A scientific theory is a proposition that is made to explain the various phenomena that are occurring in nature and it is supported by experiments that have repeatability and well-analyzed results.
Scientific theories are usually tested in experiments under controlled conditions and verified as well.
In the given situation, the theory made by the observer is not being tested through any experimentation or quantification and therefore, it is just a hypothesis and not a scientific theory.
In an ecosystem, energy enters in the form of solar energy or light energy from sun. Solar energy is transformed into various other types of energies like kinetic energy, chemical energy, potential energy, etc; but it eventually leaves the ecosystem in the form of heat energy.
