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Project: Southern California Mussel Watch

Background and Objectives

To characterize the spatial extent and temporal trends in coastal contaminant levels nationwide, NOAA’s National Status and Trends (NS&T) Program has collected and analyzed bivalve species since 1986 as part of their Mussel Watch program. This data set has provided unparalleled information on the declines of biological exposure to contaminants associated with source control and increased effluent treatment over the last 20 years. It has also demonstrated that local hot spots still exist in Southern California and provides a point of comparison with the rest of the country. Twenty-one open coastal sites in Southern California have been monitored by NS&T since 1986. These sites are visited biannually by project partners to measure levels of trace metal and organic contaminants. In 2007, SCCWRP agreed to sample 13 additional sites to increase spatial coverage, whereas NOAA continued to process the samples. A collaborative effort to select priority contaminants of emerging concern (CECs) for future assessment was also part of this project.

The goals of this study were to:

• Increase spatial and temporal resolution of Mussel Watch data in Southern California;
• Provide contaminant data in Areas of Special Biological Significance and Marine Protected Areas; 
• Compare passive sampling methods with contaminant measurement via accumulation in bivalves; and
• Prioritize emerging contaminants for future coastal monitoring and assessment.

Mussel Watch sites in Southern California (left); Mussel beds (Mytilus spp.) in the intertidal zone in Santa Barbara County, CA (right).


This project was initiated in 2007 and competed in 2013.


Collaborating organizations collect bivalves biannually, with NOAA providing analytical measurements in accordance with long-standing program QA/QC guidelines. As an additional sampling technique, passive samplers using solid-phase microextraction (SPME) were deployed at Mussel Watch sites and analyzed using methods developed by SCCWRP. Both passive samplers and bivalves were analyzed for trace constituents, and data was compiled and assessed by project participants.

Sixty-eight established NS&T sites in California were stratified by land use and sampled during the 2009-10 winter season. Passive sampling devices and caged native mussels (Mytilus spp.) were co-deployed to enhance ability to detect CECs and assess the ability of PSDs to mimic bioaccumulation. Passive sampler technologies including SPME, polyethylene, and polar organic compound integrated samplers (POCIS) were co-deployed at selected sites. Collaborators analyzed these samplers and bivalve tissues for 167 CECs, including pharmaceuticals, industrial and commercial chemicals, and current use pesticides. The seven measured CEC classes were alkylphenols, pharmaceuticals and personal care products, polybrominated diphenyl ethers (PBDE), other flame retardants, current use pesticides, perfluorinated compounds (PFC), and single walled carbon nanotubes.


The 2009-2010 sampling campaign revealed that 98% of targeted contaminants of emerging concern (CECs) were infrequently detectable at concentrations <1 ng/g. Sixty-seven of the 167 CEC analytes (40%) were detected at least once. Selected chemicals found in commercial and consumer products were more frequently detected at mean concentrations up to 470 ng/g dry wt. The number of CECs detected and their concentrations were greatest for stations categorized as urban or influenced by stormwater discharge. Alkylphenol, PBDE, and PFC concentrations increased with urbanization and proximity to stormwater discharge; pesticides had higher concentrations at agricultural stations. These results suggest that certain compounds; for example, alkylphenols, lomefloxacin, and PBDE, are appropriate for inclusion in future coastal bivalve monitoring efforts based on maximum concentrations >50 ng/g dry weight and detection frequencies >50%. Other compounds, for example PFC and hexabromocyclododecane (HBCD), may also be suggested for inclusion due to their >25% detection frequency and potential for biomagnification. The results underscore the need for focused CEC monitoring in coastal ecosystems and suggest that PSDs are complementary to bivalves in assessing water quality. Moreover, the partnership established among participating agencies led to increased spatial coverage, an expanded list of analytes and a more efficient use of available resources.

Up-to-date results from the parent NOAA NS&T Mussel Watch program can be found on the NOAA website.


National Oceanic and Atmospheric Administration (NOAA)
State Water Resources Control Board (SWRCB)
Multi-Agency Rocky Intertidal Network (MARINe)
San Francisco Estuary Institute (SFEI)
US Geological Survey (USGS)
US Environmental Protection Agency (EPA)


Pilot Monitoring of CECs in California via the Mussel Watch Program (Video) - January 2012 presentation to SCCWRP member agencies on background and preliminary findings from the pilot CEC monitoring effort.

For more information on Southern California Mussel Watch, contact Keith Maruya at (714) 755-3214.
This page was last updated on: 7/1/2014