The word “invasive” in invasive species already suggests that the certain species are unnecessary and intrusive. It has been a long-held belief of ecologists and conservationists that invasive species are generally considered harmful and detrimental to the ecosystems they are introduced to. They usually cause other species to become extinct because they are either new competition for food or they prey on that specie. Such cases of species harming their respective ecosystems are the zebra muscles, flightless wren, and the Asian tiger mosquitos. Nevertheless, Marris suggests that humans not get involved or interfere with invasive species. She states, “the vast majority are not. Science is finding that some are quite well behaved and innocuous, or even helpful.” Numerous times, invasive species have little effect or even positive effects to the ecosystems. In many cases they allow for more biodiversity and they end up furthering the ecosystem. When an invasive specie of tree was brought to Rodrigues Island, it ended up bring back three species of animals that were soon to be extinct. Eventually, environmentalists ended up removing the species because it was invasive and was not part of the original baseline. This resulted in a ton of money and time being spent on cutting down all the trees when the effort could have been put into removing an invasive species that actually had a negative effect on the ecosystem it was introduced to.
In chapter 7, Marris talks about novel ecosystems and the “brave few” who embrace and participate in them. Ecologists have been using the term novel ecosystems to mean, “the more dramatically altered systems.” By that they mean ecosystems that have had their specie composition dramatically changed over the past few centuries. For example, a forest that has remained unchanged for the past thousand years would not qualify even though some non-native species may have been introduced. I am generally not so supportive of this idea because as far as I know, little evidence has shown that the majority of invasive species have had positive effects on ecosystems. Nevertheless, one of the aspects of novel ecosystems seems to flourish in my head, the fact that novel ecosystems sometimes exist even though there has never been any human contact. This shows that somehow species have migrated and for some time they have ben able to live in harmony without disrupting the ecosystem.
