High abundance of invasive African clawed frog Xenopus laevis in Chile: challenges for their control and updated invasive distribution

Abstract

An increasing threat to U.S. waterways is the establishment and spread of invasive and injurious fishes. A species may be designated by the U.S. Fish and Wildlife Service (USFWS) as federally "injurious" under the Lacey Act (18 U.S.C. 42) either if that species causes harm (injury) without establishing and spreading (not invasive), or if that species causes harm after establishment and spread (invasive). Species designated as injurious are prohibited from being imported, which is a highly effective way of preventing invasions by nonnative species. We developed a decision-support, riskassessment system to aid USFWS's prioritization of species for injuriousness. Our system is based on USFWS's evaluation criteria of a species' potential injuriousness and consists of a semi-quantitative, rapid-assessment procedure called the Ecological Risk Screening Summary (ERSS) and a quantitative probability network model called the Freshwater Fish Injurious Species Risk Assessment Model (FISRAM). ERSS provides information on a species' history of invasiveness elsewhere in the world, and on its biology and ecology, potential or known effects of introduction, global and domestic distribution, and climate associations, and provides conclusions on potential risk of invasiveness. FISRAM calculates expected probability of injuriousness as a function of species potential establishment, spread, and harm, based on probable effects on native species and ecosystems, suitability of climate and habitat in introduced areas, ease of dispersal and transport, and harm to humans. FISRAM is used to assess risk probability when ERSS categorizes invasion risk as uncertain. We calibrated and updated the probability structure of FISRAM using a data set of 50 species with known invasiveness outcomes. We demonstrate the use of these two models for risk assessment and decision-support in identifying and documenting species for potential risk management actions, such as listing wildlife as injurious under the Lacey Act.

Bioclimatic and anthropogenic variables shape the occurrence of Batrachochytrium dendrobatidis over a large latitudinal gradient

“…Native Chilean amphibians consist of 63 anuran species, of which 45 (72%) are endemic, and adapted to a range of different ecosystems, from dry desert and altiplano in the North, to subpolar forest and cold steppe in the south 49 . In addition, feral populations of the African clawed frog ( Xenopus laevis ) have been established in central Chile since the 1970s 50 . Batrachochytrium dendrobatidis infection is widespread in Chile 20 , 36 , 43 , 51 , 52 , and chytridiomycosis has been associated with the population decline and extinction of Darwin’s frogs ( Rhinoderma rufum and R. darwinii ) 52 , 53 .…”

Knowledge status of predators of the freshwater prawn Cryphiops caementarius (Decapoda: Palaemonidae) in river systems along the North Western Andean region from Perú and Chile

“…However, so far, studies on these predators have not detected C. caementarius as a food item in the diet of these fish, but this may be due that study areas were outside the habitat range of C. caementarius. On the other hand, the recent documented expansion of X. laevis into river systems of central-North Chile (Mora et al, 2019), suggests emergent effects on C. caementarius populations comparable to those exerted by the salmonids on the crayfish S. spinifrons (Encina Vega, Lara, & Ríos-Escalante, 2017), a species with similar habits of those observed in C. caementarius. The uncontrolled introduction of exotic species corresponds to the second cause of extinction after habitat fragmentation, and therefore, a major threat to world´s biodiversity (Doherty, Glen, Nimmo, Ritchie, & Dickman, 2016).…”

Synthesis ofBatrachochytrium dendrobatidisinfection in South America: amphibian species under risk and areas to focus research and disease mitigation

“…Similarly, X. laevis is a widely distributed invasive species, often as a result of escapes or releases from research laboratories in which it has been widely used as a model for biological research since the early 1900s (Measey et al 2012). In South America, invasive populations are only known from central and northern Chile (Soto‐Azat et al 2016, Mora et al 2019). Tolerant to Bd infection, but resistant to chytridiomycosis, these two invasive species are important vectors of this pathogen, maintaining and spreading Bd as they colonize new areas (Soto‐Azat et al 2016, Borzée et al 2017).…”

“…invasive populations are only known from central and northern Chile (Soto- Azat et al 2016, Mora et al 2019. Tolerant to Bd infection, but resistant to chytridiomycosis, these two invasive species are important vectors of this pathogen, maintaining and spreading Bd as they colonize new areas (Soto- Azat et al 2016, Borzée et al 2017.…”