Vulnerability of mangroves, seagrasses and intertidal flats in the tropical Pacific to climate change

In this chapter, we assess the vulnerability of the mangrove, seagrass and intertidal flat habitats in the tropical Pacific that support coastal fisheries. We do this by examining the effects that changes to surface climate and the tropical Pacific Ocean (Chapters 2 and 3) are expected to have on the plants that define these habitats. This exposure to change is used in the framework described in Chapter 1 to assess the vulnerability of the habitats under representative low (B1) and high (A2) emissions scenarios from the Intergovernmental Panel on Climate Change (IPCC) for 2035 and 2100. We commence by describing the diversity and distribution of mangrove, seagrass and intertidal flat habitats in the tropical Pacific (25°N-25°S and 130°E-130°W), outlining the role they play in supporting coastal fisheries in the region, and summarising the critical requirements for establishing and maintaining these habitats. Next, we summarise the limited information on the observed effects of climate change on mangroves, seagrasses and intertidal flats, and assess the expected vulnerability of these habitats to the projected changes in solar radiation, air and sea temperatures, rainfall, nutrients, cyclones and storms, ocean acidity and sea-level rise. For mangroves and seagrasses, we integrate these assessments to estimate changes in area under the various scenarios. We conclude by identifying the uncertainty associated with these assessments, the important gaps in knowledge, the research required to fill these gaps, and the key management measures needed to maintain the important roles that the mangroves, seagrasses and intertidal flats of the region play in supporting coastal fisheries.