![]() ![]() Nonetheless, the GBR has been subject to severe disturbances, including COTS outbreaks, mass coral bleaching and declining growth rates of coral due to increasing seawater temperatures, terrestrial runoff, tropical cyclones, and coral diseases ( 2, 3, 12– 14). ![]() Fishing, although intense near the coast and urban centers, is banned in 33% of the GBR and is regulated elsewhere ( 11). Local anthropogenic disturbances (e.g., destructive fishing, industrial and urban pollution, tourism overuse, anchor damage, vessel groundings, oil spills) have had minor adverse effects on the GBR to date. GBR reefs have been classified as the world’s least threatened coral reefs ( 4) due to their distance from the relatively small human population centers and strong legal protection ( 10, 11). Its outstanding universal values were recognized by World Heritage listing in 1981. The Great Barrier Reef (GBR) represents a particularly relevant case study to investigate ecosystem trajectories and potential mitigation, because it is the world’s largest coral reef ecosystem, containing ∼3,000 individual coral reefs within an area of 345,000 km 2. Such strategies can, however, only be successful if climatic conditions are stabilized, as losses due to bleaching and cyclones will otherwise increase. Thus, reducing COTS populations, by improving water quality and developing alternative control measures, could prevent further coral decline and improve the outlook for the Great Barrier Reef. In the absence of COTS, coral cover would increase at 0.89% y −1, despite ongoing losses due to cyclones and bleaching. The estimated rate of increase in coral cover in the absence of cyclones, COTS, and bleaching was 2.85% y −1, demonstrating substantial capacity for recovery of reefs. Importantly, the relatively pristine northern region showed no overall decline. Tropical cyclones, coral predation by crown-of-thorns starfish (COTS), and coral bleaching accounted for 48%, 42%, and 10% of the respective estimated losses, amounting to 3.38% y −1 mortality rate. Based on the world’s most extensive time series data on reef condition (2,258 surveys of 214 reefs over 1985–2012), we show a major decline in coral cover from 28.0% to 13.8% (0.53% y −1), a loss of 50.7% of initial coral cover. ![]() This study investigates the spatial and temporal dynamics of coral cover, identifies the main drivers of coral mortality, and quantifies the rates of potential recovery of the Great Barrier Reef. The world’s coral reefs are being degraded, and the need to reduce local pressures to offset the effects of increasing global pressures is now widely recognized. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |