Effects of copper on marine invertebrate larvae in

Effects of copper on marine invertebrate larvae in surface water from San Diego Bay, CA : 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 : 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 : 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)

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

Study Site: San Diego Bay : 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

Experimental Design : 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)

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

Appropriate Test Species : Appropriate Test Species Test species sensitivity should be close to criterion concentration

Water Effect Ratio Procedure : 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 site and laboratory water for site-specific criterion development

Control 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 : 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

Slide12 : 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

Spatial Trends in Toxicity : 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 EC50 (µg/L) EC50 (µg/L)

Dissolved Organic Carbon (DOC) : 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 : 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, r 2 = 0.686 urchin, r 2 = 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, r 2 = 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 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 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 EC50 (µg/L) EC50 (µg/L) EC50 (µg/L) EC50 (µg/L)

WER Classification : WER Classification North Bay Boxes 1-17 South Bay Boxes 18-27 Bay-wide Coronado Bridge

WER Estimates : 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 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

Total to Dissolved Conversion : 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

Site-Specific Dissolved Criterion Calculation : 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

Slide20 : TR = total recoverable D = dissolved WER Studies From Other Estuaries

Summary : 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