What Are Black Smokers

Black smokers are black chimney shaped formations that are found in large numbers in “hydrothermal vent fields” in the abyssal and hadal zones of the world’s oceans.  The fields are hundreds of meters wide usually found where tectonic plates below the ocean are moving, where water seeps down into the rocks where it becomes superheated, before returning to the surface where it clouds on contact with the cold ocean water due to the abundance of dissolved minerals in it.  On contact with the cold water, these minerals fall back to the ocean floor forming a chimney structure around the vent.  Because of the large amount of sulphides in the superheated water, sulphide ore deposits are usually found at the base of each chimney.  Water at the bottom of the ocean is only around 2^oc, the water escaping the chimney of the black smoker can be as high as 400^oc. 

Where Are Black Smokers Found?

Black smokers are found in both the Atlantic and Pacific oceans along the mid-ocean ridges.  The first was found in 1977 by scientists from Scripps Institution of Oceanography, San Diego, using their submersible ALVIN near the Galapagos Islands along the East Pacific Rise.  These black smokers are found at a depth of 2100m.

Other vent fields are found as far north as Loki’s Castle, discovered in 2008 in between Norway and Greenland by scientists from the University of Bergen, and as far down as 5km beneath the ocean surface, in the Cayman Trough.

Ecology of a Black Smoker

Although the conditions at the bottom of the oceans seem to discourage life, black smokers are teeming with life.  Due to the lack of light, organisms have evolved to gain energy from inorganic minerals that seep out of the earth into the water.  This form of energy production is called chemosynthesis, and involves the oxidisation of chemicals into organic molecules.  The bases of the food chain of a black smoker are the bacteria, and it is these bacteria which use sulphates and ammonia to produce carbohydrates and other organic molecules needed for life and growth.

These bacteria are commonly classed as extremophiles, and are thought to be descended from the earliest forms of life on earth.  The conditions that these bacteria, also called autotrophs, live in are considered hazardous to all other forms of life.  The gasses that they use (ammonia and sulphate gasses) are poisonous to most organisms.  Autotrophs contain enzymes that are specially adapted to life near these vents, as they can withstand high pressures and temperatures without being damaged.

Autotrophs also help larger organisms in the black smoker food chain flourish through either symbiosis, or can take advantage of a larger organism through parasitic activities.  The tubeworm for example, will eat the autotrophs at the beginning of its life, before using the internal bacteria to produce its own food supply.

Life on Europa?

Four kilometres under the ice of Antarctica, one of the largest freshwater lakes on the planet has been isolated from the rest of the planet for over 500,000 years.  It was discovered in the Australian Antarctic Territory below the Russian research base Vostok using ice penetrating radar.  Although it is kept insulated by the ice sheet above it and warmed by heat from the earth, the water temperature is still about -3^oc.  The water does not freeze because of the pressure of the ice above it.  It has also been found that the lake is hyperoxygenated, having 50 times the concentration of dissolved oxygen compared to average world surface waters.  Core samples from the ice have shown microorganisms within the ice at around 100m above the lake’s surface.  The lake itself has not been penetrated as of yet due to worries of its contamination.

The conditions of Lake Vostok have become of increasing interest to some in the scientific community because they believe if microorganisms and possible even larger organisms can survive in the crushing pressure of the waters, then life could be able to survive in other locations.  These locations include the ice-covered oceans and lakes of Europa, Ganymede, and Callisto, aswell as the possible underground water sources on Mars, Triton and Titan.

The Galilean moon Europa is around the size of the Earth’s moon and orbits Jupiter every 3.6 days.  Even though the temperature of its surface is an average of -162^oc, the gravitational pull of Jupiter is thought to warm Europa’s unlit interior enough for the ice to become liquid.  This liquid water, along with an active molten core, could support life in similar situations to the black smokers of Earth.  This life would only be anaerobic chemosynthetic bacteria, or possible very small multicellular organisms such as algae, as the amount of heat energy provided by the gravity of Jupiter and the warmth of the moon’s core would not support a large and diverse ecosystem such as Earth’s photosynthesis based ecosystem.

References

• http://www.pbs.org/wnet/savageearth/hellscrust/html/sidebar2.html – Accessed 14/10/10
• http://www.amnh.org/nationalcenter/expeditions/blacksmokers/black_smokers.html – Accessed 14/10/10
• http://ezinearticles.com/?Lake-Vostok—An-Antarctic-Lake-of-Cosmic-Importance&id=4063729 – Accessed 14/10/10
• http://www.solarviews.com/eng/europa.htm – Accessed 15/10/10
• “An Introduction to Marine Ecology: Third Edition”; Barnes and Hughes; 1999; Pages  145/147
• “Ocean: The World’s Last Wilderness Revealed”; Frances et al.; DK Limited; 2008; pages 188/189