< Deer are expanding north. That could hurt some species like boreal caribou

EMILY KWONG, HOST:

You're listening to SHORT WAVE...

(SOUNDBITE OF MUSIC)

KWONG: ...From NPR.

Hey, SHORT WAVErs. Emily Kwong here with two beloved colleagues for our regular roundup of science news. We got Juana Summers with us. Hello.

JUANA SUMMERS, BYLINE: Hey. Thanks for having me back.

KWONG: Hey. And news roundup veteran, champion, MVP, Regina Barber.

REGINA BARBER, HOST:

Thank you. Yes.

KWONG: We bow down. OK. As you both know, we're going to share three science stories in the news that have caught our attention recently.

SUMMERS: I have heard one of the stories is about growing food on Mars.

KWONG: Yes. We have another about how to build a plastic that can break itself down.

BARBER: And lastly, we have a story about white-tailed deer and how they're expanding throughout Canada.

KWONG: All that on this episode of SHORT WAVE, the science podcast from NPR.

(SOUNDBITE OF MUSIC)

KWONG: All right. Juana, as our guest, which topic do you want to start with? What speaks to you the most?

SUMMERS: I mean, as a good steward of the environment, I feel like I've got to hear about these plastics. It sounds a little too good to be true.

KWONG: OK. Just fair warning - this is just a pilot study. It was published in the journal Nature Communications this week. But it is exciting because plastics are a global problem, Juana, right? Like, according to the EPA, less than 10% of U.S. plastic waste has been recycled.

SUMMERS: Ouch.

KWONG: Plastics also take decades to decompose. Like, they never truly go away. They just break down into smaller and smaller pieces.

SUMMERS: And if I remember correctly, these are called microplastics?

BARBER: Right. So what if I told you that there are these researchers that found a way to embed something special in the plastic to help break it down more quickly? Guess what it is.

SUMMERS: I really should have paid more attention science class. You got to tell me.

KWONG: We'll help you out. It's microbes that love to eat this kind of plastic called polyurethanes that are found in all kinds of things - watch bands, phone cases and footwear.

SUMMERS: OK. Go on.

BARBER: And to break down this polyurethane, the researchers identified a strain of bacteria, which they then engineered to withstand extreme high temperatures so that the bacteria could survive the manufacturing process.

KWONG: And the final product, this microbes-plus-plastic construction - it looked kind of like linguini pasta when it came out.

SUMMERS: Yum.

KWONG: It was this, like, long yellowish strip. And the researchers then put it directly into compost, causing the microbes to wake up and do their thing.

SUMMERS: To eat the plastic?

KWONG: Yes. And after only five months, more than 90% of the plastic had degraded.

SUMMERS: Wow.

KWONG: Adam Feist, a researcher on the study, was pretty pleased with that result.

ADAM FEIST: As our consumption of plastic, you know, skyrockets and is expected to continue to do so, we really need to think about, you know, effective lifecycles of these polymers, you know, what that time of use is and then what the time of, you know, breakdown is.

SUMMERS: That's really interesting. So here's a question. Am I going to be seeing microplastic in my shoes anytime soon?

KWONG: Not anytime soon. Plastics experts I spoke to had a lot of follow-up questions for these researchers. They wanted to know things like, would a product like this break down in a landfill as easily as it did in a lab? Or is this microplastic better than, say, plant-based alternatives already on the market? Still, it is promising. The team wants to do more tests, applying this methodology to other kinds of plastic to ultimately tackle the global plastic pollution problem.

SUMMERS: Worthy goal, for sure, but speaking of...

KWONG: Yeah.

SUMMERS: ...Innovation, Gina, I understand you've got a story about growing crops in space.

BARBER: Yes, I do. And growing food in space is, like, really crucial to future space exploration because bringing cargo from Earth is way too expensive. So scientists like Rebeca Goncalves are looking at growing tomatoes, peas and carrots in Mars-like soil called Mars regolith right here on Earth.

REBECA GONCALVES: We don't need to wait until there's an actual colony on Mars to start researching with actual Mars regolith. Like, we can get there within, like, 90% of the way done already.

SUMMERS: OK. Hold up a second. Earth does not have Martian soil, at least that I'm aware of. So how exactly did they grow these plants?

BARBER: Yeah. So scientists know from Mars rovers what Mars soil is like, and they mixed up a simulation of that using materials from Hawaiian volcanoes and the Mojave Desert.

KWONG: And like the Martian soil, this regolith soil doesn't have a lot of nutrients that plants need. It doesn't have any water. It doesn't have any organic material for them to feed on.

SUMMERS: It sounds like some pretty sad soils.

