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Subsurface Eddy Facilitates Retention of Diel Vertical Migrators in a Biological Hotspot
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  • Katherine L Hudson,
  • Matthew John Oliver,
  • Josh Kohut,
  • Jonathan H Cohen,
  • Michael S. Dinniman,
  • John Klinck,
  • Hank Statscewich,
  • Kim S. Bernard,
  • William Fraser
Katherine L Hudson
University of Delaware

Corresponding Author:[email protected]

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Matthew John Oliver
University of Delaware
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Josh Kohut
Rutgers State University of New Jersey
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Jonathan H Cohen
Universtity of Delaware
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Michael S. Dinniman
Old Dominion University
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John Klinck
Center for Coastal Physical Oceanography
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Hank Statscewich
University of Alaska Fairbanks
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Kim S. Bernard
Oregon State University
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William Fraser
Polar Oceans Research Group
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Diel vertical migration (DVM) is a common behavior in zooplankton populations world-wide. Every day, zooplankton leave the productive surface ocean and migrate to deep, dark waters to avoid visual predators and return to the surface at night to feed. This behavior may also help retain migrating zooplankton in biological hotspots. Compared to fast and variable surface currents, deep ocean currents are sluggish, and can be more consistent. The time spent in the subsurface layer are driven by day length and the depth of surface mixed layer. A subsurface, recirculating eddy has recently been described in Palmer Deep Canyon, a submarine canyon adjacent to a biological hotspot. Previous circulation model simulations have shown that residence times of particles increase with depth within this feature. We hypothesize that DVM into the subsurface eddy increases local retention of migrating zooplankton in this biological hotspot and that shallower mixed layers and longer day length would increase the time in the subsurface layer. We demonstrate that vertically migrating particles have residence times on the order of 30 days, which is significantly greater than residence times of near-surface, non-migrating particles. The interaction of DVM with this subsurface feature may be important to the establishment of the biological hotspot within Palmer Deep Canyon by retaining critical food resources in the region. Similar interactions between DVM behavior and subsurface circulation features, modulated by mixed layer depth and day length, may also increase residence times of local zooplankton populations elsewhere.