Hydrothermal Vent Ecosystems: Life Without The Sun

There is a reason why is it not physiologically possible (nor recommended) for humans to dive too deep into the ocean. The deeper you travel into the ocean, the more dangerous and hostile the environment becomes. The deep ocean is characterized by extreme pressure, temperature fluctuations and utter darkness. Such conditions should make life at the bottom of the ocean impossible, right? Wrong. Even in the face of such extreme conditions, life still persists at the deepest depths of the ocean, but perhaps not how you make think.

For centuries, scientists believed that life was not possible without energy from the Sun. They use to believe that in order for an ecosystem to persist, processes such as photosynthesis had to occur. Photosynthesis is of course driven by the sun's energy and results in plants creating sources of food and energy for other organisms within their ecosystem. This idea that life is impossible without the sun was challenged in 1977 when scientists exploring the ocean floor near the Galapagos Riff, discovered a source massive spikes in the ocean's temperature. 

The source later became known as hydrothermal vents. These vents are similar to geysers or hot springs except they exist on the ocean floor. When hot magma rises from mid ocean ridges it cools, forming crusts and volcanic mountain chains. As seawater circulates deep in ocean's crust, it becomes heated by hot magma. As the pressure builds, it begins to dissolve minerals and rise toward the surface of the crust. The hot, mineral-rich waters now leave the oceanic crust and mix with the cool seawater above. Vent structures begin to form as the vent minerals cool and solidify into mineral deposits. Below you will see a brief video of these vents in action.

Hydrothermal vents are capable of emitting hot plumes high in sulfur. Although these emissions are very toxic and have the potential to harm deep sea organisms, hydrothermal vent ecosystems still exhibit great species diversity. This abundance of life is due to the presence of chemoautotrophic bacteria. These bacteria are typically found in giant tube worms (Riftia pachyptila) which are the most common life forms found in vent communities (these worms can grow up to 8 feet long!) These worms and the chemoautotrophic bacteria co-exist in symbiosis or a mutually beneficial relationship. Chemoautotrophs convert the toxic vent materials into usable forms of energy through the process known as chemosynthesis. This process helps provide food for vent organisms, promoting species diversity.

How organisms are able to survive the extreme conditions of the deep sea including the toxic environment provided by hydrothermal vents is quite fascinating. Chemoautotrophic bacteria are an essential feature of hydrothermal vent ecosystems, providing energy and nutrients to vent species in the absence of sunlight. 

-Posted by Amanda Okpoebo (Group C)