Predicting global invasion risks: a management tool to prevent future introductions

Supplemental description of Gyrodactylus pseudorasborae (Gyrodactylidae) parasitic on topmouth gudgeon Pseudorasbora parva (Cyprinidae) in South China

Based on morphology and ITS sequence data, we identify and supplementally describe Gyrodactylus pseudorasborae Ondračková, Seifertová & Tkachenko, 2023 on the fins of topmouth gudgeon (Pseudoraspora parva) from freshwaters of southern China. The highest similarity (99.57% and 99.47%) to G. pseudorasborae suggested they were the same species. Prevalence and mean intensity were 45% and 2.3, respectively. The gyrodactylid species morphologically resembled G. pseudorasborae recorded from the same host species P. parva in Czech Republic, Ukraine, and Central China. But there were slight morphological differences in the shape and size of the marginal hook. Comparisons of marginal hook sickles of various Gyrodactylus species suggested that G. pseudorasborae and G. parvae were members of the G. wageneri-group. A molecular phylogeny of G. pseudorasborae with related species is presented and discussed within the context of the mechanism of local evolution of these sister species.

A Scoping Review on GIS Technologies Applied to Farmed Fish Health Management

Finfish aquaculture, one of the fastest growing intensive sectors worldwide, is threatened by numerous transmissible diseases that may have devastating impacts on its economic sustainability. This review (2010-2022) used a PRISMA extension for scoping reviews and a text mining approach to explore the extent to which geographical information systems (GIS) are used in farmed fish health management and to unveil the main GIS technologies, databases, and functions used to update the spatiotemporal data underpinning risk and predictive models in aquatic surveillance programmes. After filtering for eligibility criteria, the literature search provided 54 records, highlighting the limited use of GIS technologies for disease prevention and control, as well as the prevalence of GIS application in marine salmonid farming, especially for viruses and parasitic diseases typically associated with these species. The text mining generated five main research areas, underlining a limited range of investigated species, rearing environments, and diseases, as well as highlighting the lack of GIS-based methodologies at the core of such publications. This scoping review provides a source of information for future more detailed literature analyses and outcomes to support the development of geospatial disease spread models and expand in-field GIS technologies for the prevention and mitigation of fish disease epidemics.

Identifying and Managing Areas under Threat in the Iberian Peninsula: An Invasion Risk Atlas for Non-Native Aquatic Plant Species as a Potential Tool

Predicting the likelihood that non-native species will be introduced into new areas remains one of conservation's greatest challenges and, consequently, it is necessary to adopt adequate management measures to mitigate the effects of future biological invasions. At present, not much information is available on the areas in which non-native aquatic plant species could establish themselves in the Iberian Peninsula. Species distribution models were used to predict the potential invasion risk of (1) non-native aquatic plant species already established in the peninsula (32 species) and (2) those with the potential to invade the peninsula (40 species). The results revealed that the Iberian Peninsula contains a number of areas capable of hosting non-native aquatic plant species. Areas under anthropogenic pressure are at the greatest risk of invasion, and the variable most related to invasion risk is temperature. The results of this work were used to create the Invasion Risk Atlas for Alien Aquatic Plants in the Iberian Peninsula, a novel online resource that provides information about the potential distribution of non-native aquatic plant species. The atlas and this article are intended to serve as reference tools for the development of public policies, management regimes, and control strategies aimed at the prevention, mitigation, and eradication of non-native aquatic plant species.

