Short Wave: Sea Camp Episode Summary
Title: Sea Camp: The Largest Daily Migration On Earth
Release Date: July 28, 2025
Hosts: Regina Barber and Emily Kwong
Guest: Noel Boland, Fisheries Biologist at NOAA

Exploring the Twilight Zone of the Ocean

In this episode of Short Wave’s Sea Camp series, hosts Regina Barber and Emily Kwong delve into the enigmatic Twilight Zone of the ocean, also known as the mesopelagic zone, which spans depths of 200 to 1,000 meters (approximately 650 to over 3,000 feet). This zone is characterized by dim sunlight and remains one of the least explored parts of the ocean due to its challenging conditions, including high pressure and low oxygen levels.

Regina Barber opens the discussion by likening the Twilight Zone to the mysterious Twilight Zone TV show, highlighting its elusive nature (00:53). Emily Kwong emphasizes the difficulty in accessing this zone, noting the high pressure and scarcity of oxygen that deter extensive human exploration (01:09).

The Largest Synchronous Migration

The conversation shifts to a fascinating discovery from World War II, where military sonar operations inadvertently observed unusual signals bouncing off what appeared to be the ocean floor moving upwards (01:34). This anomaly puzzled scientists until Noel Boland explained that these signals were actually the result of the largest synchronous migration on Earth.

This daily migration, known as diel vertical migration, involves massive numbers of mesopelagic organisms, including mollusks, shrimps, jellyfish, and the uniquely adapted flashlight fish, ascending to the ocean's surface under the cover of night to feed and then returning to deeper waters before dawn (01:50 - 02:43). Emily Kwong humorously compares the migration distance to walking from San Diego to Los Angeles for dinner, underscoring the immense scale and energy involved (02:18).

Noel Boland highlights the significance of these organisms in global ecosystems, stating, “They matter for our ability to understand how our habitats are linked” (12:02).

Carbon Cycle and Ecological Impact

The hosts and Boland explore the crucial role these migrating organisms play in the carbon cycle. As these creatures consume carbon-rich phytoplankton at the surface, they transport carbon to deeper waters through their waste (poo and fecal matter) and when they die, effectively sequestering carbon in the mesopelagic zone (06:48 - 07:38). Emily Kwong explains, “Whatever they've consumed, they take it back down to depth and into the mesopelagic” (06:51).

This process helps mitigate atmospheric CO₂ levels, as the carbon is stored in the ocean rather than remaining in the atmosphere. However, Boland raises concerns about human activities such as mining and fishing in the Twilight Zone, which can disrupt these natural processes by disturbing sediments and releasing stored carbon back into the atmosphere (09:03 - 09:52).

Human Impact: Fishing, Mining, and Climate Change

The episode further examines the impact of climate change on the Twilight Zone. Emily Kwong notes the expansion of low-oxygen pockets within this zone, a phenomenon known as shoaling, which creates hostile environments for many organisms not adapted to such conditions (09:56 - 10:44). Regina Barber aptly compares this to desertification, where regions unsuitable for life are spreading, pushing species to the margins of their habitats (10:44 - 11:06).

Boland stresses the urgency of understanding these changes, stating, “If we can't get our science out, we can't get the word out, then I think what ends up happening is we. We all start moving in the dark” (11:23). He underscores the necessity of continued research to map the distribution and behavior of Twilight Zone organisms and to communicate these findings effectively to the public (11:08 - 11:23).

The Path Forward: Research and Communication

In discussing future research priorities, Boland emphasizes the importance of not only conducting studies on the Twilight Zone but also effectively communicating their implications for human society and the planet. He highlights the challenges posed by funding cuts to NOAA and the broader issue of public engagement in marine science (12:02). Boland expresses concern over the loss of valuable scientific data and stresses that even seemingly obscure species play critical roles in maintaining ecological balance (12:02 - 13:02).

Regina Barber and Emily Kwong conclude the conversation by reiterating the significance of the Twilight Zone’s health to the planet and humanity, encouraging listeners to support scientific research and advocacy efforts.

Key Takeaways:

• Twilight Zone (Mesopelagic Zone): A mysterious ocean layer between 200 to 1,000 meters deep, crucial for global carbon cycling.
• Diel Vertical Migration: The largest synchronous migration on Earth, where mesopelagic organisms move to the surface at night to feed and return to depth by day.
• Carbon Sequestration: Migrating organisms play a vital role in transporting carbon from the atmosphere to the deep ocean, aiding in climate regulation.
• Human Impacts: Activities like fishing and mining disrupt the Twilight Zone’s ecosystems, releasing sequestered carbon and harming marine life.
• Climate Change: Leads to expanding low-oxygen areas in the Twilight Zone, threatening many species and overall ocean health.
• Research and Communication: Ongoing scientific studies and effective public communication are essential to understand and protect this vital ocean zone.

Notable Quotes:

• Emily Kwong (02:18): “So that's like saying, oh, Emily, you know, I'm really hungry. We're in San Diego right now. What are we gonna do for dinner? I know the sun is going down. Let's start walking to Los Angeles for dinner.”
• Noel Boland (12:02): “You can do anything.”

This episode underscores the critical importance of the Twilight Zone in maintaining ecological balance and combating climate change, while also highlighting the pressing need for continued research and public awareness.