What is the significance of the Great Barrier Reef? Please answer in one paragraph and include at least three sentences. Further, make sure to mention its ecological and economic value, as well as the threats it faces. Lastly, please ensure that the word "unique" appears at least twice in your response.
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The Great Barrier Reef, a unique and immensely valuable ecosystem, is not only the largest coral reef system in the world but also a critical habitat for a vast array of marine life, making it a unique and essential part of our planet's natural heritage. Economically, it generates significant revenue through tourism, fisheries, and research, supporting local communities and contributing to the global economy. However, the reef faces severe threats from climate change, pollution, and overfishing, which endanger its delicate balance and highlight the urgent need for conservation efforts to protect this irreplaceable natural wonder.
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