Final answer:
Invasive species and other factors such as the pet trade, habitat degradation from human activity, and overfishing are impacting coral reef ecosystems, leading to declines in species diversity and economic challenges.
Step-by-step explanation:
Invasive species are impacting coral reef ecosystems by out-competing native reef animals. Numerous external factors contribute to this effect, including the pet trade, which relies heavily on wild-caught organisms for marine aquaria. This unsustainable harvesting results in declining populations of certain species. Moreover, the increase in human coastal populations causes runoff of sediment and agricultural chemicals, making waters cloudy and affecting coral health. Predatory species that consume coral are also left unchecked due to overfishing. Climate change, represented by global temperature increases, is poised to further stress these fragile ecosystems. Finally, the decline of coral reefs impacts species diversity and local economies reliant on tourism.