Coral reefs around the world are already threatened by rising temperatures brought on by climate change, and the risk of fish species extinction adds to the mix. The networks of predator fish and their prey found on coral reefs all over the world are very similar, according to a report published today in the Proceedings of the National Academy of Sciences, and those predator fish are pickier eaters than previously imagined. When these specialized hunters become extinct, these sensitive ecosystems become even more susceptible.
Coral reefs are among the world’s most diversified ecosystems, providing crucial home for thousands of species that support economies and provide food for millions of people. Researchers from France and The University of Texas at Austin discovered that coral reef food webs are more sensitive than previously assumed in the broadest and most extensive study of its type. After analyzing the stomach contents of most fish species found on six coral reef systems throughout the world, researchers came at this result.
The researchers discovered that the vast majority of reef fish species are choosy about what they consume, rather than grazing on whatever they can find. Although reefs are likely to survive the extinction of numerous prey species, the extinction of a single larger fish species could put the ecosystem in jeopardy.
“It’s amazing how identical patterns can be found in coral reef systems all across the world. Extinction of larger fish species, in particular, might have serious consequences for coral reef ecosystems “Jordan Casey, an assistant professor of marine science at the University of Texas at Austin’s Marine Science Institute (UTMSI) and one of the paper’s authors, agreed.
Climate change, commercial fishing, and pollution are just a few of the factors that might lead to local fish species extinction. As a result of these fish losses, an increasing quantity of prey may go uneaten, causing food web imbalances.
“All animals must be used efficiently on reefs,” said Simon Brandl, an author and assistant professor at UTMSI. “If a fish that specializes in eating a certain type of snail dies, the snail may not be eaten and may live happily ever after. This puts a stop to the food that it may otherwise offer to other coral reef organisms. The snail has good news. It’s bad news for everyone else who lives there.”
More than 600 species of coral reef fish were studied on six separate coral reefs around Okinawa, Hawaii, the West Indies, New Caledonia, Madagascar, and the Marshall Islands. Despite the enormous range of available food in coral reefs, the food webs had a strikingly similar structure: 67 percent of species were specialist feeders with strong preferences for specific prey items.
Casey explained, “Coral reefs are vital to humans for a variety of reasons.” “For many people, they are a vital source of nutrition. In addition, they are famous tourist attractions and economic engines for a number of countries. Coral reefs, on the other hand, can only deliver these important ecological services if food webs stay intact.”