Final answer:
Coral reefs support about 25% of marine species and face threats from climate change, acidification, and pollution. Ocean warming and carbon dioxide increase lead to less dissolved oxygen and more acidic waters, affecting coral health. Although they house a vast diversity of fish species, coral reefs are in decline, with a significant portion already lost.
Step-by-step explanation:
About 25% of all marine species are supported by coral reefs. These reefs are vital to the sea ecosystem, but face significant threats due to several factors such as climate change, oceanic acidification, and water pollution. Global climate change results in warmer oceans which in turn decreases the solubility of oxygen essential for marine life. Increased carbon dioxide levels in the atmosphere lead to higher concentrations of carbon dioxide in the oceans, contributing to the acidification that negatively affects the exoskeletons of coral polyps, as they are soluble in acidic solutions. Pollution from agricultural runoff further alters seawater composition, exacerbating the stress on coral reefs.
It is estimated that coral reefs make up only about 1 percent of marine habitat, yet they are home to a third of the world's marine fish species, approximately 4,000 species. Unfortunately, there is evidence that a significant portion of the world's coral reefs have been lost due to these environmental stresses, although exact figures on the loss vary. Studies suggest that these trends are increasing, undermining the sustainability of coral reefs and affecting local ecosystems profoundly.