Solving a Centuries-Old Maritime Mystery

Short Wave
Episode: Solving A Centuries Old Maritime Mystery
Host: Regina Barber
Release Date: June 2, 2025

Introduction to the Milky Seas Phenomenon

The episode opens with Regina Barber setting the scene in 1849, describing a serene night at sea disrupted by an inexplicable glow emanating from the ocean's surface. This luminescent phenomenon, known as "milky seas," has baffled sailors and scientists alike for over four centuries.

Regina Barber [00:16]: "You're on a ship coasting through the middle of the ocean at night... a glow not from another ship or the night sky, but from the surface of the sea."

Historical Accounts and Early Skepticism

Justin Hudson, an atmospheric science researcher at Colorado State University, delves into the historical documentation of milky seas. He highlights how early accounts, often dismissed as tall tales by intoxicated sailors, gradually gained credibility over time.

Justin Hudson [01:28]: "A lot of them were written off as just, you know, drunk sailors at the bar trying to impress each other with more... better tall tales."

Regina notes that it wasn't until approximately a century ago that these reports began to be taken seriously, thanks in part to more reliable sources like naval and commercial vessels.

Stephen Miller [02:00]: "These are trustworthy accounts. These aren't... pirates and sailors of yore talking... spinning their tall tales."

The Scientific Pursuit: Building the Milky Seas Database

Justin Hudson's PhD research involved compiling a comprehensive database of milky sea sightings and satellite images, aiming to unravel this enduring mystery. Highlighting the scarcity of scientific samples, Regina mentions the lone research vessel that successfully collected a sample in 1985.

Regina Barber [02:30]: "One group definitely not spinning... took the only scientific sample in 1985."

Stephen Miller explains the logistical challenges in studying milky seas, primarily due to their remote locations in the vast oceans.

Stephen Miller [02:40]: "Milky seas tend to be very remote and... very few people out in any one given spot."

Unraveling the Mystery: The Role of Vibrio harveyi

A significant portion of the episode is dedicated to understanding the biological underpinnings of milky seas. The leading hypothesis centers around a specific bacterium, Vibrio harveyi, known for its bioluminescent properties.

Stephen Miller [07:25]: "Certain bacteria will colonize... their population will increase... they'll start to glow."

These bacteria emit chemicals called autoinducers, which trigger them to glow once they reach a critical concentration. This bioluminescence is theorized to attract predators, facilitating the bacteria's return to the gut of marine creatures.

Stephen Miller [07:25]: "They emit... a chemical... which they can also detect as being unique... triggers these bacterial colonies to begin glowing... to attract a higher order predator like a fish."

Comparing Bioluminescent Mechanisms

Regina poses a critical question about how Vibrio harveyi differs from other bioluminescent organisms like fireflies and dinoflagellates.

Regina Barber [09:06]: "What does this bacteria do? How does it glow? And how is that different from the bioluminescence we have seen in fireflies or other marine bioluminescence?"

Justin Hudson clarifies that unlike dinoflagellates, which use bioluminescence as a defense mechanism, Vibrio harveyi uses it as an attractant for predators. This distinction underscores the unique ecological role of the bacteria in creating milky seas.

Justin Hudson [09:21]: "...with this Vibrio harveyi... it's glowing and actually not to scare away predators, but to attract predators intentionally."

Historical Insights and Modern Challenges

Justin reflects on historical perspectives, noting that figures like Benjamin Franklin and Captain Newland had already hypothesized the involvement of microscopic organisms in the 18th century. Despite their early insights, significant progress in understanding milky seas has been slow.

Justin Hudson [10:13]: "It's a little depressing and shows just kind of how hard it is to actually study this."

The Importance of the Database and Future Research

Stephen Miller emphasizes the necessity of the database in correlating milky sea occurrences with environmental parameters like sea surface temperature and wind patterns. The goal is to leverage real-time satellite imagery to predict and study these rare events more effectively.

Stephen Miller [11:31]: "We're looking for relationships between when Milky Seas happened and other parameters that we measure all the time... sea surface temperature changes... wind directions."

The researchers aim to deploy resources swiftly upon detecting potential milky seas, acknowledging the transient nature of these phenomena.

Stephen Miller [12:12]: "Milky sea may not last more than a few days."

Broader Implications and Future Directions

As the episode draws to a close, both Justin and Stephen discuss other unexplored bioluminescent phenomena in the ocean. Justin expresses interest in rare forms of bioluminescence that remain undocumented, while Stephen highlights the broader scientific intrigue of milky seas as a reflection of complex Earth system interactions.

Stephen Miller [13:13]: "Milky Seas... a really remarkable kind of natural wonder... scientifically it's very, very cool and intriguing as well."

Conclusion

Regina Barber wraps up the episode by thanking her guests and summarizing the significance of their research in demystifying a centuries-old maritime mystery. The collaboration between historical accounts, modern databases, and scientific inquiry exemplifies the ongoing quest to understand the ocean's enigmatic phenomena.

Notable Quotes:

• Regina Barber [00:16]: "You're on a ship coasting through the middle of the ocean at night... a glow not from another ship or the night sky, but from the surface of the sea."

• Justin Hudson [07:25]: "Certain bacteria will colonize... their population will increase... they'll start to glow."

• Stephen Miller [09:06]: "You know, this is a hypothesis. We don't know for sure that this is what's happening, but it's the leading hypothesis."

• Stephen Miller [13:13]: "Milky Seas... a really remarkable kind of natural wonder... scientifically it's very, very cool and intriguing as well."

This episode was produced by Rachel Carlson, edited by Rebecca Ramirez, and fact-checked by Tyler Jones. Audio engineering was handled by Jimmy Keeley, with special thanks to Mark Patience for the sailor voiceover.