From sunlit coral reefs to the dark abyssal plains, the ocean hosts an extraordinary range of life. Biodiversity describes that variety—at the level of genes, species, and ecosystems—and the ecological complexes they form.

Marine biodiversity peaks in certain hotspots such as coral reefs and tropical coastal zones, yet even the deep sea and polar waters support unique assemblages. Diversity underpins ecosystem stability, productivity, and the provision of services ranging from fisheries to coastal protection. Habitat destruction, overexploitation, pollution, and climate change are reducing marine biodiversity at rates that concern scientists and resource managers alike.

Measuring biodiversity requires standardized surveys, genetic tools, and long-term monitoring. Conservation efforts increasingly focus on protecting representative habitats and maintaining connectivity among populations. The ocean’s biodiversity remains incompletely catalogued; new species continue to be described every year, especially from deep and remote environments.

• Variety of life at genetic, species, and ecosystem levels
• Supports ecosystem function and services
• Threatened by multiple human pressures
• Still incompletely documented in the ocean