Phylogenetic risk assessment is robust for forecasting the impact of European insects on North American conifers

Some introduced species cause severe damage, although the majority have little impact. Robust predictions of which species are most likely to cause substantial impacts could focus efforts to mitigate those impacts or prevent certain invasions entirely. Introduced herbivorous insects can reduce crop yield, fundamentally alter natural and managed forest ecosystems, and are unique among invasive species in that they require certain host plants to succeed. Recent studies have demonstrated that understanding the evolutionary history of introduced herbivores and their host plants can provide robust predictions of impact. Specifically, divergence times between hosts in the native and introduced ranges of a nonnative insect can be used to predict the potential impact of the insect should it establish in a novel ecosystem. However, divergence time estimates vary among published phylogenetic datasets, making it crucial to understand if and how the choice of phylogeny affects prediction of impact. Here, we tested the robustness of impact prediction to variation in host phylogeny by using insects that feed on conifers and predicting the likelihood of high impact using four different published phylogenies. Our analyses ranked 62 insects that are not established in North America and 47 North American conifer species according to overall risk and vulnerability, respectively. We found that results were robust to the choice of phylogeny. Although published vascular plant phylogenies continue to be refined, our analysis indicates that those differences are not substantial enough to alter the predictions of invader impact. Our results can assist in focusing biosecurity programs for conifer pests and can be more generally applied to nonnative insects and their potential hosts by prioritizing surveillance for those insects most likely to be damaging invaders.

Suitable areas for invasive insect pests in Brazil and the potential impacts for eucalyptus forestry

BACKGROUND

Brazil is among the world's largest producers of eucalyptus and the damage caused by native and invasive insect pests is one of the main factors affecting eucalyptus yield. The recent history of biological invasions of eucalyptus pests in Brazil prompts demand for phytosanitary measures to prevent new invasions. This study used ecological niche models to estimate suitable areas for nine eucalyptus pests. This information was used to assess the potential ports of entry, generate invasion risk maps considering the likelihood of introducing invasive species, and estimate the eucalyptus producing municipalities and areas within the species' suitable range.

RESULTS

A large distribution range was predicted for Eucalyptolyma maideni (Hempitera: Aphalaridae), Orgya postica (Lepidoptera: Erebidae), Sinoxylon anale (Coleoptera: Bostrichidae), and Trachymela sloanei (Coleoptera: Chrysomelidae) in Brazil, while a comparatively smaller distribution was predicted for Ophelimus maskelli (Hymenoptera: Eulophidae), Mnesampela privata (Lepidoptera: Geometridae), Paropsis atomaria (Coleoptera: Chrysomelidae), Paropsisterna beata, and P. cloelia (Coleoptera: Chrysomelidae). High-risk areas of invasion near airports and seaports were predicted mainly in southern, southeastern, and northeastern Brazil. A large proportion of the municipalities (24.4% to 93.7%) and areas with eucalyptus plantations (31.9% to 98.3%) are within the climatically suitable areas estimated for the pests, especially in southern and southeastern regions, which comprises 61.5% of the Brazilian eucalyptus production.

CONCLUSION

The results indicate that eucalyptus forestry may be significantly impacted by biological invasion. The findings provided by our study can assist decision-makers in developing phytosanitary measures to prevent new invasions of forest pests in Brazil. © 2022 Society of Chemical Industry.

Climate change and alpine-adapted insects: modelling environmental envelopes of a grasshopper radiation

Mountains create steep environmental gradients that are sensitive barometers of climate change. We calibrated 10 statistical models to formulate ensemble ecological niche models for 12 predominantly alpine, flightless grasshopper species in Aotearoa New Zealand, using their current distributions and current conditions. Niche models were then projected for two future global climate scenarios: representative concentration pathway (RCP) 2.6 (1.0°C rise) and RCP8.5 (3.7°C rise). Results were species specific, with two-thirds of our models suggesting a reduction in potential range for nine species by 2070, but surprisingly, for six species, we predict an increase in potential suitable habitat under mild (+1.0°C) or severe global warming (+3.7°C). However, when the limited dispersal ability of these flightless grasshoppers is taken into account, all 12 species studied are predicted to suffer extreme reductions in range, with a quarter likely to go extinct due to a 96-100% reduction in suitable habitat. Habitat loss is associated with habitat fragmentation that is likely to escalate stochastic vulnerability of remaining populations. Here, we present the predicted outcomes for an endemic radiation of alpine taxa as an exemplar of the challenges that alpine species, both in New Zealand and internationally, are subject to by anthropogenic climate change.

