Figure 1. Oceanographic zones within the Monterey Bay, Gulf of the Farallones, and Cordell Bank National Marine Sanctuaries. [View Larger]
Local tidal currents and submarine and terrestrial physical features also influence the area's oceanographic environment. For example, local outflow from San Francisco Bay affects the Gulf of the Farallones sanctuary.
The calendar year in northern California waters consists of three general oceanographic seasons. Although these occur in each sanctuary at slightly different times (see specific details for Cordell Bank, Gulf of the Farallones and Monterey Bay), the seasons, as they pass through each sanctuary, are characterized by the same phenomena:
- the upwelling period, from early spring to summer: strong southward wind forcing and currents along with cool surface waters
- the relaxation period (or oceanic period), from late summer to early fall: wind relaxation, warmer water temperatures and mainly northward surface currents
- the winter storm period (or Davidson Current period), from late fall to late winter/early spring: rain-bearing cold fronts, rough seas and greater mixing of ocean water
ENSO refers to periodic cycling between anomalously warm (El Niño) and cool (La Niña) ocean water temperatures that spread across the equatorial Pacific Ocean. These anomalies indicate perturbations in the ocean and atmosphere that are manifested over broad scales, including the California Current ecosystem. Like ENSO, the PDO comprises a warm and a cool interval (associated with changes in surface water temperatures of several degrees), but over a longer period of time.
Conservation and Management Issues
Washing down hoop net.
Lowering a niskin bottle used for water quality sampling during a 2005 CIMT survey. Photo: CIMT
Phytoplankton blooms, including harmful algal blooms, have increased in frequency and distribution worldwide since 1980. The frequency of such blooms may be increasing with nutrient enrichment from agricultural and urban storm runoff as well as sewage effluent.
MonitoringAll three sanctuaries are involved in a variety of research and monitoring efforts.
PRBO Conservation Science, in collaboration with Cordell Bank and Gulf of the Farallones sanctuaries, study krill and oceanographic processes within these two sanctuaries:
- Distribution and Abundance of Marine Birds, Mammals and Zooplankton Relative to the Physical Oceanography of the Gulf of Farallones and Cordell Bank
- Sanctuary Ecosystem Assessment Surveys (SEA Surveys)
- Wind to Whales