Understanding social-ecological dynamics in interconnected coastal marine ecosystems off Peru: insights for fisheries management through food web modelling and time series analysis

Coastal marine ecosystems provide essential goods and services to human societies, but are under
increasing pressure from environmental change, fishing and climate variability. This thesis examines
the complex social-ecological dynamics of two bay systems along the Peruvian coast: Sechura Bay in
the north, influenced by tropical waters, and Independencia Bay in the centre-south, characterised by
the cold upwelling conditions of the Northern Humboldt Current Upwelling System (NHCUS). Using
Ecopath with Ecosim (EwE) models, time-series analyses and governance case studies, the research
explores how environmental and fisheries-related drivers, including El Niño events and marine
heatwaves, shape trophic dynamics, ecosystem resilience and resource use.
The thesis is divided into six chapters, each addressing key aspects of ecosystem-based management.
Chapter 1 introduces the socio-ecological context of the Peruvian coast and outlines the research
questions and objectives. Chapter 2 compares the trophic structures and energy flows of Sechura and
Independencia bays, highlighting key differences in species interactions, energy dynamics and
productivity. Chapter 3 examines the drivers of change in Independencia Bay, focusing on the effects
of fisheries and environmental variability, including the influence of teleconnections. Chapter 4
explores adaptation strategies under future climate scenarios, using dynamic simulations to assess the
impacts of increased warming events and redistribution of fishing effort. Chapter 5 examines
governance challenges through a case study of the Guano Islands Marine Protected Area (MPA),
highlighting institutional limitations and the importance of social-ecological connectivity in
management. Chapter 6 summarises the findings, provides recommendations for adaptive management
and explores their global relevance.
The findings reveal differences in the structure and functioning of the two bays. Sechura Bay has a
higher biodiversity but a stronger reliance on the aquaculture of scallops, and appears to be more
vulnerable to stressors such as hypoxia and warming events that disrupt trophic dynamics and species
availability. Independencia Bay shows greater resilience, rapidly returning to pre-disturbance
conditions after warming events, supported by stable upwelling processes. Comparative analyses
highlight key differences in trophic interactions and socio-economic dependencies, providing insights
into the challenges of managing these interconnected systems. Dynamic simulations suggest that
increasing frequency of warming events could significantly disrupt trophic dynamics, especially in
Sechura Bay. In Independencia Bay, redistributing fishing effort towards more resilient species suchi
as rock crabs and mussels offers a promising adaptive management strategy to maintain ecosystem
equilibrium.
The thesis also highlights the governance challenges associated with Peru's coastal ecosystems. The
case study of the Guano Islands MPA reveals fragmented management, insufficient stakeholder
participation and limited institutional capacity as obstacles to effective management of interconnected
marine systems. These findings point to the importance of integrated governance frameworks that take
into account ecological connectivity, teleconnectivity effects and socio-economic factors.
By integrating trophic modelling, time series analysis and governance studies, this research advances
the field of ecosystem-based management. It highlights the importance of adaptation strategies that
address local socio-ecological conditions while considering large-scale drivers such as climate change.
These findings provide a framework for improving the resilience of marine ecosystems and supporting
sustainable livelihoods, with implications that extend beyond Peru for other regions facing similar
challenges of climate variability and resource exploitation.