Overfishing is taking away many of the big fish species that live in coral reefs, but just as importantly, it’s taking away their pee, according to a report in EurekAlert on a new study published in the journal Nature Communications. Rich in phosphorus and nitrogen, the urine of large predator species like grouper and snapper are vital to coral ecosystems.
Research published during the 1980s showed that when fish were present, reefs grew twice as fast when they weren’t. Now scientists are beginning to understand why.
“Fish hold a large proportion, if not most of the nutrients in a coral reef in their tissue, and they’re also in charge of recycling them,” says the new study. “If you take the big fish out, you’re removing all of those nutrients from the ecosystem.” In order to protect declining coral reefs, new policies have to be enacted to also safeguard predator fish, say the study’s authors.
“Phosphorus in fish pee and nitrogen excreted through their gills are important nutrients for coral reefs to grow,” says EurekAlert. “In many reef communities, fish will take shelter in and around coral during the day — peeing out valuable nutrients — then forage for prey in and around the reef by night.” It’s a fragile balance that’s easily upset, however, when key fish species disappear.