Zooplankton in the upwelling fronts off Pt Conception, California.

Number of taxa and number of individuals decreased with increasing upwelling intensity, indicating replacement of richer surface waters by relatively impoverished subsurface waters. The exception to this pattern was in copepodid stage V of Calanus pacificus which increased in numbers nearshore as upwelling strength increased. Since copepodid V is the deep-living, diapausing stage of this copepod, its increase in numbers is consistent with the upward movement of deep water and the life cycle of C. pacificus. Frontal zones always had more individuals than non-frontal zones; these were primarily copepod nauplii. Estimated ingestion by copepod nauplii and C. pacificus in frontal zones during upwelling was twice the ingestion by these taxa outside the frontal zones, suggesting that the frontal zones associated with upwelling off Pt. Conception are sites of enhanced secondary production.-from Authors