Global ecological impacts of invasive species in aquatic ecosystems

Effects of nitrogen-driven eutrophication on the horizontal transfer of extracellular antibiotic resistance genes in water-sediment environments

Excessive nitrogen and other nutrients can trigger the eutrophication of freshwater bodies. Antibiotic resistance genes (ARGs) are now recognized as environmental pollutants, with extracellular ARGs (eARGs) being the dominant form in sediments. However, research on the propagation characteristics of eARGs remains limited. This study investigated the transfer characteristics of kanamycin resistance (KR) genes in the pEASY-T1 plasmid to intracellular DNA (iDNA) and extracellular DNA (eDNA) in water and sediment microenvironments under increasing nitrogen concentrations, as well as the community structure of free-living (FL) and particle-attached (PA) bacteria. The results revealed KR genes relative abundance in free extracellular DNA (f-eDNA) and adsorbed extracellular DNA (a-eDNA) of the water initially decreased and then increased with rising nitrogen concentrations. Its abundance in iDNA of the sediments decreased significantly with increasing nitrogen content, with relative abundance ranging from 5.09 × 10-4 to 1.14 × 10-3 copies/16SrRNA. The transfer from eDNA to iDNA in the water showed a rising and then falling trend as nitrogen concentration rose. The transfer of iDNA from the water to iDNA in sediments exhibited the opposite pattern. Additionally, copper (Cu) and zinc (Zn) were identified as key factors influencing the abundance of KR genes in the water, but total phosphorus (TP) was the primary determinant of KR gene distribution in sediments according to random forest analysis. These findings reveal novel mechanisms of eARG propagation in eutrophic environments, providing a theoretical foundation for managing antibiotic resistance in aquatic ecosystems.

Global Impacts Dataset of Invasive Alien Species (GIDIAS)

Invasive alien species are a major driver of global change, impacting biodiversity, ecosystem services, and human livelihoods. To document these impacts, we present the Global Impacts Dataset of Invasive Alien Species (GIDIAS), a dataset on the positive, negative and neutral impacts of invasive alien species on nature, nature's contributions to people, and good quality of life. This dataset arises from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services' (IPBES) thematic assessment report of this topic. Data were compiled from published sources, including grey literature, reporting a direct observation of an invasive alien species' impact. All impact records contain up to 52 fields of contextual information and attempt to link impacts to the global standard "environmental impact classification for alien taxa" (EICAT) and "socio-economic impact classification for alien taxa" (SEICAT). GIDIAS includes more than 22000 records of impacts caused by 3353 invasive alien species (plants, vertebrates, invertebrates, microorganisms) from all continents and realms (terrestrial, freshwater, marine), extracted from over 6700 sources. We intend GIDIAS to be a global resource for investigating and managing the variety of impacts of invasive alien species across taxa and regions.

Macrofaunal biodiversity and trophic structure varied in response to changing environmental properties along the Spartina alterniflora invasion stages

Spartina alterniflora has significantly altered coastal ecosystems. Understanding macrofaunal responses to its invasion is crucial for managing coastal wetlands. Five invasion stages over 16 years were analyzed: no invasion, initial, young, mature, and senescing. Macrofaunal biodiversity initially increased but later declined. Environmental properties varied by stages, creating distinct habitats. The impact on macrofauna depended on species traits and invasion stage. Key species accounting for 49.54 % of dissimilarity were Stenothyra glabra, Bullacta caurina, Pseudomphala latericea, and Potamocorbula laevis. Trophic structure initially remained stable but shifted later. Organic carbon (OC), total nitrogen (TN), and C/N ratio correlated with S. alterniflora development. Height of S. alterniflora was a key environmental indicator, while OC content and C/N ratio were crucial for shaping the macrofaunal community, indicating food source changes. This study provides valuable insights for managing coastal environments.

Movement patterns of invasive red swamp crayfish vary with sex and environmental factors

Invasive species disproportionately invade freshwater ecosystems, threatening biodiversity. Defining when, where, and why aquatic invasive species move can help inform management strategies, yet the movement ecology of some of the most pervasive invasive species remains unknown. Red swamp crayfish (Procambarus clarkii; RSC) are the most widespread invasive crayfish and negatively affect ecosystems worldwide. We employed high-dimensional acoustic telemetry to investigate the movement patterns of 24 individual RSC across three months in an invaded water body. We assessed the effects of various extrinsic factors, such as time of day, temperature, precipitation, and proximity to the water's edge, along with intrinsic factors, such as sex, reproductive form, and size, at different scales, including movement steps, range distribution, and behavioral states. We found that movement patterns across all scales were overwhelmingly driven by sex and reproductive form. Furthermore, RSC showed increased overall activity at night and near the water's edge. By establishing baseline movement patterns and identifying key contributing factors, these findings provide a foundation for the development of adaptive management strategies for controlling invasive RSC populations.

Stopping invaders: Moving towards a selective vertical slot fishway to prevent the passage of non-native cyprinids

Invasive fish species are a major driver of freshwater ecosystem degradation across the globe. This urgent problem is particularly tough to manage in dammed rivers, where the reestablishment of longitudinal connectivity for native fish is achieved through the placement of fish passage devices, which can open a new corridor for the dispersal of these taxa to previously inaccessible habitats. In an attempt to solve this dilemma and prevent their dispersal, an experimental study was conducted in a full-scale Vertical Slot Fishway (VSF) to assess the passage performance of the common carp (Cyprinus carpio), an invasive non-native cyprinid species widespread in the Iberian Peninsula. With this objective, two configurations were designed and tested, where the main hydraulic parameters that govern fishway operation (discharge, flow velocity, turbulence and slope) were adjusted to exceed design guidelines set for cyprinid species. Common carp passage trials were conducted in configuration VSFh1 and VSFh2 (N = 8 in each configuration), varying in water depth - 0.55 m and 0.80 m, respectively, and both were set up with a high slope (15,2 %), head drop (Δh = 0.28 m) and volumetric dissipation power higher than literature recommendations (Pv > 150 Wm-3). Fish movements were assessed in terms of motivation, transit time and ascent analysis using a time-to-event approach. The hydrodynamic scenarios experienced by fish during the trials were investigated with a computational fluid dynamic (CFD) model. Common carp passage results were compared with the performance of a native cyprinid species, namely the Iberian barbel (Luciobarbus bocagei), and pointed to selective fishway configurations, which hindered invasive fish passage movements, but favored the native species. In both configurations, common carp revealed a lower motivation with a significantly lower probability of performing passage attempts compared to the Iberian barbel. Regarding the ascent movements, none of the common carp tested managed to pass VSFh1 while in VSFh2 only one individual managed to ascend (of 3 that attempted - 33 %). Comparatively, the Iberian barbel managed to ascend both configurations, with VSFh1 showing a higher number (17) of these movements (of 17 that attempted to pass - 100 %). Overall, these promising results point to a selective passage under the tested configurations, specifically configuration VSFh1 that can assist managers in reestablishing river connectivity while deterring the spread of non-native invasive fish. Nonetheless, further studies and field validation are required to reinforce the present findings.

