Many species of this group perform the important role of making an essential nutrient available to other organisms and are therefore called .

producers (autotrphs)

Explanation:

The autotrpophs, also known as producers, are the organisms that are the basis of all ecosystems. The reason for this is that they are the ones that are capable of [producing their own food. By doing so, they are the ones that produce energy, energy that is transferred through the trophic levels above them. This means that the producers provide the nutrition for all the other organisms, be it the primary or secondary consumers, and if they are eliminated, then the ecosystems will crumble and fall apart very quickly.