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This contribution presents the first record of the invasive non-native red swamp crayfish Procambarus clarkii (Girard, 1852) in Greece and the Balkans. The crayfish was found during a fish monitoring expedition in the lower reaches of the Vosvozis River, near the city of Komotini, Thrace (northeastern Greece). The finding of P. clarkii in Greece expands the southernmost geographical range of the species in the Balkans and calls for immediate actions in preventing its further expansion to other water bodies and towards strict control of aquarium trade. [ABSTRACT FROM AUTHOR]

We provide the first records of threadfin shad (Dorosoma petenense) in the Delaware River estuary, and the first records of this species in the Delaware River basin since they were stocked in a pond but unable to over-winter in 1977. We collected threadfin shad by boat electrofishing on four separate sampling events and in two tributaries to the Delaware River from August 5, 2022, to August 30, 2023. We briefly speculate on the potential impacts of the species, provide mechanisms to explain their occurrence, and discuss our findings in the context of climate warming and range expansion. These records provide the northernmost account of threadfin shad on the eastern seaboard of North America, excluding a questionable record from the Atlantic Ocean near Nova Scotia in November 1998. [ABSTRACT FROM AUTHOR]

Hamsilos Bay, which is located within the first--degree natural protection area, is one of the most important regions on the southern Black Sea coast. Moreover, many fish species utilize this area for breeding and rearing activities. Small copepod Oithona davisae has been encountered in the Black Sea for two decades and spread rapidly the overall Black Sea, and become an important component in the pelagic ecosystem of the Black Sea. In this respect, the present study aims to characterize the distribution and abundance of Oithona davisae in Hamsilos Bay about environmental variables. Zooplankton samples were collected monthly from seven stations from July 2015 to June 2016 by using a plankton net with a mesh size of 112 μm and a diameter mouth opening of 50 cm. O. davisae was observed during the whole sampling period and was the dominant species from July 2015 to December 2015. The highest mean abundance of this species was recorded in September 2015 (3533.33 ind. m-3). However, the lowest mean abundance was observed between January 2016 (170.68 ind. m-3) and May 2016 (0.24 ind. m-3). Copepodites 5--4 were predominant in the O. davisae population in all months and all stations. Adult copepods and their copepodites 5--4 were more abundant between July 2015 and December 2015, whereas the abundance of copepodites 3--1 was maximum between September 2015 and December 2015. The abundance of O. davisae was highly correlated with chlorophyll-α and physiochemical variables (temperature, dissolved oxygen, and salinity). In conclusion, this species, which is known to be distributed only in the autumn conditions in close areas, extended its temporal distribution and prevailed in the copepod communities during warmer periods. This could be attributed to the acclimatization success of this species in Hamsilos Bay ecosystems. [ABSTRACT FROM AUTHOR]

The Gullele Botanic Garden was established to preserve and safeguard indigenous, rare, endemic, endangered, and economically important plant species. The objective of this study was to identify and map the exotic, invasive, and potentially invasive plant species that are present in the garden’s various land use types, such as natural vegetation, plantations, roadsides and garden edges. The research involved laying plots at different distances in each land use type and collecting vegetation data with geo-location information. Sorensen’s similarity index was used to measure the floristic similarity between the sampled land use types. Data on species density and abundance were analyzed using the corresponding formula. The Shannon–Wiener diversity index and evenness were used to compute the diversity of the species in each land use type using R packages. ArcGIS version 10.5 was used to track the geographical distribution and map the exotic, invasive, and potentially invasive species that exist in all land use types of the garden. A total of 80 plant species belonging to 70 genera in 44 families were recorded in the garden. Asteraceae, Myrtaceae, and Fabaceae comprised the highest number of species. Acacia decurrens, Acacia melanoxylon, Cuscuta campestris, Galinsoga parviflora, Nerium oleander, and Cyathula uncinulata were the most prevalent invasive and potentially invasive species. The study found that the roadside and garden edge land use types had the most diverse exotic and invasive plants. The total density of exotic species was 2.36 plants/m2. The potential possibility of these plants in displacing the native plant species is quite high unless the introduction of exotic plant species is inspected and appropriate management strategies for invasive species are put in place.

The Gullele Botanic Garden was established to preserve and safeguard indigenous, rare, endemic, endangered, and economically important plant species. The objective of this study was to identify and map the exotic, invasive, and potentially invasive plant species that are present in the garden's various land use types, such as natural vegetation, plantations, roadsides and garden edges. The research involved laying plots at different distances in each land use type and collecting vegetation data with geo-location information. Sorensen's similarity index was used to measure the floristic similarity between the sampled land use types. Data on species density and abundance were analyzed using the corresponding formula. The Shannon–Wiener diversity index and evenness were used to compute the diversity of the species in each land use type using R packages. ArcGIS version 10.5 was used to track the geographical distribution and map the exotic, invasive, and potentially invasive species that exist in all land use types of the garden. A total of 80 plant species belonging to 70 genera in 44 families were recorded in the garden. Asteraceae, Myrtaceae, and Fabaceae comprised the highest number of species. Acacia decurrens, Acacia melanoxylon, Cuscuta campestris, Galinsoga parviflora, Nerium oleander, and Cyathula uncinulata were the most prevalent invasive and potentially invasive species. The study found that the roadside and garden edge land use types had the most diverse exotic and invasive plants. The total density of exotic species was 2.36 plants/m2. The potential possibility of these plants in displacing the native plant species is quite high unless the introduction of exotic plant species is inspected and appropriate management strategies for invasive species are put in place. [ABSTRACT FROM AUTHOR]

