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Human impact on N, P, and Si cycle: an aquatic perspective

Applied ecosystem ecology. Human impact on N, P, and Si cycle: an aquatic perspective. Didier Baho Tarikul Islam Mohammad Ashraful Haque Mollah Lorenz Meire. Introduction. Nitrogen Phosphorus Silica. Nutrient balance. Low deposit of N N limiting. High deposit of N P limiting.

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Human impact on N, P, and Si cycle: an aquatic perspective

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  1. Applied ecosystem ecology Human impact on N, P, and Si cycle: an aquatic perspective Didier Baho Tarikul Islam Mohammad Ashraful Haque Mollah Lorenz Meire

  2. Introduction Nitrogen Phosphorus Silica

  3. Nutrient balance Low deposit of N N limiting High deposit of N P limiting

  4. Nutrient balance 60 % reduction in dissolved silica transport DSi

  5. Eutrophication: Ecological Consequences Increase in level of N and P Source: RMB Environmental Laboratories, 2007

  6. Consequences of Eutrophication • Increase in Cyanobacteria bloom causing a decline in the effective light regime. • Depletion of O2 due to enhanced decomposition of organic matter Cyanobacteria bloom Overwinter fish death caused by decrease O2 depletion Source: Bellingham 2008

  7. Depletion of oxygen can increase the release of phosphorus sequested in the sediments Source:http://www.elmhurst.edu/~chm/onlcourse/chm110/outlines/images/natcyles.GIF

  8. Shift in Phytoplankton communities • P limitation cause a shift towards nutrient poor phytoplankton • Shift due to DSi reduction DSi Dinoflagellates and Coccolithophore. Diatoms

  9. Biological Pump Biological pump is primarily limited by the availability of light and nutrients, and not by carbon.

  10. Impact on biological pump • Decrease in DSi shifts diatoms communities which affect carbon sequestration, consequently soft pump rate decreased • DSi demand is met up by two process • In open ocean>by upwelling • In coastal water> by river input

  11. Management options a. Preventive process: Reduction of N and P flux before water discharge (eg. ↓ P in detergent) Environment friendly agricultural methods Treatment of Sewage before discharge in catchement

  12. b. Curative process: • Biomanipulation: Introduction of Piscivores and improvement the trophic cascades ＋

  13. Conclusion N:P:Si Ratio

  14. Thank you for your attention!

  15. References

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