D. V. Robertson-Andersson; A. Govender; T. Probyn; C. Halling; M. Troell; J. Bolton & R. Anderson A preliminary investigat...
INTRODUCTION <ul><li>Previous studies in Israel here have shown that  Ulva lactuca  is capable of removing significant amo...
Benefits of a closed system <ul><li>Increase in temperature above ambient seawater equates to an increase in growth rates ...
AIMS <ul><li>Investigate and model the physico-chemical dynamics of a farm section </li></ul><ul><li>Influence of differen...
PROJECT SITES <ul><li>A balone mariculture farms </li></ul><ul><li>Danger Point  (I & J Mariculture Farm)  +   140 km east...
PROJECT DESIGN AT I & J <ul><li>2  Ulva  tanks (5 X 1 X 0.63 m)  were integrated to one abalone tank (7 X 2 X 1 m) </li></...
Longitudinal profile of tanks Transverse profile of tanks 5 m 1 m
Longitudinal profile of tanks Transverse profile of tanks
Seaweed tank  Pump Gravity feed  Abalone tanks Seaweed tank  80 % recirculation  20 % Sea water  Over flow
PROJECT DESIGN AT JSP <ul><li>Still to build an integrated system, similar to I & J but using smaller tanks and a smaller ...
RESULTS <ul><li>In this system :  </li></ul><ul><li>Ulva  can take up 90 % of ammonium during the day in abalone effluent ...
RESULTS <ul><li>Ammonium levels must remain below 0.15  u M N.L -1 </li></ul><ul><li>DO values between 2 and 12 mg.L -1 , ...
Balancing the equations Using linear mass balanced equations Multiple regression of factors Problems putting theory and re...
RESULTS Dissolved oxygen Dissolved oxygen in a recirculation system 15  16  20  00  04  08  12  16  20  00  04  08  12  16
RESULTS Dissolved oxygen Dissolved oxygen in a recirculation system 15  16  20  00  04  08  12  16  20  00  04  08  12  16
RESULTS pH in a recirculation system pH 15  16  20  00  04  08  12  16  20  00  04  08  12  16
RESULTS pH in a recirculation system pH 15  16  20  00  04  08  12  16  20  00  04  08  12  16
RESULTS Temperature in a recirculation system Temperature 15  16  20  00  04  08  12  16  20  00  04  08  12  16
RESULTS Temperature in a recirculation system Temperature 15  16  20  00  04  08  12  16  20  00  04  08  12  16
RESULTS ammonium levels in  recirculated tanks  range between 0.003 - 0.005  u M N.L -1 ammonium levels in  abalone flow t...
Major Challenges <ul><li>For farm management of such a system: </li></ul><ul><li>Diel relationship between oxygen and pH i...
The future <ul><li>Run this study over a 18 months to obtain seasonal changes  </li></ul><ul><li>Effect of diet on growth ...
  THE END Thank you  ACKNOWLEDGEMENTS I would like to extend special thanks to the following people and organizations with...
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A preliminary investigation into modelling an integrated seaweed (Ulva lactuca) & abalone (Haliotis midae) system

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This presentation was given at the Phycological Society of Southern Africa meetin in 2004 and shows prelimanary investigations into modeling and IMTA seaweed abalone land based recirculting system

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A preliminary investigation into modelling an integrated seaweed (Ulva lactuca) & abalone (Haliotis midae) system

