluent
Nominal
concentration
(mg/1)
% mortality observed
24 hour 48 hour 96 hour
rainbow trout/
soft water
3.2000
1.8000
1.0000
0.5600
0.3200
0.1000
0.0320
0.0180
0.0100
0.0075
0.0056
0.0042
0.0024
0.0018
control
90
60
40
20
40
10
0
0
0
0
0
0
0
0
0
100
100
100
100
100
80
50
40
40
0
0
0
0
0
0
100
100
100
100
100
100
100
80
70
30
20
20
10
0
0
rainbow trout/
hard water
7.500
3.200
1.000
0.320
0.075
0.042
0.024
0.016
0.012
control
0
0
0
0
0
0
0
0
0
0
100
100
100
100
50
30
40
40
0
0
100
100
100
100
100
100
100
80
0
0

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Table 2 — Continued.
Species/	Nominal	% mortality observed
diluent	concentration	24 hour 48 hour 96 hour
(mg/1)
oink shrimp 34.0	60 100	100
20.0	20 100	100
11.0	10 10	80
6.1	0 20	40
2.0	0.0	10
control	0 0	0

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Table 3 — Measured concentrations of dissolved oxygen during
96-hour exposures of bluegill (Lepomis macrochirus),
rainbow trout (Salmo gairdneri) and pink shrimp
(Penaeus duorarum) to cadmium.
Nominal	Dissolved oxygen
Species/	concentration	(mg/1 and % of saturation)	
diluent	(mg/1)	0 hour 24 hour 48 hour 96 hour
bluegill/
soft water
bluegill/
hard water
rainbow trout/
soft water
18.0
7.5
4.2
control
140.0
56.0
32.0
control
3.2000
0.0320
- 0.0056
control
8.5(96)
8.2 (92)
8.1(91)
8.4 (95)
8.4(95)
8.2 (92)
8.0(90)
8.4(95)
9.2(85)
9.1(83)
8.8(81)
8.8(81)
6.2 (67) 5.8(63) 4.5 (49)
5.8(63) 4.7(52) 2.7(31)
5.9(64) 4.7(52) 4.2(46)
6.9 (76) 6.4 (71) 6.6 (73)
6.5(72) 5.5(61) 5.5(61)
5.8(63) 5.2(56) 4.1(45)
7.7 (70)
9.1(83)
8.7(80)
8.8(81)
6.9(63)
8.0(73)
7.8 (71)
6.0(55)
5.8(53)
rainbow trout/
hard water
7.500
0.320
0. 012
control
9.5(87)
9.2 (84)
9.0 (83)
9.1(84)
9.1(83)
9.2(84)
6.2 (57)
6.4 (58)
5.3(49) 4.6(42)
5.7(52) 5.0(46)

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Table 3 — Continued.
Nominal	Dissolved oxygen
Species/	concentration	(mg/1 and % of saturation)
diluent
(mg/1)
0 hour
24
hour
48
hour
96
hour
pink shrimp/
34.0
6.8(89)

a




sea water









11.0
6.7(88)
6.
3(83)
5.
7(75)
5.
7(75)

2.0
6.8(89)
6.
6(87)
6.
1(80)
4.
4(58)

control
6.8(89)
6.
8 (89)
6.
9(79)
3.
5(46)
a
Dissolved oxygen not measured due to 100% mortality.

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