Understanding the density-dependent impacts of an invasive predator is integral for predicting potential consequences for prey populations. Functional response experiments are used to assess the rate of prey consumption and a predator's ability to search for and consume prey at different resource densities. However, results can be highly context-dependent, limiting their extrapolation to natural ecosystems. Here, we examined how simulated habitat complexity, through the addition of substrate in which prey can escape predation, affects the functional response of invasive European green crabs (Carcinus maenas) foraging on two different bivalve species. Green crabs feeding on varnish clams (Nuttallia obscurata) shifted from a Type II hyperbolic functional response in the absence of substrate to density-independent consumption when prey could bury. Green crabs ate few Japanese littleneck clams (Venerupis philippinarum) under all densities, such that no functional response curve of any type could be produced and their total consumption was always density independent. However, the probability of at least one Japanese littleneck clam being consumed increased significantly with initial clam density and crab claw size across all treatments. At mean crab claw size and compared to trials without substrate, the proportion of varnish clams consumed were 4.2 times smaller when substrate was present, but substrate had a negligible effect (1.2 times) on Japanese littlenecks. The proportion of varnish clams consumed increased with crab claw size and were higher across both substrate conditions than the proportion of Japanese littlenecks consumed; however, the proportion of Japanese littleneck clams consumed increased faster with claw size than that of varnish clams. Our results suggest that including environmental features and variation in prey species can influence the density-dependent foraging described by functional response experiments. Incorporating replicable features of the natural environment into functional response experiments is imperative to make more accurate predictions about the impact of invasive predators on prey populations. [ABSTRACT FROM AUTHOR]

The SE Baltic region harbors a diverse assemblage of alien amphipods of Ponto-Caspian origin. The composition of this fauna was shaped by three invasion waves: (1) pre-twentieth century dispersals via watershed-connecting canals, (2) deliberate introductions in the 1960s, and (3) last decade dispersals via shipping and existing canals. Given this complex history, we test whether genetic diversity (mitochondrial COI and nuclear OPS) differs between the native and invaded ranges and between the deliberately introduced species and the ones that dispersed on their own. We find that in the native range the two species groups exhibited similar COI diversity, while OPS diversity was higher in the deliberately introduced species. In the invaded range, COI diversity significantly decreased in all species, but more so in the self-dispersed group. No change in OPS diversity was detected among ranges. Mitochondrial diversity was more structured geographically in the native range, and the dominant invasive haplotypes were detected in the native populations of all but one species, further highlighting the utility of this marker in tracing invasion sources. Our comparative approach provides important insight into the inter-range genetic diversity of Ponto-Caspian invaders, highlighting the role of introduction mode. [ABSTRACT FROM AUTHOR]

Zoropsis rufipes (Lucas, 1838) is a recorded stowaway to the United Kingdom but the literature in which it was recorded is not widely known. It has thus hitherto not been recorded as a known stowaway in the modern checklists of British spiders. Recently, we discovered specimens in the Natural History Museum, London, providing further records, allowing us to discuss the prior literature, and provide images of the genitalia of this species, which shows notable epigynal variation. [ABSTRACT FROM AUTHOR]

Invasive alien species may cause substantial changes and damaging impacts. Here, we document the current distribution and ecological interactions with native biota of relatively recently introduced wasps, Vespula vulgaris and V. germanica, in the southern part of the Cape Horn Biosphere Reserve (CHBR) in southern Chile. We conducted field studies in four different habitats on Navarino Island: evergreen, deciduous and mixed forests, and shrublands. The spread of V. vulgaris throughout the island has led to it occupying suitable habitats in both urban and rural settings, while V. germanica has not been observed in the last 2 years. The presence of V. vulgaris in remote areas of the CHBR is likely the result of human-mediated movement through the channels within the reserve. The composition of foraged items was different in each of the four studied habitats, yet strongly linked to the resources of each, indicating the inherent ability of V. vulgaris to exploit available resources efficiently. V. vulgaris mainly forages berries from shrubs, and preys on a variety of arthropods, particularly hoverflies, craneflies and lepidoptera larvae. The lack of natural competitors and availability of multiple resources has allowed V. vulgaris to rapidly become a common pest in urban and rural settings in the southern extremity of South America. While we consider that eradication would now be impossible, population control at local scales may still be possible with proper planning and long-term management. Our data provide a baseline for management planning, and we strongly recommend social engagement and dialog with relevant governmental institutions to achieve this challenging task. [ABSTRACT FROM AUTHOR]

Prescribed fire and invasive species are two common land management concerns in Florida; therefore it is important that land managers have a solid understanding of their interactions and how they affect the surrounding ecosystems. These interactions can be roughly categorized into two groups: the effects of the invasive plant on the fire regime and the impacts of fire on the invasive plant or other flora. For this review we chose four invasive species in the southeastern United States that cover a range of interactions with fire: Cogon grass (Imperata cylindrica), Chinese tallow (Triadica sebifera), old world climbing fern (Lygodium microphyllum), and Japanese climbing fern (L. japonicum). This publication details basic information on each species, what is known about how it interacts with fire, and synthesizes this knowledge into concrete management recommendations.

