USA (West-Coast) - Environment

The biology and physics of the CCLME are driven by three major currents: the California Current, the Davidson Current, and the California Undercurrent, which shift in strength and distance from shore throughout the year in response to climatic forcing. The chief current, the California Current, runs widely along the surface pushing cold, nutrient-rich water from the tip of Vancouver Island southward down to Baja California, typically offshore in the fall and winter and inshore during the spring and summer. The California Undercurrent and Davidson Current both run north, bringing warmer, saltier, hypoxic waters from the equator. The subsurface California Undercurrent runs off the shelf break in the summer and fall, while the Davidson Current runs more nearshore at the surface in the winter and spring. These currents drive ecosystem variability, directly impacting the seasonal and annual dynamics of the nutrients and organisms.

Concentrated areas of upwelling are created by the latitudinal variation in continental shelf width and large geographic features like Astoria Canyon and Monterey Bay. Heavier northern flows of fresh water input introduce nutrients into the system year-round, which vary by latitudinal region. Habitat-forming marine flora such as kelp and seagrass are limited by these conditions and live scattered along the coast. The headlands and resulting eddies and jets enhance the strong winter storms and spring and summer upwelling that influence the spatiotemporal variation in primary productivity and zooplankton biomass of the CCLME.