Biological invasions are a population-level rather than a species-level phenomenon.

Biological invasions pose a rapidly expanding threat to the persistence, functioning and service provisioning of ecosystems globally, and to socio-economic interests. The stages of successful invasions are driven by the same mechanism that underlies adaptive changes across species in general-via natural selection on intraspecific variation in traits that influence survival and reproductive performance (i.e., fitness). Surprisingly, however, the rapid progress in the field of invasion science has resulted in a predominance of species-level approaches (such as deny lists), often irrespective of natural selection theory, local adaptation and other population-level processes that govern successful invasions. To address these issues, we analyse non-native species dynamics at the population level by employing a database of European freshwater macroinvertebrate time series, to investigate spreading speed, abundance dynamics and impact assessments among populations. Our findings reveal substantial variability in spreading speed and abundance trends within and between macroinvertebrate species across biogeographic regions, indicating that levels of invasiveness and impact differ markedly. Discrepancies and inconsistencies among species-level risk screenings and real population-level data were also identified, highlighting the inherent challenges in accurately assessing population-level effects through species-level assessments. In recognition of the importance of population-level assessments, we urge a shift in invasive species management frameworks, which should account for the dynamics of different populations and their environmental context. Adopting an adaptive, region-specific and population-focused approach is imperative, considering the diverse ecological contexts and varying degrees of susceptibility. Such an approach could improve and refine risk assessments while promoting mechanistic understandings of risks and impacts, thereby enabling the development of more effective conservation and management strategies.

Economic costs of non-native species in Türkiye: A first national synthesis.

Biological invasions are increasingly recognised as a major global change that erodes ecosystems, societal well-being, and economies. However, comprehensive analyses of their economic ramifications are missing for most national economies, despite rapidly escalating costs globally. Türkiye is highly vulnerable to biological invasions owing to its extensive transport network and trade connections as well as its unique transcontinental position at the interface of Europe and Asia. This study presents the first analysis of the reported economic costs caused by biological invasions in Türkiye. The InvaCost database which compiles invasive non-native species' monetary costs was used, complemented with cost searches specific to Türkiye, to describe the spatial and taxonomic attributes of costly invasive non-native species, the types of costs, and their temporal trends. The total economic cost attributed to invasive non-native species in Türkiye (from 202 cost reporting documents) amounted to US$ 4.1 billion from 1960 to 2022. However, cost data were only available for 87 out of 872 (10%) non-native species known for Türkiye. Costs were biased towards a few hyper-costly non-native taxa, such as jellyfish, stink bugs, and locusts. Among impacted sectors, agriculture bore the highest total cost, reaching US$ 2.85 billion, followed by the fishery sector with a total cost of US$ 1.20 billion. Management (i.e., control and eradication) costs were, against expectations, substantially higher than reported damage costs (US$ 2.89 billion vs. US$ 28.4 million). Yearly costs incurred by non-native species rose exponentially over time, reaching US$ 504 million per year in 2020-2022 and are predicted to increase further in the next 10 years. A large deficit of cost records compared to other countries was also shown, suggesting a larger monetary underestimate than is typically observed. These findings underscore the need for improved cost recording as well as preventative management strategies to reduce future post-invasion management costs and help inform decisions to manage the economic burdens posed by invasive non-native species. These insights further emphasise the crucial role of standardised data in accurately estimating the costs associated with invasive non-native species for prioritisation and communication purposes.

Exploring invasiveness and versatility of used microhabitats of the globally invasive Gambusia holbrooki.

