Among the coral reefs of the Chagos Archipelago
...“invasive rats have decimated seabird populations in nearly all of the world’s island chains,” including on islands near half of the reefs her team studied.” Without seabirds and their fertilizing guano, the diversity of fish species dropped by 11.4 percent around islands where rats live.
Benkwitt and her team then examined the relationship between fish diversity and the ecosystem’s properties. For every 10 percent increase in diversity, a reef’s total fish biomass—the sheer amount of piscine life it contained—rose by 15 percent. Its productivity, or the rate at which energy is converted into biomass, increased by 17 percent. If one imagines a coral reef as a giant engine, then Benkwitt’s findings suggest that biodiversity is its fuel.
Other research by Benkwitt’s team suggests that guano-nourished reef ecosystems are quicker to recover after bleaching events. Such results underscore the importance of biodiversity for maintaining healthy reefs—not only in the Chagos Archipelago, but in reef ecosystems around the world. With a more varied assemblage of fish, coral, algae, and other organisms, reefs will have a greater chance of surviving.
