Simply put, without the ocean storing carbon in the deep sea, the levels of carbon dioxide in the atmosphere would be much higher than they are today. As a human concerned with the potential for rising carbon dioxide levels in the atmosphere to disrupt our climate, it’s the quickest way you can get organic carbon to the deep ocean, effectively removing it from contact with the surface ocean and atmosphere for hundreds or thousands of years. Who cares how much organic matter or carbon goes through the twilight zone? Well, if you are an animal living in the twilight zone, that’s your main food supply.
This constant rain of organic carbon is known as “marine snow,” which drifts through the twilight zone and into the deep ocean. All of this sinking carbon becomes food for other twilight zone animals, with less and less remaining as you go deeper. Getting back to this cruise, most of the carbon either sinks out of the surface ocean directly or is carried by animals back down to the twilight zone in their guts and gets excreted. In fact, at least as far back as 1915, textbooks included discussion of the “decrease in the abundance of life from the sunlit surface layers, through the twilight zone, to the zone of darkness,” as was written in College Physiography.
#TWIGHT LIGHTZONE TV#
Credit: University of Rhode Island/Stephanie Andersonīut I am getting ahead of myself, because despite how appropriate Rod Serling’s description of the mysteries of “the middle ground between light and shadow” fits with what we are doing out here, peering with our instruments into the dimly lit depths, his TV show is not the origin of the name of a twilight zone in ocean sciences. Phytoplankton in the form of a diatom chain. This is, in fact, the largest animal migration on Earth and happens around the globe every day, and we barely know it happens. Many of these animals come up from the twilight zone at night, using the cover of darkness to feed in surface waters and then disappear come daybreak. This organic matter forms the base of the marine food web, which basically means that these microscopic plants serve as food for tiny marine animals called zooplankton, which are eaten by larger marine organisms and so on up to larger animals, like the fish that humans consume. The story of how they do this actually starts at the surface, where microscopic marine algae, or phytoplankton, turn carbon dioxide in the water into organic matter via photosynthesis, much like plants on land. What motivates us is the need to learn more about the role of the twilight zone and the animals that live there in regulating Earth’s climate.
The WHOI EXPORTS team showed off their glow-in-the-dark ocean twilight zone t-shirts prior to departure from Seattle in August.
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