Non-native species can lead to severe impacts on invaded ecosystems, including the decline of ecosystem function through deleterious impacts on species diversity. The successful establishment of non-native species in new environments is the first barrier a species must overcome, ultimately depending on its ability to either cope with or adapt to local site-specific conditions. Despite the widespread distribution and ecological consequences of many freshwater invaders, site-specific and climatic preferences are often unknown. This is also the case of the Eastern mosquitofish Gambusia holbrooki, a global invader considered as a pervasive threat to endemic species. Here, we determined the ecological features and preferred site-specific conditions of G. holbrooki in Türkiye, which spans a wide range of diverse biogeographically distinct ecosystems by surveying populations from 130 localities in 2016 and 2017. Gambusia holbrooki were detected by hand-net in 48 of these sites (19 lotic, 29 lentic). It showed a preference for shallow waters with medium sized rocks, and abundances differed spatially across a latitudinal gradient and was influenced predominantly by variations in pH. The only other factors predicting its presence were low current velocities and gravel substrate, highlighting its ecological versatility in utilising a wide range of microhabitats. Bioclimatic models suggest that G. holbrooki is found in areas with a wide average annual temperature ranging from 10 to 20 °C, but with temperature not being a limiting factor to its invasion. Gambusia holbrooki shows a preference for xeric freshwater ecosystems and endorheic basins, as well as temperate coastal rivers, temperate upland rivers, temperate floodplain rivers and wetlands, and tropical and subtropical coastal rivers. These results, particularly the wide occurrence with only few limiting factors, emphasise the invasion potential of mosquitofish and should substantiate the need for localised invasive species management and conservation efforts, particularly in smaller or insular areas where mosquitofish and endemic fish species co-exist.

Taming the terminological tempest in invasion science.

Standardised terminology in science is important for clarity of interpretation and communication. In invasion science - a dynamic and rapidly evolving discipline - the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions. A standardised framework is therefore needed for a clear, universally applicable, and consistent terminology to promote more effective communication across researchers, stakeholders, and policymakers. Inconsistencies in terminology stem from the exponential increase in scientific publications on the patterns and processes of biological invasions authored by experts from various disciplines and countries since the 1990s, as well as publications by legislators and policymakers focusing on practical applications, regulations, and management of resources. Aligning and standardising terminology across stakeholders remains a challenge in invasion science. Here, we review and evaluate the multiple terms used in invasion science (e.g. 'non-native', 'alien', 'invasive' or 'invader', 'exotic', 'non-indigenous', 'naturalised', 'pest') to propose a more simplified and standardised terminology. The streamlined framework we propose and translate into 28 other languages is based on the terms (i) 'non-native', denoting species transported beyond their natural biogeographic range, (ii) 'established non-native', i.e. those non-native species that have established self-sustaining populations in their new location(s) in the wild, and (iii) 'invasive non-native' - populations of established non-native species that have recently spread or are spreading rapidly in their invaded range actively or passively with or without human mediation. We also highlight the importance of conceptualising 'spread' for classifying invasiveness and 'impact' for management. Finally, we propose a protocol for classifying populations based on (i) dispersal mechanism, (ii) species origin, (iii) population status, and (iv) impact. Collectively and without introducing new terminology, the framework that we present aims to facilitate effective communication and collaboration in invasion science and management of non-native species.

Assessing the potential phytosanitary threat of the house cricket Acheta domesticus.

Phytosanitary threats can pose substantial risks to global agriculture and ecological systems, affecting biodiversity, human well-being, and food security. Meanwhile, global warming is projected to exacerbate these threats in the future. One in Europe already widely distributed potential phytosanitary threat that may benefit from global warming is the house cricket Acheta domesticus. This study explored the potential of A. domesticus as a relevant non-native phytosanitary threat under changing climatic conditions by conducting a series of functional response experiments across a temperature gradient (20, 25, and 30 °C). Acheta domesticus exhibited comparable patterns of seed consumption and functional responses. Seed type (millet seeds, wheat grains) and temperature increase influenced the damage inflicted on seeds, with softer and smaller seeds being more susceptible to damage, further amplified by warmer temperatures. The study's outcomes underline the phytosanitary threat that A. domesticus may pose. Considering the species' established presence and adaptable nature in urban environments exacerbates the potential for A. domesticus to transition to rural and agricultural areas. Its increasing production as a food item, paired with the here-identified potential to damage seeds, emphasizes the need for proactive and science-based strategies to address emerging phytosanitary threats driven by non-native species under changing climatic conditions. As global temperatures continue to rise, the assessment and management of potential pest species like A. domesticus will be crucial for safeguarding agriculture productivity and ecological balance.

The wild cost of invasive feral animals worldwide.