Invasive species are major drivers of ecosystem degradation globally. How invasive herbivore impacts differ from native herbivore impacts remains understudied. We examined the relationships between herbivore sign and vegetation height, foliage density, cover of forbs, weeds, bare ground, and soil compaction across environmental and herbivore activity gradients in the mainland Australian Alps. We detected native and exotic herbivore sign at 32.8% and 94.0% of sites, respectively. Total herbivore activity was primarily attributed to exotic herbivores and was associated with elevation and grassland type. Greater horse (exotic) activity was associated with lower vegetation height, lower foliage density, higher forb cover, and higher soil compaction. Greater rabbit and hare (exotic) activity was associated with lower vegetation height, lower foliage density, and a higher cover of bare ground. Greater total herbivore activity was associated with greater weed cover. Neither deer (exotic) nor kangaroo and wallaby (native) activity was related to response variables. We demonstrate that exotic herbivores dominate mammalian herbivory in these grasslands, which evolved without analogous hooved species. Given the restricted distribution and high endemism of these ecosystems, and associations between exotic herbivores and characteristics of degraded grasslands, we recommend landscape‐scale exotic herbivore management, focusing on maintaining ground cover and vegetation structure. [ABSTRACT FROM AUTHOR]

Fifty species of native snakes live in Florida, help maintain a balance in the ecosystem, and encourage healthy crops. Many non-native snakes have become established, as well, and some have harmed the ecosystem. This brochure is a guide to identifying the snakes of south Florida and differentiating between non-native and commonly confused native snake species.

Species invasions and range shifts can lead to novel host–parasite communities, but we lack general rules on which new associations are likely to form. While many studies examine parasite sharing among host species, the directionality of transmission is typically overlooked, impeding our ability to derive principles of parasite acquisition. Consequently, we analysed parasite records from the non-native ranges of 11 carnivore and ungulate species. Using boosted regression trees, we modelled parasite acquisition within each zoogeographic realm of a focal host's non-native range, using a suite of predictors characterizing the parasites themselves and the host community in which they live. We found that higher parasite prevalence among established hosts increases the likelihood of acquisition, particularly for generalist parasites. Non-native host species are also more likely to acquire parasites from established host species to which they are closely related; however, the acquisition of several parasite groups is biased to phylogenetically specialist parasites, indicating potential costs of parasite generalism. Statistical models incorporating these features provide an accurate prediction of parasite acquisition, indicating that measurable host and parasite traits can be used to estimate the likelihood of new host–parasite associations forming. This work provides general rules to help anticipate novel host–parasite associations created by climate change and other anthropogenic influences. [ABSTRACT FROM AUTHOR]

Alien invasive species not only have adverse environmental impacts, they may also pose socioeconomic and human health threats. The increase in detected non-native (alien) and cryptogenic species, followed by the necessity for up-to-date scientific information on biological invasions, prompted a thorough literature investigation on the non-native entomofauna of Greece. Supplementing previous studies concerning Europe and Greece, a checklist for the non-native insect species of the country is provided, while their number is elevated from 266 to 469. Current trends regarding species richness and taxonomy, deliberate or accidental means of introduction, as well as their native range and trophic preferences are analysed and discussed. This publication illustrates the current state of non-native insects of Greece, highlighting the need for an effective early warning system integrated in national phytosanitary legislation, survey protocols and strategies towards the eradication and mitigation of their detrimental impacts. [ABSTRACT FROM AUTHOR]

The concept of native range in invasion biology is difficult to define since, in many cases, this type of range is unknown and cannot be determined. We investigate the uncertainties related to this concept by focusing on the distribution of Faxonius rusticus (Girard, 1852), also known as the rusty crayfish, which is perceived as possibly the worst invasive crayfish species in North America. In this study, we undertake a comprehensive literature review, which includes 430 studies published between 1852 and 2018, in order to analyze the native and introduced ranges of this species. The rusty crayfish was reported to occur in 33 states in the U.S.A. and 3 Canadian Provinces. Ten of these U.S. states and one Canadian Province have been included multiple times in both the native and the non-native ranges of this crayfish. The confusion regarding the limits and history of the native range of the rusty crayfish has implications for the conservation of this species in various jurisdictions. This review also demonstrates that even for intensely studied species perceived as invasive, we often do not have a clear understanding of essential concepts such as native and non-native range. [ABSTRACT FROM AUTHOR]

The recent upsurge in the edible insect market has seen industrialisation and intensification without adequate regulatory policy guidelines in place. The species being reared and sold are often non‐native, in rearing centres not equipped to contain the species, and in areas without regional or national pre‐entry regulations, post‐entry monitoring guidelines and early response programmes to address escapee species. Such unregulated transport, trade and rearing of species, compounded by the policy and implementation loopholes at the regional, national and international levels will most likely lead to new biological invasions, as has been witnessed with other unregulated trade practices. To avoid this, it is necessary to monitor and regulate the species to be reared, to improve the quarantine guidelines of the rearing centres, and to be more stringent about the policies and practices that allow movements of non‐native species across international borders. [ABSTRACT FROM AUTHOR]

