The concept of trophic levels and the trophic-dynamic aspect of ecology was introduced in 1942 by:

Lindeman. Raymond Laurel Lindeman (1915-1942) was an American ecologist. In 1942, his paper "The Trophic-Dynamic Aspect of Ecology" was published in the journal Ecology, shortly after his early death at the age of 27. This paper is regarded as one of the founding works of ecosystem ecology.

Based on his study of Cedar Bog Lake in Minnesota, USA, Lindeman described the ecosystem in terms of the flow of energy through trophic (feeding) levels:

Producers (first trophic level): green plants and algae that make food by photosynthesis.

Primary consumers (second level): herbivores that eat producers.

Secondary consumers (third level): carnivores that eat herbivores.

Tertiary consumers (higher levels): top carnivores.

Decomposers break down dead matter from all levels.

Lindeman showed that only a small part of the energy at one trophic level is passed on to the next level; most is lost as heat through respiration and other activities. This idea led to the "ten per cent law", which says that only about 10% of the energy at one trophic level is transferred to the next. Because of this, food chains are usually short, with only four or five levels, and the number and biomass of organisms decrease at higher levels, forming ecological pyramids.

The flow of energy in an ecosystem is unidirectional (one-way): from the Sun to producers to consumers, and it is not recycled, unlike nutrients.

Why not the other options?

• ✗Charles Elton, in "Animal Ecology" (1927), introduced the ideas of food chains, food webs, the ecological niche and the pyramid of numbers.
• ✗Arthur Tansley coined the term "ecosystem" in 1935.
• ✗Eugene Odum wrote "Fundamentals of Ecology" (1953) and is called the "father of modern ecosystem ecology".