Marine conservation in a changing climate and for deep ecosystems

Abstract

Human uses of the ocean are intensifying, diversifying, and spatially expanding to respond to the ever-growing food, energy, and material demand of humanity. In this context, marine protected areas (MPAs) have been increasingly promoted as a tool to mitigate impacts from extractive activities and promote sustainable uses of marine resources. However, while the ecological benefits of highly protected coastal MPAs are well-established, many controversies remain on whether these benefits will perdure under future climatic conditions, and whether MPAs are relevant tools to protect deep offshore ecosystems. This dissertation aims at addressing these uncertainties by (1) clarifying the climate benefits that MPAs can provide, (2) assessing the conservation status across depth zones of the ocean, and (3) advancing the ecological knowledge of deep-reef ecosystems to better inform their conservation. In chapter 1, I conduct a meta-analysis and demonstrate that MPAs with high levels of protection can significantly enhance multiple climate mitigation and adaptation pathways including carbon sequestration, coastal protection, species richness, and fishers’ catch and income. In chapter 2, I found that conservation efforts are unevenly distributed among depths and tend to be biased towards areas with the lowest fishing efforts. In chapter 3 and 4, I evaluate the taxonomic and functional diversity of Caribbean reef-fish communities across multiple depth zones from the surface to the deep-sea boundary (< 300 m). This dissertation highlights the importance of MPAs in supporting the resilience of socio-ecological systems to climatic pressures and sheds light on the unique diversity of deep reefs, which require dedicated conservation efforts to achieve targets of ecological representation.