MEPS 287:23-32 (2005)  -  doi:10.3354/meps287023

Physical-biological coupling in Monterey Bay, California: topographic influences on phytoplankton ecology

John P. Ryan*, Francisco P. Chavez, James G. Bellingham

Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, California 95039-9644, USA

ABSTRACT: Physical-biological couplings impacting phytoplankton ecology are examined with synoptic, high-resolution observations of Monterey Bay, California. Influences of submarine canyon and shelf break topography on the physical-biological couplings are supported by 2 case studies. In the first case study, benthic-pelagic coupling was observed in southern shelf waters where a turbid plume extended from the bottom at ~60 m deep to the base of a phytoplankton layer centered at ~10 m deep. The alongshelf scale of the plume ranged from ~5 km near the bottom to ~1 km at its intersection with the phytoplankton layer. In situ and remote sensing data support the influence of Monterey Canyon on circulation forcing the benthic-pelagic coupling. In the second case study, a frontal zone and adjacent waters were rapidly surveyed over ~20 km2 of the northern shelf. The front was associated with an isopycnal ridge/trough structure, surface slick, and frontal eddy <1 km in diameter. The magnitude and vertical location of a chlorophyll maximum layer were closely coupled with the physical environment through the frontal zone. The layer was dispersed by the isopycnal ridge and frontal eddy, and concentrated in the isopycnal trough and along the periphery of the eddy. Influence of an internal wave generated by interaction of tidal currents with the shelf break is supported by the observed surface slick, measured water velocities, and the proximity and orientation of the shelf break. Significant and persistent influences of topography on phytoplankton ecology in Monterey Bay are indicated.

KEY WORDS: Physical-biological coupling · Topographic influence · Fronts · Eddies · Phytoplankton · Benthic-pelagic coupling · Submarine canyons · Autonomous underwater vehicle

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