Globalisation of the live pet trade facilitates major pathways for the transport and introduction of invasive alien species across longer distances and at higher frequencies than previously possible. Moreover, the unsustainable trade of species is a major driver for the over-exploitation of wild populations. Australia minimises the biosecurity and conservation risk of the international pet trade by implementing highly stringent regulations on the live import and keeping of alien pets beyond its international CITES obligations. However, the public desire to possess prohibited alien pets has never been quantified and represents a number of species that could be acquired illegally or legally under different future legislative conditions. As such, highly desirable species represent an ongoing conservation threat and biosecurity risk via the pet-release invasion pathway. We aimed to characterise the Australian desire for illegal alien pets and investigate potential sources of external information that can be utilised to predict future desire. Using public live import enquiry records from the Australian Commonwealth Department of Agriculture, Water and the Environment as a proxy for alien pet desire, we tested for differences in the proportion of species with threatened listings and records of invasions, after accounting for taxonomy. Additionally, we used a United States of America (U.S.) live imports dataset to infer pet demand in another Western market with less stringent regulations and determined whether species highly desired in Australia had higher U.S. trade demand than would be expected by chance. The Australian public desire for alien pets is heavily and significantly biased towards species threatened with extinction, species popular in the U.S. trade and species with a history of successful invasions. Not only does this indicate the potential impacts of pet desire on invasion risk and the conservation of threatened species, but we also highlight the potential role of the U.S. trade as an effective predictor for Australian desire. Our research emphasises the value of novel datasets in building predictive capacity for improved biosecurity awareness. [ABSTRACT FROM AUTHOR]

The contiguous United States (CONUS) harbor a significant non-native species diversity. However, spatiotemporal trends of some groups such as terrestrial gastropods (i.e., land snails and slugs) have not been comprehensively considered, and therefore management has been hindered. Here, our aims were to 1.) compile a dataset of all non-native terrestrial gastropod species with CONUS occurrence records, 2.) assess overarching spatiotemporal patterns associated with these records, 3.) describe the continental origin of each species, and 4.) compare climatic associations of each species in their indigenous and introduced CONUS ranges. We compiled a georeferenced dataset of 10,097 records for 22 families, 48 genera, and 69 species, with > 70% of records sourced from the citizen science database iNaturalist. The species Cornu aspersum Müller, 1774 was most prevalent with 3,672 records. The majority (> 92%) of records exhibit an indigenous Western European and Mediterranean distribution, with overlap in broad-scale climatic associations between indigenous and CONUS ranges. Records are most dense in urban metropolitan areas, with the highest proportion of records and species richness in the state of California. We show increased prevalence of non-native species through time, largely associated with urbanized areas with high human population density. Moreover, we show strong evidence for a role for analogous climates in dictating geographic fate and pervasiveness between indigenous and CONUS ranges for non-native species. [ABSTRACT FROM AUTHOR]

Alien plant pathogens are a threat to native plants and are increasingly integrating into native plant–pathogen networks, but how these novel plant–pathogen networks are structured remains unclear. Theory predicts that novel antagonists are likely to be generalists, resulting in interaction networks with greater nestedness as well as lower modularity and specialization than native networks.We tested these predictions by quantifying associations between native plants and their native and alien pathogens using a comprehensive database of plant–fungal associations in New Zealand. We compared the host ranges of alien and native pathogens and the structure of native and alien pathogen subnetworks.As predicted, alien pathogens associated with a greater number and diversity of native plant host species than native pathogens. The alien pathogen subnetwork was more nested and connected, but less modular and less specialized than the native pathogen subnetwork, consistent with expectations for novel interactions. Alien pathogens altered the overall native plant–pathogen network structure, making the full network more connected and less specialized than the native network. Modules in the native and alien subnetworks were clustered by host phylogeny but did not show a clear signal associated with host habitat or region.Synthesis. Our study provides some of the first empirical insights into the structure of novel plant–pathogen networks and the changes that occur when alien pathogens invade a native network. Because alien pathogens interacted with more hosts than native pathogens, alien pathogens have an increased risk of adverse indirect effects, including pathogen spillover, host jumps and network destabilization. [ABSTRACT FROM AUTHOR]

Because researchers and land managers in Florida have been dealing with invasive species for decades, there is an abundance of resources available to the public regarding invasive species. Sometimes, the volume of available information can be confusing. This 6-page document aims to inform the general public, land managers, researchers, local and state policy makers, and others who seek guidance in accessing regulatory and nonregulatory non-native plant lists in the state of Florida. This publication explains the origins of the lists, meaning of inclusion on a particular list, and ways to access each of the lists. Written by Deah Lieurance and Lyn A. Gettys, and published by the UF/IFAS Agronomy Department, August 2019. http://edis.ifas.ufl.edu/ag436 UF/IFAS News Release 10/22/2019: 'Lost in the Weeds?' Guide Sifts Through the Differences Among Non-Native Plant Lists

