1.   Marine scientists were pretty sure a coral reef, like any complex ecosystem, must be assembled in the correct order.

2.   He suspects, in fact, that it happens in temperate lakes as well but that the effect is masked in more complex ecosystems.

3.   In complex natural ecosystems, however, researchers say such straightforward identification of crucial species is impossible.

4.   Neopets.com is a constantly evolving alternative world with a complex ecosystem.

5.   The alternatives studied included leaving the forest alone, or harvesting parts of the forest year to year while leaving its complex ecosystem more or less intact.

6.   Which is a great example of what happens when humans fiddle with a complex ecosystem that took millions of years to evolve.

7.   A forest is actually the site of a complex ecosystem including mineral, land, water and biological resources.