The Twilight Zone, The Gate, and The Abyss

070426145055.jpgThe twilight zone is a section of water extending from the euphotic zone down to 1000m. A new study demonstrates that this region acts like a gate and that little makes it to the seafloor.

…carbon dioxide –taken up by photosynthesizing marine plants in the sunlit ocean surface layer–does not necessarily sink to the depths, where it is stored and prevented from re-entering the atmosphere as a greenhouse gas.

Instead, organisms in the twilight zone consume the material (50-80%) long before it reaches the murky depths. Understanding these processes are important for predicting the role of the deep ocean in sequestering carbon for long geological times.

“Unless the carbon that gets into the ocean goes all the way down into the deep ocean and is stored there, the carbon can still make its way back into the atmosphere. Without this long-term storage, there is little influence on atmospheric levels of carbon dioxide, a greenhouse gas that impacts the earth’s climate.”

image from Science Daily

Dr. M (1801 Posts)

Craig McClain is the Executive Director of the Lousiana University Marine Consortium. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Additionally, Craig is obsessed with the size of things. Sometimes this translated into actually scientific research. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.

2 Replies to “The Twilight Zone, The Gate, and The Abyss”

  1. Sequestration of 20-50% doesn’t sound like “little influence” to me. Also even for that material which is recyled, what is the time scale it is recycled on? It used to be assumed, that once atmosphere/ocean CO2 concentrations equilibrate (storage in solution not seafloor) that little additional CO2 would be left in the atmosphere. This view has apparently changed. What is the reasoning behind that change?

  2. 20-50% of the small amount that makes it out of the euphotic zone which I think is about 5%. So in some parts of the ocean it looks like its about half of the small amount we thought it was. To the time scale it is recycled on I am not sure, but it probably short and insufficient to be a geologic sink in the way we think of the deep sea. As to the latter question, I am not quite sure what your asking or that I am qualified to answer. Feel free to restate and I can do some research.

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