Recruitment Dynamic in Event Driven Bank Circulations

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Dr. Davis and collaborators will develop a series of models of increasing complexity to examine the effects of storms and oceanic eddies on advective loss rates of plankton and fish larvae from an idealized offshore bank. Their working hypothesis is that such "wash-out" events cause major reduction in recruitment in characteristic zooplankton (Calanus, Pseudocalanus, Centropages, Paracalanus) and fish (cod, haddock, herring) populations. Although, for simplicity, they focus on bank circulation, the work will provide insights into basic interactions between physical forcing, food web dynamics, and recruitment which can be applied to other regions of the ocean. The researchers will start with a simple 2-D kinematic model of idealized flow around a bank (Georges Bank parameter values will be used) and will then incorporate simple models of food chain and zooplankton population dynamics. Eulerian models containing simple biology will be compared with Lagrangian ones (using flow trajectories specified from the Eulerian), containing more complete biology. We will develop simplification techniques to reduce biological complexity to a minimal acceptable level given dominant scales of physical and biological forcing. Models of intermediate complexity such as contour dynamics analyses will be developed to assess impact of rings on bank circulation. Finally, they will use a primitive equation (PE) circulation model containing simplified biology and compare the results with the other models. The primitive equation model will be used to obtain realistic dynamical flows given strong topography and stratification, so that temporal-spatial correspondence between physical losses and biological distributions can be determined.