Answer:
The organisms in that habitat including the extreme bacteria, will gradually decline
Explanation:
According to the question, an extreme bacteria lives and thrives in an hydrothermal vent where extremely hot water, methane gas, and sulfur are released. The hydrothermal vent located deep in the ocean is the habitat of the bacteria, and considering the fact that it thrives there means it is better adapted to do well in such extreme environment using the sulfur and methane gas produced by the vent for its development.
If the hydrothermal vent becomes inactive i.e. no production of sulfur and methane, and cold, the extreme bacteria might not survive as the conditions required for its optimal functioning are no longer met. The bacteria also makes up the base of the food web in that habitat (constituting organisms like mussels, tube works), meaning that, it begins the feeding chain in that habitat. Hence, a decline in the number of the bacteria will result in a decline in the number of other organisms dependent on the bacteria as energy source (food).
