Agricultural intensification and aquatic ecology: impacts and trade-offs

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by P. Cecchi, R. Soleri, S. Sanogo, D. Bamba, K. Diakité, J.C. Poussin, S. Spinelli, A. Kabré and C. Gonzalez
Presented at the Final Volta Basin Development Challenge Science Workshop, September 2013

Published in: Technology, Business
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Agricultural intensification and aquatic ecology: impacts and trade-offs

  1. 1. A Partner of Agricultural intensification and aquatic ecology: impacts and trade-offs Cecchi P. (1), Soleri R. (2), Sanogo S. (3), Bamba D. (3), Diakité K. (4), Poussin J.C. (5), Spinelli S. (2), Kabré A. (3), Gonzalez C. (2) (1, 5) IRD UMR G-eau (2) LGEI, Alès, France (3) Univ. Bobo-Dioulasso (4) 2iE Philippe.Cecchi@ird.fr
  2. 2. Andes • Ganges • Limpopo • Mekong • Nile • Volta Content 1. Main message 2. Background and Purpose 3. Methodology 4. Findings 5. Lessons 6. Recommendations to defined stakeholder Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
  3. 3. Andes • Ganges • Limpopo • Mekong • Nile • Volta In the Boura Lake, evidences of eutrophication (macrophyte proliferation) and of contamination (pesticides residues) have been documented. Both are consequences of agricultural intensification and threaten the sustainability of the agro-ecosystem. Content 1. Take home message Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
  4. 4. Andes • Ganges • Limpopo • Mekong • Nile • Volta Content 1. Main message 2. Background and Purpose 3. Methodology 4. Findings 5. Lessons 6. Recommendations to defined stakeholder Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
  5. 5. Andes • Ganges • Limpopo • Mekong • Nile • Volta Ceratophyllum submersum Proliferation since a couple of years 1/ Strong LOCAL preoccupation Sensitization Workshop in Boura (2011) - Infrastructures - Fishery 2/ METABOLISM consequences - Quality & productivity 3/ SCIENTIFIC priority - causes & impacts From an ecosystem perspective: advanced eutrophication
  6. 6. Andes • Ganges • Limpopo • Mekong • Nile • Volta MACROPHYTES (clear) PHYTOPLANKTON (turbid) BEFORENOW WHEN? WHY? Both states are RESILIENT Shifts associated to DISTURBANCES Alternative Stable States theory for Shallow Lakes, Scheffer et al. 1993.
  7. 7. Andes • Ganges • Limpopo • Mekong • Nile • Volta Algae Turbidity Sediment Resuspension Nutrients Cerato ? Allelopathy ? Pesticides ? Hydrodynamics ? Land Use erosion ? Origins Fish ? Structure 1/ Diagnose: realized by V3 project 2/ Remediation: support to local communities Boura stakeholders:
  8. 8. Andes • Ganges • Limpopo • Mekong • Nile • Volta Algae Turbidity Sediment Resuspension Nutrients Cerato ? Allelopathy ? Pesticides ? Hydrodynamics ? Land Use ? Origins Fish ? Structure Implementation of a series of dedicated activities
  9. 9. Andes • Ganges • Limpopo • Mekong • Nile • Volta Content 1. Main message 2. Background and Purpose 3. Methodology 4. Findings 5. Lessons 6. Recommendations to defined stakeholder Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
  10. 10. Andes • Ganges • Limpopo • Mekong • Nile • Volta METHODOLOGY (1) 1/ Comparative studies in three sites: Boura vs two references (pristine vs impacted) 2/ Passive samplers: POCIS & ChemCatchers (3 sites) 3/ Macroinvertebrates: European Directive protocols (3 sites) 4/ Surveys (in Boura to document agricultural practices) 5/ Allelopathy (lab analyzes using a Phytoplankton Analyzer)
  11. 11. Andes • Ganges • Limpopo • Mekong • Nile • Volta METHODOLOGY (3 sites) BALA: ‘pristine’ BAMA: ‘impacted’ BOURA: ? Contamination status ?
  12. 12. Andes • Ganges • Limpopo • Mekong • Nile • Volta METHODOLOGY (passive samplers; 3 sites) 3 Floating devices 2 Pocis 2 Chemcatchers 13 days
  13. 13. Andes • Ganges • Limpopo • Mekong • Nile • Volta METHODOLOGY (passive samplers) 22 Chemicals
  14. 14. Andes • Ganges • Limpopo • Mekong • Nile • Volta METHODOLOGY (macroinvertebrate communities; 3 sites) Standard protocols (sampling, observations,…) Statistical analyzes Identification keys (taxinomy)
