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Krebs Cycle

A sequence of reactions where most living cells generate energy during aerobic respiration.

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Life Without Oxygen?
Teacher Contributed

Life Without Oxygen?

Image courtesy of the Institute for Exploration, the University of Rhode Island (URI) Graduate School of Oceanography (GSO), and the URI Institute for Archaeological Oceanography.

Student Exploration

It's A Job

Many of you may have heard of deep-sea vent communities. This term commonly refers to areas around hydrothermal vents where warm mineral rich water gushes out of the earth, and chemosynthetic bacteria use H2S (hydrogen sulfide) to power an ecosystem which doesn't depend on light. But hydrogen sulfide is not the only potential fuel source in the deep sea, in some areas you have communities built around chemosynthetic bacteria which utilize methane (CH4). Here is a look at a methane community in the Black Sea scientists are particularly interested, not only for the methane seep but also because it occurs in the anoxic Black Sea. Other methane seeps are known from oxygenated waters in other parts of the ocean (e.g. the Gulf of Mexico or Oregon) but scientists feel these anoxic types may provide clues as to how life worked when oxygen (O2) was rare on our planet. The bubbles you see in the video are actually methane gas escaping from the sea floor.

Go here to find out more about why these communities interest scientists:

You can find out more about the Black Sea here:

Extension Investigation

Use the below resources to answer the following questions

  1. What is one of the limitations to how high these "reefs' can grow? Why is this factor limiting?
  2. How does H2S oxidize CH4 in the absence of oxygen (O2)?
  3. How could these communities affect how much methane is released in to the atmosphere from the oceans? Explain your thinking.
  4. What affect do this microbial towers have on the carbon budget of the Earth? Explain your thinking.

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