Optimizing control of a freshwater invader in time and space

The global spread of invasive species in aquatic ecosystems has prompted population control efforts to mitigate negative impacts on native species and ecosystem functions. Removal programs that optimally allocate removal effort across space and time offer promise for improving invader suppression or eradication, especially given the limited resources available to these programs. However, science-based guidance to inform such programs remains limited. This study leverages two intensive fish removal programs for nonnative green sunfish (Lepomis cyanellus) in intermittent streams of the Bill Williams River basin in Arizona, USA, to explore alternative management strategies involving variable allocation of removal effort in time and space and compare static versus dynamic decision rules. We used Bayesian hierarchical modeling to estimate demographic parameters using existing removal data, with evidence that both removal programs led to at least a 0.39 probability of eradication. Simulated alternative management strategies revealed that population suppression, but not eradication, could be achieved with reduced effort and that dynamic management practices that respond to species abundance in real time can improve the efficiency of removal efforts. High removal frequency and program duration, including continued monitoring after zero fish were captured, contributed to successful population control. With management efforts struggling to keep pace with the rising spread and impacts of invasive species, this research demonstrates the utility of quantitative removal models to help improve invasive removal programs and robustly evaluate the success of population suppression and eradication.

New fish migrations into the Panama Canal increase likelihood of interoceanic invasions in the Americas

Maritime shipping is vital for commercial trade and well recognized as a main pathway for the spread of non-native species.1 For over a century, the Panama Canal in Central America has played a major role in global trade, connecting the Atlantic and Pacific oceans. Historically, the introduction of species through the Panama Canal has been relatively low, largely due to the existence of a soft barrier-the freshwater Lake Gatun-inside the canal.2,3,4 However, the 2016 expansion of the Panama Canal involved major structural changes to the canal's lock system, which may have increased the likelihood that more marine fish species and greater numbers of them enter the lake and eventually cross the canal. To test this prediction, we used standardized quantitative comparisons of the fish communities of Lake Gatun, a system with a rich record of biological introductions,5,6 before (2013-2016) and after (2019-2023) the canal expansion. We observed a shift from a freshwater-dominated to a marine-dominated fish community in several areas inside the lake after 2016. The increase in marine organisms in this aquatic corridor may represent a potential invasion in progress, with a greater likelihood of some species eventually passing through the canal and colonizing the opposite ocean. The ecological and evolutionary consequences of these changes are difficult to predict. However, as most of these marine fishes are top predators with wide niche breadths, their colonization of Atlantic and Pacific oceans will likely alter ecological interactions and potentially lead to ecosystem-level changes.

New data on Cladocera (Crustacea: Branchiopoda) of Peninsular Malaysia

Cladoceran samples from Peninsular Malaysia were collected during four sampling trips: in October 2013, November-December 2014, January-February 2018, and September 2022. More than 50 localities were sampled on each trip, including ditches, canals, rivers, ponds, swamps, lakes, old mining pools, and reservoirs. In these samples, we revealed six species new to Malaysia: two of them are planktonic (Bosmina meridionalis and Bosmina fatalis) and four are substrate-associated (Simocephalus expinosus, Anthalona spinifera, Anthalona vandammei, Karualona serrulata). Both species of the genus Bosmina appear to be recent additions to the local fauna, as this genus was not recorded in Malaysia until the last decade. New records are obtained on three rare local species: Simocephalus mixtus, Streblocerus spinulatus, and Acroperus harpae. The morphology of two uncommon East Asian species, Coronatella acuticostata and Chydorus obscurirostris tasekberae was investigated in detail for the first time. With the new records, the list of valid cladoceran species of Malaysia now consists of 72 species as compared to 62 species reported by Idris (1983) in his monograph. However, more studies are needed to produce an exhaustive final species list of the Malaysian cladocerans.

Shifts in patterns of shell utilization by the hermit crab Clibanarius erythropus following the arrival of a non-native gastropod

Hermit crabs rely on gastropod shells for protection and survival in rocky coastal habitats. This study evaluates the arrival of the non-native Phorcus sauciatus influences patterns of shell selection of the hermit crab Clibanarius erythropus along the southern coast of São Miguel Island, Azores (NE Atlantic). Field sampling from four intertidal sites revealed that P. sauciatus accounted for 22.4% of the shells occupied by hermit crabs, marking a significant shift in shell utilization since the species introduction in 2013. Morphometric analyses compared P. sauciatus shells with four others commonly used gastropod shells, revealing that P. sauciatus provides favorable characteristics, such as a high internal-to-mass ratio, which likely enhances hermit crab survival and motility. Temporal comparisons with studies from 2000 and 2009 indicate substantial changes in shell utilization, with P. sauciatus becoming a key resource. P. sauciatus establishment provides a greater diversity of shells available to C. erythropus. This study underscores the ecological consequences of non-native species, showing how they can alter resource availability and create new exploitable niches for native species, such as hermit crabs on the rocky shores of São Miguel.

Latitude and Community Diversity Primarily Explain Invasion Patterns of Widespread Invasive Plants in Small, Subtropical Lakes

Within the study of aquatic invasive species, small aquatic ecosystems are often neglected, despite representing most global freshwater bodies. This study uses community composition and environmental and geographic factors to explain the occurrence of invasive species in small lakes in the southeastern United States. Four invasive species widespread in the southeastern United States were selected as the focus of this study: Alternanthera philoxeroides, Cyperus blepharoleptos, Panicum repens, and Triadica sebifera. The aquatic plant communities of the lakes were surveyed using littoral zone point sampling. Generalized linear models for each species were fit with the probability of occurrence (P occ ) as the response variable and Secchi depth, plant species diversity (α-diversity), point richness, perimeter, latitude, and longitude as potential predictors; all predictors were subjected to model selection to define the best-fit models. All best-fit models were strongly predictive with area under the receiver operating characteristic curve values > 0.80. Plant species diversity was positively correlated with P occ of A. philoxeroides, P. repens, and T. sebifera. Latitude was negatively correlated with P occ of P. repens and T. sebifera. Perimeter was negatively related to P occ of A. philoxeroides. Secchi depth was negatively related to the P occ of C. blepharoleptos. Although plant species diversity and latitude were most commonly predictive, P occ was usually explained by multiple predictors, suggesting that these relationships are best explained with multiple environmental factors.

