ABSTRACT
The coral reef ecosystem, with its species richness and endemism, provides various ecosystem services and plays a substantial role in biosphere. The beauty of the corals lies with the mutualistic relationship of cnidarian host with endosymbiotic unicellular algae. The coral biodiversity has a unique characteristic of having narrow range of tolerance to different climatic factors mainly temperature. The coral coverage in the world found declining at an alarming rate from the tropical oceans. This chapter focuses on different abiotic and biotic causes of coral damage and loss. The change in climatic conditions, the rise in ocean water temperature, and oceanic acidification by carbon dioxide emissions are the narrow key threats to the coral reef ecosystem. The other anthropogenic stressors include the destructive fishing, sedimentation, discharge of untreated wastes and toxic substances, diseases, and outbreak of predators triggered the impact of climate change on coral cover. The chapter describes the mechanism of coral bleaching related to photoinhibition and oxidative stress. The negative impacts on coral reefs affected fish and other marine organisms, disturbing the balance in the ecosystem. The chapter explains the significance of the integrated approach of the marine protected area network in decreasing local stressors and active participatory conservation methods like coral transplanting and coral gardening aimed to improve the restoration of threatened and degraded coral reef ecosystem.
