Regional monitoring is an important component of assessing the status of Southern California’s coastal resources. The Southern California Bight 2013 Regional Monitoring Program (Bight‘13) is the fifth in a series of regional marine monitoring surveys conducted in 1994, 1998, 2003, and 2008. Collectively, these surveys provide a tool to assess both the current status and temporal changes in coastal water quality, and the influence of multiple environmental stressors. Chemistry, benthic macrofauna, and toxicity analyses of 346 sediment samples from the southern California shelf, submarine canyons, bays, and estuaries during Bight’13 indicate that sediment quality is relatively good. Indices used for assessing attainment of the Water Board’s sediment quality objective for protection of aquatic life show that approximately 98% of the southern California Bight has no or marginal effects regarding toxicity and benthic community disturbance, while chemical contamination exposure was classified as minimal or low in approximately 70% of the area. Sediments in bays and estuaries still show evidence of greater contamination and toxicity than is observed in offshore areas, an indication of the influence of contaminant inputs from multiple current and legacy sources, including watershed runoff, industrial discharge, and commercial and recreational activities. Integrated assessment of sediment condition shows a substantial improvement in overall sediment quality since 1998, indicating that management actions to improve water quality have been effective in the region. However, temporal trends in each line of evidence showed different patterns, with evidence of improvement in toxicity, little change in chemistry, and a slight decline in benthic community condition. There was a relatively low association between biological effects and specific contaminants, indicating that many important stressors are not being evaluated or that current measurement methods are poor indicators of exposure to biota.

Regional trends in sediment quality in southern California: Responses to multiple stressors

253rd National Meeting (2017)

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