The diversity of coral reefs is synthesised through estimates of species richness across major animal taxa. Although such estimates remain uncertain, they highlight the largely overlooked contribution of planktonic species, most of which are only visible at night. Tropical rainforests are widely regarded as more species-rich than coral reefs, and comparisons across equivalent taxonomic groups support this view; however, this difference is heavily driven by the extraordinary contribution of insects to rainforest diversity.
Both coral reefs and tropical rainforests reach peak diversity within the Coral Triangle, with rainforest diversity remaining relatively stable over millennia. In contrast, coral reef diversity has fluctuated markedly in this timeframe and is now in sharp decline due to mass coral bleaching. As this trend continues, corals will not retain their critical role as nurseries of reef biodiversity, with cascading consequences for the diversity of the world’s oceans.
Coral biobanks offer a potential pathway to mitigate these impacts by enabling the preservation and propagation of resilient coral genotypes, thereby supporting future reef recovery.