Dr Deborah Robertson-Andersson, Carmen Haripursad, Nadia Padayachee. Presented at the Aquaculture Association of Southern Africa Conference 2015.

1. Dr. Deborah Robertson-Andersson; Carmen Haripursad & Nadia Padayachee

2. Aquacultures balancing act
1) Close the food gap
2) Support economic development
3) Reduce Environmental impact
Bondad-Reantaso AASA 2015

5. (Gentlemangourmet, 2010)

6. Irrigated agriculture represents the bulk of the
demand for water in many countries (Wharton, 2013)
(Wikipedia,1999)(Wikipedia,1999)

7. The Blue revolution

8. “The South African landscape is littered with failed
aquaculture projects”
Tom Hecht AASA 2013

9. Reasons for failure
Ineffective institutional
arrangements
Lack of
good
quality
feed and
technical
advice
Poor market
infrastructure
Central
planning
instead of
private
sector
initiative

10. Aquaponics

11. 1) 2 honors students
2) R3500
3) Build 2 aquaponics systems each
4) USE locally sourced materials within 25 km of your
house!!!
5) Get your honors degrees

12. Aims
1) Determine if plant growth in goldfish and koi fish
systems were significantly different
2) Determine if LED light was different to sunlight on crop
production
3) Determine whether aquaponics can be considered a
form of leap frog technology
4) Evaluate the costs and benefits

13. Methods:
Experimental design
Experimental design and construction of the aquaponic systems

14. Methods
 New number of leaves produced,
 root production,
 shoot production,
 mass production,
 average leaf size,
 relative plant growth
 mean number of mortalities
were recorded for each plant type.
 Nitrate concentration & pH measured
end of each harvest
Plants:
Lettuce, Tomato, Spinach,
Coriander, mint & watercress
Fish – Koi (Cyprinus carpio L.)
Gold fish (Carassius auratus L.)
(Ecofilms, 2011)

15. Results
Round 1
27 27
14 12
1
5
6
3
0
5
10
15
20
25
30
35
Numberofmortalities
Plant type
Lettuce Spinach Mint Watercress
Goldfish
Koifish
*
Mean mortalities for each plant type
t =2.828
df = 70
p = 0.047
Goldfish Koi fish


16. Results
Round 2
Figure 4: Relative plant growth for each plant type
t = 2.885
df = 70
p = 0.005
Goldfish Koi fish
*
0,03 0,04
0,09
0,13
0,19
0,39
0,26
0,28
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
0,4
0,45
0,5
Lettuce Spinach Mint Watercress
Relativeplantgrowth(g/day)
Plant types
Goldfish
Koi fish


17. Results
Round 3
Figure 5: Root: shoot ratio for each plant type
8 3 30 28
55 50
109
89
18 18
33 32
127
167
87
95
0
50
100
150
200
250
Root:Shootratio(mm)
Plant type
Lettuce Spinach Mint Watercress
Koifish root length (mm)
Koifish shoot length (mm)
Goldfish root length (mm)
Goldfish shoot length (mm)
Goldfish Koi fish


18. Results
 Round 4
Goldfish system Koi fish system
Nitrates (*)
pH
80 mg/l (±4.4)
7.5 (±0.48)
110 mg/l (±12.9)
7.8 (±0.81)
Table 1: The nitrates concentration (n = 6) and pH levels (n = 6) in the goldfish and koi fish systems
Nitrate significance : t = 4.176, df = 5, p = 0.006
Goldfish Koi fish

19. And the winner is……
Koi fish

20. LED vs. Sunlight……
Round 1 – 9

21. Number of leaves
Average leaf size
Shoot length
Root length
Leaf area ratio
Dry plant mass
Relative growth rate
NO SIGNIFICANT
DIFFERENCE
Results
Round 1 – 7

22. Wet plant massMortality
0
2
4
6
8
10
12
14
16
Spinach Tomato Lettuce
Wetplantmass(g)
Type of plant
Sunlight
LED
The effect of LED versus sunlight on the
marginal means of the wet plant mass for
each plant species
The mean mortality of harvests for each species
under sunlight and LED light
Spinach (T-test: df = 70, t = 2.277, p = 0.026)
Tomato (T-test: df = 70, t = 2.194, p = 0.031)
Coriander (T-test: df = 70, t = 3.245, p = 0.000)
0
3
0
34
0
3
5
35
Spinach Tomato Lettuce Coriander
0
5
10
15
20
25
30
35
40
Type of plant
MeanmortalityharvestS(N=36)
Sunlight
LED
High mortality of coriander
 Insufficient nutrient supply by fish
 Possibly potassium which has a
significant relationship with other
nutrients such as calcium and
magnesium
Wet plant mass
 Increased wet mass of plants
result of many factors such as:
- plants growing environment
- water storage ability

23. Problems with aquaculture
Aquaculture is similar to the
electric network.
It depends on government
funding and a large quantity
of fries to stock a pond.
Electric stations are interlinked


24. Leapfrog technology
“An approach in which areas with poorly developed technology or
economic bases are able to move themselves forward at a rapid
pace through the adoption of modern systems, without going
through intermediary steps”
It is the implementation of advanced technology in areas where
prior technology hasn’t been implemented.
e.g. The mobile network.
Telephone stations emitting signals that is received by communication technologies

25. Ornamental trade is similar
to the the mobile network
Graphs representing all pet stores, hardware stores and nurseries within a
50km radius of the study site
DurbanRichards Bay
90 +
0 +
270 -
180 -
Stores
Nurseries
Growbed materials
Fish products
Electrical products
Plumbing supplies
Research institute
Rhodes University
Government hatchery
Scale
Stores
1 block = 1 km
Research institute
1 block = 50 km

26. Cost analysis
Items Income
Lettuce
Spinach
Mint
Watercress
Goldfish
Koifish
Total
R648.00
R2944.00
R2640.00
R3780.00
R600.00
R7500.00
18112.00
COST VS. INCOME
Items Expenditure
Nursery
Building equipment
Pipes and plumbing
pH and thermometer
Grow beds and trays
Fish tanks, fish, feed, gravel, nitrate kit
Wood
Electricity cost per annum
Total
R804.00
R615.22
R695.50
R198.80
R666.95
R1457.60
R678.00
R294.24
R5410.31
Payback time of the system (based on income from crop production)
= 11 months and 7 days
Payback time of the system (based on income from fish breeding)
= 5 months

27. Aquacultures balancing act
1) Close the food gap
2) Support economic development
3) Reduce Environmental impact
Bondad-Reantaso AASA 2015




28. Thank you!

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