Which is not a natural ecosystem?
Aquarium
Answer: (2) Aquarium
An ecosystem is defined as a community of lifeforms in concurrence with non-living components, interacting with each other. An ecosystem can be as small as an oasis in a desert, or as big as an ocean, spanning thousands of miles.
There are two types of ecosystem:
An aquarium is a man-made environment which is built for species activity mostly involving snails, fishes, snails or other marine mammals together with aquatic plants.