A recent study by Tour du Valat, conducted in collaboration with INRAE, models for the first time the interdependencies between human activities and biodiversity on the Camargue Island.
In this study, published in Ecology and Society [1], researchers developed a conceptual model in which hydrosaline dynamics, water management, economic activities (agriculture, hunting, fishing, tourism), and natural environments interact
A methodological approach in four sub-models
This conceptual model is based on four sub-models that provide complementary representations:
- Water governance
- Agriculture
- Bird communities
- Fish communities
This model highlights the strong and complex relationships between the multiple entities of the delta socio-ecosystem.
These relationships can be of several types:
- Causal chains (succession of impacts between several entities) – 17 relationships identified;
- Feedback loops (causal chain in which entity A influences a chain of entities, which then influences A in return to amplify or dampen the process) – 2 relationships identified;
- Interactions (when two entities influence each other) – 3 relationships identified;
- Side effects (when the implementation of actions aimed at achieving specific objectives has an unexpected negative or positive impact on other entities) – 8 relationships identified;
- Trade-offs (antagonism between two competing processes, i.e., an increase in one decreases the other) – 5 relationships identified.
Key findings and outlook
The study highlights paradoxical feedback loops: for example, stricter regulations on pesticides (particularly rice herbicides), intended to protect biodiversity and improve water quality, ultimately led to a reduction in rice-growing areas, thereby decreasing the availability of habitats for waterbirds in the spring.
Ongoing trade-offs
The article also highlights the constant trade-off between water quality and quantity in the management of the Vaccarès lagoon system, creating ongoing compromises between the needs of fishermen, ecological requirements, and agricultural constraints.
Water governance issues in the Camargue
The study highlights the current limitations in water governance in the Camargue. Although informal, the Executive Water Commission (CEE) does not cover all of the interconnected issues within the system. The study emphasizes the need to rethink this tool and transform it into a more comprehensive forum that integrates all stakeholders and the multiple hydrological issues affecting the Camargue region.
This conceptual model provides a starting point for developing a quantitative modeling platform and could even be adapted to other Mediterranean deltas.
Study reference
Rodier R., Boutron O., Béchet A., Therond O. 2025. Interdependencies among hydro-saline dynamics, economic activities, ecological processes, and biodiversity in a deltaic social-ecological system: insights from the Rhône delta (southern France). Ecology and Society; 30. doi: 10.5751/ES-16122-300311 [1]
Article published as part of Rose Rodier’s thesis, co-written with Olivier Boutron, Arnaud Béchet, and Olivier Therond.