Identifying paths towards coastal sustainability through collaborative-science assessments of system responses to environmental changes

Coastal marine ecosystems play a central role in hosting biodiversity and providing crucial ecosystem services for human societies. In tropical regions, biodiversity levels reach their climax in coral reefs, seagrass meadows, and mangroves, highly productive ecosystems that have long supported human wellbeing. While these ecosystems suffer growing impacts from local and global environmental changes and are declining rapidly, not all ecosystems show the same level of exposure and vulnerability to the various human and climate stressors. In this context, understanding how changing environmental conditions shape ecosystems can help elucidate the mechanisms underlying ecosystem resilience and define safe management pathways. We report a country-scale collaborative-science initiative bringing together scientific protagonists from various sectors, including research academics, coastal management officials, private consulting companies and environmental agencies, and participative-science civilians, to characterize the response of New Caledonia’s exceptional coastal system representing 6% of the world’s coral reef habitats, 0.25% of known seagrass meadows, and 0.26% of mangrove forest on the planet. Our evaluations produce environmental diagnostics of ecosystem health and current management efforts, and characterize socio-ecosystem resilience mechanisms and thresholds to define safe maneuvering spaces towards sustainable biodiversity-climate-human pathways.