Effects of copper on marine 

invertebrate larvae in surface 

water from San Diego Bay, CA

Gunther Rosen1, Ignacio Rivera-Duarte1, Lora Kear-Padilla2, 

and Bart Chadwick1

1SPAWAR Systems Center San Diego

53475 Strothe Rd., San Diego, CA 92152-6325

2Computer Sciences Corporation, San Diego, CA 92110
Background

Copper sources in San Diego Bay

 Industrial discharges

 Storm water

 Non-point source runoff

 Ship discharges (e.g. cooling water)

 Flux from sediment

 Antifouling hull coatings (67% of total load)

 Navy, commercial, and civilian hull leaching

 Navy and civilian hull cleaning

Effect in the bay

 Copper concentrations approach or exceed 

chronic water quality criterion (WQC) in some 

parts of the bay
Background

Exceedance of current national chronic Cu WQC (3.1 μg/L 

dissolved) not necessarily indicative of bioavailability or toxicity 

to biota

WQC derived from toxicity studies with laboratory water (e.g. 

Narragansett Bay, RI) with lower ability to complex Cu

EPA acknowledges that site-specific water quality characteristics 

can dramatically affect metal speciation and exposure

WER procedure current acceptable method for deriving sitespecific criteria (U.S. EPA 1994)
Study Site: San Diego Bay

 Six surveys over two-year 

period 

 Samples collected from 27 

“boxes” along the axis of the 

bay. 

 Samples were composites of 

research vessel’s track within 

each box (~ 1 km)

 Clean sampling techniques

 Boxes 1-17 = North Bay

Boxes 18-27 = South Bay

MOUTH

HEAD

Commercial 

Basin

N

Coronado Bridge
Experimental Design

 Standard EPA methods for short-term tests using west coast marine 

organisms (USEPA 1995)

 Spike surface water samples with at least 8 copper concentrations 

(range = 3–50 μg/L)

 Negative Control = site water with no added copper

 Positive Control = copper reference toxicant test in lab water

 Endpoint = normal larval development

 EC50 (concentration affecting 50% of test population) calculated with 

Probit method (ToxCalc)
Mytilus 

galloprovincialis

Mediterranean mussel

Strongylocentrotus

purpuratus

Purple sea urchin

Dendraster 

excentricus

Sand dollar

Species tested
Polychaete worm

Florida pompano

Mummichog Common rangia

Green crab

Copepod

Sheep head

Spot

Top smelt

Copepod

Polychaete worm

Mysid

Polychaete worm

Tidewater silverside

Copepod

Mysid

Atlantic silverside

Inland silverside

Winter flounder

Red abalone

American lobster

Copepod

Black abalone

Dungeness crab

Soft- shell clam

Copepod

Eastern oyster

Sea urchin

Pacific oyster

Coot clam

Summer flounder

Blue mussel

0

10

20

30

40

50

60

70

80

90

100

1 10 100 1,000

Dissolved copper concentration (μg L-1)

Cumulative probability (%)

Acute toxicity data

Cumulative probability fit

Lower 95% confidence limit

Upper 95% confidence limit

3.1 4.8

EPA 

dissolved 

copper 

acute 

WQC

EPA 

dissolved 

copper 

chronic 

WQC

Appropriate Test Species

•Test species sensitivity should be close to criterion concentration
Water Effect Ratio Procedure

Site Water Lab Water (SIO)

Simultaneous Toxicity Tests with Copper

WER = EC50 in Site Water  EC50 in Lab Water

Site-specific Criterion = WER X WQC

Purpose: Account for differences in bioavailability between site

and laboratory water for site-specific criterion development
Control Development

20 sites in the bay 

tested 1-4 times

93 ± 5% normal

larval development 

in controls across all 

test sites and 

sampling events

Indicative of no 

ambient toxicity in 

the bay

Box #

Lab 1 2 3 4 5 6 7 9 11 12 13 14 15 16 18 21 23 25 26 27

Normal Control Development (%)

0

20

40

60

80

100

120
Copper Additions

 Selected mussel data from 

survey on February 27, 

2002

 Higher Cu concentrations 

required for samples 

towards head of bay 

before toxicity observed

 Indicates less 

bioavailability of Cu 

towards South bay

Copper Concentration (μg/L)

0 5 10 15 20 25 30

Normal Larval Development (%)

0

20

40

60

80

100

120

Box 1 Box 18

February 27, 2002

Box 27
EC50s increased

with increasing 

distance towards 

back of bay

EC50 range:

-mussel: 7–24 μg/L

-urchin: 13–44 μg/L

Mussel

approximately 

twice as sensitive

to copper as urchin

Spatial Trend in Toxicity

Feb. 27, 2002

Box #

Lab 1 2 3 4 5 9 11 12 15 18 21 23 25 26 27

0

10

20

30

40

EC50 (μg/L)

purple urchin mussel
Spatial Trends in Toxicity

 Spatial trend consistent 

over course of four 

surveys

 EC50 values within surveys 

differ by factors of 1.7 

(May 2002) to 3.4 (Feb 

2002)

