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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
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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
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Content 1. Main message2. Background and Purpose3. Methodology4. Findings5. Lessons 6. Recommendations to defined stakeholder
Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
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.
Content1. Take home message
Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Content 1. Main message2. Background and Purpose3. Methodology4. Findings5. Lessons 6. Recommendations to defined stakeholder
Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Ceratophyllum submersumProliferation 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
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.
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Algae Turbidity
SedimentResuspension
Nutrients
Cerato
? Allelopathy
? Pesticides
? Hydrodynamics
? Land Use erosion
? Origins
Fish? Structure
1/ Diagnose: realized by V3 project2/ Remediation: support to local communities
Boura stakeholders:
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Algae Turbidity
SedimentResuspension
Nutrients
Cerato
? Allelopathy
? Pesticides
? Hydrodynamics
? Land Use
? Origins
Fish? Structure
Implementation of a series of dedicated activities
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Content 1. Main message2. Background and Purpose3. Methodology4. Findings5. Lessons 6. Recommendations to defined stakeholder
Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
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)
Andes • Ganges • Limpopo • Mekong • Nile • Volta
METHODOLOGY (3 sites)
BALA: ‘pristine’ BAMA: ‘impacted’
BOURA: ? Contamination status ?
Andes • Ganges • Limpopo • Mekong • Nile • Volta
METHODOLOGY (passive samplers; 3 sites)
3 Floating devices
2 Pocis
2 Chemcatchers
13 days
Andes • Ganges • Limpopo • Mekong • Nile • Volta
METHODOLOGY (passive samplers)
22 Chemicals
Andes • Ganges • Limpopo • Mekong • Nile • Volta
METHODOLOGY (macroinvertebrate communities; 3 sites)
Standard protocols (sampling, observations,…)
Statistical analyzes
Identification keys (taxinomy)
Andes • Ganges • Limpopo • Mekong • Nile • Volta
METHODOLOGY (surveys in Boura)
Two upstream Inland Valleys - agricultural practices
- intensification pathways
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)
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Content 1. Main message2. Background and Purpose3. Methodology4. Findings5. Lessons 6. Recommendations to defined stakeholder
Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
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).
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
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
Andes • Ganges • Limpopo • Mekong • Nile • Volta
FINDINGS (macroinvertebrates 2)
Within the Noteridae family (beetle):• 3 ubiquitous species;• 1 candidate as ‘sentinelle’ species.
BALABOURABAMA
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
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
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)
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Content 1. Main message2. Background and Purpose3. Methodology4. Findings5. Lessons 6. Recommendations to defined stakeholder
Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
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 eutrophicationimpact of (upstream) inland valleys
3/ Macroinvertebratesredundancy & « sentinelle » species
4/ Allelopathy (natural herbicide)? cumulative effects in presence of chemicals residues?
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?
Andes • Ganges • Limpopo • Mekong • Nile • Volta
Content 1. Main message2. Background and Purpose3. Methodology4. Findings5. Lessons 6. Recommendations to defined stakeholder
Agriculture Intensification and Aquatic Ecology: Impacts and trade-offs
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
Andes • Ganges • Limpopo • Mekong • Nile • Volta
CHALLENGING, ISN’IT ????
THANK YOU…