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 Diego53475 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 site-specific 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 BayBoxes 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 galloprovincialisMediterranean mussel

StrongylocentrotuspurpuratusPurple sea urchin

Dendraster excentricusSand dollar

Species tested

Polychaete wormFlorida pompano

Common rangiaMummichogGreen crab

Copepod

Sheep headSpot

Top smeltCopepodPolychaete worm

MysidPolychaete worm

Tidewater silversideCopepod

MysidAtlantic silversideInland silverside

Winter flounderRed abalone

American lobsterCopepodBlack abaloneDungeness crab

Soft- shell clamCopepod

Eastern oyster

Sea urchinPacific oysterCoot clam

Summer flounder

Blue mussel0

10

20

30

40

50

60

70

80

90

100

1 10 100 1,000

Dissolved copper concentration (µg L-1)

Cu

mu

lati

ve p

rob

abili

ty (

%)

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

Lab Water (SIO)Site Water

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 siteand 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

No

rma

l Co

ntr

ol D

eve

lop

me

nt

(%)

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

Nor

mal

Lar

val D

evel

opm

ent (

%)

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 26 270

10

20

30

40

EC

50

(µ

g/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 26 274

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 2710

15

20

25

30

35

40Aug. 30, 2001

Box #Lab 1 5 6 13 26

EC

50 (

µg/

L)

5

10

15

20

25

30

35

sand dollar purple urchin mussel

EC

50 (

µg/

L)

Feb. 27, 2002

Box #

Lab 1 2 3 4 5 9 11 12 15 18 21 23 25 26 270

10

20

30

40

EC

50 (

µg/

L)

EC

50 (

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 25 301.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8Feb 27, 2002

Box

0 5 10 15 20 25 300.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Sep 19, 2001

Box0 5 10 15 20 25 30

2.0

2.5

3.0

3.5

4.0

Aug 30, 2000

Box0 5 10 15 20 25 30

DO

C (

mg

/L)

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

DO

C (

mg

/L)

DO

C (

mg

/L)

DO

C (

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, 2002mussel, r2 = 0.686urchin, r2 = 0.825

DOC (mg/L)

0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00

10

20

30

40

50

Sep. 19, 2001sand dollar, r2 = 0.360

DOC (mg/L)

1.5 2.0 2.5 3.0 3.5 4.015

20

25

30

35

40Aug. 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 3.05

10

15

20

25

30

35

May 14, 2002mussel, 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 3.86

8

10

12

14

16

18

sand dollar purple urchin mussel

EC

50 (

µg/

L)

EC

50 (

µg/

L)

EC

50 (

µg/

L)

EC

50 (

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 Bay-wide 1.73

Sampling Date

May 2002 Feb 2002 Feb 2002 Sept 20010

1

2

3North Bay South Bay Bay-wide

Four datasets from three surveys used for final WERAll WERs greater than 1Mussel WERs higher than echinoderm WERs

WE R

Mussels only

2.093.092.57

Mussels only

1.652.442.03

Mussel Mussel Urchin Sand dollar

Site-Specific Dissolved Criterion Calculation

Current NationalCriterion

DissolvedWER

Site-specificCriterion

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