Invasive non-native species are a growing burden to economies worldwide. While domesticated animals (i.e. livestock, beasts of burden or pets) have enabled our ways of life and provide sustenance for countless individuals, they may cause substantial impacts when they escape or are released (i.e. become feral) and then become invasive with impacts. We used the InvaCost database to evaluate monetary impacts from species in the Domestic Animal Diversity Information System database. We found a total cost of $141.95 billion from only 18 invasive feral species. Invasive feral livestock incurred the highest costs at $90.03 billion, with pets contributing $50.93 billion and beasts of burden having much lower costs at $0.98 billion. Agriculture was the most affected sector at $80.79 billion, followed by the Environment ($43.44 billion), and Authorities-Stakeholders sectors ($5.52 billion). Damage costs comprised the majority ($124.94 billion), with management and mixed damage-management costs making up the rest ($9.62 and $7.38 billion, respectively). These economic impacts were observed globally, where Oceania, North America and Europe were the most impacted regions. Islands recorded a higher economic burden than continental areas, with livestock species dominating costs more on islands than mainlands compared to other feral species. The costs of invasive feral animals were on average twice higher than those of wild species. The management of invasive feral populations requires higher investment, updated regulations, and comprehensive risk assessments. These are especially complex when considering the potential conflicts arising from interventions with species that have close ties to humans. Effective communication to raise public awareness of the impacts of feral populations and appropriate legislation to prevent or control such invasive feral populations will substantially contribute to minimizing their socioeconomic and environmental impacts.

Economic impact disharmony in global biological invasions.

A dominant syndrome of the Anthropocene is the rapid worldwide spread of invasive species with devastating environmental and socio-economic impacts. However, the dynamics underlying the impacts of biological invasions remain contested. A hypothesis posits that the richness of impactful invasive species increases proportionally with the richness of non-native species more generally. A competing hypothesis suggests that certain species features disproportionately enhance the chances of non-native species becoming impactful, causing invasive species to arise disproportionately relative to the numbers of non-native species. We test whether invasive species with reported monetary costs reflect global numbers of established non-native species among phyla, classes, and families. Our results reveal that numbers of invasive species with economic costs largely reflect non-native species richness among taxa (i.e., in 96 % of families). However, a few costly taxa were over- and under-represented, and their composition differed among environments and regions. Chordates, nematodes, and pathogenic groups tended to be the most over-represented phyla with reported monetary costs, with mammals, insects, fungi, roundworms, and medically-important microorganisms being over-represented classes. Numbers of costly invasive species increased significantly with non-native richness per taxon, while monetary cost magnitudes at the family level were also significantly related to costly invasive species richness. Costs were biased towards a few 'hyper-costly' taxa (such as termites, mosquitoes, cats, weevils, rodents, ants, and asters). Ordination analysis revealed significant dissimilarity between non-native and costly invasive taxon assemblages. These results highlight taxonomic groups which harbour disproportionately high numbers of costly invasive species and monetary cost magnitudes. Collectively, our findings support prevention of arrival and containment of spread of non-native species as a whole through effective strategies for mitigation of the rapidly amplifying impacts of invasive species. Yet, the hyper- costly taxa identified here should receive greater focus from managers to reduce impacts of current invasive species.

The neglect of nonnative orthopterans as potential invaders: A call for awareness.

Despite the potential ecological and economic impacts of invasive species, there is a dearth of data on the presence, impacts, and management implications of potentially invasive Orthoptera species. This lack of research and inconsistent data, including risk screenings and impact assessments, is especially evident in Europe. Consequently, assessing the status, distribution, and potential threats of nonnative Orthoptera in Europe remains challenging, impeding the development of effective management strategies. To address this gap, we call for increased efforts to collect and curate data on non-native and possibly invasive Orthoptera in Europe. Such efforts will improve our understanding of this order's invasion dynamics, facilitate the identification of priority areas for conservation, and support the development of effective management policies and preventive measures.

Recent advances in availability and synthesis of the economic costs of biological invasions.

Biological invasions are a global challenge that has received insufficient attention. Recently available cost syntheses have provided policy- and decision makers with reliable and up-to-date information on the economic impacts of biological invasions, aiming to motivate effective management. The resultant InvaCost database is now publicly and freely accessible and enables rapid extraction of monetary cost information. This has facilitated knowledge sharing, developed a more integrated and multidisciplinary network of researchers, and forged multidisciplinary collaborations among diverse organizations and stakeholders. Over 50 scientific publications so far have used the database and have provided detailed assessments of invasion costs across geographic, taxonomic, and spatiotemporal scales. These studies have provided important information that can guide future policy and legislative decisions on the management of biological invasions while simultaneously attracting public and media attention. We provide an overview of the improved availability, reliability, standardization, and defragmentation of monetary costs; discuss how this has enhanced invasion science as a discipline; and outline directions for future development.

