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How does seawater affect the transmission of blue-green light?

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time-lapse photo of fireflies — Bioluminescence Time-lapse image of fireflies in the Catskill Mountains, New York. Firefly light is a cold light, with approximately 100 percent of the energy given off as light and only a minute amount as heat. Only light in the visible spectrum is emitted.

Seawater affects the transmission of light by causing both refraction and attenuation, which is the decrease in light intensity as it travels through the water column. While other wavelengths of the electromagnetic spectrum—such as ultraviolet and infrared—are absorbed rapidly, blue-green light is the most effectively transmitted through seawater.12

Because blue-green light experiences the least amount of attenuation compared to other visible wavelengths, it can penetrate to greater depths. This property is significant for marine bioluminescence, as many deep-sea organisms have evolved to produce light in the blue-green range, which is the most visible and transmissible light in their environment.12

The actual rate of light loss varies depending on the clarity of the water; in the most transparent oceanic waters, blue-green light experiences significantly less percentage loss per meter than violet, yellow, orange, or red light. Factors such as dissolved substances, organic matter, and suspended particulates like phytoplankton can increase the opacity of the water and further influence how these wavelengths are absorbed or scattered.1