(LAUGHTER)

BARBER: Mars is harsh, Juana.

SUMMERS: OK. So tell us, what did they do with the soil?

BARBER: Well, we already know that we can grow stuff in this regolith. And they experimented with this technique called intercropping, which is an ideal growing method when resources are limited. The ancient Maya used it to grow the three sisters - corn, beans and squash. The corn providing a structure for the beans. On the bottom, there was squash, where leaves would provide shade to the roots to, like, help maintain soil moisture.

SUMMERS: OK. So using this intercropping technique for the study, what did they find?

BARBER: Yeah. So in this Martian-like soil, intercropping did help. It helped the tomatoes grow better when they were grown with peas and carrots. Unfortunately, though, the peas and carrots didn't do as well. The study was published in PLOS One this week.

SUMMERS: Hopeful for me. I like tomatoes better anyway.

(LAUGHTER)

BARBER: Tomato salads on Mars.

SUMMERS: Yeah (laughter).

BARBER: Here we go - love it.

SUMMERS: So, I mean, this technique seems to help with some crops. But aren't there a whole lot of other variables to consider when you're growing stuff in space, say, like - I don't know - lower gravity?

BARBER: Well, Rebeca isn't worried about lower gravity specifically because, like, tomatoes are already grown in microgravity in the International Space Station. But Amy Grondin, another microbiologist not on the study, mentioned there are other growth and safety factors that need to be looked at, like metals and other toxins in the Mars surface. But she thinks the study has a lot of promise.

SUMMERS: Interesting. All right. Let's move on to our last story. I've heard that deer are moving north. Tell me what that's about.

BARBER: Yeah. So wildlife ecologists have seen white-tailed deer expanding their range in North America over many decades. And since the early 2000s, they've moved north into the boreal forests of western Canada. And these forests are full of, like, spruce and pine trees, sandy soil - freezing winters with a lot of snow. So living there can be, like, really harsh.

SUMMERS: I don't know about y'all, but that does not exactly sound like a place I want to live. So why...

BARBER: No.

SUMMERS: ...Are these deer moving there?

BARBER: It's kind of like a mystery because - is it the warmer climate in these forests that's happening recently, or is it human development that might be pushing them up? So Melanie Dickie, a wildlife biologist at the University of British Columbia Okanagan - she tried to disentangle these two things by hiding 300 cameras in western Canada. And she collected data for five years. And then her team used these images to estimate the number of white-tailed deer there.

KWONG: Now, the beauty of this setup, Juana, is that the team placed these cameras along two axes. Some were north to south, where the winters got more intense as you move north. Some of the cameras were east to west, where the further you move west, the more human disturbance there is. So they were able to look at both factors.

SUMMERS: And what did they find?

KWONG: Well, they found that, like, a warming climate seemed to play the most significant role in the movement of deer, although human land use was a smaller factor. And they published all of these results last week in the journal Global Change Biology.

SUMMERS: OK. And I don't want to be a hater here, but why does it matter if the deer are moving into these new areas?

KWONG: No, fair question. OK. Melanie described these deer as an invasive species. With the deer, come more predators like wolves. And while the deer are able to cope with the wolves, other species, like the boreal caribou, are not. So Melanie says these caribous - they have evolved to mostly just avoid areas with a lot of predators. They're not equipped to handle these wolves at all.

BARBER: And she also says that the deer is just, like, one piece of the puzzle for caribou. But having, like, more information about what exactly is driving the deer expansion will help her and other researchers find out, like, where to start when it comes to restoring land and protecting wildlife like caribou.

(SOUNDBITE OF MUSIC)

KWONG: Juana, thank you so much for hanging out.

SUMMERS: Thank you.

BARBER: You can also catch Juana on Consider This, NPR's afternoon news podcast.

KWONG: Before we head out, a quick shout-out to our SHORT WAVE+ listeners. We appreciate you, and we thank you for being a subscriber. SHORT WAVE+ honestly helps support our show. So if you're a regular listener, we would love for you to join so you can enjoy the show without sponsor interruptions. Find out more at plus.npr.org/shortwave.

BARBER: This episode was produced by Kai McNamee and Rachel Carlson. It was edited by Rebecca Ramirez and Christopher Intagliata.

KWONG: Me, Regina and Rachel Carlson checked the facts, and the audio engineers were Ted Mebane and Patrick Murray. I'm Emily Kwong.

BARBER: And I'm Regina Barber.

KWONG: Thank you for listening to SHORT WAVE from NPR.

(SOUNDBITE OF MUSIC)

Copyright © 2024 NPR. All rights reserved. Visit our website terms of use and permissions pages at www.npr.org for further information.

NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.