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Primary production in Spuikom lagoon, Belgium
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Primary production in Spuikom lagoon, Belgium



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  • 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 (^_^)!