Final answer:
Invasive species and human impacts such as unsustainable fishing practices and pollution are key factors impacting coral reef ecosystems. Climate change, causing ocean warming and acidification, poses another significant threat to reef health. Coral reefs are important for biodiversity and coastal economies, making their decline a major concern.
Step-by-step explanation:
Threat 1, invasive species and human impacts such as overfishing and pollution, are impacting coral reef ecosystems by out-competing native reef animals. Coral reefs, highly diverse marine ecosystems, are essential to marine life, housing approximately one-third of the world's marine fish species. However, these ecosystems face dangers from various sources, with human activity being a significant contributor to their decline.
One of the considerable threats posed to coral reefs comes from the pet trade, which often stocks home marine aquaria with wild-caught organisms. This unsustainable harvesting can lead to population declines in certain species. Furthermore, human population growth and associated runoff of sediment and agricultural chemicals cloud the tropical waters, negatively affecting reefs. Overfishing also destabilizes marine ecosystems by allowing coral-eating predators to flourish unchecked.
In addition to human activity, climate change poses a dual threat by raising ocean temperatures and causing coral bleaching. Ocean acidification, a result of increased atmospheric CO2 levels, further impedes coral growth by making it harder for corals to build their calcium carbonate structures. As a coral reef begins to die, the biodiversity of the area plummets, eliminating food and shelter for many species and threatening coastal economies that rely on tourism.