Hydrothermal vent: A mystery in the womb of oceans  

The depths of the oceans carry enormous mysteries in their wombs. One such lesser-known wonder is a hydrothermal vent. But what is this vent? A hydrothermal vent is a rift or tear on the ocean floor, from where hot water spurts out. These vents are frequently found near volcanoes, mid-ocean ridges, ocean basins, and regions with active tectonic plates. On the sea floor, these vents mimic geysers or hot springs, around which rocks and mineral ore deposits are formed. However, you’d be surprised to know that even in such a heated and toxic ecosystem, certain unique marine creatures thrive! Let’s take a closer look at these heated vents found in freezing waters! 

How are they formed? 
You probably know that our water-predominant planet has a lot of activity happening under the Earth’s surface. Because of the activity of tectonic plates in the deep ocean, seawater seeps in and is heated by the molten magma that lies inside Earth’s core. Minerals, such as iron, copper and zinc from the surrounding crust dissolve in this heated seawater, which is then pushed towards the Earth’s crust because of the pressure build-up. At the surface, these heated, mineral-rich waters combine with the freezing cold seawater above. As the minerals cool and solidify into deposits, they form hydrothermal vent structures. Simply put, these are vents that spew hot (thermal) water (hydro). 

When, where and how was the first vent discovered? 
In 1977, a team of researchers, including Dr Robert Ballard, an American professor of oceanography at the University of Rhode Island, were studying the Galápagos Rift. This is an oceanic spreading ridge situated in the East Pacific Ocean, between the Nazca tectonic plate to the south and the Cocos tectonic plate to the north.The team detected several temperature spikes in their data. So, they were intrigued as to how temperatures in the deep ocean could rise quickly from below-freezing to 400 °C (750 °F). It was then that they discovered deep-sea hydrothermal vents and the distinct and vibrant ecosystem supported by these vents!  

Later on, scientists were quick to discover more interesting findings, such as the minerals, temperatures and plume flow rates of hydrothermal vent structures. They found that the most intense, darkest plumes can reach heights of up to 55 metres! And guess what these black plumes are rich in? None other than sulphur!  

They also found vents that emit white smoke. These light-coloured plumes were abundant in barium, calcium and silicon. White smokers typically create smaller chimneys and generate cooler plumes.  

The unique creatures living in hydrothermal vents  
Despite the toxic atmosphere, high temperature, high pressure and lack of sunlight in hydrothermal vents, living creatures thrive here! And you’d be amazed to know that since their discovery in 1977, these vents have been found to house nearly 300 unique animal species! A world in itself, right? Moreover, 95% of these species are exclusive to the vent habitat. It is possible that these organisms followed different evolutionary routes and ended up in these vents. Scientists believe that the vent fauna has existed for millions of years and has barely changed!  

The compounds present in hydrothermal vents frequently support complex ecosystems. The primary food producers are chemosynthetic bacteria and Archaea spp., which then are gulped down by several other creatures, including gigantic tube worms, clams, limpets, ghostly fish and strange shrimp. These chemosynthetic bacteria provide vent organisms with energy and nutrients even in the absence of sunlight. For example, tube worms consume chemicals from vent fluids, including hydrogen sulphide, to feed the bacteria that live inside them. In exchange, the bacteria give the tube worms the carbon they need to survive! 

Threats to the fauna in hydrothermal vents 
New research from the Queen’s University, Belfast, has claimed that nearly two-thirds of the species in deep-sea hydrothermal vents are endangered. It is becoming increasingly crucial to safeguard these distinctive, insular ecosystems and their specific endemic species from industrial activities such as deep-sea mining. Leading vent scientists have suggested that active locations be forever shielded from mining, to avoid significant harm to vent ecosystem from mining extraction.