Vulnerability of freshwater habitats and fisheries to climate change in the tropical Pacific

Freshwater habitats and the fisheries they support play an important role in the culture, food security and livelihoods of people living in the Pacific islands. Climate change, and interactions with catchment hydrology and ecology have potential to affect freshwater ecosystems and fisheries production. However, information on freshwater ecology and fisheries in the region is sparse, and threats from climate change are poorly understood. We reviewed available climate models and ecological information to assess likely responses under the B1 and A2 climate change scenarios, at time scales to 2035 and 2100. Most of the region is projected to receive increased rainfall, with river discharge and habitat availability projected to increase by up to 33% in some rivers by 2050. In contrast, subtropical islands are projected to receive up to 20% less rainfall. Increases in river flow and habitat availability are projected to dominate other responses to climate change resulting in increases in fish production of up to 12.5% by 2100. In disturbed catchments, increased runoff is projected to exacerbate poor water quality, and may limit potential for increased fisheries production. Limitations to climate change adaptation include the inadequate ability to downscale climate projections to island and catchment scales, limited knowledge of freshwater ecosystem and fish ecology, and limited capacity for cross-sectoral approaches to catchment management to mitigate adverse effects on fish habitats.