What Are Flies Doing In The Middle Of The Ocean?

Summary

Short Wave Podcast Episode Summary

Episode Title: What Are Flies Doing In The Middle Of The Ocean?
Date: October 3, 2025
Hosts: Regina Barber, Emily Kwong
Guest Host: Ailsa Chang (All Things Considered)
Runtime (content): ~00:54-09:29

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Overview

This episode dives into new scientific mysteries and discoveries, all with Short Wave’s signature fun and accessibility. The hosts and their guest break down three recent head-turning studies:

• The surprising appearance of hoverflies on North Sea oil rigs and what this reveals about insect migration and plant genetics,
• Unexpected growth trends in Amazon rainforest trees in response to greenhouse gases,
• And, a fascinating peek into the underwater world of fish sounds and their importance in reef health.

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Segment 1: Hoverflies in the Middle of the Ocean

Timestamps: 02:51–05:13

Key Points

• Observation on Oil Rigs: Engineers on a North Sea oil rig noticed thousands of flies landing, staying still for hours, and then leaving together.
• Species Identified: These were hoverflies—important, if underrated, pollinators, second only to bees.
• Sample Collection & Research: Craig Hanna, the engineer, began collecting hoverflies that landed and sent them to University of Exeter scientists.
• Pollen Analysis: "These six flies were carrying more than 100 species of plants." (Regina Barber, 03:54)
  • Pollen included common nettle, black elder, and meadowsweet.
  • Wind trajectory analysis suggested some flies came from over 300 miles away (the Netherlands, N. Germany, Denmark).
• Ecological Implications:
  • Gene Exchange: Hoverflies might introduce new genes across distant plant populations.
  • Quote: “This exchange of genes that can happen in both directions might help plants to adapt to climatic change, for example.” (Entomologist Gerard Talavera, 04:58)
• Next Steps: Researchers want to test if pollen survives the journey and successfully pollinates.

Memorable Moment

• Guest Ailsa Chang’s reaction:
  “Okay, I’m impressed now.” (04:06)

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Segment 2: Amazon Rainforest Trees Growing Larger

Timestamps: 05:13–06:58

Key Points

• Study Findings: Trees in the Amazon have increased in size by about 3% each decade over the last thirty years.
• Cause: Attributed mainly to higher carbon dioxide levels due to burning fossil fuels.
• Complex Impacts:
  • Positive: Trees are absorbing more carbon, mitigating climate change.
  • Caution: Deforestation and climate-related stresses (drought, heat, fire) remain threats.
• Expert Voices:
  • “Now we have to stop deforesting because we need those forests to provide these services for us.” (Study author quoted by Regina, 06:31)
  • “It’s important to remember this study is just one snapshot of the rainforest. It doesn’t tell us how the trees will continue to respond in the future...” (Becky Banbury Morgan, paraphrased, 06:49)
• Bottom Line: Amazon forests are showing resilience, but continued threats could change this trend.

Memorable Moment

• Ailsa’s curiosity:
  “Wait, what? Our greenhouse gas pollution is actually helping these trees get bigger and bigger?” (05:37)

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Segment 3: The Strange and Secret Sounds of Fish

Timestamps: 06:58–09:15

Key Points

• Fish Are Sonorous: Fish make sounds using teeth, fins, or special muscles.
• Audio Examples Played:
  • Longspine squirrelfish vibrating its swim bladder.
  • Three spot damselfish snapping its teeth.
• Why Study These Sounds?
  • Building a “sound library” (now 50 species) helps catalog and identify fish species present in a coral reef.
  • Similar methods are used for birds and whales, but much less for fish.
  • Advanced techniques now pair underwater microphones with 360° video to match fish to specific sounds.
    • “By combining 360 video ... we can actually match the visual image of the fish with the sound it’s producing.” (Aaron Rice, Cornell University, 08:17)
• Implications for Science:
  • Monitoring reef health and fish populations non-invasively.
  • Assessing mating, migration, and environmental well-being.
  • “You can't really listen to the corals. You can listen to the fish and they can tell you something about the overall health of the reef.” (Mark Dan, lead author, 09:03)
• Future Improvements: Researchers want to fine-tune visual-audio technology to increase accuracy.

