1. Vertical Distribution and Migration of Zooplankton Stephen M. Bollens School of Biological Sciences, and School of Earth and Environmental Sciences Washington State University Vancouver

2. Variability !!!! Unpredictability?

4. Euchaeta elongata (Bollens & Frost 1991)

5. (Longhurst 1976)

6. (Wiebe et al. 1992)

8. (Lough & Potter 1992)

9. Calanus sinicus (Uye et al. 1990)

10. Euchaeta elongata Adult female (Bollens & Frost 1991)

11. Calanus pacificus Adult female (Bollens & Frost 1989)

17. Variability !!!! Unpredictability?

18. ACKNOWLEDGEMENTS

19. Coastal Ocean Processes (CoOP) Program of NSF, Wind Events and Shelf Transport (WEST) Project Overall goal: to critically examine the role that wind-driven transport plays in shelf productivity. More specific research question: Does wind-driven transport of water directly affect the distribution of zooplankton on the shelf, or are zooplankton behaviorally adapted to avoid such transport via diel vertical migration?

21. Copepod Diel Vertical Migration Behavior on the Middle Shelf Depth (m)

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24. SUMMARY OF VERTICAL MIGRATION STUDIES More generally, it is a strategy to maximize the gains of energy intake (feeding) while minimizing the probability of death (predation) Future studies of the consequences of this behavior need to explicitly link the detailed (species-specific) biological observations with circulation/hydrodynamic models In habitats that have vertically sheared, differently-directed flow fields, such as estuaries and coastal upwelling systems, position maintenance is another plausible ultimate cause of vertical migration behavior Predator avoidance is widely held to be the most likely ultimate cause or adaptive significance of diel vertical migration in zooplankton Pertinent to both upwelling and relaxation (downwelling) periods