Algae, bacteria, other micro-organisms, higher plants, snails, and other aquatic animals make up the ecosystem food chain involved in the natural purification of 
(Algae, bacteria, other micro-organisms, higher plants, snails, and other aquatic animals; make up; the ecosystem food chain involved in the natural purification of) (the ecosystem food chain; involved; in the natural purification of)
Algae, bacteria, other micro-organisms, higher plants, snails, and other aquatic animals the ecosystem food chain
make up involved
the ecosystem food chain involved in the natural purification of
in the natural purification of