Single species approach VS Ecosystem approach? (conservation)?

Question

Could somebody please give me a good description of both the Single Species Approach and the Ecosystem Approach?

I know that the single species approach (SSA) is when the focus is on helping a single species that is threatened and action is taken directly to the species, for example: introducing 3 male penguins into an unrelated population of penguins whose gene pool isn't varied enough.

And I know that the Ecosystem approach is taking direct action on the environment to help a species (or several), for example: Controlling mammalian pests in a reserve to help give the threatened species a chance to thrive.

Can anyone add anything to my descriptions to help further my understanding of the two approaches? Do they overlap in anyway or are they completely different?

Answer 1

A lot depends on the problem, the resources available, and the mindset of the people involved. There is some sort of overlap, as in the following example.

Consider a drinking-water reservoir in which blue-green algae produce a chemical that gives the water an off-taste. One way to solve the problem is to increase the filtration of water through particles of carbon. I guess you could call that the no-species approach. Another approach is to kill off the algae. That would be a multi-species approach. Still a third way is to manipulate the fish populations to remove the fishes that feed on the green algae and increase the ones that will eat the blue-greens.

Generally, a study or effort of this type focuses on a single population, at least at first. If results are promising, it can be expanded to other populations. If the results are not promising, you hope that the effects don't spread. Examples are the introductions of mongooses to control rats [rats start climbing and the mongooses wipe out ground-nesting birds and lizards] and the use of kudzu to control erosion and multiflora rose for wildlife habitat.