The SPOT station (33˚33’ N, 118˚24’ W) is located approximately 10 miles offshore from one of the busiest ports (Port of Los Angeles) and most populated regions of the United States (the greater Los Angeles area is home to over 15 million people). Coastal ecosystems provide a home for more than 50% of the U.S. population, and contribute significantly to the economic and social vitality of the nation. Human activity and development along the coastline, in turn, significantly influence the natural ecosystems at land-water interfaces. The proximity of the SPOT station to a highly impacted and urban coastline provides a unique vantage point to study the impact that human activity can have on relatively pristine marine environments.
GSA Permission Granted for Image taken from Earth Science in the Urban Ocean: The Southern California Continental Borderland
By Homa J. Lee, William R. Normark
Overall, the SPOT station is characteristic of an open ocean environment: low nutrient concentrations (oligotrophic) and low phytoplankton biomass (chlorophyll-a concentrations typically remain below 2 ug/l). The region experiences a temperate climate, with seasonal sea surface temperatures fluctuating between 14 and 20 ˚C. Light levels attenuate to 0.1% of surface irradiance levels at approximately 100 m during times of highest irradiance (July-September), and mixed layer depths extend down to ~ 50 m during times of greatest mixing (winter). The SPOT station sits above the San Pedro Basin, which has a sill depth of ~700 m and a maximum depth of approximately 890 m. Reduced horizontal advection and biological respiration in deeper waters contribute to persistent hypoxic conditions below ~ 300 m. The San Pedro basin also acts as a ‘catch-all’ for the flow of carbon and energy in the overlying waters, and the sediment record within the basin has been shown to reflect natural and anthropogenic events in the region.