Figure 3 Ambient toxicity observed in SIYB in the wet and dry season sampling events.

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Not Tested

Casey Capolupo1, Ignacio Rivera-Duarte2 , Gunther Rosen2 , Marienne Colvin3 , Brandon Swope2 and Patrick Earley2

1University of San Diego, 2SPAWAR System Center Pacific, 3San Diego State University Research Foundation

Copper Bioavailability and Toxicity to Mytilus galloprovincialis in 

Shelter Island Yacht Basin, San Diego, CA

Ambient Toxicity Tests

Wet Season: The ambient water toxicity tests for both surface and bottom

water in the wet season did not show toxicity. The mean % normal alive

(percent of larvae surviving and achieving normal D-shape) was greater than

85% for all stations, and were not significantly lower than the laboratory

control.

Dry Season: The ambient toxicity tests for the dry season showed no

toxicity in bottom water but statistically lower (based on t-tests, α=0.05) normal

development at 5 of the 16 surface water stations. Very low variability within

treatments detected statistical differences at values of 92% normal alive. Using a

biologically meaningful reduction (e.g. ,80%), only station 16 (74%) was

deemed toxic (circled in orange).

EC50 Values and Site-Specific Criteria

The range in EC50 values was from 8.0 to 10.1 [Cu] μg L-1 in the wet

season, with no spatial gradient. In contrast, during the dry season, the EC50

values ranged from 9.3 to 11.2 μg L-1

, with the stations located closer to the

mouth having the lowest values. These EC50 values, however, were about twice

the measured dissolved concentration of copper at those stations.

A site-specific criterion for SIYB was calculated from the WER results

(SSCWER). An estimated chronic limit (ECLBLM) was calculated from the BLM

output data for comparison to the SSCWER. The SSCWER was consistent with a

spatial and temporal range from 3.2 to 5.0 [Cu] μg L-1 (geomean for both events

= 4.0 μg L-1 ). In comparison, ECLBLM were more responsive to spatial and

temporal variations, ranging from 4.8 to 11.0 [Cu] μg L-1 (Geomean for both

events =8.6 [Cu] μg L-1) and are up to two-fold larger than the SSCWER.

However, both criteria provide the level of protection intended by regulation, as

both are lower than measured EC50 values with the most sensitive marine

species- Mytilus sp.

RESULTS

Total and Dissolved [Cu]

Concentration gradients in surface water show a general trend of total and

dissolved [Cu] increasing from the mouth to the head of the basin (Figure 2a-d).

There is also a radial gradient of Cu increasing from the main channel towards

the inner boat slips (e.g., Stations 3 and 11 in figure 2c). In general, the [Cu]

spatial distributions show three areas in SIYB, the mouth of SIYB with

concentrations similar to those outside the basin (Stations 1 to 7), an area where

[Cu] is at an intermediate concentration (Stations 9 to 12), and an area where

there is a gradient of increasing concentrations (Stations 13 to 16).

INTRODUCTION

Leaching of copper (Cu) from antifouling coatings on boats and vessels is a

known source of copper to coastal waters and estuaries. Near marinas and ship

berths, antifoulant leaching may elevate [Cu] above background to levels where

toxicity may be a concern. Toxicity, however, is driven by the bioavailability of

Cu, which is not adequately predicted by total or dissolved [Cu]

Shelter Island Yacht Basin (SIYB) in the San Diego Bay, which harbors

approximately 2300 recreational boats, shows consistent elevations in [Cu] and

has been the subject of various toxicological studies (Neira et al. 2009, RiveraDuarte et al. 2005). This study examined the biological effects and chemical

activity of Cu in SIYB and whether or not the dissolved [Cu], the form of copper

monitored for regulatory compliance, poses a threat to organisms inhabiting this

area. The findings of this research are important for making environmental

decisions about Cu regulation by predicting potential effects of Cu loading on

biological communities.

MATERIALS AND METHODS

Copper and a suite of chemical parameters were measured in filtered and

unfiltered water, which was collected 1 m below the surface and 1 m above the

bottom of SIYB (Figure 1) in two separate sampling events. The first event

occurred March 22, 2011 (15 stations) and represents the wet season. The second

event was on July 5, 2011 (16 stations) and represents the dry season.

Two approaches were used to assess toxicity, both of which employed 48

hour embryo-larval development toxicity tests using the mussel Mytilus

galloprovincialis. In one approach, embryos were exposed to untreated (i.e.,

unspiked) unfiltered surface and bottom seawater from each of the stations to

determine if ambient toxicity was present. A total of 62 ambient samples were

tested for mussel embryo toxicity over two seasons. In the second approach,

unfiltered surface seawater samples from four of the stations (Stations 1, 4, 10

and 12) were spiked with up to 10 copper concentrations to derive median

effective concentrations (EC50 values) for calculating a site-specific criterion for

Cu using the US Environmental Protection Agency’s Water Effect Ratio (WER)

procedure (USEPA 1994). Total and dissolved [Cu] in ambient and spiked

samples were measured using in-line preconcentration Flow Injection Analysis

with detection by ICP-MS.

The data from this study were compared to the marine Biotic Ligand

Model (BLM) for Cu, which is a mathematical model that uses site-specific water

chemistry parameters to predict toxicity (HydroQual 2011). Using the BLM, an

EC50BLM and estimated chronic limit (ECLBLM) for Cu were predicted for each

station, and for the marina as a whole.

