Norfolk Island's rare corals threatened by disease, El Niño and government-approved dredging

Unique corals fringing Australia's remote Norfolk Island face a triple threat: disease outbreaks, El Niño conditions and a federal government plan to dredge a nearby shipping channel. Researchers warn that most of the island's corals are likely undescribed species. Sediment, pollution from cattle farming and wastewater have fuelled algae blooms and disease spread.