The deepest parts of the ocean are hostile to life. A barren stretch of sea floor recently experienced an earthquake that opened up a hydrothermal vent. This vent provides heat and nutrients. Over time, the area became filled with various deep-sea life forms. What kind of
ecological activity is this?
This is a form of

Deep hydrothermal vents are located in areas with high tectonic activity, including the edges of tectonic plates, undersea mountain ranges and seamounts, and mid-ocean ridges. The water escaping from deep hydrothermal vents may be clear-ish and have low concentrations of minerals or it may be white or black and be characterized by high concentrations of minerals. These so-called white or black smokers look like chimneys, constantly blowing ‘smoke’ up from the sea floor. Minerals escaping from these vents usually include hydrogen sulfide or some other sulfur compound.

The deep-sea environment where these vents occur is completely dark, and photosynthesis (=the conversion of carbon dioxide into sugar using sunlight) is impossible. Photosynthesis is the process by which plants and algae form the bottom of the food web, wherever there is sunlight. In the deep sea, most of the food must sink from the sunlit sea surface; however, as it sinks, it is eaten by all sorts of organisms. Very little food makes it to the deep sea floor. At deep hydrothermal vents, though, specialized bacteria can convert the sulfur compounds and heat into food and energy. As these bacteria multiply, they form thick mats on which animals can graze. In some cases, they form symbiotic relationships with animals, (e.g., giant tube worms) and live in the animals’ tissues, creating energy in return for receiving protection from predators. These specialized bacteria form the bottom of the deep hydrothermal vent food web, and many animals rely on their presence for survival, including deep-sea mussels, giant tube worms, yeti crabs, and many other invertebrates and fishes.

A similar deep-sea ecosystem is called the cold seep (or cold vent), where mineral- or methane-rich water seeps from the seafloor. Cold seeps do not require high tectonic activity and may be located more sporadically across the deep sea. Again, specialized bacteria utilize the high density of sulfur or methane compounds to create food/energy, again forming the bottom of a complex food web.

Some scientists hypothesize that the first life on Earth may have originated at deep hydrothermal vents.

Explanation:

the denominator has a very specific role.