The impacts of alien species on river bioassessment

The extent of alien taxa impacts on river ecosystem health is unclear, but their frequency continues to rise. We investigated 1) the prevalence of including alien taxa in common bioindicators used in river bioassessment, 2) the effect of alien taxa on the richness and abundance of natives, and 3) whether including alien taxa in bioassessment tools increased their sensitivity to river degradation. In the 17 countries analyzed fish represented the greatest number of alien species (1726), followed by macrophytes (925), macroinvertebrates (556), and diatoms (7). Yet, alien species are only distinguished from natives in some fish and macrophyte indices. In addition, the analyses of 8 databases with fish, macroinvertebrate, or macrophyte data showed that abundance of alien taxa was associated with different stressors and pressures resulting in river degradation, and had a significant effect on native community composition. When alien species were accounted for, there was a strong negative correlation between the values of a fish index with alien richness and abundance while when alien taxa was not or only partially considered the results varied. Thus, we recommend: 1) Include specific metrics for alien species in biological quality indices. 2) Increase the investigation of alien taxa of small organisms (e.g. diatoms, small benthic invertebrates). 3) Eliminate sites with confirmed biological invasions for use as reference sites. 4) Remove alien from calculations of total richness and diversity. 5) Identify to the species level in biomonitoring programs. 6) Avoid legislation and management that protect alien species. 7) Encourage behaviors that prevent alien invasions of aquatic biota.

Environmental DNA and Hydroacoustic Surveys for Monitoring the Spread of the Invasive European Catfish (Silurus glanis Linnaeus, 1758) in the Guadalquivir River Basin, Spain

The European catfish (Silurus glanis Linnaeus, 1758) was introduced into the Ebro Basin in Spain in 1974 for recreational fishing. Since then, the species has spread throughout the country's river basins, reaching the Iznájar Reservoir (Guadalquivir River Basin) in 2011. This area is of great ecological and economic relevance, especially as it includes the Doñana National Park, one of the most important nature reserves in Europe. Recently, the presence of catfish has been reported in the lower reaches of the river. In this work, we used non-invasive vertical and horizontal hydroacoustic surveys and environmental DNA river sampling to unravel the actual distribution and dispersal pattern of the species in the lower Guadalquivir River. The hydroacoustic profiles and the species-specific detections by real-time PCR (qPCR) and droplet digital PCR (ddPCR) showed that these non-invasive methods allow the detection and quantification of catfish and provide valuable information on the species' presence. We have confirmed the presence of catfish in most of the study area, including downstream areas of the Guadalquivir Basin. The results suggest the possibility of other isolated introductions and/or human-mediated movements of specimens, and imply that a coordinated catfish prevention and mitigation strategy is therefore urgently needed.

Eutrophication triggered changes in network structure and fluxes of the Comacchio Lagoon (Italy)

Coastal lagoons, which cover about 13% of coastline, are among the most productive ecosystems worldwide. However, they are subject to significant stressors, both natural and anthropogenic, which can alter ecosystem services and functioning and food web structure. In the Comacchio Lagoon (Northern Italy), eutrophication, among other minor factors, transformed the ecosystem in the early 1980s. Here, we compiled available data for the lagoon into trophic networks (pre- and post-transformation), analyzed the ecosystem using local and global network analysis, and computed trophic fluxes of the two periods. For comparability, the networks of two periods (i.e., pre- and post- transformation) were aggregated into food webs with 23 nodes. We found differences in the trophic networks before and after eutrophication, resulting in some decrease in complexity, increase of flow diversity, and an overall shortening of the food chain. A crucial aspect of this change is the disappearance of submerged vegetation in the lagoon and the increased importance of cyanobacteria in the post-eutrophication period. We provide an approach to better understand ecosystem changes after severe disturbances which can be extended to biodiversity conservation and for the management of coastal resources in general.

Fishery and ecology-related knowledge about plants among fishing communities along Laguna Lake, Philippines

BACKGROUND

Ethnobotanical knowledge about plant roles in fisheries is crucial for sustainable resource management. Local ecological knowledge helps understand dynamics of the lake ecosystem. Fishers use plants based on availability and characteristics while adapting to the changes in the environment. Studying fishery related uses of plants and algae and the challenges interconnected with them from local perspectives can provide insights into their beneficial uses and impacts to the ecosystem.

METHODS

The study investigates the botanical knowledge of three fishing villages in Laguna Lake or Laguna de Bay (LB), Philippines, including Buhangin, Sampiruhan, and Mabato-Azufre, each with varying degrees of industrialization. The ethnobotanical study, which gathered 27 interviews between June 2022 and July 2024, included plant collection with the help of local collaborators, including local fishers as research guides.

RESULTS

Fishers in LB highlighted positive and negative plant-fishing interactions. The most frequently mentioned plant applications were fish habitat and fish hiding places. Fish food, spawning sites, conservation, and a number of challenges such as navigational concerns and aquaculture fish deaths had been previously reported in local use reports. The remaining observations provide new insights into plant-fishing interactions, including indicators of food quality and food sources for fish, the decrease in the action of waves, and how plants help in improving the quality of the water.

CONCLUSION

These results highlight that the knowledge of fishers regarding the ecosystem in which they conduct their fishing activities provides baseline information about the positive and negative relationships between plants and fishing activities in the region, which is vital for further understanding its biodiversity and ecosystem interactions. It is crucial to consider fisher knowledge and involve them as equal partners in conservation efforts of LB.

Nature-based solutions to the management of legacy plastic pollution: Filter-feeders as bioremediation tools for coastal microplastics

Plastics are one of the most topical pollutants occurring in our ocean. Given concern regarding the impacts of both macro- and micro-plastics on environmental and human well-being, a range of management approaches are required. Key in the management of microplastics will be curative measures that facilitate the removal of legacy plastics from the environment as, without their removal, impacts will continue for centuries. While a strong focus has been placed on technical, engineered solutions to plastic removal, many of these techniques are unsuitable for microplastics. Therefore, here we argue for the exploration of nature-based solutions to such issues. As a case study, we combine information available in the published academic literature with experimental results from a pilot study to highlight the potential for filter-feeding organisms - specifically mussels - to remove microplastics from the water column by transferring them into biodeposits. Such biodeposits have the potential to be transported to other parts of the system (i.e., benthic regions), or collected and removed from the environment. While initial results indicate that such approaches are promising for microplastic removal from water sources, there are a number of areas that still need investigation before widespread application of such an approach could be adopted. Key knowledge gaps include identification of the appropriate methods to be used and assessment of unintended consequences including potential impacts of microplastics on benthic organisms. We argue that there is a need for ongoing funding and policy support for the development and application of such nature-based solutions targeting legacy plastic pollution.