Assessment of the Spatial Invasion Risk of Intentionally Introduced Alien Plant Species (IIAPS) under Environmental Change in South Korea

Predicting the regions at risk of invasion from IIAPS is an integral horizon-scanning activity that plays a crucial role in preventing, controlling, and eradicating invasive species. Here, we quantify the spatial distribution area and invasion risk of IIAPS using a species distribution model under different levels of environmental change in South Korea. From the model predictions, the current average spatial extent of the 10 IIAPS is 33,948 km², and the individual spatial extents are estimated to change by -7% to 150% by 2050 and by -9% to 156% by 2070. The spatial invasion risk assessment shows that, currently, moderate-to-high invasion risk is limited to coastal areas and densely populated metropolitan cities (e.g., Seoul, Busan, and Gwangju), but that the area with this level of risk is expected to spread toward the central and northern regions of the country in the future, covering 86.21% of the total area of the country by 2070. These results demonstrate that the risk of invasion by IIAPS is estimated to enlarge across the whole country under future environmental changes. The modeling system provided in this study may contribute to the initial control and strategic management of IIAPS to maintain the dynamic ecosystems of South Korea.

Characterizing bracken fern phenological cycle using time series data derived from Sentinel-2 satellite sensor

Bracken fern is an invasive plant that has caused serious disturbances in many ecosystems due to its ability to encroach into new areas swiftly. Adequate knowledge of the phenological cycle of bracken fern is required to serve as an important tool in formulating management plans to control the spread of the fern. This study aimed to characterize the phenological cycle of bracken fern using NDVI and EVI2 time series data derived from Sentinel-2 sensor. The TIMESAT program was used for removing low quality data values, model fitting and for extracting bracken fern phenological metrics. The Sentinel-2 satellite-derived phenological metrics were compared with the corresponding bracken fern phenological events observed on the ground. Findings from our study revealed that bracken fern phenological metrics estimated from satellite data were in close agreement with ground observed phenological events with R2 values ranging from 0.53-0.85 (p < 0.05). Although they are comparable, our study shows that NDVI and EVI2 differ in their ability to track the phenological cycle of bracken fern. Overall, EVI2 performed better in estimating bracken fern phenological metrics as it related more to ground observed phenological events compared to NDVI. The key phenological metrics extracted in this study are critical for improving the precision in the controlling of the spread of bracken fern as well as in implementing active protection strategies against the invasion of highly susceptible rangelands.

Prevention is better than cure: Integrating habitat suitability and invasion threat to assess global biological invasion risk by insect pests under climate change

BACKGROUND

Invasive alien species cause substantial impacts on ecosystem, economy, and public health. Therefore, identifying areas at risk of invasion and establishment is essential for the development and implementation of preventive measures. In this study, we integrated information on species habitat suitability, location of airports and ports, and invasion threat maps to assess global invasion risk under climate change using the cucurbit beetle, Diabrotica speciosa (Germar, 1824), as a model organism.

RESULTS

Suitable and optimal habitats for D. speciosa were estimated in several regions beyond its native range and comprised all continents. A decrease in the extent of suitable and optimal habitats for D. speciosa was predicted in different climate change scenarios, resulting in a reduction in invasion risk in most regions. However, regions such as western Europe and isolated areas in southern Asia and Oceania were predicted to face an increase in invasion risk under climate change. Invasion pathways via airports and ports were identified in all continents.

CONCLUSION

Our findings can be used in the development of phytosanitary measures against D. speciosa in high-risk areas. Furthermore, the approach used in this study provides a framework for estimating the global risk of invasion by insect pests and other terrestrial organisms in different climate change scenarios. This information can be used by policy makers to develop preventive measures against species with potential to invade and spread in regions beyond their native range. © 2021 Society of Chemical Industry.

