MESCAL

Climate change threatens the long-term sustainability of marine ecosystems. Although Marine Protected Areas (MPAs) are recognized as an effective tool to protect harvested species, biodiversity and habitats, they were not designed to increase the resilience of marine ecosystems to climate change. A major issue that remains to be explored is whether and by what mechanisms current and future MPAs can simultaneously buffer intraspecific (genotypes and phenotypes) diversity and community diversity against climate change, thereby enhancing sustainability of marine ecosystems. In this context, connectivity plays a pivotal role by potentially ensuring that individuals from climate or fishing refugia can repopulate impacted areas. These questions are particularly important in the Western Indian Ocean (WIO), given that warming and fishing exploitation in this region are increasing at an alarming rate. In the WIO, fish support key ecological functions and are the primary source of protein and income for coastal human communities, and the creation or expansion of MPAs is a promising mitigation measure for the negative impacts of climate change on fish stocks. To address these issues, this project will focus on the eastern African coastline from Kenya to South Africa and address five key interconnected objectives. (1) First, we will produce high resolution estimates of future changes in environmental conditions, larval transport and connectivity for the period 2080-2100, using regional ocean circulation models based on bias-corrected climate change projections along the eastern African coastline. We will then (2) evaluate the phenotypic performance of individuals of three key fishery species from exploited and unexploited populations in relation to temperature using ecophysiology, genomics and otolith-based estimates. It will allow us to test whether MPAs harbor individuals of high physiological performance resilient to climate change and identify the genetic origins of these traits. We will also (3) use environmental DNA (eDNA) metabarcoding to obtain a standardized view of all teleosts and elasmobranchs in the WIO, and assess complementary facets of community diversity. We will test whether MPAs safeguard ecologically important and vulnerable species, and prevent marine ecosystems and associated fisheries from crossing tipping points where climate change will drastically alter their structure. (4) Previous steps will be integrated to assess how the ecological connectivity of current and potential future MPA networks can enhance resilience to temperature change at the species and community levels of organization. (5) These results will be integrated into spatial population, community and ecosystem models to quantify long-term trends in persistence and climate resilience under a variety of climate change and spatial management scenarios. Bi-lateral exchanges with stakeholders in the WIO will be used to communicate results, and to integrate their knowledge of MPA benefits and climate change into discrete choice experiments that will be used to quantify preferences for different spatial management options as mitigation for climate change and fishing exploitation. This project will provide valuable results for implementing effective and equitable management of ocean assets in the WIO.