Final answer:
The loss of herbivorous fish leads to unchecked algal growth, which, combined with nutrient enrichment from human activities, further imperils coral health. This problem is compounded by physical damage from fishing, global warming, and ocean acidification, leading to a decline in biodiversity and coral reef collapse.
Step-by-step explanation:
The loss of herbivorous fish on coral reefs, amidst varying levels of nutrient enrichment, can have significant impacts on the ecosystem. Herbivorous fish play a vital role in controlling the growth of algae, which competes with corals for space and resources. In the absence of these fish, algal blooms can overrun coral reefs, particularly in nutrient-enriched waters, due to factors like runoff of sediment and agricultural chemicals from human activities.
This can lead to a decline in coral health and the process of coral bleaching, where corals lose their symbiotic algae and become more susceptible to disease and mortality. Overfishing exacerbates the problem by removing not only herbivores but also allowing predator species that consume corals to increase unchecked. In addition, the disturbance caused by certain fishing methods can physically damage coral structures, leading to loss of biodiversity and habitat complexity.
Furthermore, global warming contributes to rising sea temperatures and ocean acidification, putting additional stress on coral reefs. Coral bleaching, caused by rising temperatures, and changes in water pH due to increased CO₂, interfere with coral calcification, destabilizing the reef structure. When combined with the decline of herbivorous fish, these factors can lead to a drastic reduction in species diversity and the ecological collapse of coral reefs, which are also economically valuable as tourist destinations.