Research Areas > Regional Monitoring > Bight Regional Monitoring > Coastal Ecology > Bight ‘08 Coastal Ecology

Project: Bight ‘08 Coastal Ecology

Background and Objectives

Three previous Bight regional surveys have focused on sampling of coastal sediments and fish to detect contaminant levels and the ecological response to contaminants. In 1994, 261 sites were sampled, followed by 416 sites in 1998, and 391 sites in 2003. Habitats sampled included the continental shelf, ports, bays and marinas, and most recently, estuaries and deep ocean basins. The Bight ‘08 effort will expand on the findings of the earlier surveys.

This project has several objectives and sub-objectives:

1. Characterize the ecological condition of the SCB within 10 targeted habitat types, as well as the deviation from reference conditions. (Indicators of ecological condition include sediment contaminant chemistry, marine debris, benthic infauna, demersal fish and megabethic invertebrate assemblages, gross fish pathology, and sediment toxicity.)

a. Determine whether differences in condition exist among the 10 habitat types
b. Examine relationships between contaminant exposure and biological response
c. Identify trends in extent and magnitude of contamination within selected habitat types

2. Compute the mass balance of pollutant inputs, outputs, and storage within the SCB

Status

This project was initiated in 2007 with anticipated completion in 2011.

Methods

Trends in Aerial Extent and Magnitude of Contamination

This project component involved sampling SCB sediments between July 1 and September 30, 2008. Sites were selected using a stratified random approach so that data could be extrapolated. The number of sites selected correspond to the habitat types of interest as shown in the table below. Approximately half of the sites revisit previously sampled sites in order to assess long-term trends.

Mass Balance

This project component focuses on contaminants in sediments of the deep ocean basins. The contaminants of interest include trace metals and chlorinated hydrocarbons (total DDT and total PCB). Previous work indicated that fifty percent or more of the contaminant mass in the SCB may be found in deep ocean basin sediments. Therefore, three basins will be targeted including Santa Monica Basin, San Pedro Basin, and the San Diego Trough. 40 box-shaped sediment cores (20x30x60cm) will be collected between 200 and 1000 m water depths from Los Angeles to San Diego. Subcores will be taken from each box core for sediment chemistry and radiochemical analysis. Sediment accumulation rates will be measured using geological radio-dating for an isotope of lead (²¹⁰Pb). Sediment chemistry analyses will be conducted on four or more sections from each box core that date back to at least 1900.

Findings

Sediment toxicity results showed that sediment toxicity was not widespread in the SCB; an estimated 76% of the region showed no toxicity. No offshore stations showed moderate or high toxicity. Marinas and estuaries contained the greatest incidence of sediment toxicity, with substantial toxicity in 24% of marina sediments and 22% of estuary sediments. In addition, marina and estuary sites had the greatest prevalence of high toxicity relative to the other strata. Temporal analysis indicated that the extent of sediment toxicity in the SCB has declined over the past five years, in that substantial toxicity was absent from the offshore shelf, and the extent of toxicity in embayments has declined by approximately 50%. Additional surveys are needed to confirm these trends.

Sediment chemistry results found that the distribution of many sediment contaminants in the SCB was a function of their source inputs. The greatest concentrations of total DDT, for example, were located on the continental shelf near historic outfall sites, whereas other contaminants such as copper, zinc, and total PAHs that come primarily from vessel antifouling paints and land-based runoff ended up in embayment strata such as marinas and estuaries. When applying California's new multiple line of evidence sediment assessment tool, roughly three-quarters of the SCB sediments were in acceptable condition based on exposure to sediment contamination. The remaining one-quarter was not evenly distributed, and unacceptable condition was much more prevalent in marinas, estuaries, and ports. Over the last 10 years, sediment condition generally improved in the SCB as a whole, but this trend did not hold true for some areas like estuaries. Special studies measuring contaminants of emerging concern found pyrethroid pesticides at levels great enough to induce toxicity in the laboratory in 35% of the SCB embayment area. PBDEs, a flame retardant, were also widespread in SCB sediments.

These findings are briefly summarized in a synthesis report on Bight '08 Coastal Ecology.

Demersal fish and invertebrate communities of the SCB were relatively healthy in 2008 based on biointegrity assessment tools. Approximately 96% of the SCB had fish communities that were similar to reference conditions, and approximately 84% had megabenthic invertebrate communities similar to reference conditions. Nonreference conditions were found primarily on the inner continental shelf (<30 m depth) and bay/harbor areas, suggesting nearshore influences. Fish populations showed only background levels of anomalies and diseases, such as parasites, tumors, ambicoloration, skeletal deformities, and albinism. Debris was found throughout most (90%) of the SCB, but generally in trace amounts. Natural debris was observed three times as frequently as anthropogenic debris.

Bight '08 Coastal Ecology data was also used in a statewide assessment of sport fish tissue contamination (summarized in a fact sheet). The survey found high contaminant concentrations in a few areas, and widespread moderate contamination throughout urban coastal regions. Methylmercury and PCBs posed the most widespread potential health concerns. Methylmercury was highest in sharks and striped bass, and PCBs were most elevated in San Francisco Bay and San Diego Bay.

Partners

This project is being conducted in close cooperation with all of the SCCWRP’s member organizations. In addition, over 60 different organizations including regulated, regulatory, and non-governmental agencies are expected to collaborate on this study.