1. Effects of copper on marine invertebrate larvae in surface water from San Diego Bay, CA Gunther Rosen 1, Ignacio Rivera-Duarte 1, Lora Kear-Padilla 2, and Bart Chadwick 1 1 SPAWAR Systems Center San Diego 53475 Strothe Rd., San Diego, CA 92152-6325 2 Computer Sciences Corporation, San Diego, CA 92110

2. 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

3. 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)

4. Objectives 1.Demonstrate toxicity of copper in San Diego Bay as a function of metal speciation (presented by Rivera-Duarte et al.) 2.Characterize spatial and temporal variability of copper bioavailability to sensitive marine invertebrates in the bay 3.Use EPA’s Water Effect Ratio (WER) guidance to estimate a site-specific WQC for copper

5. 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 N Coronado Bridge

6. 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  EC 50 (concentration affecting 50% of test population) calculated with Probit method (ToxCalc)

7. Mytilus galloprovincialis Mediterranean mussel Strongylocentrotus purpuratus Purple sea urchin Dendraster excentricus Sand dollar Species tested

8. Appropriate Test Species Test species sensitivity should be close to criterion concentration

9. Water Effect Ratio Procedure Lab Water (SIO)Site Water Simultaneous Toxicity Tests with Copper WER = EC 50 in Site Water  EC 50 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

10. 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 # Lab12345679111213141516182123252627 Normal Control Development (%) 0 20 40 60 80 100 120

11. 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

12.  EC 50 s increased with increasing distance towards back of bay  EC 50 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 # Lab123459111215182123252627 0 10 20 30 40 EC50 (µg/L) purple urchinmussel

13. Spatial Trends in Toxicity  Spatial trend consistent over course of four surveys  EC 50 values within surveys differ by factors of 1.7 (May 2002) to 3.4 (Feb 2002)  On average, South Bay (Boxes >18) EC 50 values 65% higher than North Bay May 14, 2002 Box # Lab131215182123252627 4 6 8 10 12 14 16 18 Sept. 19, 2001 Box # Lab13457911121315162123252627 10 15 20 25 30 35 40 Aug. 30, 2001 Box # Lab1561326 EC50 (µg/L) 5 10 15 20 25 30 35 sand dollarpurple urchinmussel EC50 (µg/L) Feb. 27, 2002 Box # Lab123459111215182123252627 0 10 20 30 40 EC50 (µg/L)

14. 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 051015202530 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 051015202530 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Sep 19, 2001 Box 051015202530 2.0 2.5 3.0 3.5 4.0 Aug 30, 2000 Box 051015202530 DOC (mg/L) 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 DOC (mg/L)

15. Toxicity and DOC  Significant relationship in all but May 2002 sampling event.  Overall r 2 = 0.71  DOC complexes free copper, limiting its bioavailability Feb. 27, 2002 mussel, r 2 = 0.686 urchin, r 2 = 0.825 DOC (mg/L) 0.60.81.01.21.41.61.82.0 0 10 20 30 40 50 Sep. 19, 2001 sand dollar, r 2 = 0.360 DOC (mg/L) 1.52.02.53.03.54.0 15 20 25 30 35 40 Aug. 30, 2000 2 sand dollar, r = 0.954 DOC (mg/L) 1.61.82.02.22.42.62.83.0 5 10 15 20 25 30 35 May 14, 2002 mussel, r 2 = not sig. DOC (mg/L) 1.82.02.22.42.62.83.03.23.43.63.8 6 8 10 12 14 16 18 sand dollarpurple urchinmussel EC50 (µg/L)

16. WER Classification  North Bay  Boxes 1-17  South Bay  Boxes 18-27  Bay-wide N Coronado Bridge

17. WER Estimates Total Recoverable WER All datasets North Bay1.80 South Bay2.72 Bay-wide 2.20 Dissolved WER All datasets North Bay 1.43 South Bay 2.15 Bay-wide1.73 Sampling Date May 2002Feb 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 UrchinSand dollar

18. Total to Dissolved Conversion  Dissolved/total ratio for bay = 0.79  Calculated from 150 samples over six surveys  Ratio consistent spatially and temporally  For Dissolved WER:  Site Water: multiply total recoverable EC50 values by conversion factor  Lab Water: pre-filtered, no conversion needed

19. 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 datasetsMussels only 2.03 = 9.7 µg/L 2.03 = 6.3 µg/L

20. TR = total recoverable D = dissolved WER Studies From Other Estuaries

21. 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 EC 50 s (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