Ecological theory on the trophic impacts of invasive fauna on native competitors is equivocal. Whilst increased interspecific competition can result in coexisting species having constricted and diverged trophic niches, the competing species might instead increase their niche sizes to maintain energy intakes. Empirical experiments can test invasion theory on competitive interactions and niche sizes across different spatial scales and complexity.The consequences of increased interspecific competition from a model alien fish Leuciscus idus were tested on two taxonomically and trophically similar native fishes, Squalius cephalus and Barbus barbus. Competitive interactions were tested in tank aquaria using comparative functional responses (CFRs) and cohabitation trials. The consequences of these competitive interactions for the trophic niche sizes and positions of the fishes were tested in pond mesocosms.Comparative functional responses revealed that compared to B. barbus, L. idus had significantly higher attack and consumption rates; cohabitation trials revealed B. barbus growth rates were depressed in sympatry with L. idus. For L. idus and S. cephalus, differences in their functional response parameters and growth rates were not significant.Pond mesocosms used stable isotope metrics to quantify shifts in the trophic niche sizes of the fishes between allopatry and sympatry using a substitutive experimental design. Isotopic niches were smaller and more divergent in sympatric paired species than predicted by their allopatric treatments, suggesting trophic impacts from interspecific competition. However, an all‐species sympatric treatment revealed similar niche sizes with allopatry. This maintenance of niche sizes in the presence of all species potentially resulted from the buffering of direct competitive effects of the species pairs by indirect effects.Experimental predictions from tank aquaria assisted the interpretation of the constricted and diverged trophic niches detected in the paired‐species sympatric treatments of the pond mesocosms. However, the all‐species sympatric treatment of this experiment revealed greater complexity in the outcomes of the competitive interactions within and between the species. These results have important implications for understanding how alien species integrate into food webs and influence the trophic relationships between native species. [ABSTRACT FROM AUTHOR]

We review various applications of biocontrol for invasive fish and aquatic invertebrates. We adopt a broader definition of biocontrol that includes traditional methods like predation and physical removal (biocontrol by humans), and modern approaches like genetic engineering and use of microbes (including pathogens). While physical removal and predation (by native predators) are used relatively commonly, use of genetic technologies and microbes is in developmental stages. The two latter strategies are most advanced in case of the common carp (Cyprinus carpio), one of the world's most invasive fish; virus release to control carp might soon occur in Australia. Drawing from empirical examples in North America, we emphasize that biocontrol strategies are most likely to be successful if they include multiple approaches that target specific behaviors or weaknesses in pests' life histories. This is illustrated by reviewing case studies on the common carp and rusty crayfish (Orconectes rusticus) in Midwestern North America. In case of the common carp, basic research on movement patterns and recruitment bottlenecks identified a strategy where winter aggregations of adults were targeted for removal with nets, while native predators of carp eggs and larvae were instrumental in controlling carp's reproductive success. In the case of the rusty crayfish, basic research on interactions between crayfish, habitat, and native predators identified a successful strategy of stocking selected native predators to control juvenile crayfish in conjunction with physical removal of adult crayfish using traps. We are also reviewing the case of the round goby (Neogobius melanostomus) in the Great Lakes. In this example, multiple pieces of evidence (diet, bioenergetics) illustrate how initially abundant pest was brought under control (in some areas) by several species of native predators in a large, natural ecosystem. Overall, examples of successful biocontrol of aquatic pests have been rare and have relied on physical removal and predation. We expect that new technologies (e.g. genetic technologies) will occur in the next decade but will have to clear regulatory and ethical concerns before they are applied. While developing more sophisticated control techniques, we advocate for more basic research on the life history of the pests to identify behavioral or developmental weaknesses that could be targeted with specific tools to increase chances of success while minimizing impacts on native ecosystems. [ABSTRACT FROM AUTHOR]

To improve the suitability of the Darwin Core standard for the research and management of alien species, the standard needs to express the native status of organisms, how well established they are and how they came to occupy a location. To facilitate this, we propose 1. To adopt a controlled vocabulary for the existing Darwin Core term dwc:establishmentMeans 2. To elevate the pathway term from the Invasive Species Pathways extension to become a new Darwin Core term dwc:pathway maintained as part of the Darwin Core standard 3. To adopt a new Darwin Core term dwc:degreeOfEstablishment with an associated controlled vocabulary These changes to the standard will allow users to clearly state whether an occurrence of a species is native to a location or not, how it got there (pathway), and to what extent the species has become a permanent feature of the location. By improving Darwin Core for capturing and sharing these data, we aim to improve the quality of occurrence and checklist data in general and to increase the number of potential uses of these data. [ABSTRACT FROM AUTHOR]

Priority effects can be used to promote target species during restoration. Early planting can provide an advantage over later-arriving species, increasing abundance of these early-arrivers in restored communities. However, we have limited knowledge of the indirect impacts of priority effects in restoration. In particular, we do not understand how priority effects impact non-target species. Of particular conservation concern is how these priority effects influence establishment by non-native species. We use a field-based mesocosm experiment to explore the impacts of priority effects on both target and non-target species in California grasslands. Specifically, we seeded native grasses and forbs, manipulating order of arrival by planting them at the same time, planting forbs one year before grasses, planting grasses one year before forbs, or planting each functional group alone. While our study plots were tilled and weeded for the first year, the regional species pool was heavily invaded. We found that, while early-arrival of native grasses did not promote establishment of non-native species, giving priority to native forbs ultimately left our restoration mesocosms vulnerable to invasion by non-native species. This suggests that, in some cases, establishment of non-native species may be an unintended consequence of using priority treatments as a restoration tool.

