Between biodiversity protection and food security, how can we identify and activate the management levers that are essential to the resilience of the South-West Indian Ocean?

The South-West Indian Ocean is one of the hotspots of global marine biodiversity and represents an essential resource for coastal populations. Under the double pressure of direct human activities and climate change, this biodiversity is no longer just a heritage to be preserved but also the very foundation of the region’s fishing economy. According to researcher Emmanuel Roque, nearly 10% of the population of the South-West Indian Ocean is employed in the sea fishing sector. For the researchers of the BRIDGES programme, the challenge is not only to protect this marine biodiversity in isolation, but to find solutions to reconcile the conservation of ecosystems and the exploitation of resources (fisheries). From this perspective, wouldn’t understanding the dynamics of these systems be the first step towards integrated governance?

 

Ecosystem reconfiguration

In this interview, Marta Coll, a researcher at the Institute of Marine Sciences in Barcelona, highlights the intrinsic links between changes in biodiversity and human uses of marine resources. Biodiversity is not static; it evolves over time as a direct result of human activities and climate change. Coll explains that these mutations cause species to migrate or decline, reconfiguring ecosystems in many places. This reconfiguration leads to the disappearance or rarity of certain species, thus disrupting traditional fishing practices. Thus, the conservation of biodiversity and fishing activity maintain an inseparable relationship of interdependence. As the expert points out, preserving the integrity of ecosystems is the guarantee of prosperous fisheries. In other words, protecting the habitat means securing the resource of tomorrow. It is therefore appropriate to ask ourselves how to protect the habitat and secure resources?

Faced with these challenges, Marta Coll introduces two pivotal concepts: change trajectories that allow humans to project themselves and anticipate future changes, and spatial management tools (such as marine protected areas (MPAs)) presented as essential levers for restoring biomass and securing resources. Indeed, the trajectories of change make it possible to model the future of biodiversity according to our current decisions. The factors (temperature, sedimentation, fishing etc.) that cause changes in the ecosystem are also subject to evolutions, so it is up to man to trace alternative changes and what should happen to these factors to achieve the desired sustainability goals. Therefore, to make the link between the trajectory of change and concrete management, comes the creation of MPAs, which consists of “imposing rules and conditions on the activities that humans carry out in an area”, says Marta Coll.

Regional Modeling and Connectivity

To extend Marta Coll’s reflection, modern science today relies on ecosystem modelling tools such as Ecopath with Ecosim (EWE). These models make it possible to virtually test the impact of different fishing intensities on the structure of the food web in the South-West Indian Ocean (Science direct, ecological modeling, 2016). These tools therefore promote better spatial management. However, there are other aspects to consider for effective management, including biological connectivity. Recent studies show that the biodiversity of the region depends on a complex network of currents (Coral Reefs, 2024). Indeed, a protected species in an MPA in Reunion Island may very well be derived from larvae from the Malagasy coast.

Taking these different elements into account, it is clear that an integrated spatial approach is essential. Marta Coll presents spatial management as the most effective lever. But, for it to work, it must be multi-level (ranging from full MPA to regulated MPA), based on solid scientific data (Change Trajectories and modelling tools), and socially just. Marta Coll sends a clear message in this video; Protecting biodiversity is the most cost-effective investment in securing the future of fisheries. Activating these management levers in the South-West Indian Ocean is no longer an option, but a necessity in order to transform the climate emergency into an opportunity for resilience for humanity and the ocean.

Marta Coll sends a clear message in this video; Protecting biodiversity is the most cost-effective investment in securing the future of fisheries. Activating these management levers in the South-West Indian Ocean is no longer an option, but a necessity in order to transform the climate emergency into an opportunity for resilience for humanity and the ocean.