1.   After clearing the choking debris, they watched as a healthy ecosystem gathered steam and native cattails began to spread.

2.   That may worry biologists who are concerned about the potential disappearance of broad categories of plants and smaller animals that help knit healthy ecosystems.

3.   The Pew Commission has sought to engage all stakeholders in the pursuit of healthy marine ecosystems.

4.   Its presence is a sign of a healthy ecosystem.

5.   Tigers, leopards, black panthers, sun bears and elephants abound in quantities that suggest a healthy ecosystem.