Antarctica, with its severe conditions, is poor in terrestrial fauna species. However, an increase in human presence together with climate change may cause an influx of non-native species. Here we report a significant increase in colonized area of one of the few known invasive species to date in Antarctica. Non-native flies of Trichocera maculipennis have been recently observed in the Admiralty Bay area on King George Island, South Shetlands Islands, West Antarctica, 10 years after its first record in Maritime Antarctica (Maxwell Bay, King George Island). Its rapid spread across the island, despite geographic barriers such as glaciers, indicates successful adaptation to local environmental conditions and suggests this species is invasive. The mode of life of T. maculipennis, observed in natural and anthropogenous habitat and in laboratory conditions, is reported. The following adaptations enabled its invasion and existence within the sewage system in Antarctic scientific stations: the ability to survive in complete darkness, male ability to mate on the substrate surface without prior swarming in flight, and adaptation of terrestrial larvae to survive in semi-liquid food. Possible routes of introduction to Antarctica and between two bays on King George Island are discussed, as well as further research leading to the containment and eradication of this species.

We report a first record of the widely invasive bryozoan Bugula neritina in Ketchikan, Alaska (USA), on Revillagigedo Island (southeast Alaska). This represents the northernmost record of this fouling organism in the northeast Pacific Ocean. We also report a new occurrence of the solitary ascidian Ciona savignyi not found in Alaska since 1903, along with recent occurrences of the invasive colonial ascidians Botryllus schlosseri and Botrylloides violaceus in new localities. The high level of vessel traffic in this region and the precedent for historical ship-borne invasions worldwide suggest that future population growth and establishment of these taxa in the Ketchikan area could set the stage for further poleward range expansion, highlighting the need for continued monitoring. [ABSTRACT FROM AUTHOR]

Antarctica, with its severe conditions, is poor in terrestrial fauna species. However, an increase in human presence together with climate change may cause an influx of non-native species. Here we report a significant increase in colonized area of one of the few known invasive species to date in Antarctica. Non-native flies of Trichocera maculipennis have been recently observed in the Admiralty Bay area on King George Island, South Shetlands Islands, West Antarctica, 10 years after its first record in Maritime Antarctica (Maxwell Bay, King George Island). Its rapid spread across the island, despite geographic barriers such as glaciers, indicates successful adaptation to local environmental conditions and suggests this species is invasive. The mode of life of T. maculipennis, observed in natural and anthropogenous habitat and in laboratory conditions, is reported. The following adaptations enabled its invasion and existence within the sewage system in Antarctic scientific stations: the ability to survive in complete darkness, male ability to mate on the substrate surface without prior swarming in flight, and adaptation of terrestrial larvae to survive in semi-liquid food. Possible routes of introduction to Antarctica and between two bays on King George Island are discussed, as well as further research leading to the containment and eradication of this species. [ABSTRACT FROM AUTHOR]

The genetic variability and population structure of introduced species in their native range are potentially important determinants of their invasion success, yet data on native populations are often poorly represented in relevant studies. Consequently, to determine the contribution of genetic structuring in the native range of topmouth gudgeon Pseudorasbora parva to their high invasion success in Europe, we used a dataset comprising of 19 native and 11 non-native populations. A total of 666 samples were analysed at 9 polymorphic microsatellite loci and sequenced for 597 bp of mitochondrial DNA. The analysis revealed three distinct lineages in the native range, of which two haplogroups were prevalent in China (100%), with a general split around the Qinling Mountains. Dating of both haplogroups closely matched past geological events. More recently, its distribution has been influenced by fish movements in aquaculture, resulting in gene flow between previously separated populations in Northern and Southern China. Their phylogeography in Europe indicate as few as two introductions events and two dispersal routes. Microsatellite data revealed native populations had higher genetic diversity than those in the invasive range, a contrast to previous studies on P. parva. This study confirms the importance of extensive sampling in both the native and non-native range of invasive species in evaluating the influence of genetic variability on invasion success. [ABSTRACT FROM AUTHOR]

