The PIs will develop a mechanistic understanding of how circulation interacts with hypoxia-induced behavioral and physiological changes to affect the population dynamics of coastal zooplankton. They will do this by assessing two potentially contrasting mechanisms influencing the dynamics of the copepod Acartia tonsa in the hypoxic zone of Chesapeake Bay. The first hypothesis is that maintenance of copepod populations in the hypoxic region requires replenishment by advection (immigration) of animals through wind-driven lateral transport processes. The second, counteractive, hypothesis is that bottom water hypoxia alters the vertical distribution of A. tonsa, thereby making them more susceptible to advective losses from the region (emigration) via surface water transport in the estuarine circulation. They will take advantage of a current NSF-funded physical oceanography research program in Chesapeake Bay that will comprehensively measure and model axial and lateral water exchanges in the mid-Bay region.
The present study will use the physical oceanography study site as a Controlled Volume (CV) in which the oceanographic exchanges of water and the driving mechanisms for those exchanges will be well defined. The PIs will conduct high-resolution spatial and temporal sampling of zooplankton and combine the data with measurements of copepod behavior, mortality and egg production in the hypoxic region. They will use an improved Individual-Based Model of the life history of A. tonsa coupled with the circulation to explore the combined effects of advection, behavior, egg production, and mortality on population dynamics. In addition to increasing our knowledge of the impacts of bottom water hypoxia on copepod populations in Chesapeake Bay, the study will improve our general understanding of the regulation of zooplankton populations by physical and biological processes and the impacts of hypoxia on secondary production and food webs in coastal waters.
The project will enhance existing public education and outreach efforts so that the public can be better informed about the effects of hypoxia on Chesapeake Bay. This will be accomplished in part through the Center for Ocean Science Education Excellence (COSEE) Coastal Trends program (now the Horn Point Laboratory STEM Center Student Learning Activities program). The PIs will enhance an existing set of online education modules (www.teachoceanscience.net/) that focus on the causes and consequences of the Chesapeake Bay's "Dead Zone" through development of an online interactive version of their synthetic plankton model. The study also includes participation by undergraduate summer interns through a Research Experience for Undergraduates (REU) program. In addition, this research will contribute information toward the development and improvement of dissolved oxygen criteria for Chesapeake Bay, will support broad initiatives of the Chesapeake Bay Program by providing information on the role of zooplankton in supporting productivity of fisheries, and will contribute information to ecosystem-based fisheries management plans.
