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

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. 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. 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. 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. 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

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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. 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. 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. 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. 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. Andes • Ganges • Limpopo • Mekong • Nile • Volta
METHODOLOGY (3 sites)
BALA: ‘pristine’ BAMA: ‘impacted’
BOURA: ? Contamination status ?

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METHODOLOGY (passive samplers; 3 sites)
3 Floating devices
2 Pocis
2 Chemcatchers
13 days

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METHODOLOGY (passive samplers)
22 Chemicals

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METHODOLOGY (macroinvertebrate communities; 3 sites)
Standard protocols (sampling, observations,…)
Statistical analyzes
Identification keys (taxinomy)

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METHODOLOGY (surveys in Boura)
Two upstream Inland Valleys
- agricultural practices
- intensification pathways

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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. 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. 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. 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

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FINDINGS (macroinvertebrates 1)
26,400 specimens belonging to 33 families:
• 30 in Bala;
• 25 in Bama;
• 23 in Boura.
BALA
BOURA
BAMA
DISTANCE

21. Andes • Ganges • Limpopo • Mekong • Nile • Volta
FINDINGS (macroinvertebrates 2)
Within the Noteridae family (beetle):
• 3 ubiquitous species;
• 1 candidate as ‘sentinelle’ species.
BALABOURABAMA

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FINDINGS (surveys 1)
100% of farmers used pesticides and fertilizers
• quantities of fertilizers are proportional to the surfaces of
Inland valleys’ fields

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. 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. 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. 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. 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. 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. 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. Andes • Ganges • Limpopo • Mekong • Nile • Volta
CHALLENGING, ISN’IT ????
THANK YOU…