Assisted colonisation is a strategy often used by conservationists to reduce the likelihood of the extinction of a particular species by relocating it to another location in the hope it will increase its population and function in its new ecosystem. The rise of human-induced climate change has created panic as many species of animal cannot cope with the consequences caused by change in average temperature rise across the globe. Conservationists are eager to attempt any option possible to save species from extinction. There have been some successful attempts at assisted colonisation, with results of the endangered species coexisting well in its new habitat and becoming a species no longer at risk of extinction. In many cases the movement of one alien species has even benefited many native species. However, there are many negative implications which moving a non-native species to an area can cause. Disease and predation is an effect which alien species can have on native species, making them fall in the category of critically endangered and in some cases extinct, thus not making it a viable conservation strategy. In this paper I will discuss my views, supported with examples, on why assisted colonisation is a good strategy to reduce the effects that climate change is having on species as well as my views on why it may not be such a good approach after all.
Conservationists everywhere are running out of options and are struggling to come up with ways to reduce the effect that human-induced climate change has on species around the world. One method they are introducing is assisted colonisation or assisted migration. Assisted colonisation is a conservation strategy which purposely moves a species from its habitat to another suitable habitat. The species are moved because their habitats are rapidly changing, mainly due to climate change, and they can no longer cope and adjust to survive (Science 2.0, 2011)1. It is believed that this relocation can allow for species to thrive in their new habitats rather than declining and possibly becoming extinct in their original places. Whilst it may seem like this option is completely fault free because of the benefits for the species, there are indeed some complications that may cause some opposition to the strategy as negatives can seem to outweigh the positives in some cases.
Why assisted colonisation is a viable conservation strategy
Of course, the main reason why assisted colonisation should take place is because it potentially saves the global extinction of particular species who are hugely important to ecosystems. It allows for species to survive the ever increasing human-induced climate change and for them to thrive and possibly impact species in and around their new habitat positively. An example of successful assisted colonisation is the movement of the UK butterflies species, Melanargia galathea (marbled white) and Thymelicus sylvestris (small skipper) to two places in the north of England. They were introduced in northern England because the conditions in this area were more suited to the two species of butterfly. Their previous habitats were becoming degraded due to habitat destruction. Population of these butterflies were slowly declining and so conservationists believed assisted colonisation was the most cost-effective method of conservation. Figure 12 clearly shows that since their introduction to one particular area, Wingate, in 2000, the population of the Melanargia galathea has increased steadily. This therefore gives an indication that assisted colonisation can indeed increase the population of species, if done correctly.
Predicting outcomes of the assisted colonisation of each species always occurs when deciding whether it is the best method of conservation for that particular species. Predictive tools such as, climate models, population viability analysis and species distribution models can be used to determine whether the movement will be an overall success in helping conserve the species or not (Gallagher, et al., 2014)3. Other research is also undertaken and every detail is looked into before the go ahead of the migration. Information on the genetic diversity of the new habitat is researched along with every type of species information available on the species being moved researched. Species information includes ideal growing conditions, breeding systems and niches (Gallagher, et al., 2014)4. This information allows for conservationists and scientists to work together and decide whether the species is suited for the move and its ability to cope and expand in the chosen location. Obviously, if it is unlikely that a species will be able to do so, the assisted colonisation would not go ahead. It is this great amount of research into the conservation method that shows that no migration would go ahead without strong confidence that it would be successful thus meaning it is a viable conservation strategy.
The introduction of a new species in an area could indeed benefit the ecosystem. The new species may contribute to the ecosystem in a way that the native species haven’t and this could cause an increase in different types of species of animals and plants. They may do so by reducing the number of predators in the area and therefore the pre flourish and bring along a whole range of benefits. This has occurred in the introduction of wolves to the Yellowstone National Park. The introduction of them meant that population of the deer reduced because they were avoiding the wolves. This led to a cascade of growth and development in the ecosystem. Vegetation increased and so many other species of animals came along after the growth to feed and settle. The wolves were also able to transform the rivers within the area as an effect of the cascade and so marine life also thrived. (Sustainable human, 2014)5. If such thing can be done by one species being added to a new habitat, surely that is an incentive to allow for assisted colonisation to go ahead for endangered species across the world. The movement of this one species gained the ecosystem heath drastically. Habitats which are suffering from overgrazing of vegetation and decline of species could indeed begin to develop into strong and functioning habitats and therefore species numbers will increase; not only of the introduced species but the native ones too. This therefore supports the idea of assisted colonisation being a viable conservation strategy.
