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

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.

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)

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)

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)

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)

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.

Further Listening

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