Predicting the Potential Distribution of Non-Native Mammalian Species Sold in the South African Pet Trade

The pet trade is one of the main pathways of introduction of several mammals worldwide. In South Africa, non-native mammalian species are traded as pets, and so far, only four of these species are considered invasive. We used a list of 24 companion mammalian species compiled from a previous study. We selected a subset of 14 species for species distribution modeling (SDM) based on their trade popularity, invasion history and potential economic and socio-economic impacts. We aimed to estimate their potential distribution using their distribution records. Our SDM indicated that climate in South Africa was suitable for most traded species. However, commonly and easily available species had the broadest areas of suitable climates, such as house mice (Mus musculus) and Norwegian rats (Rattus norvegicus). In addition, the model with a human footprint suggested a high risk of invasion for Norwegian rats but less for house mice distribution. This assessment suggests the need of strict trade regulations and management strategies for pet mammals with broader suitability, which are already invasive, and most available for sale. In addition, our results provide a baseline approach that can be used to identify mammalian pet species with a potential risk of invasion so that urgent preventive measures can be implemented.

The failed invasion of Harmonia axyridis in the Azores, Portugal: Climatic restriction or wrong population origin?

We tested two questions: (i) whether the climatic conditions of the Azorean Islands in Portugal may have restricted the invasion of Harmonia axyridis across this archipelago and (ii) determine what population of this species could have a higher probability of invading the islands. We used MaxEnt to project the climate requirements of different H. axyridis populations from three regions of the world, and the potential global niche of the species in the Azorean islands. Then we assessed the suitability of the islands for each of the three H. axyridis populations and global potential niche through histograms analysis, Principal Component Analysis (PCA) of climate variables, and a variable-by-variable assessment of the suitability response curves compared with the climatic conditions of the Azores. Climatic conditions of the Azores are less suitable for the U.S. and native Asian populations of H. axyridis, and more suitable for European populations and the global potential niche. The PCA showed that the climatic conditions of the islands differed from the climatic requirements of H. axyridis. This difference is mainly explained by precipitation of the wettest month, isothermality, and the minimum temperature of the coldest month. We concluded that the climatic conditions of the Azores could have influenced the establishment and spread of H. axyridis on these islands from Europe. Our results showed that abiotic resistance represented by the climate of the potentially colonizable zones could hinder the establishment of invasive insects, but it could vary depending of the origin of the colonizing population.

Can Invasiveness in Freshwater Fishes Be Predicted From Life-History Traits?

We review a model we developed in 2007 to predict the invasion potential of an introduced population, based on the relationship between juvenile growth (mean total length at age 2) and mean age-at-maturity, and test the model with data from 75 non-native populations of pumpkinseed Lepomis gibbosus in nine countries of Europe and western Asia. The database used to construct the model was derived from a mix of primary and secondary data collected between 1981 and 2016. Based on number of specimens collected or catch-per-unit-effort data, and/or comments by the original authors, populations were classified a priori as “invasive” or “non-invasive.” The plot of the proposed model placed populations in three invasiveness categories (non-invasive, transitional, invasive). Of those predicted by the model to be invasive, only 57% were correct with regard to their a priori classification, a result that was not statistically significant. For populations predicted by the model to be non-invasive, 70% were correct with regard to their a priori classification when “transitional” were grouped with non-invasive (P = 0.0024), and 64% were correct when “transitional” were excluded from the test (P = 0.12). Applications of the model to two other non-native freshwater fishes (black bullhead Ameiurus melas and crucian carp Carassius carassius) are also discussed. The lack of stronger statistical support for the model may have been the result of using life-history traits from the populations after they were introduced, as the source populations were unknown, as well as to shortcomings in the dataset that could affect a priori and modeled classifications. We conclude that such life-history models can be useful for predicting invasiveness status in non-native freshwater fishes, though the basis of the predictions, statistical or heuristic, will depend on the size and quality of the underlying life-history database.

