Polychlorinated biphenyl spatial patterns in San Francisco Bay forage fish

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Marine Biology

Background:

• Industrialized waterways often exhibit localized contamination hotspots of legacy polychlorinated biphenyls (PCBs).
• The contribution of these hotspots to overall aquatic food web contamination remains uncertain.
• Estuarine ecosystems are particularly vulnerable to persistent organic pollutants.

Purpose of the Study:

• To assess the effectiveness of estuarine forage fish as biosentinels for local PCB contamination.
• To compare PCB levels in forage fish from historically polluted sites versus ambient conditions in San Francisco Bay.
• To understand the relationship between sediment contamination and PCB bioaccumulation in forage fish.

Main Methods:

• Collected and analyzed PCB congeners in topsmelt and Mississippi silverside from targeted and probabilistic sites in San Francisco Bay.
• Compared PCB concentrations between fish from historically polluted locations and representative ambient sites.
• Correlated fish PCB levels with spatial patterns of sediment contamination.

Main Results:

• Fish from targeted sites had significantly higher PCB concentrations (441±432 ng g⁻¹) than those from probabilistic sites (138±94 ng g⁻¹).
• PCB levels in forage fish were comparable to sport fish and correlated with sediment contamination.
• Highest concentrations were found near Hunter's Point Naval Shipyard and Stege Marsh, with a prevalence of lower chlorinated congeners suggesting local sources like Aroclor 1248.

Conclusions:

• Naturally occurring forage fish serve as reliable biosentinels for localized PCB exposure in estuarine environments.
• Current PCB bioaccumulation patterns in San Francisco Bay reflect historical industrial contamination.
• The study highlights the utility of forage fish in monitoring the impact of industrial activities on aquatic ecosystems.