Chapter 19 – Southern California Bight

The Southern California Bight (SCB) is a unique and valuable ecological and economic resource. It is also vulnerable to environmental pressures, with > 30 million inhabitants. Collectively since 1994, SCB dischargers, regulators, academics, and nongovernmental organizations have collaborated in a regional monitoring program to assess ocean health. In this chapter, we describe the most recent key findings and trends, focusing on sediment quality, trash, beach water quality, and ocean acidification (OA).

Sediment quality in the SCB is generally good, with only 6% of the region having impacted sediment chemistry, sediment toxicity, and/or benthic infauna. However, not all habitats are in equally good condition, with embayments (i.e., marinas, estuaries) experiencing the greatest extent of impacts. Despite their impacts, SCB embayment sediment quality has improved over the past 15 years.

Trash is widespread in the SCB, especially plastic, covering 25% of the seafloor. This extent has been increasing steadily for 20 years. The results are consistent with coastal SCB watershed surveys, where trash is observed in every urbanized stream sampled. This trash is subsequently discharged to the ocean during storm events.

Beach water quality in the SCB is generally safe to swim. Only 3% of the SCB shoreline km-days exceed water quality standards for bacteria during the summer months, which attracts 1.75 × 108 beachgoers each year. During or immediately following wet weather, however, the extent quickly increases to 65% of the shoreline km-days exceeding standards.

The SCB is vulnerable to OA owing to its narrow continental shelf, which can bring deeper corrosive water close to shore. SCB surveys observed corrosive water (defined as aragonite saturation state < 1.0) region-wide. Corrosive water was observed as shallow as 20 m depth, but was most frequently observed at depths > 100 m. Corrosive waters were most widespread in spring, consistent with regional upwelling events.

Schiff K., McLaughlin K., Moore S. & Cao Y., 2019. Southern California Bight. In: Sheppard C. (ed.), World seas: an environmental evaluation. Volume 1: Europe, the Americas and West Africa (Second edition), pp. 465-482. Academic Press. Chapter (restricted access).

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