Vertical Distribution and Migration of Zooplankton

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Vertical Distribution and Migration of
Zooplankton
Stephen M. Bollens School of Biological Sciences,
and School of Earth and Environmental
Sciences Washington State University Vancouver
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Variability !!!!
Unpredictability?
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Euchaeta elongata (Bollens Frost 1991)
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(Longhurst 1976)
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(Wiebe et al. 1992)
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(Wiebe et al. 1992)
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(Lough Potter 1992)
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Calanus sinicus (Uye et al. 1990)
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Euchaeta elongata Adult female (Bollens Frost
1991)
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Calanus pacificus Adult female (Bollens Frost
1989)
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Variability !!!!
Unpredictability?
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ACKNOWLEDGEMENTS
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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?
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Copepod Diel Vertical Migration Behavior on the
Middle Shelf
Depth (m)
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Jun 20
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SUMMARY OF VERTICAL MIGRATION STUDIES

• Predator avoidance is widely held to be the most
  likely ultimate cause or adaptive significance of
  diel vertical migration in zooplankton

• More generally, it is a strategy to maximize the
  gains of energy intake (feeding) while
  minimizing the probability of death (predation)

• 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

• Pertinent to both upwelling and relaxation
  (downwelling) periods

• Future studies of the consequences of this
  behavior need to explicitly link the detailed
  (species-specific) biological observations with
  circulation/hydrodynamic models