General Misconceptions

People have a lot of ideas about invasive species that might not be entirely accurate. For instance, while many can recognize invasive species (such as kudzu, knapweed, etc) because of the problems they cause, their idea of native plants can be slightly skewed. Many of the crops grown in the US today are not native to the Americas. They arrived during the settling of the New World with the Europeans for use in agriculture. While not technically invasive because the spread is mostly controlled by the farmers who grow them, they are non-native.

Another misconception about the science of invasive species is that it is rather sure that these species have negative impacts on the ecosystems they invade. But it is not entirely sure whether this is true or not. In a previous post, I mentioned that there is a one-to-one ratio of invasive and native plants on the islands in the Pacific ocean according to Sax et al.. In that same paper, Sax mentions that it is too early to tell if this pattern of native and invasive species will continue or if it will level off, or possibly the native populations will decline towards extinction. It is the same with the issue in the Mediterranean sea. Although several of the species invading from the Red sea are displacing the native species, the majority of them are filling an ecological 'vacuum' that was present in the eastern part of the sea. This is because even before global warming, this part of the Mediterranean was warmer than typically supports the native species, so the invasive Red sea creatures are filling niches that were previously empty. In this case, it seems like the invasive species from the Red sea were beneficial to the eastern Mediterranean by reviving, in a way, a dead ecosystem. But the point is that the scientists are still unsure as to what will occur in the Mediterranean. Will the invasive species stay separate from the native species, or will the new species take over the jobs of the native Mediterranean aquatic life and kill them off? There is just too much uncertainty to tell for sure at this point.

Finally, as mentioned in the previous post, there is an alternative hypothesis to invasive species being the cause of biodiversity loss. Some scientists believe that the invasion of exotic plants and animals is an effect of the degradation of the ecosystem, not the other way around. Humans cause environmental issues that alter the climate and destroy the landscape, and the invasive species come in to fill in the gaps left by anthropogenic activities. This would make sense in terms of the issue in the Mediterranean at the moment. There was a hole in the ecosystem in the eastern side where native species would not thrive, and so those of the Red sea came in to fill it in. But, again, the certainty is not there.