Hydrothermal Vents

Although 70% of the earth's surface is covered by water with vast and deep oceans, a large portion of it still remains uncharted. The seabed itself is one of the most isolated and unexplored places on earth with much of what goes on down there remaining as a mystery. Yet, it is here that many of the most intriguing orders of nature occur. Many of them complex and difficult to understand and just as many of them simple yet with interesting effects that kindle the interests of researchers everywhere.

Unbeknown to man until very recently, underwater hydrothermal vents located in the deepest parts of the sea have been actively spewing out hot water into the oceans and seas. Up till 1977, these vents would not have been discovered if not for a deep see underwater submersible named 'Alvin' which made this amazing discovery while diving in the East Pacific Rise near the Galapagos Islands in the Pacific.

Hydrothermal vents can occur up to 5,000 metres underwater where tectonic plates on the sea bed move apart and the sea water is free to flow into underlying layer of molten lava. The lava in turn heats the almost freezing cold water, usually around 2°C, and the water bursts back out in fumes from below the seafloor. The superheated water travels upwards now laden with dissolved minerals. As the extremely hot water makes contact with the chilling water of the deep ocean, the minerals in the fumes harden thus forming long cylindrical-like structures which come to be known as hydrothermal vents. Some of these structures are known to be 6 kilometres long. They hold some similarities to volcanoes and logically thinking, if they can occur above water, why not underwater too? Just on a smaller scale.

Essentially there are two types of vents. The black smokers and the white smokers. Black smokers, as the names suggests, release plumes of black material into the sea caused by high levels of sulphur in the dissolved superheated water. Black smokers are also considerably hotter than white smokers. White smokers on the other hand, emit particles which are lighter and brighter. Another difference is that white smokers result in alkaline conditions whereas acidic conditions exist for black smokers.

The long cylindrical structures of hydrothermal vents that resemble volcanoes are metal sulphide ore deposits and their rich mineral content like zinc, copper, lead and sulphur have been highly sought after by resource and mineral companies because of their value to them. The race between these companies have produced some impressive results with many new and advanced mining techniques applied in modified ways to mine and transport the minerals on a large scale. However, the act of carrying out this economic endeavour has its detrimental effects on the ecosystem in the sea. The increase in the frequency of movement around these vents has the potential to stir up dust particles, reopening 'dormant' vents or sub-oceanic landslides.

The amazing thing about these vents is that once the activity on them has died down and they lay 'dormant' for the time being, they become hosts to a large variety of aquatic life. They form a temporary community of organisms with an organism density of over 10,000 times higher than that of the surrounding sea floor. The transformation of the bare fields of underwater vents into gigantic underwater communities is a miraculous spectacle to behold and is another one of nature's many wonders.