Memorable Moment

• Ailsa Chang’s surprise:
  “Wait, fish make sounds? I had no idea fish can even make sounds.” (07:06)

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Notable Quotes

• On hoverflies:
  “These six flies were carrying more than 100 species of plants.”
  (Regina Barber, 03:54)

• On gene exchange via hoverflies:
  “This exchange of genes that can happen in both directions might help plants to adapt to climatic change, for example.”
  (Gerard Talavera, 04:58)

• On Amazon resilience:
  “Now we have to stop deforesting because we need those forests to provide these services for us. And they can resist, at least for now.”
  (Study author, paraphrased by Burleigh McCoy, 06:31)

• On fish sounds & reef health:
  “You can't really listen to the corals. You can listen to the fish and they can tell you something about the overall health of the reef.”
  (Mark Dan, 09:03)

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Episode Tone & Style

• Conversational, playful and accessible: The hosts riff on insects being both "gross and cool," marvel at fish sounds, and keep the science relatable.
• Science-first: The focus is on surprising findings, their implications, and the ongoing questions each study raises.
• Encouragement for Curiosity: The episode closes with gratitude for curiosity and an invitation to explore more.

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Further Listening

• More of guest host Ailsa Chang can be heard on NPR’s “Consider This,” as promoted at the end of the episode.

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Transcript

[A]

This message comes from W.W. norton & Company, publishers of replaceable Adventures in Human Anatomy, the new book by Mary Roach, best selling author of Fuzz and Stiff, Mary Roach's Replaceable you, now available wherever books are sold. This week is a milestone. The first week that NPR and stations across the country operate without federal funding. That might sound like a loss, but to me it sounds like a declaration that our strength has always come from you. And I think about the connection we share every time you turn on the radio or hit play. Your trust in me, in us, is what fuels everything we do. We won't go dark. We'll keep bringing you the stories, the music, the conversations that matter to you and our country. Because we belong to you, the people who power us. You're listening to short wave from NPR. Hey, shortwavers.

[B]

Regina Barber here and Burleigh McCoy with.

[A]

Our bi weekly science news roundup featuring the hosts of All Things Considered. And today, we have the west coast host with the most Ailsa Chang.

[C]

West coast is the best coast. Thank you so much, guys. So I hear we are going to be talking about flies on oil rigs. So gross.

[B]

So gross. Oh, they're cool. But also a surprising finding in the Amazon forest.

[A]

And lastly, fish sounds in a coral reef.

[C]

Cool. Okay, so we've got flies hovering in the air. We've got some forest action and we got some snow.

[A]

Yeah, yeah, we have it all. You're listening to Short Wave, the science podcast from npr.

[D]

Support for npr, and the following message come from Edward Jones. What does it mean to live a rich life? It means brave first leaps, tearful goodbyes, and everything in between. With over a hundred years of experience navigating the ups and downs of the market and of life, your Edward Jones financial advisor will be there to help you move ahead with confidence. Because with all you've done to find your rich, they'll do all they can to help you keep enjoying it. Edward Jones Member, SIPC this message comes from Schwab. Everyone has moments when they could have done better. Same goes for where you invest. Level up and invest smarter with Schwab. Get market insights, education and human help when you need it. This message comes from Bonterra. Your nonprofit's mission is big, but your team is small. With fundraising software from Bonterra's network, for good, you can focus on changing lives. Big impact, less stress. Learn [e-mail] NFG all right, to start.

[C]

Us off, tell me about these flies hanging out in the middle of the ocean.

[B]

Yeah. So this story Starts with an oil rig in the North Sea that's between the U.K. norway and Denmark. And on this rig, engineer Craig Hanna noticed that sometimes thousands of flies would land on the rig in the middle of the ocean, stay really still for hours, and then take off again all at once.

[C]

Okay, so what exactly are these flies doing out there?

[A]

Yeah, so they're a type of fly called a hover fly. They're stripy, they're often confused with be, and they're an unsung pollinator. They're in the second most important group after bees, and they migrate often hundreds of miles, which explains why they're in the middle of the ocean. Craig, who's also a bit of a naturalist, thought scientists might be interested in studying these insects in the open ocean, since most bugs are studied from land. So he started collecting fly samples whenever groups of hoverflies landed, and he sent them to a research team at the University of Exeter.

[C]

I'm sorry, I think bees are way cooler than flies, but. Okay, what did the team learn about these flies?

[B]

Okay, so Eva Jimenez Guri, a biologist on the team, says they were surprised by how much pollen the hoverflies were carrying. And These are the six flies were carrying more than 100 species of plants.

[C]

Wow. Okay, I'm impressed now.

[B]

Yeah. And that included common nettle, black elder, and meadow sweet. And when the team looked at wind trajectories for the flies Craig collected, they determined that some of them likely came from the Netherlands, northern Germany, and Denmark, north, more than 300 miles away. So Eva and her team published the results in the Journal of Animal Ecology earlier this month.

[C]

Wait, what does it mean that these hover flies are carrying so much pollen over these huge distances?