Effects of chemical cues and prior experience on predator avoidance in crayfish.

Multisensory stimuli provide organisms with information to assess the threat present in the surroundings. Olfactory cues show dominance over other sensory modalities in the aquatic environment. The impact of chemical predator cues combined with experiences gained (learning) in species without previous contact is not fully understood. We investigated the foraging and shelter-seeking behaviour of naïve and experienced marbled crayfish Procambarus virginalis juveniles in response to the chemical signals of pumpkinseed Lepomis gibbosus alone and in combination with alarm chemicals produced by preyed-upon conspecifics. Naïve and experienced (previously exposed to pumpkinseed predation) juveniles were stocked in an arena with shelter and feed and exposed (1) to water from a tank containing a predator actively feeding on conspecifics, (2) water from a tank with predator only and (3) water only as control. Crayfish exposed to the combined stimuli avoided the inlet zone and gravitated to shelter zone of the arena to a greater extent than did those exposed to predator-only cues and the control. Regardless of the treatment, experienced crayfish showed significantly reduced interest in feeding. Our findings imply that crayfish response to threat-associated odours with the greatest potency when visual or tactile cues are present, while previous encounters with predators may make them more cautious.

Effect of psychoactive substances on cardiac and locomotory activity of juvenile marbled crayfish Procambarus virginalis.

Pharmaceutically active compounds are common and increasing in the aquatic environment. Evidence suggests they have adverse effects on non-target organisms, and they are classified as emerging pollutants for a variety of aquatic organisms. To determine the effects of environmentally relevant levels of psychoactive compounds on non-target organisms, we analyzed cardiac and locomotory activity in early developmental stages of marbled crayfish Procambarus virginalis. Responses to sertraline, methamphetamine, and a mixture of citalopram, oxazepam, sertraline, tramadol, venlafaxine, and methamphetamine at a concentration of 1 µg L-1 of each compound were assessed. On day four of exposure, cardiac activity was recorded for 5 min, and on day eight, locomotory activity was recorded for 15 min. There was a significant increase (p < 0.01) in heart rate in methamphetamine-exposed and Mix-exposed juveniles compared to the unexposed control and there was significant difference (p < 0.01) in proportion of time (activity %) was observed with sertraline-exposed, whereas velocity, and distance moved did not significantly differ (p > 0.05) in exposed and control animals. These findings revealed that low concentrations of chemicals and their mixtures can modify the physiological state of aquatic animals without outward manifestations (activity, distance moved, and velocity). Aquatic animals can be impacted earlier than is visible, but effects can potentially lead to substantial changes in populations and in ecosystem processes. Additional research to investigate chemical combinations, exposure systems, and organism physiological and molecular responses may provide evidence of broad impact of environmental pharmaceuticals.

A Novel Traffic Prediction Method Using Machine Learning for Energy Efficiency in Service Provider Networks.

This paper presents a systematic approach for solving complex prediction problems with a focus on energy efficiency. The approach involves using neural networks, specifically recurrent and sequential networks, as the main tool for prediction. In order to test the methodology, a case study was conducted in the telecommunications industry to address the problem of energy efficiency in data centers. The case study involved comparing four recurrent and sequential neural networks, including recurrent neural networks (RNNs), long short-term memory (LSTM), gated recurrent units (GRUs), and online sequential extreme learning machine (OS-ELM), to determine the best network in terms of prediction accuracy and computational time. The results show that OS-ELM outperformed the other networks in both accuracy and computational efficiency. The simulation was applied to real traffic data and showed potential energy savings of up to 12.2% in a single day. This highlights the importance of energy efficiency and the potential for the methodology to be applied to other industries. The methodology can be further developed as technology and data continue to advance, making it a promising solution for a wide range of prediction problems.

Unveiling the hidden economic toll of biological invasions in the European Union.

