The study, published in this month's Environmental Science and Policy, looked at 27 countries that depend significantly on coral reef fisheries for food and ranked them according to their exposure and sensitivity to the effects of climate change and man-made disturbances, as well on their capacity to adapt to changes.
Coral reefs are globally valued for their high biodiversity. For millions of people, they are a productive source of food. An average Indonesian gets almost 60 per cent of its animal protein from fish, while in Pacific island countries this figure is between 50 to 90 per cent.
However, coral reef fisheries are expected to decline with climate change and other human caused disturbances.
In the new study, a higher sensitivity indicates that a country is highly dependent on coral reef fisheries for human protein sources, and is already close to or below the minimum protein consumption level, while capacity to adapt is the potential to respond to changes in the contribution of reef fisheries to the food system.
They found that Indonesia is the most vulnerable because of the combined effects of man-made disturbance and very high sensitivity. Liberia, the second most vulnerable, has very high sensitivity to coral reef fisheries decline and the lowest level of adaptive capacity. Kenya, Ivory Coast and the Philippines complete the top five most vulnerable.
"These [vulnerable] countries are priorities for developing adaptation actions before the effects of climate change undermine their ability to feed themselves," said the study's co-author Tim McClanahan of the Wildlife Conservation Society.
On the other end of the scale, Malaysia is the least vulnerable because of its high adaptive capacity relative to its levels of exposure and sensitivity, followed by Sri Lanka.
The study identified two common types of vulnerability categories: low income countries with low adaptive capacity, and middle-income countries with higher adaptive capacity but also high sensitivity. The study points to the need for to policies to build adaptive capacity in low-income countries, and to decrease sensitivity in middle-income countries.
McClanahan warned that some countries will have enough capacity to adapt — while others will not.
"Making [countries] realise this early will save considerable human suffering in the future," he said.
The authors say the results of the study should be a wake-up call for nations to begin enacting policies to promote alternative protein sources, either through land-based means such as growing beans and poultry farming, or increased aquaculture.