Socio-ecological system | EPFL Graph Search

A social-ecological system consists of 'a bio-geo-physical' unit and its associated social actors and institutions. Social-ecological systems are complex and adaptive and delimited by spatial or functional boundaries surrounding particular ecosystems and their context problems. A social-ecological system (SES) can be defined as:(p. 163) A coherent system of biophysical and social factors that regularly interact in a resilient, sustained manner; A system that is defined at several spatial, temporal, and organisational scales, which may be hierarchically linked; A set of critical resources (natural, socio-economic, and cultural) whose flow and use is regulated by a combination of ecological and social systems; and A perpetually dynamic, complex system with continuous adaptation. Scholars have used the concept of social-ecological systems to emphasise humans as part of nature and to stress that the delineation between social systems and ecological systems is artificial and arbitrary. While resilience has somewhat different meaning in social and ecological context, the SES approach holds that social and ecological systems are linked through feedback mechanisms, and that both display resilience and complexity. Social-ecological systems are based on the concept that humans are a part of — not separate from — nature. This concept, which holds that the delineation between social systems and natural systems is arbitrary and artificial, was first put forth by Berkes and Folke, and its theory was further developed by Berkes et al. More recent research into social-ecological system theory has pointed to social-ecological keystones as critical to the structure and function of these systems, and to biocultural diversity as essential to the resilience of these systems. Through to the final decades of the twentieth century, the point of contact between social sciences and natural sciences was very limited in dealing with social-ecological systems.

A field-based modelling framework of the ecohydrology of schistosomiasis

Francisco Javier Perez Saez

Successful control of schistosomiasis, a water-borne parasitic disease, is challenged by the intricacy of the wormâs lifecycle, which depends on aquatic snail intermediate hosts, and involves environmental, ecologic, and socio-economic factors. Current strategies rely on deworming through mass drug administration which however do not protect against reinfection and the persistence of hotspots. It is recognized that multifaceted approaches will be necessary to reach elimination, whose development will require a renewed focus on the diseaseâs social-ecological drivers. Taking cue from the hydrological underpinning of these drivers, this Thesis aims at developing an ecohydrological approach to schistosomiasis with a view to identifying and exploiting the points in which its cycle can be broken. Schistosomiasis is a poverty-reinforcing disease affecting more than 150 million people in sub-Saharan Africa, being the parasitic disease causing the largest health burden after malaria. However, the impairing morbidity it causes has been undervalued in the past, qualifying it as a neglected tropical disease. Moreover, water resources development often exacerbate transmission, posing scientific and ethical challenges in addressing the ensuing trade-off between economic development and public health. The relevance of this Thesisâ work lies in furthering tools to offset this trade-off by unlocking the predictive appraisal of the social-ecological drivers of transmission. An integration of fieldwork applied in Burkina Faso (West Africa) and theoretical methods are employed to address this aim. This Thesis establishes the use of spatially explicit mathematical models of schistosomiasis at the national-scale, allowing to study the effect of human mobility and spatial heterogeneity of transmission parameters. Weekly ecological samplings of snail abundance and continuous environmental monitoring were preformed at three sites along the countryâs climatic gradient, leveraged through ecological modelling. A novel methodology for the large-scale prediction of river network ephemerality allowed for refined snail species distribution models, and the analysis of the diseaseâs geography in link with socio-economic covariates. Finally, surveys and participatory workshops shed light on local-scale water contact patterns. The obtained results substantiate the stance that hydrology is a first-order control of disease transmission. Stability analysis of the spatially explicit model generated additional insight into the impact of the expansion of suitable snail habitat due to water resources development, highlighting the interplay between local and country-wide effects driven by human mobility. Models of snail ecology revealed key hydrological drivers, and disputed density feedbacks. Uncovered phase shifts between permanent and ephemeral habitats were adequately reproduced at the national scale through model regionalization. Characterization and predictions of hydrological ephemerality improved the estimation of the snailsâ ecological range, mirroring the diseaseâs geography. Finally a national-scale association between ephemerality and disease risk was observed, possibly due to human-water contacts aggregation, as supported by preliminary results at village-level. The future incorporation of these ecohydrological findings into spatially explicit models of schistosomiasis is considered promising for optimizing control strategies and attaining disease elimination.

EPFL2018

A field-based modelling framework of the ecohydrology of schistosomiasis

Francisco Javier Perez Saez

EPFL2018