Ecological and Environmental Impacts of Invasive Alien Species
Abstract : Background: Due to the rapidly changing climatic conditions, South Korea faces the grand challenge of exotic species. With the increasing human movement, the influx of alien species to novel regions is prevalent across the globe. The latest research suggests that it is easy to prevent the introduction and establishment of alien species rather than controlling their spread and eradication. Like other countries, the Korean Ministry of Environment released a list (in 2018) of 45 potential risky exotic fish species considered likely to be invasive candidate fish species if they ever succeed in entering the Korean aquatic ecosystems.Results: The investigation into the invasion suitability traits showed that potential risky fish species could utilize those features in becoming invasive once they arrive in the Korean aquatic ecosystems. If the novel species establish viable populations, they are likely to incur higher economic costs, damage the native aquatic fauna and flora, and jeopardize the already perilled species. Furthermore, they can damage the installed infrastructure, decline overall abundance and biodiversity, and disturb the ecosystem services. Here we reviewed the list of fish species concerning their family, native origin, preferred aquatic biomes, main food items, current status in Korea, and potential threats to humans and the ecosystems. Data shows that most species are either already designated as invasive in the neighboring counties, including Japan, Vietnam, Thailand, and China, or originate from these countries. Such species have a higher climate match with the Korean territories.Conclusions: Therefore, it is exceptionally essential to study their most critical features and take regulatory measures to restrict their entry. The incoming fish species must be screened before letting them in the country in the future. The regulatory authorities must highlight the threatening traits of such species and strictly monitor their entrance. Detailed research is required to explore the other species, especially targeting the neighboring countries fish biodiversity, having demonstrated invasive features and matching the Korean climate.
Abstract : Background: Parthenium hysterophorus L. (Asteraceae; hereafter Parthenium) is an invasive alien species of global significance because of its’ negative ecological and socioeconomic impacts. This species is spreading rapidly from lowland Tarai to Middle Mountain regions in Nepal. In the present study, we analyzed the impacts of Parthenium on plant community composition including their soil seedbank in subtropical grasslands located in central Nepal. Data was collected in a 10 m long transects passing through areas of high (> 90% cover), medium (40%-60%) and low (< 10%) levels of Parthenium cover using a plot of 1 m2. Altogether, we sampled 90 plots in 30 transects. Seedling emergence method was used to estimate soil seedbank density in the soil samples (0-10 cm depth) collected from the plots with high Parthenium cover.Results: There was no significant difference in the plant species richness at different levels of Parthenium invasion whereas there was a significant change in the species composition of above ground flora due to Parthenium invasion. There was also a significant difference in species composition between soil seedbank and aboveground flora in the highly invaded plots. Parthenium was the most dominant in soil seedbank, contributing 65% to the total soil seedbank.Conclusions: Our study suggests that Parthenium has considerable negative impact on the native grassland flora, and the dominance of Parthenium in the soil seedbank means there is a challenge for its management. It also suggests the need of monitoring the soil seedbank dynamics while managing Parthenium weed.
Abstract : Background: In this study, we proposed that the population dynamics of non-native red-eared sliders (Trachemys scripta elegans) depends on the species’ habitat extension and survivorship. We used a logistic equation with time-dependent habitat carrying capacity. In detail, the present carrying capacity depends on the red-eared slider population of the previous year. Anthropogenic activities such as the abandonment of previously captive red-eared sliders or the release due to religion customs would supply new habitats to the species. Therefore we assumed that anthropogenic spread increases the habitat carrying capacity. Based on the urbanization increase rate of 3% in Korea from 1980 to 2000, we assumed an annual spread of 3% to simulate the population dynamics of the red-eared slider. In addition, the effect on the population of an increase of natural habitats due to migration was simulated.Results: The close relationship between the distributions of non-native red-eared sliders and of urbanized areas demonstrates that urbanization plays an important role in providing new habitats for released individuals. Depending on the survivorship, the population of the red-eared slider in Korea increased 1.826 to 3.577 times between 1980 and 2000. To control population growth, it is necessary to reduce carrying capacity by reducing habitat expansion through prohibition of release into the wild ecosystem and careful managements of the wetland or artificial ponds. Changes in the habitat carrying capacity showed that the population fluctuated every other year. However, after several years, it converged to a consistent value which depended on the survivorship. Further, our results showed that if red-eared sliders expand their habitat by natural migration, their population can increase to a greater number than when they have a 99% survivorship in a fixed habitat.Conclusions: Further introductions of red-eared sliders into wetlands or artificial ponds should be prohibited and managed to prevent future spread of the species. Moreover, it is important to reduce the species’ survivorship by restoring disturbed ecosystems and maintaining healthy ecosystems.
Abstract : BackgroundSome of the introduced alien species introduced settle, multiply, and spread to become invasive alien species (IAS) that threaten biodiversity. To prevent this, Korea and other countries legally designate and manage alien species that pose a risk to the environment. Moreover, 2160 alien species have been introduced in South Korea, of which 1826 animals and 334 plants are designated. The inflow of IAS can have negative effects such as ecosystem disturbance, habitat destruction, economic damage, and health damage to humans. To prevent damage caused by the inflow of IAS in advance, species that could potentially pose a risk to the environment if introduced in South Korea were designated as alert alien species (AAS).>ResultsThe designation criteria were in accordance with the “Act on the Conservation and Use of Biological Diversity” and the “Regulations on the Ecological Risk Assessment of AAS and IAS” by the National Institute of Ecology. The analysis result of risk and damage cases indicated that mammals affect predation, competition, human economic activity, virus infection, and parasite infection. Birds have been demonstrated to affect predation, competition, human economic activity, and health. It was indicated that plants intrude on the ecosystem by competing with native species with their high-population density and capacity to multiply and cause allergic inducement. Interestingly, 300 species, including 25 mammals, 7 birds, 84 fishes, 28 amphibians, 22 reptiles, 1 insect, 32 spiders, 1 mollusk, 1 arthropod, and 99 plants, are included in the list of AAS.>ConclusionsAAS designation plays a role in preventing the reduction of biodiversity by IAS in South Korea and preserving native species. Moreover, it is determined to provide considerable economic benefits by preventing socio-economic losses and ecological damage.
Jyoti Khatri-Chettri1 , Maan Bahadur Rokaya2,3 and Bharat Babu Shrestha1*
Daniel Bisrat1,2* and Chuleui Jung1,3
Bajaree Chuttong1* , Lakkhika Panyaraksa1, Chantaluk Tiyayon2, Wilawan Kumpoun3, Parinya Chantrasri3, Phurichaya Lertlakkanawat1, Chuleui Jung4 and Michael Burgett1,5
Jyoti Khatri-Chettri1 , Maan Bahadur Rokaya2,3 and Bharat Babu Shrestha1*