1. NarrCHRP: Ecological Modeling Mark J. Brush Virginia Institute of Marine Science Annual Managers’ Meeting CHRP Narragansett Bay Project October 2008

2. USE OF MODELS IN MANAGEMENT

3. Generality Realism Precision R. Levins (1966, 1968) Empirical Models Complex, Mechanistic Systems Models A Simplified, Intermediate Complexity Model MODELS … A TRADEOFF BETWEEN:

4. Phytoplankton Nutrients OxygenBOD Sed Carbon Estuarine Eutrophication Model

5. 1. Phyto Production 5. Macro Metabolism 3. C flux to sediments * Need to accurately model both states and rates Estuarine Eutrophication Model 2. Water Column Respiration 4. Denitrification 6. Sediment Respiration

6. 1 2 3 45 8769 1112 10 1314 RI Sound Boxing Scheme

7. Boxing Scheme: Physical Exchanges 3D ROMS ModelOfficer Box Model

8. Freshwater Inputs Watersheds delineated for each box 7 gauged rivers extrapolated to include ungauged areas. Flow in the completely ungauged watersheds was computed from flow/area for the Hunt watershed. 2001 - 2006 Box Model: Exchanges = f(freshwater, salinity)

9. Salinity Distributions Current: Simple seasonal functions using Insomniacs and GSO data. Future: include event-scale with buoy data Box Model: Exchanges = f(freshwater, salinity)

10. Computed Residence Times Providence River (Box 1-3) Greenwich Bay (Box 6-7) Entire Narragansett Bay RT, DAYS 1/1/01 12/31/06 Box Model: Computed Residence Times

11. Ecological Model: How are we doing?

12. Ecological Model: Surface Chl-a

13. Ecological Model: Surface DIN

14. Ecological Model: Surface DIP

15. Ecological Model: Bottom DO

16. Current Directions: Calibration to Chl-a, DIN, DIP, and rates Finish GEM Box and compare the physical approaches Formulation to translate predicted DO and metabolism to instantaneous criteria Potential Applications: Understanding formation, spread, & alleviation of hypoxia in NB Effect of changes in nutrient loading Effect of climate warming Effect of loss of spring bloom Stochastic simulation to assess Pr.(criteria attainment) Ecological Model

17. Stochastic Simulation Bottom O 2