Background: Biological invasions threaten the functioning of ecosystems, biodiversity, and human well-being by degrading ecosystem services and eliciting massive economic costs. The European Union has historically been a hub for cultural development and global trade, and thus, has extensive opportunities for the introduction and spread of alien species. While reported costs of biological invasions to some member states have been recently assessed, ongoing knowledge gaps in taxonomic and spatio-temporal data suggest that these costs were considerably underestimated. Results: We used the latest available cost data in InvaCost (v4.1)-the most comprehensive database on the costs of biological invasions-to assess the magnitude of this underestimation within the European Union via projections of current and future invasion costs. We used macroeconomic scaling and temporal modelling approaches to project available cost information over gaps in taxa, space, and time, thereby producing a more complete estimate for the European Union economy. We identified that only 259 out of 13,331 (~ 1%) known invasive alien species have reported costs in the European Union. Using a conservative subset of highly reliable, observed, country-level cost entries from 49 species (totalling US$4.7 billion; 2017 value), combined with the establishment data of alien species within European Union member states, we projected unreported cost data for all member states. Conclusions: Our corrected estimate of observed costs was potentially 501% higher (US$28.0 billion) than currently recorded. Using future projections of current estimates, we also identified a substantial increase in costs and costly species (US$148.2 billion) by 2040. We urge that cost reporting be improved to clarify the economic impacts of greatest concern, concomitant with coordinated international action to prevent and mitigate the impacts of invasive alien species in the European Union and globally. Supplementary Information: The online version contains supplementary material available at 10.1186/s12302-023-00750-3.

Long-term trends in abundances of non-native species across biomes, realms, and taxonomic groups in Europe.

Rates of biological invasion have increased over recent centuries and are expected to increase in the future. Whereas increasing rates of non-native species incursions across realms, taxonomic groups, and regions are well-reported, trends in abundances within these contexts have lacked analysis due to a paucity of long-term data at large spatiotemporal scales. These knowledge gaps impede prioritisation of realms, regions, and taxonomic groups for management. We analysed 180 biological time series (median 15 ± 12.8 sampling years) mainly from Long-Term Ecological Research (LTER) sites comprising abundances of marine, freshwater, and terrestrial non-native species in Europe. A high number (150; 83,3 %) of these time series were invaded by at least one non-native species. We tested whether (i) local long-term abundance trends of non-native species are consistent among environmental realms, taxonomic groups, and regions, and (ii) if any detected trend can be explained by climatic conditions. Our results indicate that abundance trends at local scales are highly variable, with evidence of declines in marine and freshwater long-term monitoring sites, despite non-native species reports increasing rapidly since the late 1970s. These declines were driven mostly by abundance trends in non-native fish, birds, and invertebrate species in three biogeographic regions (Continental, Atlantic, and the North Sea). Temperature and precipitation were important predictors of observed abundance trends across Europe. Yet, the response was larger for species with already declining trends and differed among taxa. Our results indicate that trends in biological invasions, especially across different taxonomic groups, are context-dependent and require robust local data to understand long-term trends across contexts at large scales. While the process of biological invasion is spatiotemporally broad, economic or ecological impacts are generally realised on the local level. Accordingly, we urge proactive and coordinated management actions from local to large scales, as invasion impacts are substantial and dynamics are prone to change.

A New COVID-19 Detection Method Based on CSK/QAM Visible Light Communication and Machine Learning.

This article proposes a novel method for detecting coronavirus disease 2019 (COVID-19) in an underground channel using visible light communication (VLC) and machine learning (ML). We present mathematical models of COVID-19 Deoxyribose Nucleic Acid (DNA) gene transfer in regular square constellations using a CSK/QAM-based VLC system. ML algorithms are used to classify the bands present in each electrophoresis sample according to whether the band corresponds to a positive, negative, or ladder sample during the search for the optimal model. Complexity studies reveal that the square constellation N=22i×22i,(i=3) yields a greater profit. Performance studies indicate that, for BER = 10-3, there are gains of -10 [dB], -3 [dB], 3 [dB], and 5 [dB] for N=22i×22i,(i=0,1,2,3), respectively. Based on a total of 630 COVID-19 samples, the best model is shown to be XGBoots, which demonstrated an accuracy of 96.03%, greater than that of the other models, and a recall of 99% for positive values.

Sigmoidal curves reflect impacts and dynamics of aquatic invasive species.