Mapping habitat suitability of invasive crayfish in aridland riverscapes: Virile crayfish (Faxonius virilis) in the Lower Colorado River Basin, USA

Correlative species distribution modeling (SDM) is an important tool to predict distributions of invasive species. A unique challenge of implementing SDMs in aridland stream networks is identifying which streams are perennial and which of those offer suitable habitat for obligate aquatic species. Here, we map perennial streams and habitat suitability of invasive virile crayfish (Faxonius virilis) in the Lower Colorado River Basin (LCRB) in the southwestern USA, and quantify drivers of uncertainty in these projections. First, we surveyed F. virilis at 122 stream sites in May-July of 2021, 2022, and 2023. We then implemented an ensemble of SDMs fit using combinations of randomly drawn sites, categories of environmental covariates measured at different spatial scales, survey years, and statistical algorithms. Next, we used open-source street view images from May-July of 2022 and 2023 to assess dry-wet status at 326 road-stream intersections and the same ensemble framework to map perennial stream reaches. Lastly, we quantified drivers of variation in predictive accuracy and mapped habitat suitability across replicates. Median true skill statistic (TSS) across F. virilis replicates was 0.613 and habitat suitability was highest in mountain ecoregions and lowest in desert ecoregions. Of the 130,847 stream km in the LCRB, we estimate 29,078 km (22.2 %) have wetted channels during the May-June dry season and median 50.3 % of these perennial streams provide suitable habitat for F. virilis. The statistical algorithm was the strongest driver of TSS variation across replicates, whereas the spatial scale at which covariates were measured was the strongest driver of variation in mapped habitat suitability across replicates. We confirm the widespread invasion of F. virilis throughout the LCRB, particularly in perennial mountain streams. The modest predictive accuracy highlights the generalistic niche of F. virilis. Overall, we demonstrate that spatiotemporally comprehensive datasets combined with ensemble modeling can guide management at regional extents.

Trophic Structure and Isotopic Niche of Invaded Benthic Communities on Tropical Rocky Shores

When a species is introduced in a new location, it is common for it to establish itself when it finds favorable conditions in the receptor community with regard to interspecific interactions with native species. The azooxanthellate corals Tubastraea coccinea and Tubastraea tagusensis are invasive species introduced in the Caribbean Sea, the Gulf of Mexico, and the Brazilian Southwest Atlantic. They are successful competitors for space, have multiple reproductive modes, and have high larval dispersion and recruitment, but studies on food and trophic relationships of the genus Tubastraea are still scarce. In the present study, we used isotopic values of δ13C and δ15N to investigate trophic relationships in rocky shore communities invaded by T. tagusensis and T. coccinea corals under different oceanographic and anthropogenic contexts. Using metrics derived from the isotopic values, we show that invaded communities have a lower degree of trophic diversity, with species characterized by similar trophic ecologies while abiotic factors seem to contribute to the biotic resistance of communities exposed to invasion events. Tubastraea spp. occupy a niche space similar to that occupied by the native community of suspension feeders, sharing resources already consumed by the receptor community, which makes invading corals successful competitors for food.

Introduction of a snake trematode of the genus Ochetosoma in eastern Japan

In Japan, trematodes of the family Ochetosomatidae are not naturally distributed. However, the introduced ochetosomatid Ochetosoma kansense (Crow, 1913) has been reported from the oral cavity of native snakes in western Japan since 2010s. In this study, trematodes were isolated from the oral cavities of the native Japanese snakes, Elaphe quadrivirgata (Boie, 1826), E. climacophora (Boie, 1826), and Rhabdophis tigrinus (Boie, 1826), in the central Kanto region of eastern Japan. Morphological and molecular analyses of the isolated trematodes revealed that all trematodes were identifiable to a newly introduced ochetosomatid species to Japan, O. elongatum (Pratt, 1903), which originated from North America; Lechriorchis tygarti Talbot, 1933 was synonymized with O. elongatum based on identical molecular data and morphological similarity. To identify first intermediate hosts of O. elongatum, seven freshwater snail species were examined in eastern Japan. Molecular analysis was used to identify O. elongatum sporocysts in the freshwater snail Physella acuta (Draparnaud, 1805), which also originated from North America. The other six species did not host O. elongatum, suggesting that Ph. acuta is the only first intermediate host of O. elongatum in Japan. Although O. elongatum has been detected in Japan, its invasion route and period of introduction are unclear. Frequent imports of freshwater snails and wild snakes from North America, after the 1990s and 2005, respectively, presumably introduced O. elongatum in Japan.

Long-term contamination by non-native fish assemblages in a Neotropical floodplain

Biological invasions are a major threat to biodiversity in species-rich regions. Therefore, it is important to understand mechanisms behind the long-term establishment of non-native fish species in aquatic environments in the Neotropical region. Here, we associated fish biomass, species richness, and the proportion of non-native species (contamination and Kempton's indices) to quantify the non-native pressure over fish biodiversity in lakes and rivers of the Parana River floodplain, seasonally, from 2000 to 2017. We divided species into native and non-native assemblages sampled in spatio-temporal gradients. Temporal trends were examined using linear regressions and generalised additive models. Fish biomass in gillnets increased for both native and non-native fish species, but their Kempton indices were inversely correlated. Extinction of native species occurred locally with biotic differentiation of non-native species in lakes, rivers, and ecosystem contamination. A constant increase in fish biomass resulted in overwhelming biodiversity of non-natives at the end of the time series evaluated. Native biotic resistance to introductions was not detected in deterministic trends. The observed patterns were consistent with previous studies showing native biotic homogenisation and extinction of species in response to biological invasions, landscape fragmentation, and riverine impoundments. Increases in abundance and species richness of non-native fish were the biodiversity drivers that resulted in non-native species outweighing native species in the Parana floodplain.

High functional vulnerability across the world's deep-sea hydrothermal vent communities

At the nearly pristine hydrothermal vents of the deep sea, highly endemic animals depend upon bacteria nourished by hydrothermal fluids that emerge as outflows from the seafloor. These animals are remarkable in tolerating extreme conditions, including high heat, toxic reduced sulfide, and low oxygen. Here, we test whether the extreme vent environment has selected for functionally similar species across the world's deep ocean, despite well-established global geographic patterns of high phylogenetic distinctness. High functional redundancy in species pools within regions suggests that the extreme environments select for species with specific traits. Yet, some regions emerge as functional hotspots where species pools with distinct functional trait compositions may represent geological idiosyncrasies of the habitats. Moreover, many species are functionally unique, an outcome of low species richness in a system where the species pool is small at all scales. Given the high proportion of functionally unique species, simulated species extinctions indicate that species losses would rapidly translate to the elimination of functionally irreplaceable species and could tip vent systems to functional collapse. Ocean changes and human-induced threats are expected to significantly impact many vent species as human activities expand in the remote deep sea. The opportunity exists now to take precautionary actions to limit the rates of extinction now ubiquitous in more accessible areas of Earth.

