1. Azong Valery Funwie
Eric Raes
Fiddy Semba Prasetiya
Is the primary production in the Spuikom lagoon
influenced by water depth ?
Presented by:

2. Overview
Introduction
Objectives
Material and Methods
Results
Discussion
Conclusion

3. Introduction
• The flow of energy through a community starts with the fixation of sunlight
by plants photosynthesis
light
• 6CO2 + 6H2O => C6H12O6 + 6O2
• Autotrophes are those organisms in an ecosystem system who convert
inorganic raw materials into organic substances.
– Phytoplankton are such autotrophic organisms and are responsible for
approximately 40 per cent of the planet's total annual photosynthetic
(`primary') production. (Baer 2002)
– They are found in the water’s top layer (euphotic zone) where they
receive enough solar radiation for their photosynthetic requirements as
well as nutrients.
– Light inhibition will effectively lead to an optimal level of light intensity for
the phytoplankton. (Christopher A, et al., 2000)
 Energy accumulated by plants = primary production

4. Introduction
Gross Primary Production, GPP, is the total amount of CO2 that is
fixed by the plant in photosynthesis
Respiration, R, is the energy required for biological functions such
as maintenance and reproduction.
Net Primary Production, NPP, is the energy remaining after
respiration and stored as organic matter, or plant growth.
NPP = GPP - R

5. Objectives
Is the primary production in the Spuikom lagoon
influenced by water depth ?
• Questions:
– How do we measure oxygen ?
– Will their be a difference in time ?
– Is there a difference in NPP between surface and bottom water ?

6. Material and Methods
Both ‘light’ and
‘dark’ bottles are
filled with surface
and bottom water
Before incubating the
bottles initial O2
concentration, from
bottom and surface
water, was determined
and expressed as mg
of O2 per litre of water
(mg/L).
Bottles are closed
with stoppers and
are suspended for
4 hours at the
same depth from
where water
originally was
taken.
Final O2 concentrations
were measured in light
and dark bottles after 4
hours of incubation.
Oxygen quantity was
measured by chemical
titration, Winkler
titration method.

7. 1. Production of a manganous hydroxide in
the water sample to which manganous
sulfate is introduced when KOH plus KI
are added:
 MnS04 + 2KOH=>Mn(OH)2 + K2S04
2. Oxidation of manganous hydroxide to
manganic hydroxide by the dissolved
oxygen in the sample:
 2Mn(OH)2 + 02 + 2H20=>2Mn(OH)4
3. Conversion of manganic hydroxide to
manganic sulfate when concentrated
sulfuric acid is added:
 2Mn(OH)4 + 4H2S04=> 2Mn(SO4)2 +
8H20
Material and Methods : Steps in Winkler Method

8. 4. Replacement of iodine in an iodide (KI) by sulfate, releasing free iodine:
 2Mn(OH)4 + 4KI=>2MnS04 + 2 K2S04 + 2I2
5. Titration of the iodine solution with sodium thiosulfate until all free iodine
combines into sodium iodide. The endpoint, marked by the disappearance
of the yellow color:
 4Na2S2O3+ 2I2=>2Na2S406 + 4NaI
Material and Methods : Steps in Winkler Method (2)

9. Material and Methods
 Light bottle:
 Has photosynthesis,
 Gross Primary Production (GPP),
 Respiration (R).
 The difference between these two processes is Net Primary Production
 NPP = (GPP - R)
=> The quantity of oxygen ,measured after titration, in the light bottle
indicates the net photosynthesis, or gross primary production.
(GPP)
• Dark bottle:
– No photosynthesis
– Only respiration.
=> The quantity of oxygen ,measured after titration, in the drak bottle
indicates the respiration (R)
• Initial bottle:
– Time zero, to calculate the Respiration or Net Primary Production

10. Material and Methods
• Light Bottle DO - Initial DO = NPP
• Light Bottle DO - Dark Bottle DO = GPP
• Initial Bottle DO - Dark Bottle DO = Respiration
– (DO = Dissolved Oxygen)

11. Material and Methods
 The whole aquatic ecosystem can be
represented by this bottle method.
 Light bottle representing the daytime
 Dark bottle representing the night.
 Where the rise and fall of oxygen
during the day and night can be
plotted on a diurnal curve.

12. Results
Day 1, 2:30 pm Oxygen quantity
0
5
10
15
20
25
30
35
40
Time Zero (Light) (Dark)
After 4hrs
time (h)
mgO2/l
Day 1 2:30pm
SURFACE mg O2/L
Day 1 2:30pm
BOTTOM mg O2/L

13. Results
Oxygen concentration in surface and bottom at time
zero
0
10
20
30
40
7:00 AM 11:00 AM 2:30 PM
time (h)
mgO/l
SURFACE
BOTTOM

14. Results
Oxygen concentration mgO/l
0
5
10
15
20
25
30
35
40
Day 2
7:00am
Day2
7am
Day 2
11:00 am
Day2
11:00am
Day 1
2:30pm
Day 1
2:30pm
SURFACE BOTTOM SURFACE BOTTOM SURFACE BOTTOM
time (h)
mgO/l
Time Zero After 4hrs (Light) After 4hrs (Dark)

15. Results
 NPP
0
0.2
0.4
0.6
0.8
1
1.2
1.4
7:00 AM 11:00 AM
Time (h)
mgC/l
NPP Surface

16. Results
NPP, R and GPP at the surface
-3
-2
-1
0
1
2
3
4
07.00 (day 2) 11.00 (day 2)
Time (h)
mgc/l
NPP
Respiration
GPP

17. Conclusions
 Slight increase in NPP
 Slight increase in O2 concentration over time
 Measuring PAR, secchi disk
 Individual titration, less errors
 Minimise oxygen bubbles when moving water from bottom water to bottles
 Not enough sampling points/ data
 Data doesn’t reflect hyothesis
 No difference between surface and bottom

18. Dank u well
(^_^)!