Harvesting from land and sea : Social relationships, trade networks, and spatial connectivity in changing social-ecological systems

In the era of global change, the connectivity of aquatic and terrestrial food production systems across spatial scales is increasing. At the same time, diverse actors that participate in food systems, from production to consumption, face the need to adapt their daily activities to an increasingly changing context. This thesis aims to better understand actors’ responses to social or environmental changes in food systems that are characterized by their cross-scale dynamics and social-ecological interactions. The four papers that constitute this thesis address this overarching aim by investigating two processes that are important in responding to changes and creating spatial connectivity between geographical locations: trade (Papers I-III), and spatial diversification or actor’s geographical mobility (Paper IV). The papers analyze fisheries and agricultural systems in Mexico and South Africa, using interview-based data collection and analysis, network analysis, agent-based modeling, and combinations of these methods. Papers I-III specifically examine how trade networks, which are embedded in social relationships and networks that operate across spatial scales, can influence the responses of food system actors to multiple types of changes. Paper I shows that trade relationships across fisheries and agricultural systems are generally embedded in stable business relationships characterized by reciprocity. Paper II finds that different trade network structures in a multi-species Mexican fishery can buffer changes in fish availability and create cascading effects between different species and geographical regions. Paper III describes four types of social networks consisting of relationships within and across scales that enable responding to multiple types of changes in a South African agricultural trade network. Paper IV identifies potential factors, such as environmental changes, that could influence changes in fisheries actors’ spatial diversification observed in Mexico. The thesis contributes to social-ecological systems research with theoretical insights regarding the embeddedness of trade networks in multidimensional social relationships within and across scales, where diverse types of social relationships and networks can influence fishing and farming practices. In addition, it highlights that spatial and temporal heterogeneity can have a key role in responses to changes based on spatial connectivity. Finally, the mixed-method methodology applied in this thesis enables simultaneously analyzing networks and processes in social-ecological systems, while illustrating the challenges and opportunities of method integration.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Submitted. Paper 3: Manuscript.