A global systematic map of knowledge of inland commercial navigation effects on freshwater ecosystems

Inland navigation is one of the most sustainable transport alternatives to help decarbonise the world economy. However, the likely impacts of intensifying inland navigation on freshwater ecosystems are difficult to predict. A global map of knowledge that considers both abiotic and biotic responses to increasing shipping traffic and developing infrastructures is lacking. Deriving general evidence-based assessments is challenging, because most studies on inland navigation impacts are merely descriptive and either consist of local case studies, or address single navigation stressors or specific taxa only. We conducted a systematic mapping of the published literature (1908-2021) to provide a global synthesis of the effects of inland navigation on the biotic and abiotic components of freshwater ecosystems. We show that only half of the reported navigation-related impacts were statistically tested. Navigation itself (vessel operation) had mainly negative effects on native taxa (57%), followed by waterway management (40%), and navigation infrastructures (35%). Navigation has direct negative impacts caused by physical disturbances such as vessel-induced waves, and indirect impacts that facilitate the spread of aquatic invasive species, and altering the abiotic habitat conditions. Thirty percent of the tested relationships showed non-significant impacts on the biotic environment, while in 10% of cases impacts were context-dependent. We identified the main gaps of knowledge, namely (i) impacts of waterway management on communities, (ii) underlying processes of navigation impacts on river ecosystems; and (iii) interactions between multiple navigation factors and cascading effects on multi-taxa responses. These future research directions should improve the diagnosis, mitigate the negative impacts of navigation on rivers and provide guidelines for improving navigated river management.

Functional traits of exotic submerged macrophytes mediate diversity-invasibility relationship in freshwater communities under eutrophication

Plant diversity may respond differently in terms of whether it can drive plant invasions in freshwater ecosystem. Linkages and interactions between diversity and invasibility have not been clearly resolved, and it is unclear how nutrient enrichment (e.g., eutrophication) will affect this relationship. As a key predictor of plant growth, the ability of functional traits to mediate trade-offs in the diversity-invasibility relationship is unknown. Here, we conducted a series of experiments to determine the role of exotic plant functional traits in the diversity-invasibility relationship of submerged macrophyte communities under eutrophication. We selected common native and exotic submerged macrophytes in the subtropics to construct different diverse submerged macrophyte communities to simulate invasion. Meanwhile, to test the adaptability and importance of functional traits, we experimentally verified the differences in functional traits between exotic and native species. Our results showed a positive correlation between native plant diversity and community invasibility. Moreover, the invader's performance was predominantly determined by functional traits of exotic species, such as plant biomass and tissue nutrients, which were significantly altered by species diversity. Furthermore, our results suggested that functional traits contribute significantly more to the invasiveness of exotic submerged macrophytes than the other factors to which they are subjected. Plant functional traits can mediate the diversity-invasibility relationship because of the higher intrinsic dominance of exotic submerged macrophyte species. In summary, our study revealed diversity-invasibility relationship in submerged macrophyte communities and highlighted functional traits as key drivers of invasion of high-risk exotic submerged macrophyte species. Although previous studies have elucidated the importance of functional trait studies for plant invasions, our study provides the only current evidence demonstrating the important role of invaders' functional traits in mediating the diversity-invasibility relationship. This novel perspective offers valuable insights into the management and control of invasive aquatic plants.

To be or not to be: The fate of submerged macrophyte biodiversity in the plateau lakes after restoration for the last decade

The preservation of biodiversity is crucial for sustaining ecosystem functioning, and recently the ongoing loss of biodiversity in lake ecosystems due to human activities has raised significant concerns. This study aimed to assess the impact of human activities on the biodiversity of aquatic plants through long-term empirical evidence. By comparing species composition and genetic diversity of submerged macrophyte within last decade, this research focused on the long-term changes of submerged macrophyte biodiversity resulting from human disturbances and restoration efforts. Three plateau lakes - Lake Erhai, Lake Fuxianhu, and Lake Jianhu - were selected as study sites, exhibiting varying biodiversity alterations in response to different levels of human disturbance and restoration activities. The oligotrophic Lake Fuxianhu demonstrated a stable level of both biodiversity levels, and the eutrophic Lake Jianhu exhibited a significant reduction in species diversity and genetic diversity. Meanwhile, the strong restoration measures in Lake Erhai between the 2010s and the 2020s effectively safeguard species diversity and alleviate declines in genetic diversity due to eutrophication during the last decade. We also found that improper use of alien species and the transplantation of clones of aquatic plant may pose ecological risks to biodiversity. Given the importance of aquatic plant re-establishment for the long-term recovery of plateau lakes, conservation strategies could prioritize large-scale propagation of aquatic plant materials through local seed banks.

Transferability of ecological forecasting models to novel biotic conditions in a long-term experimental study

Ecological forecasting models play an increasingly important role for managing natural resources and assessing our fundamental knowledge of processes driving ecological dynamics. As global environmental change pushes ecosystems beyond their historical conditions, the utility of these models may depend on their transferability to novel conditions. Because species interactions can alter resource use, timing of reproduction, and other aspects of a species' realized niche, changes in biotic conditions, which can arise from community reorganization events in response to environmental change, have the potential to impact model transferability. Using a long-term experiment on desert rodents, we assessed model transferability under novel biotic conditions to better understand the limitations of ecological forecasting. We show that ecological forecasts can be less accurate when the models generating them are transferred to novel biotic conditions and that the extent of model transferability can depend on the species being forecast. We also demonstrate the importance of incorporating uncertainty into forecast evaluation with transferred models generating less accurate and more uncertain forecasts. These results suggest that how a species perceives its competitive landscape can influence model transferability and that when uncertainties are properly accounted for, transferred models may still be appropriate for decision making. Assessing the extent of the transferability of forecasting models is a crucial step to increase our understanding of the limitations of ecological forecasts.

Rapid expansion and ecosystem health risk of invasive biopollutants dispersed by maritime traffic in French Polynesia

The introduction of biopollutant species challenge ecosystem health and economy in remote islands. Here we checked the advance of invasive fouling species in five French Polynesian islands. Expansion of invasive species (Acantophora spicifera, Bugula neritina, Chthamalus proteus, Dendostrea frons) was detected using individual barcoding (COI for animals, RBLC for algae), and metabarcoding on biofouling (COI and 18S sequences). They were especially abundant in Port Phaeton (Tahiti), Bora Bora and Rangiroa atoll. Chthamalus proteus is a vector of bacterial diseases and may harm native French Polynesian mollusks. Dendostrea frons is a vector of Perkinsus, a parasite to which black pearl oysters, the mainstay of the Polynesian economy, are susceptible. High ecological and epidemiological risks were estimated for C. proteus and D. frons, and ecological risks also for A. spicifera and especially for B. neritina. Strengthening marine biosecurity measures is highly recommended to conserve these unique ecosystems and their associated services.

