The secondary invasion of giant African land snail has little impact on litter or seedling dynamics in rainforest

How Will the Distributions of Native and Invasive Species Be Affected by Climate Change? Insights from Giant South American Land Snails

Climate change and invasive species are critical factors affecting native land snail diversity. In South America, the introduced Giant African Snail (Lissachatina fulica) has spread significantly in recent decades into the habitat of the threatened native giant snails of the genus Megalobulimus. We applied species distribution modeling (SDM), using the maximum entropy method (Maxent) and environmental niche analysis, to understand the ecological relationships between these species in a climate change scenario. We compiled a dataset of occurrences of L. fulica and 10 Megalobulimus species in South America and predicted the distribution of the species in current and future scenarios (2040–2060). We found that L. fulica has a broader environmental niche and potential distribution than the South American Megalobulimus species. The distribution of six Megalobulimus species will have their suitable areas decreased, whereas the distribution of the invasive species L. fulica will not change significantly in the near future. A correlation between the spread of L. fulica and the decline of native Megalobulimus species in South America was found due to habitat alteration from climate change, but this relationship does not seem to be related to a robust competitive interaction between the invasive and native species.

Relative condition factor and predictive model for the presence of the invasive snail Achatina (Lissachatina) fulica in Sergipe, Northeast Brazil

Abstract: Achatina fulica is among the world’s 100 most impactive invasive species, and is now found in almost all Brazilian states, including Sergipe. This exotic snail is known to have negative impacts, not only on the environment, due primarily to the rapid growth of its populations, but also on public health, given that it is an intermediate host of nematodes that cause zoonotic diseases. However, relatively little is known of the development of this snail, including its relative condition factor. We investigated the occurrence of A. fulica in 24 municipalities distributed in the eight subregions of the state of Sergipe in the dry and rainy season. Furthermore, we present here a predictive model for the occurrence of A. fulica based on the variation in climate and soil chemistry. This snail was more frequent on soils with a pH of 6.5-7.5. A negative correlation was found between the growth of A. fulica and the soil pH, then, the more acidic the soil, the more allometric the growth of A. fulica. The relative condition factor indicated differences in the development pattern of A. fulica among the eight subregions. The influence of rain in increasing the frequency of A. fulica showed a significant correlation. As well, higher temperatures influenced the resting behavior of A. fulica. The mathematical model used to identify the potential presence of A. fulica presented a high degree of agreement. This is the first ecological study of A. fulica to verify the association between the body mass-length relationship and the relative condition factor, and the results indicate that the development of this exotic land snail in Sergipe is influenced by climatic factors and principally, the soil pH. The predictive mathematical model provides valuable insights into the biotic and abiotic factors associated with the presence of A. fulica, and the influence of climatic variables and the chemical parameters of the soil on the occurrence of this species. These findings provide important guidelines for the development of measures for the control of A. fulica populations, which will contribute to both public and environment health.

Invasive species trait-based risk assessment for non-native freshwater fishes in a tropical city basin in Southeast Asia

Biological invasions have created detrimental impacts in freshwater ecosystems. As non-native freshwater species include economically beneficial, but also harmful, species, trait-based risk assessments can be used to identify and prevent the import of potentially invasive species. Freshwater fishes are one of the most evaluated freshwater taxa to date. However, such assessments have mostly been done in sub-temperate to temperate regions, with a general lack of such research in the tropics. In view of this knowledge gap, this study aims to determine if a different set of traits are associated with successful establishment of non-native fishes within the tropics. In tropical Southeast Asia, Singapore represents a suitable model site to perform an invasive species trait-based risk assessment for the tropical region given its susceptibility to the introduction and establishment of non-native freshwater fishes and lack of stringent fish import regulation. A quantitative trait-based risk assessment was performed using random forest to determine the relative importance of species attributes associated with the successful establishment of introduced freshwater fishes in Singapore. Species having a match in climate, prior invasion success, lower absolute fecundity, higher trophic level, and involvement in the aquarium trade were found to have higher establishment likelihood (as opposed to native distributional range and maximum size being among the commonly identified predictors in subtropical/temperate trait-based risk assessments). To minimize invasive risk, incoming freshwater fishes could be screened in future for such traits, allowing lists of prohibited or regulated species to be updated. The findings could also potentially benefit the development of invasive species action plans and inform management decisions in the Southeast Asian region. Considering a geographical bias in terms of having relatively less documentation of biological invasions in the tropics, particularly Asia, this study highlights the need to perform more of such risk assessments in other parts of the tropics.

Appropriate uses of EICAT protocol, data and classifications

The Environmental Impact Classification for Alien Taxa (EICAT) can be used to classify alien taxa according to the magnitude and type of their environmental impacts. The EICAT protocol, classifications of alien taxa using the protocol (EICAT classification) and the data underpinning classifications (EICAT data) are increasingly used by scientists and practitioners such as governments, NGOs and civil society for a variety of purposes. However, the properties of the EICAT protocol and the data it generates are not suitable for certain uses. Therefore, we present guidelines designed to clarify and facilitate the appropriate use of EICAT to tackle a broad range of conservation issues related to biological invasions, as well as to guide research and communication more generally. Here we address common misconceptions and give a brief overview of some key issues that all EICAT users need to be aware of to take maximal advantage of this resource. Furthermore, we give examples of the wide variety of ways in which the EICAT protocol, classifications and data can be and have been utilised and outline common errors and pitfalls to avoid.

Non-marine invasive gastropods on Ilha Grande (Angra dos Reis, Rio de Janeiro, Brazil): distribution and implications for conservation

Abstract Invasive species are one of the main causes of biodiversity loss and the knowledge of their distribution is essential for conservation efforts. The present study inventoried the land and freshwater invasive molluscs of 25 villages of Ilha Grande (Rio de Janeiro, Brazil), an island with Atlantic Rainforest remnants. Three invasive species are found: Melanoides tuberculata (Müller, 1774), Physa acuta Draparnaud, 1805, both on two localities; and Achatina fulica Bowdich, 1822, on 16 localities. Most records were done on the island continental side, in anthropic areas, probably due to ease of access. One record was inside a conservation area, that calls concern about the spread of those species on the island and possible effects.

Updated distribution and experimental life-history traits of the recently invasive snail Lissachatina fulica in Havana, Cuba

The giant African snail Lissachatina fulica has been reported invading Cuba since 2014 and is now well established in areas of Havana and several nearby regions. This invasive species is of major concern to health authorities given its role as an important vector of parasites such as Angiostrongylus cantonensis, the causative agent of eosinophilic meningoencephalitis in humans. Here, we update the distribution within Cuba. We also report on our studies of experimental life-history traits to assess the population dynamics and potential for spread of this species in Cuba. The experimental population had a very low probability of dying at first age intervals (Type I survival curve) with a life expectancy of 71 weeks. During our experiment, sexual maturity was reached after 22 weeks (individuals of 70 mm shell length) and eggs were laid regularly (mean batch size: 188 ± 111.79 SD). We failed to detect any deviations from the mortality curve and individuals reached an average of 77.3 mm (shell length) and weighted 57.7 g after one year. Predicted curve models indicate that snails reaching their average lifespan of five years should attain 10-12 cm (shell length) and weight 160 g. The spreading of this invasive and vector snail has been tracked for four years in Cuba showing a steady increase of invaded localities. How fast and how far this species develops in Cuba is unknown but the life history parameters indicated in this paper show that it has a large potential to invade all areas of Cuba quickly unless a systematic abatement strategy is developed.