[A]

Yeah. Eva says this is likely the first time scientists have looked at the pollen that flies are carrying over water at this distance. Gerard Talavera, an entomologist who wasn't involved in this paper, says these flies could have a big impact on pollination when they arrive at their destinations. And he says hoverflies could be important in introducing brand new genes to faraway plants on their journey.

[D]

And this exchange of genes that can happen in both directions might help plants to adapt to climatic change, for example.

[B]

So next, the researchers want to test if this long distance pollen survives the journey and can actually pollinate plants.

[C]

Hmm. Okay, let's jump to a totally different part of the world. The Amazon rainforest. Burleigh, what is the news over there?

[B]

Yeah, so a new study out in the journal Nature Plants found that trees in the Amazon rainforest have increased in size on average in the last three decades. The researchers say that's likely a result of more carbon dioxide in the atmosphere from burning fossil fuel.

[C]

Wait, what? Our greenhouse gas pollution is actually helping these trees get bigger and bigger?

[B]

Yeah, in a way. The trees grew by about 3% each decade the researchers studied, which is more than expected. They say that's a reminder that trees play a significant role in taking in carbon dioxide, CO2, and helping fight climate change.

[A]

But the researchers wanted to clarify that this finding doesn't mean the Amazon is totally fine. Even though the trees seem to be getting bigger. Deforestation does pose a huge threat to the Amazon. And climate change more broadly is linked to drought, which kills trees and means the forest can't store as much carbon. Right.

[C]

So what does all that carbon mean for the long term health of the Amazon then?

[A]

Yeah, so it means that the forest is resilient for now. One of the study authors, Adriani Esquivel.

[C]

Muehlbert, the Amazon has this capacity to.

[B]

Tolerate changes in climate. Now we have to stop deforesting because we need those forests to provide these services for us. And they can resist, at least for now. Another study author, Becky Banbury Morgan, added, it's important to remember this study is just one snapshot of the rainforest. It doesn't tell us how the trees will continue to respond in the future, especially with those climate related factors like heat, stress, w fires and drought.

[C]

Okay, let's go under the sea now, under the sea and listen to some sounds that. Wait, fish make. I had no idea fish can even make sounds.

[A]

I, I mean, I didn't really realize this either until I started reporting on it, but fish can make sounds. They sometimes use their teeth or their fins or like muscles attached to their swim bladder. Here, Elsa, take a listen. So that's a long spine squirrelfish vibrating its swim bladder off the coast of Curacao, an island north of Venezuela. And it lives in the coral reef reefs there. And here is a three spot damselfish and it's rubbing or snapping its teeth.

[C]

Okay, why are these researchers even listening to these fish?

[B]

So these sounds allow them to take a sort of census of which fish are living in a certain area. And scientists have sound libraries like this for various birds and whales. But it's much more limited for fish. So these researchers just built a sound library of 50 fish species which they wrote about in the journal Methods in Ecology and Evolution.

[C]

But to record these sounds, like, is it as simple as sticking a special microphone into the water? Like, how do they do this?

[B]

Well, they do use underwater Microphones, but they couple those with a 360 video system. Here's Aaron Rice from Cornell University and a co author of the study.

[D]

By combining 360 video and being able to sort of look all the way around us for the first time, we can actually match the visual image of the fish with the sound that it's producing.

[A]

Although the researchers do note that this camera mic system needs improvement to, like, more accurately match the visuals with specific sound.

[C]

Okay, well, tell me, how can these sounds help marine biologists?

[B]

Yeah. If, if they listen to a fish population, they can decipher which fish are thriving there, whether they're mating because they make different sounds for courting, and also whether they're migrating to different parts of the ocean. And that can tell scientists something about their environment. Here's Mark Dan. He's a marine biologist and lead author of the study. You can't really listen to the corals. You can listen to the fish and they can tell you something about the.

[A]

Overall health of the reef. He's hopeful that knowing more about which fish exist in which reefs and how many of them there are there can tell us more about the reef without using, like, more intrusive methods like catching fish.

[C]

Ooh, very cool.

[A]

I think so. Elsa, thank you so much for hanging out with us. It's always a pleasure.

[C]

Oh, I love doing this, you guys.

[B]

We love having you on the show.

[A]

Please, thank you so much.

[C]

I love being here. Thank you to both of you.

[A]

You can hear more of Elsa on consider this NPR's afternoon podcast about what the news means for you. This episode was produced by Jordan Marie Smith and Rachel Carlson. It was edited by Rebecca Ramirez, Patrick Jaron Watananan and Christopher Intagliata.

[B]

Tyler Jones checked the facts. Tiffany Vera Castro and Patrick Murray were the audio engineers. I'm Burley McCoy.

[A]

And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from npr.

[D]

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