Limited Migration From Physiological Refugia Constrains the Rescue of Native Gastropods Facing an Invasive Predator

Biological invasions have caused the loss of freshwater biodiversity worldwide. The interplay between adaptive responses and demographic characteristics of populations impacted by invasions is expected to be important for their resilience, but the interaction between these factors is poorly understood. The freshwater gastropod Amnicola limosus is native to the Upper St. Lawrence River and distributed along a water calcium concentration gradient within which high-calcium habitats are impacted by an invasive predator fish (Neogobius melanostomus, round goby), whereas low-calcium habitats provide refuges for the gastropods from the invasive predator. Our objectives were to (1) test for adaptation of A. limosus to the invasive predator and the low-calcium habitats, and (2) investigate if migrant gastropods could move from refuge populations to declining invaded populations (i.e., demographic rescue), which could also help maintain genetic diversity through gene flow (i.e., genetic rescue). We conducted a laboratory reciprocal transplant of wild F0 A. limosus sourced from the two habitat types (high calcium/invaded and low calcium/refuge) to measure adult survival and fecundity in home and transplant treatments of water calcium concentration (low/high) and round goby cue (present/absent). We then applied pooled whole-genome sequencing of 12 gastropod populations from across the calcium/invasion gradient. We identified patterns of life-history traits and genetic differentiation across the habitats that are consistent with local adaptation to low-calcium concentrations in refuge populations and to round goby predation in invaded populations. We also detected restricted gene flow from the low-calcium refugia towards high-calcium invaded populations, implying that the potential for demographic and genetic rescue is limited by natural dispersal. Our study highlights the importance of considering the potentially conflicting effects of local adaptation and gene flow for the resilience of populations coping with invasive predators.

An Invasion Risk Assessment of Alien Woody Species in Potential National Park Sites in Xinjiang, China, Under Climate Change

The invasion of alien woody species may have broad ecological, economic, and health impacts on ecosystems and biodiversity under climate change. Previous studies showed that disrupting the biodiversity conservation mechanisms in protected areas can seriously threaten natural ecosystems and the protection of rare and endangered species in such protected areas. However, there is currently no standard for evaluating the invasion risk of woody plants under climate change when establishing national parks in China. Therefore, we used a species distribution model to evaluate the invasion risk of 250 invasive alien woody species in potential national park sites in Xinjiang under climate change. The results indicated that the probability of forest invasion in the potential Altai Kanas National Park was determined to be significantly higher than that of the average level in Xinjiang nature reserves, both under current and future climate conditions. At the same time, the probability of invasive woody species invading coniferous forests, broad-leaved forests, and grassland ecosystems is higher in the Altai Kanas and Tianshan potential national parks. We found that Acer negundo, Robinia pseudoacacia, and Amorpha fruticose in potential parks in Xinjiang have higher invasion potential and thus require heightened vigilance to stop their spread. This study contributes to the monitoring and management of national parks and provides an actionable foundation for protecting ecosystem functions and minimizing the potential risk of invasive alien species under climate change.

Assessing the Impacts of Adaptation to Native-Range Habitats and Contemporary Founder Effects on Genetic Diversity in an Invasive Fish

Species invading non-native habitats can cause irreversible environmental damage and economic harm. Yet, how introduced species become widespread invaders remains poorly understood. Adaptation within native-range habitats and rapid adaptation to new environments may both influence invasion success. Here, we examine these hypotheses using 7058 SNPs from 36 native, 40 introduced and 19 farmed populations of tench, a fish native to Eurasia. We examined genetic structure among these populations and accounted for long-term evolutionary history within the native range to assess whether introduced populations exhibited lower genetic diversity than native populations. Subsequent to infer genotype-environment correlations within native-range habitats, we assessed whether adaptation to native environments may have shaped the success of some introduced populations. At the broad scale, two glacial refugia contributed to the ancestry and genomic diversity of tench. However, native, introduced and farmed populations of admixed origin exhibited up to 10-fold more genetic diversity (i.e., observed heterozygosity, expected heterozygosity and allelic richness) compared to populations with predominantly single-source ancestry. The effects of introduction to a new location were also apparent as introduced populations exhibited fewer private alleles (mean = 9.9 and 18.9 private alleles in introduced and native populations, respectively) and higher population-specific Fst compared to native populations, highlighting their distinctiveness relative to the pool of allelic frequencies across tench populations. Finally, introduced populations with varying levels of genetic variation and similar genetic compositions have become established and persisted under strikingly different climatic and ecological conditions. Our results suggest that lack of prior adaptation and low genetic variation may not consistently hinder the success of introduced populations for species with a demonstrated ability to expand their native range.

Interaction Between Climate Change Scenarios and Biological Invasion Reveals Complex Cascading Effects in Freshwater Ecosystems

Climate change often facilitates biological invasions, leading to potential interactive impacts of these global drivers on freshwater ecosystems. Although climatic mitigation efforts may reduce the magnitude of these interactive impacts, we are still missing experimental evidence for such effects under multiple climate change scenarios within a multi-trophic framework. To address this knowledge gap, we experimentally compared the independent and interactive effects of two climate change scenarios (mitigation and business-as-usual) and biological invasion on the biomass of major freshwater trophic groups (phytoplankton, zooplankton, periphyton, macroinvertebrates, and a native macrophyte) and the decomposition rate of allochthonous material. Among the independent effects, we found that the business-as-usual climate treatment resulted in lower native macrophyte biomass and higher periphyton biomass compared to the climatic baseline and mitigation treatments. This indicates the potential of climate change to alter the relative dominance of different freshwater producers and demonstrates that climate mitigation efforts can counteract these effects. Biological invasion alone increased the biomass of chironomids, a dominant macroinvertebrate group in tropical freshwater ecosystems, demonstrating a compensatory effect on climate change. Climate change and biological invasion interactively reduced the decomposition rate of allochthonous detritus, likely mediated by the feeding preference of abundant chironomids for periphytic algae associated with the presence of non-native macrophytes. We concluded that (i) climatic mitigation can maintain climate baseline conditions in freshwater ecosystems, and (ii) the interactive effects between future climate scenarios and biological invasion are related to complex cascading interactions among trophic groups on ecosystem processes.

