Coral Reefs Need Fish Pee To Survive, Says New Study

First Posted: Aug 17, 2016 03:55 AM EDT

Beautiful fish can usually be found in equally beautiful coral reefs, but while it seems that they are taking advantage of these corals to use as their homes, it was found that corals too, take advantage of fish.

Recent studies showed that coral reefs are actually as depended to fish, as these animals have key nutrients to help them grow. It was found that when fish urinate, they release phosphorus - which, along with nitrogen excreted as ammonium through fish gills, is crucial for the survival of corals.

The study, published in Nature Communications said that in coral reefs where fishing occurs, nearly half of the key nutrients are absent from the ecosystem because fewer large-bodies and predator fish get to pee nutrients in the water.

 "Part of the reason coral reefs work is because animals play a big role in moving nutrients around," Jacob Allgeier, a postdoctoral researcher at the University of Washington School of Aquatic and Fishery Sciences said. "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. If you take the big fish out, you're removing all of those nutrients from the ecosystem."

Co-authors Abel Valdivia from the Center for Biological Diversity in San Francisco and Courtney Cox of the Smithsonian Marine Station at Fort Pierce, Florida surveyed 143 species of fish from 110 sites across 43 Caribbean coral reefs. They found that those with more predatory fish had healthy levels of nutrients, while those with less large fish had nearly 50 percent fewer nutrients.

Allgeier shared, "Simply stated, fish biomass in coral reefs is being reduced by fishing pressure. If biomass is shrinking, there are fewer fish to pee."

Coral reefs are a very delicate ecosystem - while they are highly productive for the biodiversity that they support, they don't have a lot of nutrients to spare, so there must be an efficient transfer of these nutrients for the coral to grow. Today, coral reefs have been declining in health, and fish practices had been targeting large predator fish - leading to their poor recovery.

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