  15. 15. Andes • Ganges • Limpopo • Mekong • Nile • Volta METHODOLOGY (surveys in Boura) Two upstream Inland Valleys - agricultural practices - intensification pathways
  16. 16. Andes • Ganges • Limpopo • Mekong • Nile • Volta METHODOLOGY (allelopathy) C. Submersum (fresh leaves and powder) • Preparation of Aqueous & Methanolic extracts • Phytoplancton exposure (different concentrations, 24-72h) • Phyto PAM analyzes (photosynthesis efficiency)
  17. 17. Andes • Ganges • Limpopo • Mekong • Nile • Volta Content 1. Main message 2. Background and Purpose 3. Methodology 4. Findings 5. Lessons 6. Recommendations to defined stakeholder Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
  18. 18. Andes • Ganges • Limpopo • Mekong • Nile • Volta FINDINGS (pesticides 1) Among the 22 chemicals targeted: • 12 exhibited concentrations up to the detection limits; • All were all present in Boura (i.e. N > Bala & Bama).
  19. 19. Andes • Ganges • Limpopo • Mekong • Nile • Volta FINDINGS (pesticides 2) The 6 principal have been quantitatively assessed: • No pesticide residues in Bala (Pristine = OK); • Comparable concentrations in Boura and Bama; • Cocktail in Boura: 5 herbicides & 1 insecticide
  20. 20. Andes • Ganges • Limpopo • Mekong • Nile • Volta FINDINGS (macroinvertebrates 1) 26,400 specimens belonging to 33 families: • 30 in Bala; • 25 in Bama; • 23 in Boura. BALA BOURA BAMA DISTANCE
  21. 21. Andes • Ganges • Limpopo • Mekong • Nile • Volta FINDINGS (macroinvertebrates 2) Within the Noteridae family (beetle): • 3 ubiquitous species; • 1 candidate as ‘sentinelle’ species. BALABOURABAMA
  22. 22. Andes • Ganges • Limpopo • Mekong • Nile • Volta FINDINGS (surveys 1) 100% of farmers used pesticides and fertilizers • quantities of fertilizers are proportional to the surfaces of Inland valleys’ fields
  23. 23. Andes • Ganges • Limpopo • Mekong • Nile • Volta FINDINGS (surveys 2) 100% of farmers used pesticides and fertilizers • quantities of pesticides are inversely proportional to the size of exploitation
  24. 24. Andes • Ganges • Limpopo • Mekong • Nile • Volta FINDINGS (allelopathy) Both aqueous & methanolic extracts are potent • in the range [0.05 – 50] mg/L (dw) of C. submersum Photosynthetic efficiency after 24h (MeOH extract)
  25. 25. Andes • Ganges • Limpopo • Mekong • Nile • Volta Content 1. Main message 2. Background and Purpose 3. Methodology 4. Findings 5. Lessons 6. Recommendations to defined stakeholder Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
  26. 26. Andes • Ganges • Limpopo • Mekong • Nile • Volta LESSONS (1) 1/ Pesticide residues in Boura Below Norm values ? impacts of chronic exposures to cocktail? Associated to present/past landuse on watershed 2/ Fertilizers and eutrophication impact of (upstream) inland valleys 3/ Macroinvertebrates redundancy & « sentinelle » species 4/ Allelopathy (natural herbicide) ? cumulative effects in presence of chemicals residues?
  27. 27. Andes • Ganges • Limpopo • Mekong • Nile • Volta LESSONS (2) 1/ Polyactivity of households in Boura => increased incomes => multiple uses of available water resource (direct / indirect) 2/ Management strategies (1) => evaluation of externalities (economy-health-water quality) 3/ Footprints of ecological disturbances in Boura => impacts on resilience?
  28. 28. Andes • Ganges • Limpopo • Mekong • Nile • Volta Content 1. Main message 2. Background and Purpose 3. Methodology 4. Findings 5. Lessons 6. Recommendations to defined stakeholder Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
  29. 29. Andes • Ganges • Limpopo • Mekong • Nile • Volta RECOMMENDATIONS 1/ Farmers => to control the origin and quality of phytosanitary products 2/ Managers => to preserve the multiple uses vocation of Small Reservoirs (irrigation is marginal in terms of livelihood…) 3/ Researchers => to quantify the impacts => to explore the trade-offs
  30. 30. Andes • Ganges • Limpopo • Mekong • Nile • Volta CHALLENGING, ISN’IT ???? THANK YOU…

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