Modeling Singapore's First African Swine Fever Outbreak in Wild Boar Populations

African swine fever (ASF) is a virulent and lethal disease affecting domestic pigs and wild boars, with serious implications for biodiversity, food security, and the economy. Since its reemergence in Europe, ASF has become widespread, and Singapore reported its first ASF outbreak in its wild boar population. To understand the transmission dynamics in Singapore's urban landscape, an agent-based spatiotemporal model was designed to mechanistically model the wild boar dispersal and their interactions for ASF transmission. We investigated the impacts of wild boar dispersal capacity and carcass removal actions on the spatiotemporal dynamics of disease transmission. The model predictions were validated using observed wild boar mortality reports in Singapore and suggested multiple disease entry points into our wild boar population. Our simulations estimated that the ASF outbreak in Singapore would peak within 3 weeks and lasts for less than 70 days. Carcass-mediated transmission was evident with epidemic reoccurrence through infectious carcasses accounting for 18%-75% of the iterations. Increasing wild boar dispersal capacity expanded the geographic extent of ASF infection, potentially spreading further inland. Simulated carcass removal and decontamination measures slightly reduced the epidemic duration by up to 13.5 days and reoccurrence through infectious carcass by 10.8%. Carcass removal and decontamination efforts, along with identifying and blocking high-risk areas (e.g., dispersal corridors), are important in controlling the transmission of ASF through contaminated fomites and limiting the dispersal of infected animals. Establishing surveillance programmes and enhancing detection capabilities are also crucial for the successful management and control of infectious diseases.

Assessing the role of non-native species and artificial water bodies on the trophic and functional niche of Mediterranean freshwater fish communities

Habitat alterations and the introduction of non-native species have many ecological impacts, including the loss of biodiversity and a deterioration of ecosystem functioning. The effects of these combined stressors on the community trophic web and functional niche are, however, not completely clear. Here, we investigated how artificial ecosystems (i.e. reservoirs) and non-native species may influence the trophic and functional niche space of freshwater fish communities. To do so, we used carbon and nitrogen stable isotope and abundance data to compute a set of isotopic, trait, and functional metrics for 13 fish communities sampled from 12 distinct ecosystems in Türkiye. We show that in reservoirs, fish were more similar in their trophic niche compared to lakes, where the trophic niche was more variable, due to higher habitat complexity. However, there were no differences in the trait and functional metrics between the two ecosystem types, suggesting a higher prey diversity than assumed in reservoirs. We also found that the number of non-native species did not affect the trophic niche space, nor the trait or functional space occupied by the fish community. This indicates that non-native species tended to overlap their trophic niche with native species, while occupying empty functional niches in the recipient community functional space. Similarly, the proportion of non-native species did not affect any trophic, trait, or functional metric, suggesting that changes in community composition were not reflected in changes in the community niche space. Moreover, we found that trait richness, but not functional richness, was positively related to the isotopic niche width and diversity, indicating that a wider occupied trait niche space corresponded with a wider occupied trophic niche and lesser interspecific similarity. Our findings underscore the complexity of ecological relationships within freshwater ecosystems and highlight the need for comprehensive management strategies to mitigate the impacts of human activities and biological invasions.

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.

Nine Lessons about Aquatic Invasive Species from the North Temperate Lakes Long-Term Ecological Research (NTL-LTER) Program

Freshwater ecosystems can serve as model systems that reveal insights into biological invasions. In this article, we summarize nine lessons about aquatic invasive species from the North Temperate Lakes Long-Term Ecological Research program and affiliated projects. The lessons about aquatic invasive species are as follows: Invasive species are more widespread than has been documented; they are usually at low abundance; they can irrupt from low-density populations in response to environmental triggers; they can occasionally have enormous and far-reaching impacts; they can affect microbial communities; reservoirs act as invasive species hotspots; ecosystem vulnerability to invasion can be estimated; invasive species removal can produce long-term benefits; and the impacts of invasive species control may be greater than the impacts of the invasive species. This synthesis highlights how long-term research on a freshwater landscape can advance our understanding of invasions.

Modeling the risk of aquatic species invasion spread through boater movements and river connections

Aquatic invasive species (AIS) are one of the greatest threats to the functioning of aquatic ecosystems worldwide. Once an invasive species has been introduced to a new region, many governments develop management strategies to reduce further spread. Nevertheless, managing AIS in a new region is challenging because of the vast areas that need protection and limited resources. Spatial heterogeneity in invasion risk is driven by environmental suitability and propagule pressure, which can be used to prioritize locations for surveillance and intervention activities. To better understand invasion risk across aquatic landscapes, we developed a simulation model to estimate the likelihood of a waterbody becoming invaded with an AIS. The model included waterbodies connected via a multilayer network that included boater movements and hydrological connections. In a case study of Minnesota, we used zebra mussels (Dreissena polymorpha) and starry stonewort (Nitellopsis obtusa) as model species. We simulated the impacts of management scenarios developed by stakeholders and created a decision-support tool available through an online application provided as part of the AIS Explorer dashboard. Our baseline model revealed that 89% of new zebra mussel invasions and 84% of new starry stonewort invasions occurred through boater movements, establishing it as a primary pathway of spread and offering insights beyond risk estimates generated by traditional environmental suitability models alone. Our results highlight the critical role of interventions applied to boater movements to reduce AIS dispersal.

Impact of Personality Trait Interactions on Foraging and Growth in Native and Invasive Turtles

Animal personalities play a crucial role in invasion dynamics. During the invasion process, the behavioral strategies of native species vary among personalities, just as the invasive species exhibit variations in behavior strategies across personalities. However, the impact of personality interactions between native species and invasive species on behavior and growth are rarely illustrated. The red-eared slider turtle (Trachemys scripta elegans) is one of the worst invasive species in the world, threatening the ecology and fitness of many freshwater turtles globally. The Chinese pond turtle (Mauremys reevesii) is one of the freshwater turtles most threatened by T. scripta elegans in China. In this study, we used T. scripta elegans and M. reevesii to investigate how the personality combinations of native and invasive turtles would impact the foraging strategy and growth of both species during the invasion process. We found that M. reevesii exhibited bolder and more exploratory personalities than T. scripta elegans. The foraging strategy of M. reevesii was mainly affected by the personality of T. scripta elegans, while the foraging strategy of T. scripta elegans was influenced by both their own personality and personalities of M. reevesii. Additionally, we did not find that the personality combination would affect the growth of either T. scripta elegans or M. reevesii. Differences in foraging strategy may be due to the dominance of invasive species and variations in the superficial exploration and thorough exploitation foraging strategies related to personalities. The lack of difference in growth may be due to the energy allocation trade-offs between personalities or be masked by the slow growth rate of turtles. Overall, our results reveal the mechanisms of personality interaction effects on the short-term foraging strategies of both native and invasive species during the invasion process. They provide empirical evidence to understand the effects of personality on invasion dynamics, which is beneficial for enhancing comprehension understanding of the personality effects on ecological interactions and invasion biology.

