Observations of zooplankton vertical migration are usually made using samples from net tows that show the distribution of the population at a given point in time, but offer no information on the condition or behavior of those individuals. We developed zooplankton "traps" to test the hypothesis that zooplankton make repeated nighttime "forays" into the food-rich surface water from the food-poor layer immediately below, and we tested our field observations against the results of an individual-based numerical model of zooplankton behavior. Both our field observations and model results suggest that copepods engage in foray behavior, and that it may confer a significant fitness advantage to those individuals who do it by increasing ingestion and minimizing predation mortality.

Dr. Pierson is currently a postdoc at the Horn Point Laboratory of the University of Maryland Center for Environmental Science, working with Dr. Mike Roman on a number of projects, including a study to explore trophic interactions in the estuarine turbidity maximum of the Chesapeake Bay. He received his Ph.D. in oceanography from the University of Washington in 2006, where his work was on the trophic interactions of copepods and diatoms in the sea. Before entering graduate school, Dr. Pierson worked at the University of Rhode Island, Graduate School of Oceanography, where he was a research scientist on the GLOBEC Georges Bank Project and participated in numerous broad-scale surveys of the bank. He received a B.S. in biology at the University of New Hampshire and grew up in central New Jersey.

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