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Grazing impact of diverse zooplankton taxa on thin layers

Principal Investigators: Stephen Bollens, Alexander Bochdansky (Old Dominion University), Gretchen Rollwagen-Bollens
Students: Joel Quenette
Funded by: Office of Naval Research
Award period: 2006 – 2009

Project Summary:

The US Navy needs to know how distributions and abundances of light-scattering and sound-scattering organisms in the ocean vary in space and time. Perhaps the most striking example of such variability is in the vertical dimension, where biological properties have long been known to vary several orders of magnitude over a few meters, and have more recently been shown to vary over even smaller scales (e.g. “thin layers”). Our previous research has allowed us to begin to understand how zooplankton interact with thin layers and how they can take advantage of biomass of prey concentrated in these small-scale features. However, there is almost no information on how zooplankton can influence the characteristics and persistence of thin layers.
The two important questions in this regard are: 1) To what extent do zooplankton graze and export carbon from thin layers, and 2) Do zooplankton influence the physical (e.g., optical and acoustical), chemical, and biological characteristics of thin layers with their presence? These two questions are tightly coupled to rate processes such as feeding activity and excretion, which are very difficult to assess in the field.

Therefore we have designed a detailed set of experimental studies that will examine biological rate processes that contribute to the recycling and export of material in and around thin layers. As in our previous investigations, we will be able to separate physical from biological processes in a controlled laboratory setting. Moreover, we will directly link our experiments with current “thin layer” field programs by employing the same taxa and densities observed at the field sites.

Publications/Presentations resulting from this project:

  • Bollens, S.M., G. Rollwagen-Bollens, J.A. Quenette, and A.B. Bochdansky (2011) Cascading migrations and implications for vertical fluxes in pelagic systems.  Journal of Plankton Research 33(3): 349-355.
  • Bochdansky A. B., S. M. Bollens, G. C. Rollwagen-Bollens, and A. H. Gibson (2010) Effect of the heterotrophic dinoflagellate Oxyrrhis marina and the copepod Acartia tonsa on vertical carbon flux in and around phytoplankton thin layers of the phytoflagellate Isochrysis galbana. Marine Ecology Progress Series 402:179-196.
  • Breckenridge, J. K and S. M. Bollens (2010) Biological thin layer formation:  Interactions between the larval decapod, Neotrypaea californiensis, haloclines and light. Journal of Plankton Research 32(7): 1097-1102.
  • Rollwagen-Bollens, G., A. Bochdansky, S.M. Bollens, A. Gibson, and J. Quenette.  Upward biological pump mediated by the vertically migrating, thin-layer forming dinoflagellate Akashiwo sanguinea.  2008 Ocean Sciences Meeting, Orlando, FL, USA.
  • Bollens, S.M., J. Quenette, A. Bochdansky, and G. Rollwagen-Bollens. Vertical migration of “thin layers” of the dinoflagellate Akashiwo sanguinea in relation to varying light and nutrient conditions.  2008 Ocean Sciences Meeting, Orlando, FL. USA.