The niche is a theoretical concept first fully developed
and brought forward by numerous other distinguished
ecologists. It attempts to define all physical, chemical and biological
factors that influence a single organism throughout its life. Energy
consumption is also part of the complex equation defining the “essential”
niche. This global concept cannot be tested by experimental approach,
yet it is a useful notion when considering the interactions of all life
forms within a given ecosystem. The statement that no two organisms
can occupy the same niche suggests that competition plays a significant
role in the interactions between assemblages and communities of organisms.
Defining the essential niche of any macro invertebrate is an impossible
task, considering its constantly changing environment. This fact, alone
adds to the romance and mystery of river ecology.