The role of connectivity in the interplay between climate change and the spread of alien fish in a large Mediterranean river

Understanding how global change and connectivity will jointly modify the distribution of riverine species is crucial for conservation biology and environmental management. However, little is known about the interaction between climate change and fragmentation and how movement barriers might impede native species from adjusting their distributions versus limit the further spread of alien species. In this study, we modelled the current and future distributions of 11 native and five alien fishes in the large and heavily fragmented Ebro River, located within the Mediterranean region, which has many freshwater endemics severely threatened by global change. We considered 10 climate change models and five modelling algorithms and assessed the effects of connectivity on the accessibility of future suitable habitats. Thereby, we identify most conflict-prone river reaches, that is, where barriers pose a particular trade-off between isolating and negatively impacting native species versus potentially reducing the risk of alien species spread. Our results projected upstream habitat shifts for the vast majority of the species. Climate change affected species differently, with alien species generally showing larger habitat gains compared to natives. Most pronounced distributional changes (i.e. losses of native species and gains of alien species) and compositional turnover might be expected in the lower and mid reaches of large tributaries of the Ebro River. The role of anthropogenic barriers in this context is often ambiguous but rather unfavourable, as they not only restrict native fishes but also alter stream habitats and flow conditions. However, with our spatial modelling framework, we could identify specific river reaches where the connectivity trade-off in the context of climate change is particularly relevant. Overall, our findings emphasize the importance of the complex effects that climate change, riverine connectivity and alien species are expected to impose on river communities and the urgent need to adapt management strategies accordingly.

Native drivers of fish life history traits are lost during the invasion process

Rapid adaptation to global change can counter vulnerability of species to population declines and extinction. Theoretically, under such circumstances both genetic variation and phenotypic plasticity can maintain population fitness, but empirical support for this is currently limited. Here, we aim to characterize the role of environmental and genetic diversity, and their prior evolutionary history (via haplogroup profiles) in shaping patterns of life history traits during biological invasion. Data were derived from both genetic and life history traits including a morphological analysis of 29 native and invasive populations of topmouth gudgeon Pseudorasbora parva coupled with climatic variables from each location. General additive models were constructed to explain distribution of somatic growth rate (SGR) data across native and invasive ranges, with model selection performed using Akaike's information criteria. Genetic and environmental drivers that structured the life history of populations in their native range were less influential in their invasive populations. For some vertebrates at least, fitness-related trait shifts do not seem to be dependent on the level of genetic diversity or haplogroup makeup of the initial introduced propagule, nor of the availability of local environmental conditions being similar to those experienced in their native range. As long as local conditions are not beyond the species physiological threshold, its local establishment and invasive potential are likely to be determined by local drivers, such as density-dependent effects linked to resource availability or to local biotic resistance.

Spatial pattern and determinants of global invasion risk of an invasive species, sharpbelly Hemiculter leucisculus (Basilesky, 1855)

Invasive species have imposed huge negative impacts on worldwide aquatic ecosystems and are generally difficult or impossible to be eradicated once established. Consequently, it becomes particularly important to ascertain their invasion risk and its determinants since such information can help us formulate more effective preventive or management actions and direct these measures to those areas where they are truly needed so as to ease regulatory burdens. Here, we examined the global invasion risk and its determinants of sharpbelly (Hemiculter leucisculus), one freshwater fish which has a high invasive potential, by using species distribution models (SDMs) and a layer overlay method. Specifically, first an ensemble species distribution model and its basal models (developed from seven machine learning algorithms) were explored to forecast the global habitat-suitability and variables importance for this species, and then a global invasion risk map was created by combining habitat-suitability with a proxy for introduction likelihood (entailing propagule pressure and dispersal constraints) of exotic sharpbelly. The results revealed that (1) the ensemble model had the highest predictive power in forecasting sharpbelly's global habitat-suitability; (2) areas with high invasion risk by sharpbelly patchily spread over the world except Antarctica; and (3) the Human Influence Index (HII), rather than any of the bioclimatic variables, was the most important factor influencing sharpbelly' future invasion. Based on these results, the present study also attempted to propose a series of prevention and management strategies to eliminate or alleviate the adverse effects caused by this species' further expansion.