Why assisted colonisation isn’t a viable conservation strategy
Ethics is an issue when discussing assisted colonisation. Although the introduction of a species with a declining population to another area may be of benefit to that species, it could have a negative effect on some native species or effect the ecosystem in a negative way as a whole (Minteer and Collins, 2010)6.When considering assisted colonisation, you have to ask, is the growth and flourish of one species any more important than that of another? Especially a native species who has naturally occurred in the place of introduction. It is very easy to disregard a species in its native area in order to help a species in danger and this causes the problems. Introducing a new species to an area technically makes it an invasive species. There are many examples of invasive species that have made a particular native species critically endangered or extinct. A well-known example is the Sciurus carolinensis (grey squirrel) in the UK. Before grey squirrels arrived in the UK, the most common was the Sciurus vulgaris (red squirrel). The grey squirrels had a disease which killed red squirrels and eventually made them very rare, so rare that even some people who live in the UK didn’t even realise that the grey squirrel wasn’t native to England. This decline in the native species is not only unethical but also damaging to the ecosystem as those red squirrels had niches and contributed in some ways.
Of course, the main way of solving species endangerment or extinction would be to combat the actual cause of what is making species habitats degrade. It is common knowledge that since industrialisation in the 19th century, human-induced climate change has caused many issues. The increased use of coal and oil for electricity and energy has added mass amounts of greenhouse gases, particularly carbon dioxide, into our atmosphere, creating a greater warming effect on the earth. Average temperature rise along with many other effects of these greenhouse gases are damaging our ecosystems. They are causing seasons to change more rapidly, confusing species. The greenhouse gases are creating holes in the ozone layer which is allowing extra UV radiation through rather than shielding it. Decreasing the actual human use of electricity, for example, could mean that assisted colonisation wouldn’t have to be done in the first place and therefore, species could remain in their natural habitats with population levels maintained at a good level without risk of extinction.
Whilst there are prediction methods and tools in place to predict what the outcome of assisted colonisation would be, majority of the time, the species being moved hasn’t itself been moved before. This therefore means that it is impossible to predict what the actual response of the animal and indeed the environment will be and so is a complete risk to use as a conservation strategy as it may lead to greater conservation problems. What may have worked for one species may not work for another. In most cases there is lack of knowledge on the biotic interactions and other data, especially for rare species, which are almost always the endangered species (NCCARF, n.d)7.
It is vital to take into account public opinion too. If the community does not support the idea of a foreign animal being brought into their area then it is important to understand why. It is generally opposed when assisted migration is suggested because of the level of uncertainty involved. Many introductions have failed such as the Cane toad (Rhinella marina) in Australia. They were introduced in limited numbers to eat the larvae of beetles which were feeding on sugar cane crops. The cane toads began multiplying in numbers very fast and there is believed to be around 200 million of these toads in Australia now. The toads spread their disease amongst other organisms and as a result effected the ecosystem. This made Australian citizens very angry and against the introduction of alien species. Media coverage of this, and other events of alien species damaging native organisms has encouraged people around the globe to want to protect their ecosystems and protest against assisted migration just in case the results are repeated. Public opinion can very often determine whether something is going to work or not and without the support of the public it is very likely assisted colonisation will not work and so is pointless to continue with that tactic.
Conclusion
In conclusion I believe that assisted colonisation is a viable conservation strategy to mitigate the effects of human-induced climate change in many ways. There have been successful migrations in the past which have benefited ecosystems and the species in it greatly. Species which were once endangered grew in numbers meaning they were no longer under threat of extinction and that is a true sign of a successful conservation strategy. However, I do also believe that this strategy may not work for every specie of animal or plant and it is important to study each species behaviour and likelihood of survival when considering assisted colonisation. There have been some case studies which have proven to have negative effects on native species or ecosystems which of course is not the outcome conservationists wish would occur; thus indicating that assisted colonisation is not the only answer to mitigating the effects human-induced climate change has on some species. I strongly believe that the most effective way of conserving species across the globe and maintaining ecosystem health is to reduce human-induced climate change enormously by switching from over use of fossil fuels for energy to other methods of extracting energy, such as renewable sources which have do not have any, or very little negative effect on the environment.