 On average, South Bay 

(Boxes >18) EC50 values 

65% higher than North 

Bay

May 14, 2002

Box #

Lab 1 3 12 15 18 21 23 25 26 27

4

6

8

10

12

14

16

18

Sept. 19, 2001

Box #

Lab 1 3 4 5 7 9 11 12 13 15 16 21 23 25 26 27

10

15

20

25

30

35

40

Aug. 30, 2001

Box #

Lab 1 5 6 13 26

EC50 (μg/L)

5

10

15

20

25

30

35

sand dollar purple urchin mussel EC50 (μg/L)

Feb. 27, 2002

Box #

Lab 1 2 3 4 5 9 11 12 15 18 21 23 25 26 27

0

10

20

30

40

EC50 (μg/L)

EC50 (μg/L)
Dissolved Organic Carbon (DOC)

DOC known to play 

large role in complexation 

of cationic metals

DOC ranged from <1 to 

about 4 mg/L

DOC concentration 

generally increased with 

increasing distance towards 

head of bay

Upward trend in DOC 

not as clear for samples 

tested from May 2002 

survey

May 14, 2002

Box

0 5 10 15 20 25 30

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

Feb 27, 2002

Box

0 5 10 15 20 25 30

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Sep 19, 2001

Box

0 5 10 15 20 25 30

2.0

2.5

3.0

3.5

4.0

Aug 30, 2000

Box

0 5 10 15 20 25 30

DOC (mg/L)

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

DOC (mg/L)

DOC (mg/L) DOC (mg/L)
Toxicity and DOC

Significant 

relationship in all but 

May 2002 sampling 

event.

Overall r2 = 0.71

DOC complexes free 

copper, limiting its 

bioavailability

Feb. 27, 2002

mussel, r2= 0.686

urchin, r2= 0.825

DOC (mg/L)

0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

0

10

20

30

40

50

Sep. 19, 2001

sand dollar, r2= 0.360

DOC (mg/L)

1.5 2.0 2.5 3.0 3.5 4.0

15

20

25

30

35

40

Aug. 30, 2000

2

sand dollar, r = 0.954

DOC (mg/L)

1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0

5

10

15

20

25

30

35

May 14, 2002

mussel, r

2

= not sig.

DOC (mg/L)

1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8

6

8

10

12

14

16

18

sand dollar purple urchin mussel

EC50 (μg/L)EC50 (μg/L)

EC50 (μg/L)

EC50 (μg/L)
WER Classification

North Bay

Boxes 1-17

South Bay

Boxes 18-27

Bay-wide

MOUTH

HEAD

Commercial 

Basin

N

Coronado Bridge
WER Estimates

Total Recoverable WER

All datasets

North Bay 1.80 

South Bay 2.72 

Bay-wide 2.20 

Dissolved WER

All datasets

North Bay 1.43 

South Bay 2.15 

Sampling Date Bay-wide 1.73 

May 2002 Feb 2002 Feb 2002 Sept 2001

0

1

2

3

North Bay

South Bay 

Bay-wide

Four datasets from three surveys used for final WER

All WERs greater than 1

Mussel WERs higher than echinoderm WERs

WER

Mussels only

2.09

3.09

2.57

Mussels only

1.65

2.44

2.03

Mussel Mussel Urchin Sand dollar
Site-Specific Dissolved Criterion 

Calculation

Current 

National

Criterion

Dissolved

WER

Site-specific

Criterion

Acute: 4.8 μg/L ×

Chronic: 3.1 μg/L ×

1.73 = 8.3 μg/L

1.73 = 5.4 μg/L

All datasets Mussels only

2.03 = 9.7 μg/L

2.03 = 6.3 μg/L
Study Site WER Species Reference

Hampton Roads, 

VA

2.30 (TR)

1.76 (D)

Acartia tonsa CH2M Hill, 

1999

New York/New 

Jersey Harbor

1.5 (D) Mytilus edulis

Arbacia punctulata

Mulinia lateralis

U.S. EPA 1994

San Francisco Bay 1.7 (TR) Crassostrea gigas S.R. Hansen & 

Associates, 1992

South San 

Francisco Bay

3.66 (TR)

2.77 (D)

M. galloprovincialis City of San Jose, 

1998

San Diego Bay 2.20-2.57 (TR)

1.73–2.03 (D)

M. galloprovincialis

S. purpuratus

D. excentricus

This study

TR = total recoverable D = dissolved

WER Studies From Other Estuaries
Summary

Ambient conditions in San Diego Bay do not appear to be 

toxic to bivalve or echinoderm embryos

Bioavailability of copper consistently decreases (up to 3.4 

times) with increasing distance from mouth of the bay

Higher EC50s (lower toxicity) generally strongly correlated 

with higher DOC concentrations.

Current national WQC for copper appears overprotective 

by a factor between 1.7 and 2 for San Diego Bay