The Ecology of Vertical Migration in Three Common Zooplankters in the La Jolla Bight, April—August 1967

Abstract

AbstractNearshore submarine canyons concentrate the migratory zooplankton descending into them and thereby provide an index of the organisms' migratory activity. A vertical migration index was constructed based upon the relative concentration of migratory to non-migratory stages of plankton found within La Jolla Canyon compared to their relative concentration at a nearby non-canyon control station. The patterns of vertical migration derived from this index for Calanus pacificus, Rhincalanus nasutus, and Euphausia pacifica over La Jolla Canyon for an 18-week period (April—August 1967) were consistent with their known temporal patterns of migratory activity.Principal component analysis was performed on 13 variables measured weekly during the study period. The first component separated upwelling and diatom blooms from periods of downwelling dominated by flagellates. C. pacificus (C IV—VI) migrated most actively during non-upwelling periods; E. pacifica migrated most actively during upwelling episodes. Upwell...