Seasonal intrusions of equatorial waters in
Monterey Bay

Brian Schlining
Monterey Bay Aquarium Research Institute

Wednesday, March 17, 1999
3:00 p.m.—Pacific Forum

Between January 30, 1991 and July 31,1995, the Monterey Bay Aquarium Research Institute’s remotely-operated vehicle (ROV) Ventana made 104 dives to observe hydrography and abundances of mesopelagic animals. The locations of the dives were 36d 42’ N, 122d 02’ W, near the center of the mouth of Monterey Bay and over the axis of the Monterey Submarine Canyon.

Analysis of hydrography between the surface and 1,000 meters showed annual intrusions of three water masses into Monterey Bay. Using characteristics of these intrusions along with information from acoustic Doppler current profiler data, the year was divided into four hydrographic periods: Upwelling (April-June, days 90-182); Oceanic-CUC (July-September, days 183-274); Early Davidson (October-November, days 275-334), and Late Davidson (December-March, days 335-89). Evidence collected by the ROV supports the hypothesis that the California Undercurrent (CUC), which occurs during the Oceanic-CUC Period, transports the mesopelagic zooplankton, Nanomia bijuga, into Monterey Bay.

Next: Long-term in situ chemical analyzers-works in progress