This is a presentation at the Abalone Farmers Assosiation of Southern Africa project meeting in 2003. It details the progress we made from 2000 - 2002 on using seaweeds as biofilters in aquaculture effluent

1. Robertson-Andersson, D. V .; Bolton, J. B.; Anderson, R. J. & Probyn, T. A. CULTIVATION OF ULVA IN AQUACULTURE EFFLUENT AFASA project meeting 2003

6. Longitudinal profile of tanks Transverse profile of tanks 5 m 1 m

8. Small tanks Medium tanks 0.5 m 1 m 1 m 1 m

9. 0 1 2 3 4 5 6 7 8 sea shaded sea fert shaded fert abalone shaded abalone SGR % day -1 J J A S O N D J F M A M J J A S O RESULTS SGR of Ulva from June ‘01 to October ‘02 in sea, fertilized & abalone effluent water. (2) where water exchanges increased at I & J 2

10. RESULTS RGR of Ulva from June ‘01 to October ‘02 in sea, Turbot & abalone effluent water at JSP.

11. RESULTS SGR of Ulva from June ‘01 to October ‘02 in sea, Turbot & abalone effluent water at JSP.

12. RESULTS SGR of Ulva from June ‘01 to October ‘02 in sea, Turbot & abalone effluent water at JSP.

14. RESULTS Myrionema strangulans (MS) BAD INFECTION DEAD HEALTHY INFECTED

15. RESULTS MS infestation of Ulva thalli

20. RESULTS Tissue Nitrogen vs. Thallus Colour Tissue nitrogen vs. thallus colour

22. Results ECONOMICS

23. RESULTS ECONOMICS Abalone growth curves

24. RESULTS 31.2 % increase in weight using rotation diet vs kelp only diet over 9 months Cost: $30 per kg X R 8 = R 240 10 (100g) abalone in 1 kg cost per abalone = R 24 less profit and freight = R 15 per abalone ECONOMICS

25. RESULTS Increase in SGR: 49 – 68 % per year Normal Growth to 100g = 5 years accelerated growth = 3.3 – 3.6 years @ R 15 per abalone New cost : R 12.40 – R 13.50 per abalone Savings: 17 – 28 % R 1.50 - R 2.60 per abalone ECONOMICS

26. RESULTS Average farm (50 tons @ 100 g per abalone) = 500 000 100g abalone X R 1.50 or R 2.60 EQUALS Savings: R 800 000 – R 1.3 million ECONOMICS

28. THE END Thank you ACKNOWLEDGEMENTS I would like to extend special thanks to the following people and organizations without whose help this project would be impossible: I & J Mariculture farm particularly N. Loubser, H. Otto and L. Ansara JSP Mariculture farm particularly K. Ruck N R F Swedish and South African Collaborative Programme