Final answer:
Charles Darwin's voyage is associated with a theory on the formation of coral reefs and atolls, where ring-like coral islands surrounding a lagoon form as a volcanic island subsides and corals build up. The significance of coral reefs to marine biodiversity and the current threats they face are also noted.
Step-by-step explanation:
The voyage associated with a suggestion on how coral reef islands grow is that of Charles Darwin during the voyage of the HMS Beagle. Darwin proposed a theory on the formation of coral atolls, which are ring-like coral islands or strings of small islands surrounding a lagoon. His theory involved a multi-stage process where a volcanic island subsides, coral build-up occurs around it, and eventually, only a ring of coral remains where the island once was, creating what is known as an atoll.
Coral reefs are foundational to marine ecosystems and are formed by the slow deposition of calcium carbonate by coral animals over millions of years. These ecosystems are critical as they house enormous marine biodiversity and provide numerous benefits including coastal protection, fishing grounds, and tourism attractions. However, coral reefs are facing global declines due to factors such as climate change, overfishing, and pollution, leading to calls for urgent conservation efforts.