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Fish consider the ocean their own personal toilet. Well, researchers found out that's not such a bad thing!

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Fish pee in coral reefs

Earth’s Virome

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The ocean is full of mysterious deep sea life, sunken historical artifacts, and a whole lot of pee. And I'm not just talking about those of you who think that the ocean is your personal porta potty. There are millions of animals that live, eat, and make lots of waste in there. Might sound kind of gross, but a recent study in nature communications showed just how much the nutrients in fish pee help keep coral reefs healthy. Coral reefs get plenty of energy from the sun, but nutrients, like compounds rich in nitrogen and phosphorus are harder to come by.

Fish are like mobile nutrient reservoirs, storing them in their bodies or spreading them around. See, fish excrete waste through their gills, pee, and poop, creating a delicious nitrogen and phosphorous bath for the reef!

So a team led by a researcher from the University of Washington wanted to study how fishing affects the nutrients in 43 Caribbean reefs. Specifically, they analyzed around 73,000 fish, representing 143 species, to learn how the fish excretions changed the chemistry of a sample of ocean water. Using statistical models, they estimated that heavily-fished coral reefs had around half of the measured nutrients of well-protected areas. And the key to a healthy cycle of nutrients? Balance.

Just like a company needs the right mix of employees, a coral reef needs the right mix of fish, because different fish excrete different amounts and different kinds of waste. Some smaller fish, for example, have higher metabolisms and excrete nitrogen faster. Hungry predators, like groupers and barracuda, on the other hand, store more nutrients and pee out more phosphorus thanks to the food they eat.

Unfortunately, these big fish also happen to be very popular with fishermen. That's bad news for the coral ecosystems, because they are losing a lot of nutritious waste. Conservation efforts usually focus on maintaining numbers of different species, and that's still important, but these reefs also need the right balance of fish: big fish, small fish, predators, and prey.

According to these researchers, if we really want to protect coral reefs, we need to understand how these organisms interact and share nutrients, even and especially through their pee.

But you know what else is in sea water and soil and your body? Viruses. There might be more viruses on earth than there are stars in the observable universe, and we think they can infect every known life form: bacteria, humans; nothing is safe.

We know a lot about a few viruses, mostly the ones that infect humans, but now, thanks to some powerful computing and a tool called CRISPR, the global scope of viruses is becoming clearer than ever before.

A research team at the US Department of Energy analyzed over five trillion DNA bases, that's five terabases, looking for new viral genes. They took 3,000 DNA samples from around the world, from sea water to soil and hot springs to the human body, and they combed through these samples using software that recognized viral DNA sequences. Viral genes could be anywhere in those terabases, usually embedded in the DNA of some infected organism.

After years of searching and improving their software, we now know of around 16 times more viral genes than we used to. Using those genes, the researchers wanted to figure out which viruses infect which species, mostly focusing on bacterial hosts, so they used CRISPR.

Recently, CRISPR has been hitting the headlines as a revolutionary gene editing tool, but in the wild, bacteria use CRISPR to defend themselves against their viral enemies, bacteriophages. Whenever they defeat a virus, the bacteria snip out a gene fragment and store it in a special part of their DNA called a CRISPR locus. Like a row of Most Wanted posters, CRISPR helps them find and destroy bacteriophages if they return.

The team of researchers compared these Most Wanted posters to their viral database, and found nearly 10,000 new matches. But what's the point of knowing which viruses can infect most bacteria?

Turns out, we have our own uses for bacteriophages. A couple types are used in FDA-approved treatments for meat and cheese, keeping bacteria at bay so food is safe to eat. Others can screen for bacterial infections like the deadly MRSA. Or, these bacteriophages could eventually be used as phage therapy instead of antibiotics to target, infect, and kill certain harmful bacteria without destroying our friendly microbes.

Not to mention, with a huge viral database, it might be easier to fight off a new virus that infects humans, especially if we've seen something like it infecting other species. Thinking beyond human health, bacteria are really important for global nutrient cycles, kind of like the fish pee in the coral reefs, but everywhere. And viruses that infect that infect these bacteria could have a major influence on these cycles, but we barely know anything about them right now.

So these researchers are working on expanding their database and creating an open resource for scientists worldwide. With a catalogue of genes that encode nearly 3 million new viral proteins, they've made a strong head start!

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