Coral reef food webs threatened by the loss of picky eaters

Coral reefs are threatened by the loss of picky-eating fish species, according to a new study from UT Austin. The experts report that coral reef food webs are more delicate than what was previously realized. 

The researchers analyzed the stomach contents of most fish species found on six coral reef systems all over the world. The study revealed that reef fish networks are remarkably similar, and that the predators in these food webs are picky eaters. 

The study showed that the vast majority of reef fish species are very particular when it comes to what they eat, and do not simply eat what they can find. 

The findings also suggest that reef communities could tolerate the loss of several prey species, but the loss of a single predator fish species could potentially cause the ecosystem to collapse. 

“It’s remarkable that we see similar patterns in coral reef systems all over the world. Extinctions, particularly of larger fish species, may have significant impacts for coral reef systems,” said study co-author Professor Jordan Casey.

Fish species are threatened with extinction locally as a result of many stressors, including climate change, pollution, and overfishing. As the number of large fish decline, an increasing number of their prey will survive uneaten, which creates an imbalance in the food web. 

“Reefs rely on the efficient utilization of all creatures,” explained study co-author Professor Simon Brandl. “If a fish specializes on eating a certain type of snail and that fish disappears, the snail might not be eaten and live happily ever after. This creates a dead end for the food it could provide to other coral reef creatures. Good news for the snail. Bad news for everything else living there.”

The researchers examined the feeding habits of more than 600 species of reef fish near Okinawa, Hawaii, the West Indies, New Caledonia, Madagascar and the Marshall Islands. The food webs had a strikingly similar structure in which 67 percent of species were specialized feeders with strong preferences for specific prey – despite an incredibly diverse selection of prey available.

“Coral reefs are important to humans for a number of reasons,” said Casey. “They are a critical source of food for many people. They are also popular tourist destinations and economic engines for a number of countries. However, coral reefs can only provide these key ecosystem services if food webs remain intact.”

The study is published in the journal Proceedings of the National Academy of Science.

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By Chrissy Sexton, Earth.com Staff Writer