[♪ INTRO] Imagine you’re an adorable black rat.

You’re eking out a living when you accidentally end up on a ship bound for a distant land. A tropical island in the Chagos  Archipelago in the Indian Ocean.

And life there is great. So great you and all your rat  buddies become an invasive species, and wreak all sorts of havoc  on the native wildlife. Last week in the journal Nature Ecology &  Evolution, scientists proposed how these invasive rats can not only  impact the happenings on land.

They can also influence the behavior of fish. Jewel damselfish can be found farming in  the coral reefs around the Chagos islands, aggressively defending their  small fields of algae turfs. Yes, you heard me right.

These fish do really seem to farm…pruning,  pooping, and protecting their fields in a manner that makes them more productive. But these farms are especially  worthy of defense because, under typical circumstances, a lot of  seabirds call the Chagos Archipelago home. These birds nest on the islands and  do a lot of their own pooping there.

That poop eventually washes out to sea,  where it can provide oodles and oodles of delicious nitrogen fertilizer, making  the algae chock full of nutrients. On some level, the fish know  just how valuable this algae is, so they invest energy into defending their turf. They’ll chase away other fish in high-speed  bursts, bite them, and head-butt them.

Presumably because doing this is  harder when you’re underwater. But back in the 1700s, ships carried  invasive black rats to some of the islands. With no natural predators, they  basically had their run of the place.

And the native seabirds  offered up a pretty easy feast. Today, the rat-free Chagos islands  have about 760 times as many birds as the invaded islands do. And fewer birds means less bird poop.

So the team behind this study wanted to see what that decrease in bird poop  meant for the fish farmers. In the coral reefs around ten different islands, they installed GoPros to monitor the territory  and behavior of six jewel damselfish. Five of the islands were home to invasive  rats, while the other five were rat-free.

They also used the cameras to estimate the  size of one fish’s territory at each island. It turns out that fish near the rat-infested  islands tended to have larger territories. And that’s likely because the algae they  were farming was less nutrient-dense.

With fewer birds to contribute  their fertilizing poop, each fish would have to farm more than  their counterparts near rat-free islands to get the same amount of  nutrients from their food. But interestingly, these fish with larger  territories also tended to protect them less. They were less aggressive.

Now, we can’t actually know the thoughts  that are running through the brains of these fish, but the researchers  interpreted this change in behavior as the fish deciding it just wasn’t  worth defending their algae as much if they’re not getting this nutrient gold mine. That being said, maybe the fish  whose farms got fewer poop nutrients were also choosing to spend more time farming, which would make less time available for fighting. Unfortunately, the researchers didn’t  investigate their farming behavior.

But the results of this  experiment do at least suggest that invasive species on land have the  ability to influence marine ecosystems. Which the ultimate invasive species,  us, can definitely also attest to. And having a bunch of gentler fish  farmers isn’t the only outcome, here.

The jewel damselfish’s behavior  influences the social behaviors and space use of other fishes in the  area…which means it’s absolutely possible that the rats’ impacts reach  even farther than this. We’ll just need some follow up  studies, with more ocean-based GoPros, to see just how strong an influence  these small furry immigrants have on their new home. But black rats aren’t the only  invasive species in the news.

Our second story looks not only at how an  invasive species can impact ecosystems, but at how hard it can be for  scientists to study how they spread. Two weeks ago in the journal Computers,  Environment, and Urban Systems, one team explored how observations  from news and social media could be used to help those scientists out. If you want to successfully control  the spread of an invasive species, you’ve got to act fast.

That requires lots of data about  how pests have spread in the past and up-to-the-minute data on  how they’re spreading now. And while field observations,  official reports, and genetic records are often eventually available,  getting through red tape or peer review means they can be pretty delayed. So what’s super fast?

Well, news and social media. Now, using these sources to  supplement ecological observations, or as a kind of citizen science, isn’t a new idea. But these researchers wanted to make sure  it held up for invasive species, too.

They picked two invasive insects: spotted  lanternflies and tomato leaf miners. While the lanternflies are mostly  a problem local to Pennsylvania and its neighboring states, the miners  have spread all around the world. Because they’re looking at invasions  that have already happened, the team wanted to see if online  aggregators like Google News could do a good job scraping news sites and social media platforms (or at least  Twitter) for old mentions of each pest.

In addition to comparing a local versus  global invasion, they also looked for mentions across different timescales: in different  years and across a whole decade. And while there was some variation  between the three aggregators they tested, all of them were able to find  Tweets and news media mentions that provided accurate and useful information. Not only did the information generally match up with the stuff found in  official science-y sources, it also provided more specific details  about when and where the insects had spread.

And because people often had  some pretty snarky things to say about how their governments  were managing the situation, the authors noted that tweets  could help scientists understand how well different management  strategies are being implemented. After all, what is social media for  if not to post photos of your pets and complain about the government? But overall, this is good news.

This research suggests that social  and traditional news media could have an important role to play in getting  citizen observations to researchers. Which is awesome, because honestly, we  need all the help we can get to understand and combat the wild ways that invasive  species can impact the ecosystems they join. And also it’s nice to hear  about a way that social media is being used to do something that’s not bad.

Thanks for watching this episode of SciShow news. If you’d like to learn more about  invasive species, we’ve got you covered. Like this episode on weird ways  we’ve fought off invasive species, or this one about how some  non-native species aren’t all bad.

Just click to continue  learning more about your world. Because it doesn’t actually take up  any physical space in your brain. …maybe it does. Electrons aren’t very big. [♪ OUTRO]