Abstract: A growing awareness of the destructive effects of non‐native invasive species has led to a massive increase in removal programmes around the world. However, little is generally known about what happens to sites following the removal of the invasives and the implicit assumption that the native community will return, unaided, to pre‐invasion conditions is often left untested. We assessed recovery of the native understorey plant community following removal of the non‐native invasive Rhododendron ponticum L. from Scottish Atlantic oak woodland. We recorded understorey community composition in sites covering a gradient of increasing R. ponticum density, and across a separate series of sites covering a chronosequence of time since R. ponticum removal. We then compared both of these series to the target community found in uninvaded sites. We also analysed differences in soil chemistry between the sites to test for chemical legacy effects of invasion in the soil. Native understorey cover declined as R. ponticum density increased, with bryophytes dropping to less than a third of the cover present in uninvaded sites and forbs and grasses being completely extirpated under dense stands. Cleared sites showed no evidence of returning to the target community, even after 30 years of recovery, and instead formed a bryophyte‐dominated “novel community,” containing few of the typical oak woodland vascular plants. Contrary to expectation, soil pH, C:N ratio and nutrient concentrations (N, P, K, Ca and Mg) were not affected by the invasion of R. ponticum, and chemical legacy effects in the soil were not responsible for the failure of the native community to revert to pre‐invasion conditions. Instead, we hypothesise that the rapid formation of a bryophyte mat, coupled with the often substantial distances to potential seed sources, hindered vascular plant recolonisation. Synthesis and applications. Clear evidence of invasion history can be detected in the understorey plant community even decades after the successful removal of the invasive Rhododendron ponticum L. This finding demonstrates that native communities may be unable to recover effectively of their own accord following invasive species removal, and will require further management interventions in order to achieve restoration goals. [ABSTRACT FROM AUTHOR]

Ornamental horticulture is the primary pathway for invasive alien plant introductions. We critically appraise published evidence on the effectiveness of four policy instruments that tackle invasions along the horticulture supply chain: pre-border import restrictions, post-border bans, industry codes of conduct and consumer education., Effective pre-border interventions rely on rigorous risk assessment and high industry compliance. Post-border sales bans become progressively less effective when alien species become widespread in a region., A lack of independent performance evaluation and of public disclosure, limits the uptake and effectiveness of voluntary codes of conduct and discourages shifts in consumer preference away from invasive alien species., Policy implications. Closing the plant invasion pathway associated with ornamental horticulture requires government-industry agreements to fund effective pre- and post-border weed risk assessments that can be subsequently supported by widely adopted, as well as verifiable, industry codes of conduct. This will ensure producers and consumers make informed choices in the face of better targeted public education addressing plant invasions. [ABSTRACT FROM AUTHOR]

The spread of non-native species raises concerns about native species displacement, while other negative effects on native species (e.g., habitat degradation) should also be considered. The highly invasive non-native apple snail Pomacea maculata has raised such concerns as it has become established in a wide range of aquatic systems worldwide. While monitoring native Florida P. paludosa populations in Lake Tohopekaliga (LTOHO) from 2001 to 2009 and in Water Conservation Area 3A (WCA3A, Everglades) from 2006 to 2015, we opportunistically documented the establishment and distribution of P. maculata. We estimated snail densities and recorded egg cluster presence in three study sites (12 total plots, LTOHO) and 137 sites (WCA3). On LTOHO, native snails were absent or at very low densities prior to finding P. maculata. Few snails of either species were found in high-stem-density vegetation of the littoral zone. Pomacea maculata immigration into the littoral zone occurred following managed vegetation removal, and Hydrilla verticillata proliferation in LTOHO likely contributed to the spread of P. maculata. We found both native and non-native apple snail species in many WCA3A sites following P. maculata invasion. We initially found the non-native snail in two sites in southern WCA3A; they were mostly restricted to within three kilometers of initial sites over the next four years. Overall plant community compositions in LTOHO and WCA3A appeared less impacted than expected based on previous reports of P. maculata invasions.

Following the recent discovery of the brush-clawed shore crab, Hemigrapsus takanoi Asakura & Watanabe, 2005, in Great Britain, new data are presented here on the occurrence of this species from additional locations, five in north Kent and one in Suffolk. This study provides significant evidence to suggest that in Suffolk the species has become well established and now forms a large reproducing population. A new earliest date for introduction of the species to Great Britain is given and the possible vectors involved at the various localities in the SE of England are discussed. Management and eradication of H. takanoi from this area are now considered to be unfeasible. The future spread and potential impact of H. takanoi in Great Britain should be carefully monitored. [ABSTRACT FROM AUTHOR]

Introduced species are a threat to biodiversity. Burbot, Lota lota, a fish native to the Wind River Drainage, Wyoming and a species of conservation concern, have been introduced into the nearby Green River Drainage, Wyoming, where they are having negative effects on native fish species. We compared these native and introduced burbot populations to evaluate potential mechanisms that could be leading to introduction success. We examined genetic ancestry, physical habitat characteristics, community composition, and burbot abundance, relative weight, and size structure between the native and introduced range to elucidate potential differences. The origin of introduced burbot in Flaming Gorge Reservoir is most likely Boysen Reservoir and several nearby river populations in the native Wind River Drainage. Burbot populations did not show consistent differences in abundance, size structure, and relative weight between drainages, though Fontenelle Reservoir, in the introduced drainage, had the largest burbot. There were also limited environmental and community composition differences, though reservoirs in the introduced drainage had lower species richness and a higher percentage of non-native fish species than the reservoir in the native drainage. Burbot introduction in the Green River Drainage is likely an example of reservoir construction creating habitat with suitable environmental conditions to allow a southwards range expansion of this cold-water species. An understanding of the factors driving introduction success can allow better management of species, both in their introduced and native range. [ABSTRACT FROM AUTHOR]

