| 英文摘要: | Ecosystems are linked within landscapes by the physical and biological processes they mediate. In such connected landscapes, the response of one ecosystem to climate change could have profound consequences for neighbouring systems. Here, we report the first quantitative predictions of interdependencies between ecosystems in response to climate change. In shallow tropical marine ecosystems, coral reefs shelter lagoons from incoming waves, allowing seagrass meadows to thrive. Deepening water over coral reefs from sea-level rise results in larger, more energetic waves traversing the reef into the lagoon1, 2, potentially generating hostile conditions for seagrass. However, growth of coral reef such that the relative water depth is maintained could mitigate negative effects of sea-level rise on seagrass. Parameterizing physical and biological models for Lizard Island, Great Barrier Reef, Australia, we find negative effects of sea-level rise on seagrass before the middle of this century given reasonable rates of reef growth. Rates of vertical carbonate accretion typical of modern reef flats (up to 3 mm yr−1) will probably be insufficient to maintain suitable conditions for reef lagoon seagrass under moderate to high greenhouse gas emissions scenarios by 2100. Accounting for interdependencies in ecosystem responses to climate change is challenging, but failure to do so results in inaccurate predictions of habitat extent in the future. Climate change affects the distribution, extent and functioning of ecosystems3. Ecosystems comprise living organisms and the non-living components of their environment in an interacting system. Interactions between distinct ecosystems also occur—for instance, where one ecosystem modifies adjacent environments, allowing other ecosystems to thrive where they otherwise would not exist. At the species level, interdependencies in response to climate change occur when interacting species have different responses to a climate stressor. This can alter interactions such as competition, rates of pathogen infection, herbivory and predation4, 5, 6. Interdependencies in response to climate change at the ecosystem level may also exist, but have not previously been quantified in a predictive framework. In shallow tropical seas, coral and seagrass exist in a patchy habitat mosaic, connected by numerous biological, physical and chemical linkages7, 8. Seagrass supports early life-stages of many reef fish7; provides a buffer against low pH (ref. 8); binds sediments to reduce erosion9 and filters nutrients and sediments from water9. In turn, the distribution of shallow seagrass meadows which thrive in low-energy wave environments9 depends on wave sheltering by coral reefs. Seagrass and coral reefs support the livelihoods of many of the 1.3 billion people who live within 100 km of tropical coasts10. Unfortunately, rapid and widespread declines of these habitats are occurring worldwide11, 12, 13. Accurately predicting effects of climate change on tropical marine ecosystems is essential for developing appropriate management plans to maintain human well-being. Sea-level rise (SLR) drives changes in the distribution of seagrass14 and coral reefs15. Despite considerable uncertainty, SLR of up to 1 m by 2100 may occur given business-as-usual greenhouse gas emissions scenarios16, 17, 18. Rising seas result in inland migration of coastal habitats, loss of habitat at the seaward edge, vertical accretion to maintain relative position with sea level, adaptation to new conditions, or a combination thereof14. Coral reef growth (carbonate accretion) occurs by calcification of corals and coralline algae, and subsequent in-filling of the reef matrix19, 20. Sediment accretion in seagrass meadows occurs by the production of roots and rhizomes, and by promotion of high rates of sediment deposition and retention9. Our aim was to predict the response of seagrass distribution to altered wave conditions resulting from rising seas and the responses of distinct ecosystems (coral reefs and seagrass) to changes in sea level (Fig. 1). We examined this process at an intensively studied coral reef environment at Lizard Island, Great Barrier Reef (Fig. 2a), where there is a gradient of wave exposure over shallow water habitats15, 21, 22.
| http://www.nature.com/nclimate/journal/v4/n8/full/nclimate2274.html
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