Identifying general patterns and trends underlying the impacts and dynamics of biological invasions has proven elusive for scientists. Recently, the impact curve was proposed as a means to predict temporal impacts of invasive alien species, characterised by a sigmoidal growth pattern with an initial exponential increase, followed by a subsequent rate of decline and approaching a saturation level in the long-term where impact is maximised. While the impact curve has been empirically demonstrated with monitoring data of a single invasive alien species (the New Zealand mud snail, Potamopyrgus antipodarum), broadscale applicability remains to be tested for other taxa. Here, we examined whether the impact curve can adequately describe the invasion dynamics of 13 other aquatic species (within Amphipoda, Bivalvia, Gastropoda, Hirudinea, Isopoda, Mysida, and Platyhelminthes) at the European level, employing multi-decadal time series of macroinvertebrate cumulative abundances from regular benthic monitoring efforts. For all except one tested species (the killer shrimp, Dikerogammarus villosus), the sigmoidal impact curve was strongly supported (R2 > 0.95) on a sufficiently long time-scale. For D. villosus, the impact had not yet reached saturation, likely reflecting the ongoing European invasion. The impact curve facilitated estimation of introduction years and lag phases, as well as parameterisation of growth rates and carrying capacities, providing strong support for the boom-bust dynamics typically observed in several invader populations. These findings suggest that impact can grow rapidly before saturating at a high level, with timely monitoring often lacking for the detection of invasive alien species post-introduction. We further confirm the applicability of the impact curve to determine trends in invasion stages, population dynamics, and impacts of pertinent invaders, ultimately helping inform the timing of management interventions. We hence call for improved monitoring and reporting of invasive alien species over broad spatio-temporal scales to permit further testing of large-scale impact consistencies across various habitat types.

Long-term trends in crayfish invasions across European rivers.

Europe has experienced a substantial increase in non-indigenous crayfish species (NICS) since the mid-20th century due to their extensive use in fisheries, aquaculture and, more recently, pet trade. Despite relatively long invasion histories of some NICS and negative impacts on biodiversity and ecosystem functioning, large spatio-temporal analyses of their occurrences are lacking. Here, we used a large freshwater macroinvertebrate database to evaluate what information on NICS can be obtained from widely applied biomonitoring approaches and how usable such data is for descriptions of trends in identified NICS species. We found 160 time-series containing NICS between 1983 and 2019, to infer temporal patterns and environmental drivers of species and region-specific trends. Using a combination of meta-regression and generalized linear models, we found no significant temporal trend for the abundance of any species (Procambarus clarkii, Pacifastacus leniusculus or Faxonius limosus) at the European scale, but identified species-specific predictors of abundances. While analysis of the spatial range expansion of NICS was positive (i.e. increasing spread) in England and negative (significant retreat) in northern Spain, no trend was detected in Hungary and the Dutch-German-Luxembourg region. The average invasion velocity varied among countries, ranging from 30 km/year in England to 90 km/year in Hungary. The average invasion velocity gradually decreased over time in the long term, with declines being fastest in the Dutch-German-Luxembourg region, and much slower in England. Considering that NICS pose a substantial threat to aquatic biodiversity across Europe, our study highlights the utility and importance of collecting high resolution (i.e. annual) biomonitoring data using a sampling protocol that is able to estimate crayfish abundance, enabling a more profound understanding of NICS impacts on biodiversity.

Alien species and climate change drive shifts in a riverine fish community and trait compositions over 35 years.

