An analysis of fossilized parrotfish teeth and sea urchin spines by researchers at Scripps Institution of Oceanography at the University of California San Diego showed that when there are more algae-eating fish on a reef, it grows faster.
In the new study, published in the Jan. 23 issue of the journal Nature Communications, Scripps researchers Katie Cramer and Richard Norris developed a 3,000-year record of the abundance of parrotfish and urchins on reefs from the Caribbean side of Panama to help unravel the cause of the alarming modern-day shift from coral- to algae-dominated reefs occurring across the Caribbean.
"Our reconstruction of past and present reefs from fossils demonstrates that when overfishing wipes out parrotfish, reef health declines," said Cramer, a postdoctoral researcher at Scripps and lead author of the study.
Algae-eating parrotfish, like other herbivorous reef fish, play an important role in coral reef ecosystems by removing the algae that compete with corals. According to the study, the decline in herbivorous fish such as parrotfish over the last several decades from fishing is considered a main factor in the shift to more algae-dominated reefs in the Caribbean.
The Scripps researchers examined the amount and composition of fish, coral, and urchin fossils in 3 to 5-meter (10 to 33-feet) long sediment cores from three reef sites offshore of Bocas del Toro, Panama to understand the natural state of the reefs before humans began intensive fishing and land clearing, and to assess the role of these activities in recent reef declines. The analysis was aimed at determining if coral growth rates are affected by change in the population levels of parrotfish or urchins that eat algae.
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