New aggressive alga threatening the health of Caribbean coral reefs

Hurricanes, pollution, disease, bleaching and the effects of an increasingly warmer planet are all negatively impacting the health of coral reefs around the world. However, those in the Caribbean are facing a new threat - an aggressive, golden-brown, crust-like alga that is rapidly overgrowing shallow reefs. The algae, known as peyssonnelid algal crusts (PAC), are taking over the reefs at such an aggressive rate that they are interfering with the ability of coral larvae to find places to settle on the reefs, and interfering with the reef's natural ecosystem. Marine biologists from the University of Oxford, California State University Northridge and the Carnegie Institution for Science, have been studying the biology and ecology of this alga on these reefs for the past four years. Today in Scientific Reports they describe this new threat and what it might mean for reefs already teetering on the brink of collapse. Dr Bryan Wilson from the Department of Zoology, University of Oxford, said: 'This alga seems to be something of an ecological winner in our changing world; it aggressively occupies any vacant space on the reefs, rapidly overgrows and kills live corals, prevents free-swimming coral larvae from settling on the benthos and becoming adult colonies, and is unaffected by the regular destructive hurricanes that sweep through the area.