Reef decline puts thousands of decapod species 'in real danger'


Many species of crabs, shrimp and lobsters could become extinct if reefs continue to decline at their current rate.

A large number of ancient crustacean species were wiped out following a massive collapse of reefs across the planet, and a study by University of Florida research suggests modern species may now be at risk.

The study shows a direct correlation between the amount of prehistoric reefs and the number of decapod crustaceans, a group that includes shrimp, crabs and lobsters. The decline of modern reefs due to natural and human-influenced changes also could be detrimental, causing a probable decrease in the biodiversity of crustaceans, which serve as a vital food source for humans and marine animals such as fish, said lead author Adiël Klompmaker, a postdoctoral researcher at the Florida Museum of Natural History on the UF campus who started the study at Kent State University.

"We estimate that earth’s decapod crustacean species biodiversity plummeted by more than 50% during a sharp decline of reefs nearly 150 million years ago, which was marked by the extinction of 80% of crabs," Klompmaker said.

"If reefs continue to decline at the current rate during this century, then a few thousand species of decapods are in real danger. They may adapt to a new environment without reefs, migrate to entirely new environments or, more likely, go extinct."

Some scientists predict as much as 20% of the world’s reefs may collapse within 40 years, with a much higher percentage affected by the end of the century due to natural and human-influenced changes such as ocean acidification, diseases and coral bleaching.

The study is the first comprehensive examination of the rise of decapod crustaceans in the fossil record. Researchers created a database of fossils from the Mesozoic Era, 252 million to 66 million years ago, from literature records based on museum specimens worldwide. The data included 110 families, 378 genera and 1,298 species. They examined the patterns of diversity and found an increase in the number of decapod species was influenced by the abundance of reefs, largely due to the role of reefs as a provider of shelter and foraging. Researchers call this period the "Mesozoic decapod revolution" because of the 300-fold increase in species diversity compared with the previous period and the appearance and rapid evolution of crabs.

"This new work builds a good case for the role of reefs in promoting the evolutionary diversification of crustaceans," said David Jablonski, a paleontologist in the department of geophysical sciences at the University of Chicago who was not involved in the study. "We have to take their argument for the flipside of that story very seriously. The positive relation between reefs and crustaceans implies that the damage caused to reefs by human activities — from overfishing to ocean acidification — is likely to have cascading consequences for associated groups, including crustaceans."

The study is available online and scheduled to appear in the November issue of Geology.

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