title: Use of laboratory toxicity tests with bivalve and echinoderm embryos to evaluate the bioavailability of copper in San Diego Bay, California, USA.
abstract: Copper concentrations in parts of San Diego Bay (CA, USA) exceed ambient water quality criteria (WQC; currently 3.1 microg/L dissolved, U.S. Environmental Protection Agency [U.S. EPA]). In order to better understand the bioavailability of copper to water-column organisms in the bay, toxicity tests were performed with copper added to surface water collected from various sites in the estuary over a three-year period. The species and endpoints used, bivalve and echinoderm embryo-larval development, are among the most sensitive in the U.S. EPA's national toxicity dataset, which is used to derive WQC. No toxicity was observed in ambient bay water samples, as indicated by high proportions of normally developed larvae in control treatments, averaging 93+/-5% across all sites and all sampling events. Median effects concentrations (EC50), obtained by copper spiking of ambient water samples, ranged from 1.7 to 3.4 times lower at sites located near the mouth compared to sites near the back of the bay. These data indicate a gradient in complexation capacity increasing from the mouth to the back of the bay, which is consistent with similar trends in dissolved organic carbon and total suspended solids. For the bay as a whole, estimates for total recoverable and dissolved water-effect ratios (WER) ranged from 2.07 to 2.27 and 1.54 to 1.67, respectively. Water-effect ratios of this magnitude suggest that adoption of a somewhat higher site-specific WQC for San Diego Bay still would achieve the level of protection that is intended by the WQC guidelines.
authors.affiliation: Space and Naval Warfare Systems Center, Environmental Sciences Division, San Diego, California 92152, USA. gunther.rosen@navy.mil
authors.forename: Gunther
authors.initials: G
authors.lastname: Rosen
authors.forename: Ignacio
authors.initials: I
authors.lastname: Rivera-Duarte
authors.forename: Lora
authors.initials: L
authors.lastname: Kear-Padilla
authors.forename: D Bart
authors.initials: DB
authors.lastname: Chadwick
mesh_terms: D000818:Animals; D001682:Biological Availability; D002140:California; D003300:Copper / Q000032:analysis / Q000493:pharmacokinetics* / Q000633:toxicity; D004447:Echinodermata / Q000196:embryology / Q000378:metabolism*; D004784:Environmental Monitoring; D012623:Seawater / Q000032:analysis / Q000737:chemistry*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000493:pharmacokinetics* / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical; D003300:Copper