MEPS 336:203-210 (2007)  -  doi:10.3354/meps336203

Retention of dormant copepods in deep basins of the Southern California Bight

Catherine L. Johnson*

Integrative Oceanography Division, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, California 92093-0218, USA Present address: Ocean Process Analysis Laboratory, University of New Hampshire, 142 Morse Hall, Durham, New Hampshire 03824-3525, USA

ABSTRACT: The vertical distribution and abundance of dormant Calanus pacificus were described in deep basins and at deep, non-basin locations in waters off Southern California in October 1999 and 2000 and January 1999. Dormant C. pacificus were present in deep water at all stations sampled. In each month, vertical distributions were similar across the region sampled. The abundance of dormant C. pacificus was higher and their depth range was broader and deeper in October than in January. There was no difference in the abundance of dormant C. pacificus in basins and at deep, non-basin locations in October. Except for the Santa Barbara Basin, Southern California Bight basins were too deep relative to the vertical distribution of dormant C. pacificus to trap dormant copepods. Migration to deep water during dormancy in this region removes copepods from equatorward flow in surface waters. Dormant copepods are exposed either to poleward flow at the shallow end of their depth range in the continental borderlands of Southern California, or to very low current velocities in deeper water, both at basin and non-basin locations. The broad horizontal distribution of dormant C. pacificus in this region implies that non-point sources are dominant in re-seeding surface waters at the end of the dormant season.

KEY WORDS: Calanus pacificus · California Current · Copepod · Diapause · Dormancy · Retention

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