Environment: Coral species at risk of extinction in Mexican Caribbean due to deadly disease

An outbreak of stony coral tissue loss disease has led to mortality rates of up to 94% among some coral species in the Mexican Caribbean, according to surveys of a 450 kilometre reef track. The findings, published this week in Communications Biology, highlight the need for human interventions to prevent the extinction of some coral species within this region.

Stony coral tissue loss disease was first reported in Florida in 2014 and has since spread across the Caribbean. Previous research has found that the disease can kill infected corals within weeks, however prior to this study, the regional impacts and extent of population declines were unclear.

Lorenzo Álvarez-Filip and colleagues surveyed 35 sites between 2016 and 2017 — before stony coral tissue loss disease reached the Mexican Caribbean — and 101 sites between July 2018 and January 2020 — after the disease reached the region.

The authors found that of the 29,095 coral colonies surveyed after the outbreak in the Mexican Caribbean, 17% were already dead and an additional 10% were afflicted with the disease. Out of 48 species surveyed, mortality rates among the 21 afflicted with the disease ranged from less than 10% up to 94%. Species belonging to the reef-building maze and brain coral groups were the most severely affected, with maze coral species and the pillar coral Dendrogyra cylindrus experiencing population losses greater than 80%. These numbers indicate that some species are at risk of extinction within the region and the authors suggest that the loss of reef-building species could impair the ability of coral reefs to cope with environmental changes.

In addition to population losses, the researchers observed a 30% reduction in the ability of coral communities to produce calcium carbonate, the material required to make the complex three-dimensional structures of coral reefs. They propose that this could lead to reef frameworks being destroyed faster than they are produced.

The authors conclude that stony coral tissue loss disease could become the most deadly disturbance ever recorded in the Caribbean. Human interventions such as rescuing colonies of vulnerable species, preserving their genetic material, and implementing restoration efforts will likely be needed to facilitate reef recovery and prevent the region-wide extinction of some species, they add.