Coupling an Individual-Based Model to the Regional Ocean Model System (ROMS): Application on larval dispersal studies

Narváez, Diego A.1; Klinck, John M.1; Powell, Eric2; Hofmann, Eileen E.1; Wilkin, John3; Haidvogel, Dale B.3

1 Center for Coastal Physical Oceanography, Old Dominion University, Norfolk, VA, 23508
2 Haskin Shellfish Research Laboratory, Rutgers University, Port Norris, NJ, 08349
3 Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901.


Most physiological process in marine organisms are controlled by environmental parameters such as temperature, salinity, food, etc. which can be estimated from hydrodynamic models with appropriate processes. Individual-Based Models (IBM) are used to study dispersal of freely drifting marine organisms, such as larvae, which are affected by growth and behavior in response to environmental conditions. In this study we convert the particle-tracking module in the ROMS code into an IBM representing eastern oyster larvae which has growth and vertical migration. ROMS was configured for Delaware Bay to calculate the estuarine circulation in response to winds and river discharge. Larvae are released from a number of points (reefs) at several times and tracked for 2 to 4 weeks which is sufficient for them to mature (attain a length of 330 micron) at which point they sink and attach to the bottom. The results show that variations in temperature and salinity have a large impact in the larval survival, dispersal and settlement. Increased larval mortality is associated with areas having low salinity or low temperature. Simulations show that behavior is important and favors settlement of larvae within the Bay; particles without behavior are mostly exported to the shelf. A recirculation in the lower Bay is important in retaining larvae, increasing the settlement in this area. River discharge variation also affects the dispersion pattern, causing a shift between middle and lower Bay settlement. These results confirm that both physical and biological processes influence the dispersion pattern of larvae, and thereby, the pattern of recruitment and genetic dispersal over Delaware Bay. We are able to map which reef is the source of recruits to each oyster bed based on the results of this work. Finally the modification of ROMS drifters into an IBM provides a new tool for studies of larval dispersion and other individual-based studies.