Positive and negative effects on ecosystem services from plantation forestry in Europe have led to conflicts regarding non-native tree species. Sitka spruce (Picea sitchensis (Bong.) Carr.) is the most common plantation species in northwest Europe, covering 1.3 Mha. In costal Norway, Sitka spruce was intentionally introduced and is currently occupying about 50,000 ha. Sitka spruce was blacklisted in Norway in 2012, mainly based on the risk for invasive spreading, but little quantitative documentation exists on spread. Here we quantify spread from plantations into abandoned heathland and pastures in thirteen sites where natural regeneration occurs. Spread distances and zero-square distributions related to the nearest edge of the parent stand were fitted by use of Weibull. The median expansion rate was 0.8 m·year-1 in north Norway and 4.4 m·year-1 in west Norway. The maximum establishment distance measured was 996 m. A peak in sapling density occurred within 50 m from the edge, and there was a general decrease in saplings with increasing distance. Conversely, increase in zero-squares percentages occurred with increasing distance. We argue that inclusion of abundance in assessing spread is necessary to define invasiveness. Based on spread models and prevailing forestry practices we recommend that the establishment of new Sitka spruce plantations within 200 m of protected areas should be avoided. [ABSTRACT FROM AUTHOR]

In contemporary environmental conservation, species are judged in terms of their origin (‘nativeness’), as well as their behaviour and impacts (‘invasiveness’). In many instances, however, the term ‘non-native’ has been used as a proxy for harmfulness, implying the need for control. Some scientists have attempted to discourage this practice, on the grounds that it is inappropriate and counterproductive to judge species on their origin alone. However, to date, no empirical data exist on the degree to which nativeness in itself (that is, a species’ origin) shapes people's attitudes towards management interventions in practice. This study addresses this void, demonstrating empirically that both the public and invasive species professionals largely ignore a species’ origin when evaluating the need for conservation action. Through a questionnaire-based survey of the general public and invasive species experts in both Scotland and Canada, the study revealed that perceived abundance and damage to nature and the economy, rather than non-nativeness, informed attitudes towards species management, empirically substantiating the claim that a species’ perceived abundance and impact, and not its origin, is what really matters to most people. Natural resource management should thus focus explicitly on impact-related criteria, rather than on a species’ origin. [ABSTRACT FROM PUBLISHER]

A recent publication (Pedreschi et al., 2014, Journal of Biogeography, 41, 548-560) casts doubt over the status of pike (Esox lucius) as a non-native species in Ireland by reporting two distinct genetic groups of pike present: one a human introduction in the Middle Ages, the other hypothesized to result from natural colonization after the Last Glacial Maximum (LGM). While the existence of two groups is not disputed, the hypothesized natural colonization scenario conflicts with the sequence in which the islands of Britain and Ireland became isolated from Europe after the LGM. An alternative natural colonization scenario raised herein was rejected, leaving an earlier, two-phase, human introduction of pike from Britain or Europe to Ireland as a realistic alternative hypothesis explaining the results of Pedreschi et al. (2014). This leaves the debates on human introduction versus natural colonization, introduced versus native species status, and pike management in Ireland wide open. [ABSTRACT FROM AUTHOR]

Nesting of Double-crested Cormorants (Phalacrocorax auritus) in western Lake Ontario is associated with reduced abundance and nest density of European Fire Ants (Myrmica rubra). The impact on fire ants may be substrate related. It is of potential importance because of the negative effect of fire ants on ground-nesting water birds. [ABSTRACT FROM AUTHOR]

Aim Climate change is expected to drive range shifts among a wide array of organisms. Non-indigenous species ( NIS) provide a unique opportunity to observe the establishment of range boundaries in a way that cannot be directly seen for native species. Recent studies have indicated that climate change facilitates biological invasions at local scales. However, the generality of these effects is unclear, as there is a dearth of comparative studies that assess how rapid environmental change affects species ranges across taxa and biogeographic provinces. Location The South African coast and other coastlines across the world. Methods We first studied the distribution of shallow-marine benthic organisms along the South African coastline and analysed the global distribution of NIS. We then obtained DNA sequence data from a suite of co-occurring NIS from along the studied coastline and compared these data with available genetic information from other regions of the world. Subsequently, we conducted physiological experiments to assess how thermal tolerance was related to species distribution. Finally, we analysed ship-based seawater temperature records and compared these with past changes in the range size and abundance of NIS. These records were used to estimate shipping intensity and NIS propagule pressure. Results We found that NIS with a variety of thermal tolerances and distributions have expanded their ranges and increased in abundance as seawater temperature regimes have changed. We found little interannual variation in shipping transport intensity. Most haplotypes of the studied NIS in South Africa were shared with other regions. Main conclusions This study provides empirical evidence that NIS, regardless of their thermal tolerance, range size and genetic variability, are expanding their ranges and increasing in abundance. This trend is uncorrelated with levels of human-mediated NIS transport but concurrent with changes in seawater temperature, which suggests that climate change fosters the spread and abundance of NIS across multiple spatial scales. [ABSTRACT FROM AUTHOR]