  1. 1. D. V. Robertson-Andersson; A. Govender; T. Probyn; C. Halling; M. Troell; J. Bolton & R. Anderson A preliminary investigation into modelling an integrated seaweed ( Ulva lactuca ) & abalone ( Haliotis midae ) system
  2. 2. INTRODUCTION <ul><li>Previous studies in Israel here have shown that Ulva lactuca is capable of removing significant amounts of nutrients (60 – 85%) from aquaculture effluents </li></ul><ul><li>Modelling these systems is built on vertical integration (i.e. not closed systems) </li></ul><ul><li>Models of such systems use whole farm approaches </li></ul>
  3. 3. Benefits of a closed system <ul><li>Increase in temperature above ambient seawater equates to an increase in growth rates </li></ul><ul><li>Decrease in pumping costs </li></ul><ul><li>Additional safety in times of red tide and oil spills </li></ul>
  4. 4. AIMS <ul><li>Investigate and model the physico-chemical dynamics of a farm section </li></ul><ul><li>Influence of different diet on abalone growth health and excretion rates in a closed system compared to a flow through system </li></ul><ul><li>Seasonal changes in the above </li></ul>
  5. 5. PROJECT SITES <ul><li>A balone mariculture farms </li></ul><ul><li>Danger Point (I & J Mariculture Farm) + 140 km east of CT </li></ul><ul><li>Jacobs Baai (Jacobs Baai Sea Products) + 120 km N of CT </li></ul>
  6. 6. PROJECT DESIGN AT I & J <ul><li>2 Ulva tanks (5 X 1 X 0.63 m) were integrated to one abalone tank (7 X 2 X 1 m) </li></ul><ul><li>Run under normal farm operating conditions </li></ul><ul><li>Control are 3 flow through abalone tanks </li></ul><ul><li>Seaweeds initial stocking density 2.5 kg.m -2 </li></ul><ul><li>Harvested every two weeks </li></ul><ul><li>+ 13 200 abalone (10 – 15g), total biomass 165 kg </li></ul><ul><ul><li>20 % fresh seawater input (800 L.h -1 ) </li></ul></ul><ul><ul><li>80 % recirculated through seaweeds (3 200 L.h -1 ) </li></ul></ul>
  7. 7. Longitudinal profile of tanks Transverse profile of tanks 5 m 1 m
  8. 8. Longitudinal profile of tanks Transverse profile of tanks
  9. 9. Seaweed tank Pump Gravity feed Abalone tanks Seaweed tank 80 % recirculation 20 % Sea water Over flow
  10. 10. PROJECT DESIGN AT JSP <ul><li>Still to build an integrated system, similar to I & J but using smaller tanks and a smaller biomass of animals due to lower flow rates </li></ul>
  11. 11. RESULTS <ul><li>In this system : </li></ul><ul><li>Ulva can take up 90 % of ammonium during the day in abalone effluent at 12 volume exchanges per day </li></ul><ul><li>DO values don’t go below 9 mg.l -1 at night </li></ul><ul><li>Using stocking density of 3 kg. wwt.m -2 gives best uptake rates in the existing system </li></ul><ul><li>Toxic ammonia never reaches levels harmful to abalone at above stocking density </li></ul>Seaweed uptake
  12. 12. RESULTS <ul><li>Ammonium levels must remain below 0.15 u M N.L -1 </li></ul><ul><li>DO values between 2 and 12 mg.L -1 , preferred 4 - 9 </li></ul><ul><li>Temperature range 9 – 22 °C, 16 – 18 °C preferred </li></ul><ul><li>pH 6.5 – 8.4, 7.6 - 8.2 preferred </li></ul>Abalone critical points
  13. 13. Balancing the equations Using linear mass balanced equations Multiple regression of factors Problems putting theory and reality together
  14. 14. RESULTS Dissolved oxygen Dissolved oxygen in a recirculation system 15 16 20 00 04 08 12 16 20 00 04 08 12 16
  15. 15. RESULTS Dissolved oxygen Dissolved oxygen in a recirculation system 15 16 20 00 04 08 12 16 20 00 04 08 12 16
  16. 16. RESULTS pH in a recirculation system pH 15 16 20 00 04 08 12 16 20 00 04 08 12 16
  17. 17. RESULTS pH in a recirculation system pH 15 16 20 00 04 08 12 16 20 00 04 08 12 16
  18. 18. RESULTS Temperature in a recirculation system Temperature 15 16 20 00 04 08 12 16 20 00 04 08 12 16
  19. 19. RESULTS Temperature in a recirculation system Temperature 15 16 20 00 04 08 12 16 20 00 04 08 12 16
  20. 20. RESULTS ammonium levels in recirculated tanks range between 0.003 - 0.005 u M N.L -1 ammonium levels in abalone flow through tanks = 0.01 u M N.L -1 Ammonium levels
  21. 21. Major Challenges <ul><li>For farm management of such a system: </li></ul><ul><li>Diel relationship between oxygen and pH in the seaweed systems. </li></ul><ul><li>As the seaweeds start to respire at night, abalone experience an increase in oxygen demand, due to night time feeding activity and excretion in the abalone systems, which has implications for the management of ammonia. </li></ul><ul><li>Seaweed uptake decreases at night when abalone excretion reaches a maximum </li></ul><ul><li>Where is the missing oxygen? </li></ul>
  22. 22. The future <ul><li>Run this study over a 18 months to obtain seasonal changes </li></ul><ul><li>Effect of diet on growth and health </li></ul><ul><li>Health of abalone in an integrated closed system vs. normal farm flow through conditions </li></ul>
  23. 23.   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

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