Deep-sea hydrothermal vents
photo credit: ROVE KIEL 6000/GEOMAR (CC BY 4.0)
HYDROTHERMAL VENTS ARE REMARKABLE GEOLOGICAL FORMATIONS THAT SUPPORT THRIVING ECOSYSTEMS FUELED BY CHEMOSYNTHESIS.
Deep-sea hydrothermal vents are fascinating and unique ecosystems typically located along mid-ocean ridges, where tectonic plates diverge and magma rises to the surface. These vents are generated by volcanic activity under the seabed, where superheated water and minerals are released into the surrounding environment.
The water can reach temperatures as high as 400 degrees Celsius (752 degrees Fahrenheit), making it one of the hottest environments on the planet.
The superheated water, laden with dissolved minerals such as sulfides, metals, and methane, gushes out of the vents in towering plumes called black smokers. As the hot, mineral-rich water meets the cold seawater, chemical reactions occur, causing the minerals to precipitate and form chimney-like structures.
Black smoker in 2,980 meters of water on the Mid-Atlantic Ridge
photo credit: MARUM− Zentrum für Marine Umweltwissenschaften, Universität Bremen
A black smoker known as the brothers
photo credit: National Oceanic and Atmospheric Administration (NOAA)
Hydrothermal vent structures exhibit a wide range of physical and chemical characteristics, contributing to the diversity and complexity of these ecosystems. One of the distinguishing factors is the composition and temperature of the plumes emitted from the vents.
Black smokers, named for their dark appearance, release the hottest plumes among hydrothermal vents. These plumes are rich in sulfur compounds and can reach temperatures as high as 400 degrees Celsius (752 degrees Fahrenheit). The high sulfur content contributes to the formation of tall chimney-like structures, which can tower up to 55 meters (180 feet) in height, equivalent to an 18-story building.
On the other hand, white smokers emit plumes that have a lighter colouration compared to black smokers. These plumes contain higher concentrations of barium, calcium, and silicon. White smokers generally have less warm plumes and smaller chimneys than black smokers.
In addition to black and white smokers, there are seeps with cooler but weaker flows. Seeps often exhibit a shimmering effect caused by variations in water temperatures surrounding the vent.
Carbon dioxide bubbles from white smokers, Eifuku
photo courtesy: NOAA
White smokers emitting liquid rich in barium, calcium, silicon and carbon dioxide
photo courtesy: NOAA
HYDROTHERMAL VENTS NURTURE INTRICATE ECOSYSTEMS WITHOUT THE PRESENCE OF SUNLIGHT, UNDERSCORING THE INCREDIBLE DIVERSITY AND ADAPTABILITY OF LIFE FORM IN OUR PLANET'S MOST EXTREME ENVIRONMENTS.
Unlike other ecosystems on Earth, where sunlight is the primary energy source, vent ecosystems rely on chemosynthesis.
Bacteria and archaea, collectively known as chemosynthetic microorganisms, use the energy from chemical reactions, such as the oxidation of hydrogen sulfide, to produce organic matter. These microorganisms form the base of the vent food chain.
The unique combination of extreme temperatures, high pressures, and the presence of toxic chemicals creates a challenging environment for life. However, around the hydrothermal vents, numerous species of animals, including tubeworms, clams, mussels, shrimp, and crabs, have evolved specialized adaptations to exploit the available resources. Some organisms, like tubeworms, have symbiotic relationships with chemosynthetic bacteria living inside their bodies, allowing them to utilize the bacteria's metabolic capabilities.
Giant tube worms (Riftia pachyptila) cluster around vents in the Galapagos Rift
photo courtesy: NOAA Okeanos Explorer Program, Galapagos Rift Expedition 2011
Riftia pachyptila commonly known as the giant tube worm is a marine invertebrate. This gigantic worm, more than 2 meters long, have no mouth or digestive system but house chemosynthetic bacteria in its tissues that convert the vent fluids into organic compounds. In return, the tube worms provide a protective habitat and access to the vent fluids for the bacteria.
A dense population of deep-sea shrimps at a black smoker
photo courtesy: ROVE KIEL 6000_GEOMAR
A swarm of shrimp from the genus Alvinocaris near a vent in the Pacific Ring of Fire
photo courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program
Shrimp (Alvinocaris), a few squat lobsters, and hundreds of bivalves (Bathymodiolus)
photo courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program
A dense fauna (Kiwa anomurans and Vulcanolepas-like stalked barnacles) near East Scotia Ridge vents
photo credit: © A. D. Rogers et al.
Kiwa is a crustacean genus first discovered in 2005 during a scientific expedition on the Pacific-Antarctic Ridge. Kiwa has a white, furry appearance due to the dense covering of setae on its limbs, which may host chemosynthetic bacteria. Unlike most other crabs, Kiwa is a filter feeder, collecting organic particles and bacteria from the vent water.
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Bathymodiolus mussels (both dead and alive) are seen underneath a carbonate overhang
photo courtesy: NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2014
The discovery of hydrothermal vents stands as a groundbreaking achievement in advancing our understanding of the origins of life on Earth. Scientists employ Remotely Operated Vehicles (ROVs) to delve into the mesmerizing depths of the ocean. These ROVs are meticulously designed to endure the extreme pressures of the deep sea. Tethered to research vessels, they are equipped with a versatile array of tools, including cameras, lights, sampling equipment, manipulator arms, and a diverse range of scientific instruments. The data and real-time imagery provided by ROVs empower scientists to conduct comprehensive studies of these extraordinary ecosystems, facilitating sample collection and fostering a deeper understanding of the unique conditions present in these extreme environments.
