Solutions to the NNS Problem
The apparent difficulty in solving the NNS problem is that the relevant methods are hard to implement, and the targets are mostly too abundant to be effectively annihilated. However the successful examples of eradication are encouraging, and now the efforts of the governments, general public and individuals of many countries are determined to focus on combating NNS. Having also briefly introduced the practical methods of curbing the disaster of exotic species in their individual accounts, we will expand these solutions in detail through classifying the solutions into several main streams.
1. Physical Control
There are several aspects to this, namely removing the invaders directly, hunting the NNS or marketing them so that the general public has more incentive to assist in the removal of the species. Physical removal is slow and time-consuming, but it does not affect the natives we are trying to save negatively. There has been large-scale shooting of Rabbits in Australia, manual removal of the ubiquitous Pacific Sea Star from the South Australian Harbours by volunteers, and various traps designed for catching introduced Rats on the Pacific Islands, but none are extremely successful. Physical control can be useful in selectively harvesting introduced predatory fish, for example the Pike, Brown Trout, Largemouth Bass and those palatable, marketable species in order to keep their numbers down. In conjunction with other methods, physical control can be effective in the sense that the removal can be more thorough in special cases, but in most it can readily be apprehended that success is at any rate limited, as the manual clearing of overgrown weeds and Mikania vines exemplifies.
2. Chemical Control
Pesticides, herbicides and poisons are quick and effective in killing off the NNS if applied properly. Important herbicides include glyphosate, Sonar, Weedar and Copper sulphate. They are rather easily applied to large and small areas alike, penetrate keep into the aquatic environment where it is frequently applied in places, and are inexpensive in many cases relative to other controls. The universal poisoning effect, however, affects not only the target organism but tends to kill all others in the path of the poison. When the plants are killed by herbicide, bacteria that initiate their decomposition use up a lot of oxygen in the water and the fish in the habitat can be killed as a result. Poison baits used to kill Mice, Foxes and Cats may be ingested by other terrestrial mammals; pesticides can kill off predatory arthropods that may otherwise have controlled the introduced pests better than the pesticide could accomplish. Poisonous substances can also leach away from the applied area and affect localities miles away, polluting the ecosystems around. These contaminate drinking water and sometimes affect human health, and it would not deviate much from the truth in saying that it is equivalent to chemical weapons that hit the wrong targets, leaving behind unsightly scars in the face of the environment. The last thing that the planet has not got enough of is the release of noxious chemicals that affect all life in its path without exemption.
(Pesticides, herbicides and poisons are quick and effective in killing off the NNS)
3. Biological Control
Nature has the superb design that encompasses organisms in a certain area, and the rules are that they are intricately inter-dependent as in departments within a factory, which is why severing links do not allow the rest of the system to work terribly well. Biological controls are usually organisms known to feed or parasitize on a specific (range of) NNS, and as they are the natural predators of the target NNS, they purportedly do not feed on other native species we are striving to allow some breathing room for. The Cactus Moth from Argentina has been introduced in 1925 to control the Cactus Opuntia Stricta (see Species Accounts) and the success was unprecedented and inspiring, as the Prickly Pear numbers plummeted to virtual oblivion before a decade had passed. The Beetle Lebia grandis have saved the potato plantations in Southern United States as they have been discovered to be the indigenous natural predator of the Colorado Potato Beetle Leptinotarsa decemlineata, as the adult Lebia Beetle devours the larvae of the Potato Beetle quite happily when the former is introduced into infested zones.
(Beetle Lebia grandis)
Problems surface when we consider such species as the predatory Mite Euseius tularensis, which feeds on a variety of pests in Citrus tree plantations, such as Citrus Thrips, Scale Insects, Red Mites, as well as sap and pollen of the plants on a small extent. This generalist feeding behaviour does not ensure that its introduction will keep the numbers of the pests down, and the control may not be successful with this lack of specificity in the relationship between the non-native pests and the predator. However, if conditions that ensure optimum growth of the predator are achieved, it is not difficult for the parasitic wasp Eretmocerus eremicus to reduce introduced whitefly populations (Trialeurodes sp.) to extremely low levels, with the whitefly mortality within 8 weeks of application of the parasitic wasp as a biological control exceeding 98%. Given the susceptibility of the parasitic wasp, and many other species, to pesticides that in general are non-discriminatory between different insect species, it is inferred that chemical control is to a certain extent not compatible with biological control. When appropriately applied, biological controls are very effective and eco-friendly, provided that the predator is specific. Fiascos could take place as in the Cane Toad introduction to Australia to deal with Cane Beetles. Despite the titular similarity the Cane Toads are not confined to cane fields and have not been found to specialize on Cane Beetles, but they ate anything in their path as they spread from the plantations into the wild, raging all across Northern Australia. Applying biological control does require a lot of research before hand so that the biology, food preference, environmental requirements and tolerance are known and provided for in schemes that involve the use of their natural aptitude.
