Coral Reefs: A Very Short Introduction

Reefs and the coral life that builds them were for centuries a source of mystery to naturalists and hazard to seafarers. Many ideas were developed of what built them and why they all existed so close to sea level but never above it. Darwin developed the theory of how they were built, which was proven a century later. The coral polyp is central to each coral colony and to the reef. Each houses countless symbiotic algal cells that provide the energy that supports the coral reef ecosystem, and the energy needed to extract minerals from seawater to deposit as solid limestone. These are the ocean’s most biodiverse ecosystem. The islands perched on them include many entire nations, and reefs provide land, food, and protection to these as well as parts of many others. The diversity and abundance of other species, from microbial systems that are key to nutrient and energy transfer, to the large predatory fish, are similarly vast, and various components of the reef system have been researched intensively since the advent of scuba techniques. Today, however, local impacts and pressures from pollution to overfishing have degraded and damaged many, and more recently, warming of ocean water resulting from climate change is causing an existential threat to the survival of this rich ecosystem. Arresting the decline is no longer a scientific problem but one for society and governments, and failure to do so will result, indeed already is, in untold damage to human societies that depend on coral reefs.