They are, in turn, central prey items for higher trophic levels.

Trophic levels can be represented by numbers, starting at level 1 with plants.

However, the intermediate trophic level is only represented by one or two species.

Example: Assume 500 units of energy are produced by trophic level 1.

Typically, these processes operate only between two trophic levels, with no effect on the others.

A greater variety of species at a higher trophic level are exploited in the sea than on land.

The trophic level of a fish is the position it occupies on the food chain.

Trophic level - The position that a species occupies in a food chain.

Fish that occupy the higher trophic levels are less efficient sources of food energy.

If one species is significantly depleted, that will have an effect throughout the rest of the trophic levels.

Usually relative species abundances are described for a single trophic level.

Because such species occupy the same trophic level they will potentially or actually compete for similar resources.

The phrase, trophic level, refers to the different levels or steps in the energy pathway.

In other words, the producers, consumers, and decomposers are the main trophic levels.

The energy they produce is important for the community because it may be transferred to higher trophic levels via consumption.

It also takes account of the energy flows through the different trophic levels in the ecological networks.

There is consecutively less energy available to succeeding trophic levels.

Fisheries catches, at least to begin with, will tend to increase as the trophic level declines.

However, predators can also influence the structure of lower trophic levels from the top-down.

Despite having low dimension, the top and bottom trophic levels displayed complex dynamics (Table 1).

The detailed reasons for these increases in productivity at higher trophic levels are unknown.

This energy stored in the organism represents the amount available to be passed on to the next trophic level.

Predators and parasitoids were also found, showing an additional trophic level.

However, determining the trophic level of some plankton is not straightforward.

Thus, it is more energetically efficient to form a diet from lower trophic levels.