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

Why cultivate seaweeds on abalone farms? Mixed diet gives better growth rates MSY of kelp bed reached in 2002 Potential over-harvesting Decrease in epiphyte densities Limited suitable coastal areas ‘ HAB’s’ Recirculation I ntegration will improve water quality

Mixed diet gives better growth rates

MSY of kelp bed reached in 2002

Potential over-harvesting

Decrease in epiphyte densities

Limited suitable coastal areas

‘ HAB’s’

Recirculation

I ntegration will improve water quality

AIMS 1) F easibility of growing commercially useful amounts of Gracilaria and Ulva Influence of different growth media (seawater, abalone and turbot effluent water and fertilized seawater) on growth rates and yields. Seasonal changes in tissue N and P content Relationships between stocking density and yield Uptake rates of various nutrients at differing stocking densities

1) F easibility of growing commercially useful amounts of Gracilaria and Ulva

Influence of different growth media (seawater, abalone and turbot effluent water and fertilized seawater) on growth rates and yields.

Seasonal changes in tissue N and P content

Relationships between stocking density and yield

Uptake rates of various nutrients at differing stocking densities

PROJECT SITES A balone mariculture farms Danger Point (I & J Mariculture Farm) + 140 km east of CT Jacobs Baai (Jacobs Baai Sea Products) + 120 km N of CT

A balone mariculture farms

Danger Point (I & J Mariculture Farm) + 140 km east of CT

Jacobs Baai (Jacobs Baai Sea Products) + 120 km N of CT

PROJECT DESIGN AT I & J 12 Ulva tanks (5 X 1 X 0.63 m) & 12 Gracilaria tanks Run as a commercial operation + 4 volume exchanges per day (later changed to 12) 8 filtered seawater tanks 8 pulse fertilized sea water tanks 8 abalone effluent tanks 1 2 3 4 1 2 3 4 1 2 3 4 Sea water Fertilized sea water Abalone waste water 4 V 4 V 12 V 12 V 12 V 12 V

12 Ulva tanks (5 X 1 X 0.63 m) & 12 Gracilaria tanks

Run as a commercial operation

+ 4 volume exchanges per day (later changed to 12)

8 filtered seawater tanks

8 pulse fertilized sea water tanks

8 abalone effluent tanks

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

PROJECT DESIGN AT JSP 20 Ulva tanks (100 L) & 20 Gracilaria tanks Run as a experimental operation + 20 volume exchanges per day 8 filtered seawater tanks (control) 4 small and 4 medium 6 turbot effluent tanks 6 abalone effluent tanks 1 2 3 4 1 2 3 4 1 2 3 4 Sea water Turbot effluent Abalone effluent 20 20 20

20 Ulva tanks (100 L) & 20 Gracilaria tanks

Run as a experimental operation

+ 20 volume exchanges per day

8 filtered seawater tanks (control) 4 small and 4 medium

6 turbot effluent tanks

6 abalone effluent tanks

Small tanks Medium tanks 0.5 m 1 m 1 m 1 m

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

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

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

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

RESULTS Myrionema strangulans (MS) Brown spots Numbering between 5 and 10 on the holdfast section of Ulva thalli The spots are regular discs, 1 – 3 mm in diameter First record for South Africa Identified by Dr. Herre Stegenga Negative correlation between infection density and SGR

Brown spots

Numbering between 5 and 10 on the holdfast section of Ulva thalli

The spots are regular discs, 1 – 3 mm in diameter

First record for South Africa

Identified by Dr. Herre Stegenga

Negative correlation between infection density and SGR

RESULTS Myrionema strangulans (MS) BAD INFECTION DEAD HEALTHY INFECTED

RESULTS MS infestation of Ulva thalli

RESULTS In Quasi-commercial system using 10 tanks: Summer 291 kg. wwt.m -2 .d -1 Winter 135 kg. wwt.m -2 .d -1 Increase by using fertilizer and Kelpak® in effluent media at 12 volume exchanges per day RESULT Summer 740 kg. wwt.m -2 .d -1 Winter 234 kg. wwt.m -2 .d -1 YIELDS

In Quasi-commercial system using 10 tanks:

Summer 291 kg. wwt.m -2 .d -1

Winter 135 kg. wwt.m -2 .d -1

Increase by using fertilizer and Kelpak® in effluent media at 12 volume exchanges per day

RESULT

Summer 740 kg. wwt.m -2 .d -1

Winter 234 kg. wwt.m -2 .d -1

RESULTS Are important because: Low water exchange rate leads to: Carbon and nutrient limitation Poor condition of thalli (bleached & broken) Low Nitrogen content Low SGR therefore low yield Measures Carbon limitation in seaweeds can be shown by an increase in pH values FLOW RATES (4, 12 & 20)

Are important because:

Low water exchange rate leads to:

Carbon and nutrient limitation

Poor condition of thalli (bleached & broken)

Low Nitrogen content

Low SGR

therefore low yield

Measures

Carbon limitation in seaweeds can be shown by an increase in pH values

RESULTS SHADING Shading helps to reduce epiphytes Helps in decreasing MS infestations Helps to increase tissue N and P Tanks should be shaded from September to January Shade cloth must be 20 % not 50 %

Shading helps to reduce epiphytes

Helps in decreasing MS infestations

Helps to increase tissue N and P

Tanks should be shaded from September to January

Shade cloth must be 20 % not 50 %

RESULTS Important because: Increases protein from wild harvest (3.7- 24 % wild to 49.8 % cultured) Abalone receive more protein Faster growth rates How do you increase tissue nutrients? Faster flow rates (12 – 20 volume exchanges) Grown in turbot/fish or abalone effluent Add Fertilizer and Kelpak® Tissue Nitrogen

Important because:

Increases protein from wild harvest (3.7- 24 % wild to 49.8 % cultured)

Abalone receive more protein

Faster growth rates

How do you increase tissue nutrients?

Faster flow rates (12 – 20 volume exchanges)

Grown in turbot/fish or abalone effluent

Add Fertilizer and Kelpak®

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

RESULTS Ulva can take up 90 % of ammonium in abalone effluent at 12 volume exchanges per day DO values don’t go below 9 mg.l -1 at night Using stocking density of 3 kg. wwt.m -2 gives best uptake rates but is system specific Toxic ammonia never reaches levels harmful to abalone at above stocking density RECIRCULATION

Ulva can take up 90 % of ammonium in abalone effluent at 12 volume exchanges per day

DO values don’t go below 9 mg.l -1 at night

Using stocking density of 3 kg. wwt.m -2 gives best uptake rates but is system specific

Toxic ammonia never reaches levels harmful to abalone at above stocking density

Results ECONOMICS

RESULTS ECONOMICS Abalone growth curves

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

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

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

CONCLUSIONS This study has shown that it is possible to grow Ulva in abalone effluent and that it has economic benefits as well Yields lower than those reported in literature by 3 - 5 % day-1, but smaller tanks were used in those studies It is possible to increase yields by using a pulse fertilization, Kelpak® and effluent water as the culture medium By growing a combination of Ulva and Gracilaria you can account for seasonal growth in seaweeds and maintain a constant yield

This study has shown that it is possible to grow Ulva in abalone effluent and that it has economic benefits as well

Yields lower than those reported in literature by 3 - 5 % day-1, but smaller tanks were used in those studies

It is possible to increase yields by using a pulse fertilization, Kelpak® and effluent water as the culture medium

By growing a combination of Ulva and Gracilaria you can account for seasonal growth in seaweeds and maintain a constant yield

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