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NOVA ScienceNOW

Exploring the Arctic Seafloor

  • Teacher Resource
  • Posted 08.28.09
  • NOVA scienceNOW

Take a virtual expedition deep under the Arctic ice along with a research team from the Woods Hole Oceanographic Institution in this interactive activity adapted from NOVA scienceNOW. Through two collections of photos and video footage, learn about the obstacles the team faced at the frozen sea surface, as well as the geological and biological discoveries deep down near the Gakkel Ridge, an 1,100-mile-long section of the Mid-Atlantic Ridge. There, volcanic activity generates new ocean crust, and the combination of chemical reactions and lack of sunlight supports a web of unusual life forms.

NOVA scienceNOW Exploring the Arctic Seafloor
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  • Media Type: Interactive
  • Size: 2.2 MB
  • Level: Grades 6-12

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Source: NOVA scienceNow: "Mystery of the Gakkel Ridge"

This media asset was adapted from NOVA scienceNOW: "Exploring the Arctic Seafloor".

Background

It's no wonder that the bottom of the Arctic Ocean is considered to be one of Earth's last frontiers. Much of the year it is located under thick ice in a remote location, making it difficult and expensive for research teams to plan expeditions. Even without these logistical challenges, the depth and darkness of the frigid water make exploration even more daunting. But with the use of an icebreaker, a team of researchers from the Woods Hole Oceanographic Institution set out in 2007 to explore the Gakkel Ridge, part of the mid-ocean ridge system that runs almost directly below the North Pole. They used cutting-edge submersible vehicles to document in pictures and video the geology and biology of this undersea feature for the very first time.

At Earth's mid-ocean ridges, hot rock from Earth's core is forced up to the seafloor's surface and new ocean floor forms in a process known as seafloor spreading. It's here, too, that the emerging molten rock produces formations called vents, or chimneys. Scientists study these features to better understand geological processes, in particular aspects of plate tectonics. But they also seek to learn more about deep-sea communities that live around these vents.

The Gakkel Ridge has been geologically isolated from other mid-ocean ridges for more than 20 million years. This isolation has long intrigued scientists. Team researchers learned from a 2001 expedition that Gakkel Ridge rocks are made of mantle rock, which is different than the basalt rock found at other known mid-ocean ridges in the world. Scientists suspect that the chemical reactions between the Gakkel Ridge rocks and seawater may produce a different mix of chemicals—one that would in turn support the unique forms of life discovered there. In fact, because the Gakkel Ridge rocks were thought to be similar in composition to rocks that emerged billions of years ago, early on in Earth's history, researchers suspect life at these Arctic vents may provide clues to the earliest life on our planet.

What's been discovered at deep-sea ridges like the Gakkel Ridge offers a clear lesson in how geology drives biology; that is, that the physical conditions dictate the kinds of life that evolve. Through a process called chemosynthesis, bacteria use energy stored in the mix of chemicals around them to grow and multiply. These bacteria, then, are equivalent to land plants, which derive energy from sunlight and serve as the base of the terrestrial food web. In the absence of sunlight, deep-sea bacteria derive the energy to support life from reactions between oxygen and abundant chemical compounds such as hydrogen sulfide and ammonia. Larger, more complex organisms either live on the bacteria that grow in their bodies or they feed on each other. As is confirmed by the still images and video footage in this interactive activity, a variety of vent life has evolved to take advantage of this strategy.

To learn more about how and where life might have originated on Earth, check out Deep-Sea Vents and Life's Origins, Life Before Oxygen, and Caves: Extreme Conditions for Life.

To learn more about plate tectonics, check out Tectonic Plates, Earthquakes, and Volcanoes, Mountain Maker, Earth Shaker, and Tectonic Plates and Plate Boundaries.

To learn about undersea scientific exploration at the South Pole, check out Studying the Antarctic Sea Floor.

Questions for Discussion

    • Why did the scientists believe that the Gakkel Ridge might have unique life forms not found in any other extreme environment? Name some of the life forms that were identified in this expedition.
    • During the expedition, scientists discovered the remains of colonies of sea sponges. Why do you think the colonies might have all died at the same time? What questions can you think of that you'd like to investigate?
    • Why did they expect the ecosystem around the Gakkel Ridge's hydrothermal vents to be very different from terrestrial systems? What do you think is the most fundamental difference between terrestrial and hydrothermal ecosystems?
    • From what you've seen and read, how does the biology of the Gakkel Ridge help scientists understand the geology, and vice versa?

Resource Produced by:


					WGBH Educational Foundation

Collection Developed by:


						WGBH Educational Foundation

Collection Funded by:


						National Science Foundation

						HHMI

						Alfred P. Sloan Foundation

						Public Television Viewers



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