(Parasitic Wasp) |
(A Red Mite [*right] attacking its prey) |
Other strategies that have been employed in terms of biological methods include the release of sterile males of a NNS that are expected to mate freely with the females of the introduced populations, causing sterility in the offspring they produce and thus interfering with the continuity of the species in its introduced range. This method has been quite effective, but is limited by the reproductive biology of the NNS under concern. Some plants reproduce largely vegetatively and it is conceivable that this strategy is not applicable.
4. Prevention and Quarantine
Pre-emptive measures, as the problem is ubiquitous nowadays and remedies have proved demoralizing, are enacted widely across the globe. Quarantine is useful for preventing a wide range of accidental introductions through the gateways and ports, and some deadly viruses such as the West Nile and anthrax have been found during routine immigration checking. Imports of livestock that may carry microorganisms that can cause an epidemic outbreak in the farms are in many places restricted and strictly quarantined. The invasion history of many NNS and their subsequent impact have shown to us how important it is to take all necessary precautions in thwarting the initial entry efforts, and stowaways such as the Brown Tree Snake, other possibly invasive Serpents, Rats, various types of insects that could rapidly establish themselves as agricultural pests, and perhaps the planktonic larvae of some invasive marine organisms contained in the ballast water of trans-oceanic vessels should be quarantined as appropriate in the future.
The applicability of quarantine varies a lot from different target organisms, as many NNS are difficult to pick out while others may readily succumb to such efforts. Nevertheless it is of the utmost importance that the screening is strictly carried out in order to minimize the chance of such a problem occurring over and over again. The cost-effectiveness of this approach simplifies a lot of subsequent hubbub about relevant measures, as the NNS is not established in the first place. Early detection of the invasion allows the related bodies to react quickly and annihilate the NNS whilst the scale of introduction is small enough that complete removal has not become impossible as in many documented cases.
5. Education and Government Regulations
What many conservation groups are doing at present is trying to make the public aware of the most pressing problems that are occurring to the fundamental entity we are all dependent on --- the environment that we live in. To a great extent, what it is defines what we are and what we could and could not do. A deprived, lifeless environment is depressing to the mind; the presence of wildlife strikes a chord within us, though the level of harmony varies. It must be realized after all though, that our lives are strictly dependent on environmental health. We have seen the effects of NNS on our environments and that we have caused it as a species implicates our obligation in trying to rectify the problem. Education about the non-native species problems is the expansion of this concept, the promotion of an awareness of the need to be pragmatic but contrite towards the issues related to the whimsical displacement of natural organisms with respect to their surroundings, and why this is so with a final word about how the situation could be reversed.
The solution of this problem relies on the joint effort of the government and people. In 2003 as many as 20 Acts about the tackling of NNS has been raised in the American Congress, and many of these regulations aim at reduction, prevention, and assistance towards the recovery of the affected ecosystems, notably the Great Lakes, the Hawaiian Islands and Florida. Worldwide, NNS hotspots include Australia and the surrounding islands, the Pacific Islands, South Africa, and parts of China. Most of these Acts raise awareness towards the NNS problem and initiate the flow of funds towards measures that help to alleviate the currently observed effects. Improved funding can be a great help to research on NNS that allows more of the biology of these successful species to be learnt and investigated, and databases of these species to be created in facilitation of public reference and for subsequent efforts to have a sound scientific support.
6. Wise management of the Environment
Humans are the stewards of the world, so says the Bible. Many people have not realized how much wisdom is contained in these lines. The integrity and health of an ecosystem, as that of a healthy body, can resist attack on its own. It is the debilitated ecosystems that are now unfortunately all over the world under the continued harassment of the human race --- overexploited ones, that are susceptible to introduced species, not to mention the isolated, fragile ones. What humans can do instead of adding to the planet's plight is to manage the environment wisely and sustainably. Restoration of the original environment after invasions have occurred will reinforce the native species and ensure that they have a firm grip on the natural resources, leaving little for the NNS to seize --- indeed studies have shown that intact ecosystems are less prone to invasion than those from which certain ecologically important species have been lost.
The fate of the planet is literally in human hands. It cannot be conjectured whether the NNS problem will be solved within our lifetime, but we hope that you have enjoyed using this site and have learnt much from the information.
