In the sixth chapter of her book, Marris discusses the different views that ecologists have developed regarding exotic species. On one end of the spectrum is the idea only the native species of an ecosystem should be considered as “good”, while any foreign or genetically crossed breeds of a species are considered “bad”. The concept of “good versus evil”, synonymizing exotic species with negative invasive species, leaves no room for deliberation about whether a species may be doing more good than harm in an ecosystem, or even if the ecosystem is minutely affected by the introduction of a new habitant.
Marris sides more with ecologist Mark Davis’s attitude on exotic species, which is much more open and flexible than the popularly engrained attitude. Davis proposes that the changes that are made, by introducing new species to different ecosystems, may not be as radical as they are made out to be because “change is the order of the day in all ecosystems…species move around constantly, on multiple scales” (Marris 104). Davis asserts that even though humans are making changes to the ecosystem, this does not necessarily mean that the changes are all that different from what may happen in the future without human interference.
Davis also demonstrates the positive effects of allowing exotic species to thrive. Instead of “[traveling] from park to park – all-terrain vehicle in tow for the off road-areas – read to pull, poison, or burn anything that has been declared out of place” as many park service teams do (Marris 100), Davis examines how “sometimes newcomers might help natives flourish” (Marris 105). Such is the case of the “Pyura praeputialis, a squidgy brown sea-squirt-like creature from Australia [which] has increased biodiversity on Chilean rocky tidal shores by cementing itself down and creating a gelatinous landscape in which large invertebrates and algae can thrive” (Marris 105). Though non-native to the area, the Pyura praeputialis has proven to be produce more benefits than harm to a new ecosystem, which is why Davis does not want the value of these potential benefits to be overlooked.
Some scientists as have categorized these types of ecosystems, ones where exotic species are welcomed and embraced rather than targeted for removal, as “novel ecosystems.” However, a strong distinction that Marris makes about novel ecosystems is that they are any ecosystems “dominated by nonnative species…even if humans” never interfered with it (Marris 114). Even with this distinction, many scientists are still reluctant to accept exotic species as positive contributors to the ecosystem as it challenges the notion of pristine, unaltered nature, the nature that many scientists have tried to recreate and preserve. Even though in some cases, the presence of these exotic species throws off the balance of the ecosystem, the fluctuation is only temporary, as “’high dominance lasts forty for fifty years; after eighty years, the species composition becomes mixd and sometimes the species dominance goes back to the natives’” according to Ariel Lugo (Marris 116-117). In other cases, novel ecosystems have also become ideal conditions for exotic species that would be close to extinction in their native countries to thrive. The potential that novel ecosystems offer if they were embraced rather than feared by most scientists would drastically change how humans approach conservation and preservation.