Improving Species Distribution Modelling of freshwater invasive species for management applications

Freshwater ecosystems rank among the most endangered ecosystems in the world and are under increasing threat from aquatic invasive species (AIS). Understanding the range expansion of AIS is key for mitigating their impacts. Most approaches rely on Species Distribution Models (SDMs) to predict the expansion of AIS, using mainly environmental variables, yet ignore the role of human activities in favouring the introduction and range expansion of AIS. In this study, we use five SDM algorithms (independently and in ensemble) and two accuracy measures (TSS, AUC), combined with a null modelling approach, to assess the predictive performance of the models and to quantify which predictors (environmental and anthropogenic from the native and introduced regions) best explain the distribution of nine freshwater invasive species (including fish, arthropods, molluscs, amphibians and reptiles) in a large island (Great Britain), and which species characteristics affect model performance. Our results show that the distribution of invasive species is difficult to predict by SDMs, even in cases when TSS and AUC model accuracy values are high. Our study strongly advocates the use of null models for testing SDMs performance and the inclusion of information from the native area and a variety of both human-related and environmental predictors for a more accurate modelling of the range expansion of AIS. Otherwise, models that only include climatic variables, or rely only on standard accuracy measures or a single algorithm, might result in mismanagement of AIS.

The rise of the rosette agent in Europe: An epidemiological enigma

International biodiversity assessments often overlook the role of emerging infectious pathogens in the decline of freshwater fish populations despite the many examples of emerging diseases in other more visible taxa on a global scale. Whilst the introduction of the rosette agent Sphaerothecum destruens in Europe remained an epidemiological enigma, recent findings have shown that this parasite arrived in Europe with the introduction of the healthy carrier Pseudorasbora parva from China nearly 60 years ago and its emergence went unnoticed for over 45 years despite its severe impact on European fish biodiversity. Recent reports on the host and pathogen phylogeny point towards an ancient host-pathogen co-evolution with direct implications on disease risk. Here, we postulate that the observed rapid population decline of native fish species following their infection with virulent strains of S. destruens has underpinned the rapid establishment of P. parva populations during the invasion process. We reviewed the existing evidence supporting the claim of an S. destruens' emergence worldwide and also suggest that the origin of the US strains is to be found among contaminated Asian Oncorhynchus tshawytscha living in sympatry with native Asian P. parva population. Finally, several important preventative steps are suggested as a way to manage the impact of S. destruens on local fish communities.

Insights from modeling studies on how climate change affects invasive alien species geography

Climate change and biological invasions are threatening biodiversity and ecosystem services worldwide. It has now been widely acknowledged that climate change will affect biological invasions. A large number of studies have investigated predicted shifts and other changes in the geographic ranges of invasive alien species related to climate change using modeling approaches. Yet these studies have provided contradictory evidence, and no consensus has been reached. We conducted a systematic review of 423 modeling case studies included in 71 publications that have examined the predicted effects of climate change on those species. We differentiate the approaches used in these studies and synthesize their main results. Our results reaffirm the major role of climate change as a driver of invasive alien species distribution in the future. We found biases in the literature both regarding the taxa, toward plants and invertebrates, and the areas of the planet investigated. Despite these biases, we found for the plants and vertebrates studied that climate change will more frequently contribute to a decrease in species range size than an increase in the overall area occupied. This is largely due to oceans preventing terrestrial invaders from spreading poleward. In contrast, we found that the ranges of invertebrates and pathogens studied are more likely to increase following climate change. An important caveat to these findings is that researchers have rarely considered the effects of climate change on transport, introduction success, or the resulting impacts. We recommend closing these research gaps, and propose additional avenues for future investigations, as well as opportunities and challenges for managing invasions under climate change.