| Abstract: |
The multidisciplinary nature of larval dispersion constitutes a challenge for management and restoration efforts of many commercially important estuarine species. In this study we address these challenges using a combination of numerical models that allow us to study the relative importance of biotic and abiotic factors in the dispersion of eastern oyster. A numerical model (ROMS) was configured for Delaware Bay to determine the estuarine circulation in response to winds and river discharge. Water-following Lagrangian floats in the model were modified to include larval growth and vertical migration in response to temperature and salinity. Model simulations follow larvae from a number of release points (reefs) and release times over a span of 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. An along estuary survival gradient is related to the salinity gradient observed for the Bay, long development times are 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 seems to be important for the retention of larvae, increasing the settlement in this area. River discharge also affects the settlement pattern, causing a shift between middle and lower Bay settlement. These results present new evidence of how climate variability might affect the exchange of individuals among oyster populations, and therefore the structure of marine ecosystem. |
