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CPWF V3: Ecological Externalities

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CPWF V3: Ecological Externalities

  1. 1. CPWF-V3 Ecological externalities Ph. Cecchi (IRD G-eau) S. Sanogo (Univ. Bobo) (logos to be added)
  2. 2. 1. Lakes monitoring (water level) Level and temperature loggers installation (June 2011) Usable? ? By whom => Conflicts? Relative Variations of Water Level (cm) 550 500 4.2 Mm3 450 ? Hydro. => Filing up? 400 350 300 250 15/6 1.2 Mm3 ≈ 30% 15/7 15/8 15/9 15/10 Andes • Ganges • Limpopo • Mekong • Nile • Volta 15/11 15/12 15/1 15/2 15/3
  3. 3. 1. Lakes monitoring (temperatures) Daily Variations of Temperatures (°C) 25 20 15 10 dT (air) 5 dT (Bottom of the Lake) 0 15/6 15/7 15/8 15/9 15/10 15/11 15/12 15/1 15/2 15/3 Mean depth = 2.1 m Vertical Mixing sensitivity Mechanical Buffer? Andes • Ganges • Limpopo • Mekong • Nile • Volta
  4. 4. 2. Ceratophyllum submersum Proliferation since a couple of years 1/ Strong LOCAL preoccupation: - Infrastructures - Fishery 2/ METABOLISM consequences - Quality & productivity 3/ SCIENTIFIC priority - causes & impacts From an ecosystem perspective, the simultaneous dominance of cyanobacteria in the phytoplankton pool (> 60%) and the invasion of water masses by huge amounts of macrophyte do point out without ambiguity the advanced eutrophication status of the Boura reservoir. Andes • Ganges • Limpopo • Mekong • Nile • Volta
  5. 5. Both states are RESILIENT NOW BEFORE WHEN? MACROPHYTES (clear) PHYTOPLANKTON (turbid) WHY? Andes • Ganges • Limpopo • Mekong • Nile • Volta
  6. 6. ? Pesticides Algae Turbidity ? Agri. practices ? Allelopathy Cerato ? Origins Nutrients ? Hydrodynamics Fish Sediment Resuspension ? Structure Diagnose: realized by V3 project Remediation: support to local communities Andes • Ganges • Limpopo • Mekong • Nile • Volta
  7. 7. 3. Allelopathy? Y (%) A F= 41.643; P< 0.001 A 100% AB BC 90% C 80% 70% 60% D 50% 40% REF PICK1 PICK2 PICK3 PICK4 PICK5 Preliminar experiments have confirmed the allelopathic potential of Ceratophyllum submersum. Andes • Ganges • Limpopo • Mekong • Nile • Volta
  8. 8. 4. Pesticides? 70% 60% 50% 40% Dytiscidae 30% Hydrophylidae 20% 10% 0% Agri Ref Macro-invertebrates communities exhibited contrasted patterns in agriculture-impacted versus reference stations Andes • Ganges • Limpopo • Mekong • Nile • Volta
  9. 9. 4. Pesticides? Tee shirt distributed by an agrochemical company in Ghana (Binaba, April 2011). Andes • Ganges • Limpopo • Mekong • Nile • Volta Commercial formulation (paraquat-based) found in fields (Boura, March 2012).
  10. 10. 5. Perspectives: towards chemical ecology 1/ What could be the cumulative effects (antagonism / synergy / others) of both allelopathic metabolites and phytosanitary by-products on the aquatic productivity and diversity? 2/ What could be the effects on the growth performances of irrigated cultures? 3/ Implementation of dedicated experiments using pesticides collected by passive samplers (in situ), pure molecules (paraquat) and allelopathic metabolites 4/ Impacts on aquatic food web structure and on selected irrigated crops. Output: better understanding of the nexus linking ‘Agricultural Intensification’ & ‘Ecosystem Resilience’… Andes • Ganges • Limpopo • Mekong • Nile • Volta

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