SPATIAL AND TEMPORAL VARIABILITY OF ZOOPLANKTON COMMUNITIES IN THE SAN JUAN CHANNEL

Abstract

The San Juan Channel is a transitional area between marine and freshwater environments that influences the distribution, abundance and community composition of zooplankton. Zooplankton communities are highly variable seasonally and interannually due to the complexity of physical oceanography in the region. During the fall season in 2011, tidal regimes that characterize this estuarine environment appeared to spatially influence highly abundant Calanoid copepods and copepod nauplii. The results of this study suggest that tidal forcing exhibits a significant influence Calanoid copepods and copepod nauplii in the San Juan Channel, where spring flood tides influenced the Northern region and neap flood tides influenced the Southern region at depth. Spatial variation in the distribution of juvenile and adult copepods between these regions may be explained by behavioral patterns in copepod diapause, while depth variation in the Southern region may be driven by behavioral patterns in diel vertical migration. These investigations may begin to enhance our understanding of the relative life history stages of copepods as an influence on their distribution and abundance in the San Juan Channel.