Final answer:
At a hot spot, fringing reefs are susceptible to bleaching due to increased temperatures and may die if stress continues. Ocean acidification from higher CO₂ levels further prevents corals from maintaining their skeletons, affecting reef ecosystems and biodiversity.
Step-by-step explanation:
At a tropical hot spot, fringing reefs can experience severe stress due to increased ocean water temperature, leading to a decline in their health and vitality. This elevated temperature causes a process called bleaching wherein corals expel the symbiotic algae living within their tissues. The algae contribute not only to the corals' vibrant colors but also to their nutrient supply through photosynthesis. Without these algae, corals lose their color, a clear sign of stress, and can eventually die if conditions do not improve.
Rising levels of CO₂ in the atmosphere compound the problem through ocean acidification. As CO₂ dissolves in the ocean, it lowers the pH, making the water more acidic. This acidity hampers the coral's ability to create and maintain their calcium carbonate skeletons, which they rely on for structure and protection. As a result, not only does the coral structure weaken, but the entire reef ecosystem can suffer as organisms that depend on the coral for food and shelter experience declines in population and biodiversity.
Compounding the effects of these environmental changes, human activities further threaten the long-term survival of these delicate ecosystems. Coral reefs provide numerous ecosystem services and are also economically significant due to their role in supporting fisheries and tourism. The loss of coral reefs thus represents a substantial loss to marine biodiversity and to the economic welfare of coastal communities that depend on them.