1. www.whatiftechnologies.com Food Nutrient Dynamics Model for Pond Aquaculture A seminar presented at Centre for Nutrition Modelling Department of Animal and Poultry Science University of Guelph, Guelph, Ontario Oct. 13, 2005 By Dr. Lanhai Li whatIf? Technologies Inc. Ottawa

2. www.whatiftechnologies.com Related Research Experience 4 Fish Bioenergetics modeling 4 Aquaculture pond dynamics 4 Hydrodynamics and Eutrophication process Modeling 4 Aquaculture Research Priorities Survey & Analysis in Asia and Pacific 4 Demographic dynamics

3. www.whatiftechnologies.com Outline of the Presentation 4 Introduction 4 Objectives 4 Methodologies 4 Model construction 4 Results 4 Conclusions

4. www.whatiftechnologies.com Introduction 4 Aquaculture: Promising Industry 4 Aquatic products: 25% of human protein consumption (Johnson and Associate, 1998) 4 32% of aquatic production from aquaculture Total aquatic products increased about 38.6% Aquaculture production increased 299.1% (FAO Statistics)

5. www.whatiftechnologies.com Introduction 4 Successful management of Pond Aquaculture –Constant supply of necessary nutrients Organic and inorganic –Balanced diets 4 Feeding strategies –No fertilizer or feed input –Fertilization –Supplementary feeding –Complete diet feeding

6. www.whatiftechnologies.com Problem 4 Complete diet feeding: –Supply of necessary food nutrients: Energy, Protein etc. –Cost: 50% of total operating cost 4 Alternatives: –Fertilization –Supplementary Feeding 4 Problem: –Lack of an insight view on the food nutrient dynamics (including quality and quantity) of aquacultural ponds

7. www.whatiftechnologies.com Objectives  To examine the impacts of fertilization strategies on food nutrient dynamics  To determine qualitative and quantitative requirements for food nutrients from supplementary feed

8. www.whatiftechnologies.com Process of food nutrient dynamics in an aquacultural pond

9. www.whatiftechnologies.com Methodology 4 System Dynamics Principles 4 Feedback and Loops 4 Dynamic Hypothesis

10. www.whatiftechnologies.com Food production feedback loops

11. www.whatiftechnologies.com Fish growth in a fertilized pond

12. www.whatiftechnologies.com Fish growth in a fertilized pond with supplementary feeding

13. www.whatiftechnologies.com Nitrogen feedback loops

14. www.whatiftechnologies.com Feedback loops for DO

15. www.whatiftechnologies.com Mathematical Equations 4 State variables 4 Rate variables 4 Auxiliary variables 4 Parameters 4 Based on mass balance Y t -Y t-  t =  t * (inflow t – outflow t )

16. www.whatiftechnologies.com Mathematical Equations –Autotrophic –Heterotrophic –Fish growth –Elementary Nutrients –DO

17. www.whatiftechnologies.com Field Experiment 1 4 Fertilization –Treatments: Low rate: 1 kg P/ha/day + 2 kg N/ha/day High rate: 2 kg P/ha/day + 4 kg N/ha/day –Three replicates –Fertilization once a week –At Bangkok from Jun 6 th to Sept 1 st, 1994 –Pond size: 200 m 2 area * 100 cm depth –Species: Nile Tilapia: all male monoculture with 3 fish per m 2

18. www.whatiftechnologies.com Field Experiment 2 Fertilization + supplementation –Treatments: Energy supplements (Cassava Starch) Energy + protein supplement (25% Protein) With 2 kg P/ha/day + 4 kg N/ha/day –Three replicates –Fertilization once a week –At Bangkok from Nov. 28 th 1994 to Mar 24 th 1995 –Pond size: 200 m 2 area * 100 cm depth –Species: Nile Tilapia: all male monoculture with 4 fish per m 2 –Feeding rate: 3% of fish body weight

19. www.whatiftechnologies.com Simulation 4 Original model was developed by STELLA

20. www.whatiftechnologies.com Results: Fertilization Experiment --Elementary nutrients

21. www.whatiftechnologies.com Results: Fertilization Experiment Food Nutrients

22. www.whatiftechnologies.com Results: Fertilization Experiment --Food consumption

23. www.whatiftechnologies.com Results: Fertilization Experiment --Mean fish weight

24. www.whatiftechnologies.com Results: Fertilization + supplementation Experiment --Food Nutrients

25. www.whatiftechnologies.com Results: Fertilization + supplementation Experiment --Food consumption

26. www.whatiftechnologies.com Results: Fertilization + supplementation Experiment --Mean fish weight

27. www.whatiftechnologies.com Results: Fertilization + supplementation Experiment – feed requirement Feed Protein

28. www.whatiftechnologies.com Conclusion 4 Fertilization can improve elementary nutrient supply and increase food nutrient production and fish biomass 4 Supplementary feeding is necessary for further fish growth under fertilization 4 Energy Supplements is enough at initial stage, but later energy + protein supplements are necessary 4 Modeling as a powerful methodology

29. www.whatiftechnologies.com References Li Lanhai, Amararatne Yakupitiyage and Khalid Saeed, 1998, Food nutrient dynamics model for fertilized ponds. System Dynamics: An International Journal of Policy Modeling. Vol. X, Nos. 1 & 2, pp.85-115. L. Li and A. Yakupitiyage, A Model for Food Nutrient Dynamics of Semi-intensive pond Fish Culture. Aquacultural Engineering 27 (2003) 9-38. *** 4 *** This paper was granted as Superior Paper Award by the Aquaculture Engineering Society in 2005

30. www.whatiftechnologies.com