CONCLUSIONS

•Two gradients are apparent in surface water total and dissolved [Cu] in SIYB,

an increase from the mouth to the head, and an increase from the main channel

towards the boats

•The elevated [Cu] at stations 3 and 8 (wet season) and stations 3 and 11 (dry

season) appear to be related to proximity and density of boats surrounding the

area

•Although [Cu] in SIYB are elevated in comparison to the main body of San

Diego Bay, the ambient water is generally not toxic to mussel embryos (1 out of 

62 samples somewhat toxic)

•Dissolved [Cu] as high as 8.8 μg L-1 were not toxic to mussel embryos

•The BLM estimated chronic limit (ECL) for Cu (mean of 8.6 μg L-1 for wet

season and 8.5 μg L-1 for dry season) is protective of M. galloprovincialis based

on the ambient toxicity data

•Traditional water effects ration calculation (SSCWER) for Cu is overly

conservative based on EPA’s intended level of protection. EPA suggested WQC

(3.1 μg L-1 dissolved Cu) is over conservative as well

•Lack of ambient toxicity and verified protection by BLM suggest that SIYB is

not impaired due to copper

REFERENCES

HydroQual 2011. Draft update of aquatic life ambient saltwater quality criteria for copper

Neira, C., Delgadillo-Hinojosa, F., Zirino, A., Mendoza, G., Lenis, L.A., Porrachia, M. and Deheyn, D. 2009. Spatial 

distribution of copper in relation to recreational boating in a California shallow-water basin. Chemistry and Ecology 25: 417-

433

Rivera-Duarte, I., Rosen, G., Lapota, D., Chadwick, D., Kear-Padilla, L. and Zirino, A. 2005. Copper toxicity to larval stages of 

three marine invertebrates and copper complexation capacity in San Diego Bay, California. Environmental Science and 

Technology 39: 1542-1546.

Rosen, G., Rivera-Duarte, I., Chadwick, B. D., Ryan, A., Santore, R. C. and Paquin, P. R. 2008. Critical tissue copper residues 

for marine bivalve (Mytilus galloprovincialis) and echinoderm (Strongylocentrotus purpuratus) embryonic development: 

Conceptual, regulatory and environmental implications. Marine Environmental Research 66: 327–336.

U.S. EPA 1994 a. Interim guidance on determination and use of water effect ratios for metals. EPA-823-B-94-001

U.S. EPA 1995. Short-term methods for estimating the chronic toxicity of estuarine organisms: Section 15. EPA 600-R-95-136.

United States Environmental Protection Agency 2000. Water quality standards; establishment of numeric criteria for priority 

toxic pollutants for the State of California. United States Environmental Protection Agency. Federal Register. Vol. 65, No.97, 

May 18, 2000. Rules and Regulations 

ACKNOWLEDGEMENTS

Bob Santore (HydroQual), Ron Kaufmann, Bethany O’Shea, William Davis, Helen Meigs, Sarah Douglass, Christa Zacharias, 

Figure 1. Aerial view of Shelter Island Yacht Basin (SIYB), in San Diego Bay, California.

Location and number of the stations is presented, the yellow locations are those for the WER.

View downloaded from Google Earth.

*Significantly different from control

Dissolved Cu Total Cu Dissolved Organic Carbon

Wet Season Total and Dissolved Cu

Dry Season Total and Dissolved Cu

Figure 2. Spatial distribution of total (orange squares) and dissolved (blue circles) [Cu] (μg L1), and dissolved organic carbon (mg L-1; black diamonds). Figures a and b are for the wet 

season sampled on March 22, 2011. Figures c and d are for the dry season sampled on July 5, 

2011

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EC50 Dissolved Cu Dry Season SIO Lab Water

GC Lab Water

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Station 12

EC 50

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EC50

Figure 4. Results for the end point (EC50) measured for the WER under laboratory 

conditions.

Station EC50BLM EC50WER

95% LCL 

WER

95% UCL 

WER

ECLBLM SSCWER

SIO (Lab Water) - 7.9 7.8 8.0 - -

1 9.4 8.0 7.9 8.1 7.5 3.2

4 8.7 10.1 10.0 10.2 6.9 4.0

10 12.1 9.6 9.4 9.7 9.6 3.8

12 6.1 8.2 8.1 8.3 4.8 3.2

SIO (Lab Water) - 7.0 6.9 7.1 - -

GC (Lab Water) - 6.9 6.8 7.0 - -

1 13.8 9.3 9.3 9.3 11.0 4.1

4 10.3 9.5 9.4 9.6 8.2 4.2

10 9.6 11.2 11.1 11.2 7.6 5.0

12 10.2 11.1 11.1 11.2 8.2 5.0

WET SEASON Dissolved Cu

DRY SEASON Dissolved Cu

Table 1 Site-Specific criteria for SIYB derived from the Biotic Ligand Model, and by the 

USEPA-approved WER approach.

ECLBLM

EC50BLM

SSCWER

EC50WER

Dissolved Cu

WQC

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Dissolved Cu

WQC

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Figure 5. Summary of the different criteria that could be applied to SIYB. These criteria 

include the 3.1 μg L-1 WQC, WER derived and BLM calculated criteria. Dissolved [Cu] (μg 

L-1 ) are included for comparison.

Surface Bottom

Figure 6. Geometric mean values for the site-specific criteria applied to the dry season (a), wet 

season (b), and the overall values (c).