Alien fish substantially impact aquatic communities. However, their effects on trait composition remain poorly understood, especially at large spatiotemporal scales. Here, we used long-term biomonitoring data (1984-2018) from 31 fish communities of the Rhine river in Germany to investigate compositional and functional changes over time. Average total community richness increased by 49 %: it was stable until 2004, then declined until 2010, before increasing until 2018. Average abundance decreased by 9 %. Starting from 198 individuals/m2 in 1984 abundance largely declined to 23 individuals/m2 in 2010 (-88 %), and then consequently increased by 678 % up to 180 individuals/m2 until 2018. Increases in abundance and richness starting around 2010 were mainly driven by the establishment of alien species: while alien species represented 5 % of all species and 0.1 % of total individuals in 1993, it increased to 30 % (7 species) and 32 % of individuals in 2018. Concomitant to the increase in alien species, average native species richness and abundance declined by 26 % and 50 % respectively. We identified increases in temperature, precipitation, abundance and richness of alien fish driving compositional changes after 2010. To get more insights on the impacts of alien species on fish communities, we used 12 biological and 13 ecological traits to compute four trait metrics each. Ecological trait dispersion increased before 2010, probably due to diminishing ecologically similar native species. No changes in trait metrics were measured after 2010, albeit relative shares of expressed trait modalities significantly changing. The observed shift in trait modalities suggested the introduction of new species carrying similar and novel trait modalities. Our results revealed significant changes in taxonomic and trait compositions following alien fish introductions and climatic change. To conclude, our analyses show taxonomic and functional changes in the Rhine river over 35 years, likely indicative of future changes in ecosystem services.

A Novel and Adaptive Angle Diversity-Based Receiver for 6G Underground Mining VLC Systems.

Visible light communication (VLC) is considered an enabling technology for future 6G wireless systems. Among the many applications in which VLC systems are used, one of them is harsh environments such as Underground Mining (UM) tunnels. However, these environments are subject to degrading environmental and intrinsic challenges for optical links. Therefore, current research should focus on solutions to mitigate these problems and improve the performance of Underground Mining Visible Light Communication (UM-VLC) systems. In this context, this article presents a novel solution that involves an improvement to the Angle Diversity Receivers (ADRs) based on the adaptive orientation of the Photo-Diodes (PDs) in terms of the Received Signal Strength Ratio (RSSR) scheme. Specifically, this methodology is implemented in a hemidodecahedral ADR and evaluated in a simulated UM-VLC scenario. The performance of the proposed design is evaluated using metrics such as received power, user data rate, and bit error rate (BER). Furthermore, our approach is compared with state-of-the-art ADRs implemented with fixed PDs and with the Time of Arrival (ToA) reception method. An improvement of at least 60% in terms of the analyzed metrics compared to state-of-the-art solutions is obtained. Therefore, the numerical results demonstrate that the hemidodecahedral ADR, with adaptive orientation PDs, enhances the received optical signal. Furthermore, the proposed scheme improves the performance of the UM-VLC system due to its optimum adaptive angular positioning, which is completed according to the strongest optical received signal power. By improving the performance of the UM-VLC system, this novel method contributes to further consideration of VLC systems as potential and enabling technologies for future 6G deployments.

Global economic costs of herpetofauna invasions.

Biological invasions by amphibian and reptile species (i.e. herpetofauna) are numerous and widespread, having caused severe impacts on ecosystems, the economy and human health. However, there remains no synthesised assessment of the economic costs of these invasions. Therefore, using the most comprehensive database on the economic costs of invasive alien species worldwide (InvaCost), we analyse the costs caused by invasive alien herpetofauna according to taxonomic, geographic, sectoral and temporal dimensions, as well as the types of these costs. The cost of invasive herpetofauna totaled at 17.0 billion US$ between 1986 and 2020, divided split into 6.3 billion US$ for amphibians, 10.4 billion US$ for reptiles and 334 million US$ for mixed classes. However, these costs were associated predominantly with only two species (brown tree snake Boiga irregularis and American bullfrog Lithobates catesbeianus), with 10.3 and 6.0 billion US$ in costs, respectively. Costs for the remaining 19 reported species were relatively minor (< 0.6 billion US$), and they were entirely unavailable for over 94% of known invasive herpetofauna worldwide. Also, costs were positively correlated with research effort, suggesting research biases towards well-known taxa. So far, costs have been dominated by predictions and extrapolations (79%), and thus empirical observations for impact were relatively scarce. The activity sector most affected by amphibians was authorities-stakeholders through management (> 99%), while for reptiles, impacts were reported mostly through damages to mixed sectors (65%). Geographically, Oceania and Pacific Islands recorded 63% of total costs, followed by Europe (35%) and North America (2%). Cost reports have generally increased over time but peaked between 2011 and 2015 for amphibians and 2006 to 2010 for reptiles. A greater effort in studying the costs of invasive herpetofauna is necessary for a more complete understanding of invasion impacts of these species. We emphasise the need for greater control and prevention policies concerning the spread of current and future invasive herpetofauna.