Arena, Pt. Reyes, Pt. Finally, at Pt. Conception, where the coastline abruptly changes direction, upwelling does not occur because the orientation of the coastline and winds are no longer conducive to pushing surface waters offshore. Upwelling plays an important role for the rich marine resources in each of the five sanctuaries along the west coast.
However, the effects on each vary. For example, winds favorable to upwelling tend to be somewhat weaker and more seasonal in the Pacific Northwest than further to the south. Nonetheless, they draw up a rich pool of nutrients that is enhanced by the presence of several deep water canyons nearshore. The resulting food web diversity is spectacular.
More species of kelps and marine mammals exist here than anywhere else in the world. By contrast, one of the strongest regions of upwelling along the California coast is located south and west of Pt.
Reyes see Figure 3. The upwelling filament that extends from the Point bathes Cordell Bank and the Gulf of the Farallones. The resulting nutrient-rich water supports one of the most productive food webs in the marine world. When the winds slow or reverse direction, the upwelling ceases and warm surface waters from the Gulf of the Farallones move back north and toward the coast.
These surface waters may transport larval fish and invertebrates to mainland reefs, where they eventually settle and grow. Figure 4. The abrupt change in coastline orientation at Pt. Conception creates a sharp transition between upwelling regions to the north of the Point and warmer waters of the Santa Barbara Channel. The vast extent of the Monterey Bay Sanctuary, spanning miles of coastline, is characterized by its diversity of oceanographic settings.
Upwelling centers located north and south of Monterey Bay see Figure 3 are the primary source of cool, nutrient-rich water in the sanctuary. No scientific evidence supports the commonly-held belief that the deep Monterey Submarine Canyon contributes to upwelling within the Bay itself. The spatial variability in upwelling and the equally large variation in upwelling intensity over time likely play key roles in the recruitment of fish and invertebrates to coastal reefs.
Finally, the complex geography of Pt. Conception has a profound influence on the oceanographic conditions in the Channel Islands National Marine Sanctuary. The primary direction of the coastline abruptly shifts from north-south to east-west at Pt. Conception see Figure 4. In the northern hemisphere, if the wind blows parallel to the coast, then the Ekman transport can produce a net movement of surface waters, potentially resulting in coastal upwelling.
At the equator there are no Coriolis forces present. This causes upwelling either side of the equator and bring nutrients to the Galapagos Islands via the Cromwell Current.
Upwelling also occurs around islands and archipelagos as the sea floor becomes shallower, forcing deeper ocean currents to the surface. Upwelling brings cold water from the deep ocean to the surface. This cold water is typically rich in nutrients such as nitrate and phosphate because of the dead and decaying matter that has sunk to the ocean floor.
These nutrients are important for the primary producers of the oceanic food chain, the phytoplankton. The West Coast of the United States, for example, experiences summer upwelling and winter downwelling, as the winds change directions with the seasons. Artificial Upwelling Scientists and businesses are working to create areas of "artificial upwelling" to pump cold water to the surface. Researchers hope artificial upwelling will increase fish crops from the Gulf of Mexico to southwest Australia.
Artificial upwelling involves complex technology using the motion of waves to bring cold, nutrient-rich water from the deep ocean to the surface. Experiments in artificial upwelling have been tried in the Pacific Ocean near the Hawaiian Islands.
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