"Connectivity of Oyster Populations in Delaware Bay: A Modeling Study"
Diego Narvaez
Center for Coastal Physical Oceanography
Monday, February 16, 2009
3:30 PM
Room 3200, Research Innovations Building I
Abstract
Numerical models of population genetics, larval growth-behavior and circulation are combined to investigate
the relative importance of physical and biological processes in the dispersion of genes and larvae of Eastern oyster
(Crassostrea virginica) in Delaware Bay. Eastern oyster larvae develop while freely drifting in the water.
Thus, currents and larval vertical migration determine the final settlement location, which ultimately determines the
gene flow among populations. The Regional Ocean Modeling System (ROMS) has been configured to simulate
circulation in Delaware Bay. Water-following Lagrangian floats released in the simulated circulation fields included
larval growth and vertical migration in response to food, temperature and salinity. Model simulations follow larvae
from a number of release points (reefs) over a time span (2 to 4 weeks) sufficient for them to mature and set.
Simulations were done with and without larval growth and behavior. The results show that behavior and growth
influence the settlement pattern of larvae, and thereby, the pattern of recruitment and genetic dispersal in Delaware
Bay. The effect of the addition of new individuals on the genetic structure of the population was also investigated
using the genetics model. In these simulations, the allele added to the population by the immigrants was either
neutral or conferred a specific benefit. Continual addition of immigrants allowed the new allele to become dominant,
even if it was neutral. Dominance occurred in several decades for 1000 immigrants per year. Adding more
immigrants reduced the time to dominance. With benefit, the new allele was established quicker. These simulations
have implications for the introduction of disease-resistant oysters to populations that are significantly impacted by
disease.
Biography
Diego Narvaez received a B.S. degree in Oceanography from the Catholic University of Valparaiso in Chile. After
graduating, he worked as a research assistant at Estacion Costera de Investigaciones Marinas (ECIM), focusing his
research in physical processes affecting larval dispersion and transport. In 2006, he received a M.S. degree from the
OEAS Department at Old Dominion University and in the spring of 2007, he entered the OEAS Ph.D. program. His
Ph.D. research is part of the NSF-funded Ecology of Infectious Diseases program.
Reception before seminar at 3:00 PM
Research Innovations Building I
Old Dominion University
Norfolk, VA 23529
757-683-5548
Last updated 2/04/2009.
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