Hydrothermal Vents- ecosystems below the sea


The hydrothermal vents are essentially geysers on the sea floor that support unusual chemical based ecosystems. Some scientists think that vents are the origin environments where life began on Earth billions of years ago. And the vents might also hold clues to life on other planets. This ecosystem may be one of the most ancient of Earth and have had a long-term effect on global geochemical cycles, however it is one of the least well understood. Hydrothermal vent ecosystems are in an unstable state of disequilibrium with large gradients of thermal and chemical energy. Along this thermal and chemical gradient a complex ecosystem of tube worms, thermophilic microbes, and specially adapted crustaceans and fish survive. (Science & Nasa, 2001)


These blooming communities of life that surround these hydrothermal vents stunned the scientific world when the first vent was discovered in 1977.


Before 1977, scientists believed that most living things on earth depend on sunlight as the ultimate source of energy. Thus, the basis of the food chain was photic energy that generated photosynthesis and green plants went down the chain with animals eating plants, and animals eating animals. Soon after hydrothermal vents were discovered, it was so surprised that there is an enriched biological environment which totally remote from the surface sunlight. So how do living things survive in such an environment? The answer is there are certain bacteria that can use another source of energy to make food. Unlike plants that rely on sunlight, the vent ecosystems depend on the bacteria that live in and around the dark vents which can extract their energy from hydrogen sulfide in the geyser water and other molecules that haze out of the seafloor. And just like plants, the bacteria use their energy to build sugars out of carbon dioxide and water. Sugars then supply fuel and raw material for the rest of the bacteria's activities. Therefore for all vents ecosystems that known to exist, plants or photosynthetic microbes constituted the base of the food chain. (Science & Nasa, 2001)


(Science & Nasa, 2001)


Water pouring out of vents can reach temperatures up to about 400 C, which is rich not only in dissolved minerals but also in chemosynthetic bacteria. However, the intense heat is limited to a small area. The most widespread chemical dissolved in vent water is hydrogen sulfide, which smells like rotten eggs, being produced when seawater reacts with sulfate in the rocks below the ocean floor. Chemosynthetic bacteria are capable of utilizing sulfur compounds to produce organic material, small nutrient compounds, which form the basis of their nutrition. What they do with the hydrogen sulfide is similar to what plants do with photic energy. So it is called chemosynthesis rather than photosynthesis. So the bacteria are autotrophs that oxidize hydrogen sulfide in vent water to obtain energy instead of sunlight in order to produce organic material. These chemosynthetic bacteria are the primary producers that form the base of vent food webs. Thus, all vent animals depend on the bacteria for food. Therefore, these bacteria in turn sustain larger organisms in the vent community. (Science & Nasa, 2001)


There are great deals of biological life around the hydrothermal vents, include rocky substrates and clams are wedged into the fissures between the pillow lava on the foreground. As you get in closer to the vent, there are tubeworms, white smoker chimneys and black smoker chimneys with the hot water haze out and a lot of free ranging animals like Brachyuran crabs, Galatheid crabs, and several species of fish moving in and out of the vent environment. (Dover, 2000)


When a vent forms, the first organisms to populate the vents are bacteria, and then other microorganisms, including amphipods and copepods appear to feed on the bacteria. Other animals, such as octopi, prey on those that eat bacteria. Later the tube worms and other species of shrimp join in the expanding community. Gradually, in their most advanced stages, the vent crabs act as both predator and scavenger, whereas some of the most successful colonizers in vent, tube worms and giant clams, form symbiotic relationships with chemosynthetic bacteria. (Dover, 2000)


One of the most impressive animals from the hydrothermal vent environment is the giant tubeworm. This animal is one of the most noticeable members of a diverse community that