Climate change implications for the Arafura and Timor Seas region: Assessing vulnerability of marine systems to inform management and conservation

The Arafura and Timor Seas (ATS) region is shared by Indonesia, Timor Leste, Australia, and Papua New Guinea (PNG), and is at the intersection of the Pacific and Indian oceans. High coastal population densities, degraded habitats, overexploited fisheries, low profile coasts, shallow continental shelves and macro-tidal conditions mean that coastal and marine environments in the region are currently facing multiple pressures. Climate change is expected to exacerbate these pressures and have profound effects on the status and distribution of coastal and marine habitats, the fish and invertebrates they support and, as a consequence, dependent communities and industries. Downscaled climate change projections for 2041–2070 for air and sea temperature, ocean chemistry and rainfall were modelled to provide spatially relevant regional and local data for a structured semi-quantitative vulnerability assessment. Results of the assessment were spatially variable and identified shallow coral reefs as highly vulnerable, particularly in the Timor Leste and Indonesia-Arafura sub-regions. Seagrass meadows were most vulnerable in the Gulf of Carpentaria, Indonesia-Arafura, and Timor Leste sub-regions. Mangroves and estuarine habitats were most vulnerable in Timor Leste and Western PNG sub-regions. Drivers of vulnerability include poor habitat condition, non-climate pressures, low connectivity, and limited formal management. Marine species vulnerability was also spatially variable, with highly vulnerable and priority species identified for each sub-region, including finfish and marine invertebrates. A key driver of species vulnerability was their stock status, with many species in Timor Leste, Western PNG and Indonesia, and several in northern Australia, overfished or potentially overfished. Limited management in some sub-regions, as well as non-climate pressures such as habitat decline, poor water quality and illegal, unregulated and unreported fishing were also key drivers. Species of conservation interest (dugong and marine turtles) were also highly vulnerable to climate change, driven by their threatened status and the fact that they are low productivity species that take years to recover from impacts. Priority species and habitats for local action were identified, and current pressures that undermine condition and/or resilience, with strategic recommendations aimed at minimising climate change vulnerability.