Biological invasions negatively impact global protected areas

Protected areas underpin global biodiversity conservation and sustainability agendas. Biological invasions increasingly threaten the ecological functioning and long-term conservation value of protected areas, while a lack of information on impact impedes management decisions. We collated data from effects of biological invasions in protected areas to provide the first quantitative analysis of their global impacts. Based on 300 reported effects from 44 invasive species, we show that there are overall negative impacts from invasive species on both biotic and abiotic characteristics of protected areas globally. Impacts were pervasive across population, community, and ecosystem scales, and for the vast majority of invasive taxa with sufficient data. Negative impacts have been incurred around the world, with National Parks and World Heritage Sites in the Neartic and Neotropical regions the most studied. Notwithstanding context-dependencies and uneven research efforts, the recurrent negative impacts of invasive species indicate that current efforts are insufficient to curb current stressors and meet conservation and sustainability targets on land and in water. To address the risk of biological invasions in protected areas, it is imperative to prioritise fundamental research on ecological interactions, establish robust monitoring and prevention programs, and raise awareness through global initiatives.

Food web collapse and regime shift following goldfish introduction in permanent ponds

In a global context of invasive alien species (IAS), native predators are often eradicated by functionally different IAS, which may induce complex cascading consequences on ecosystem functioning because of the key role predators play in structuring communities and stabilizing food webs. In permanent ponds, the most abundant freshwater systems on Earth, global human-mediated introductions of alien omnivores such as the pet trade goldfish are driving broad-scale patterns of native predators' exclusion, but cascading consequences on food web structure and functioning are critically understudied. We compared food webs of naturally fishless ponds versus ponds where dominant native predators (newts) had been extirpated by invasive goldfish within the last decade. Integrating community-wide isotopic, taxonomic and functional traits approaches, our study reveals that pond food webs collapsed in both vertical and horizontal dimensions following goldfish introduction and the associated exclusion of native predators. Consumer taxonomic diversity was drastically reduced, essentially deprived of amphibians as well as predatory and mobile macroinvertebrates to the profit of burrowing, lower trophic level consumers (detritivores). Changes in community structure and function underlined a regime shift from a macrophyte-dominated system mainly characterized by benthic primary production (periphyton), to a macrophyte-depleted state of ponds hosting communities mainly associated with phytoplankton primary production and detritus accumulation, with higher tolerance to eutrophication and low dissolved oxygen concentration. Results underline major impacts of widely introduced omnivores such as the goldfish on the functioning of pond ecosystems with potentially dramatic consequences on the key ecosystem services they deliver, such as global biodiversity support or water quality improvement. They also shed light on the key role of submerged aquatic vegetation in supporting diverse communities and complex food webs in shallow lentic systems and call for urgent consideration of threats posed by IAS on ponds' ecosystems by managers and policymakers.

Complete mitochondrial genome of the European common barnacle Perforatus perforatus Bruguière, 1789 (balanomorpha: balanidae)

This study is the first to sequence the complete mitochondrial genome (mitogenome) of Perforatus perforatus Bruguière, 1789 (Balanomorpha: Balanidae). The 15,536-bp long P. perforatus mitogenome contained a typical set of animal mitochondrial genes, along with one control region. The P. perforatus mitogenome had an inverted gene block (trnP-ND4L-ND4-trnH-ND5-trnF) between trnS(gct) and trnT. This inverted gene block had been detected six species in three subfamilies of the Balanidae family (Balaninae, Acastinae and Megabalaninae), but our results show that it is also present in Concavinae, in which P. perforatus is included. The phylogenetic tree based on the concatenated sequences of the 13 protein-coding genes and two rRNA genes showed that P. perforatus is closely associated with Acasta sulcate and Balanus trigonus within Balanidae.

Invasive species drive cross-ecosystem effects worldwide

Invasive species are pervasive around the world and have profound impacts on the ecosystem they invade. Invasive species, however, can also have impacts beyond the ecosystem they invade by altering the flow of non-living materials (for example, nutrients or chemicals) or movement of organisms across the boundaries of the invaded ecosystem. Cross-ecosystem interactions via spatial flows are ubiquitous in nature, for example, connecting forests and lakes, grasslands and rivers, and coral reefs and the deep ocean. Yet, we have a limited understanding of the cross-ecosystem impacts invasive species have relative to their local effects. By synthesizing emerging evidence, here we demonstrate the cross-ecosystem impacts of invasive species as a ubiquitous phenomenon that influences biodiversity and ecosystem functioning around the world. We identify three primary ways by which invasive species have cross-ecosystem effects: first, by altering the magnitude of spatial flows across ecosystem boundaries; second, by altering the quality of spatial flows; and third, by introducing novel spatial flows. Ultimately, the strong impacts invasive species can drive across ecosystem boundaries suggests the need for a paradigm shift in how we study and manage invasive species around the world, expanding from a local to a cross-ecosystem perspective.

Distribution, abundance, population structures, and potential impacts of the invasive snail, Tarebia granifera in aquatic ecosystems of north-eastern South Africa

Aquatic ecosystems globally have been invaded by molluscs. Tarebia granifera is a highly successful invader, often becoming the dominant aquatic invertebrate species in an invaded ecosystem. Resultingly, it has been suggested that T. granifera may have severe negative impacts on these invaded ecosystems. Limited information is available regarding the population structures and densities of T. granifera, particularly in invaded countries such as South Africa, and information on this could assist in developing management and control strategies for this invasive species. The present study aimed to assess the current distribution, densities, and population structures of T. granifera in invaded habitats on the Limpopo and Phongolo River systems in South Africa. This was accomplished by collecting aquatic molluscs from sites across these systems. Water quality parameters were measured at each site and water samples were collected for chemical nutrient analyses. The density of snails was determined for each site and the population size and structure as well as birth rate was calculated for T. granifera. Tarebia granifera was found to be the dominant molluscan species in habitats where it was present and all size classes from newborn to mature adults were found throughout at some of the highest densities globally. Worryingly, native molluscan species, were often absent or in much lower densities than reported in literature at sites where T. granifera was present, suggesting a negative effect on the native molluscan density and diversity. Contrary to most previous studies, there were no significant correlations between T. granifera and the selected water quality parameters. Higher densities and newborn recruitment of T. granifera were observed in the spring than in autumn, likely in response to shifts in environmental conditions. This study provides crucial insights into the population structure, densities, and impacts of T. granifera in invaded habitats, particularly for relatively newly invaded regions such as southern Africa.

Heterogeneity in breeding productivity is driven largely by factors affecting nestlings and young fledglings in an imperiled migratory passerine

Identifying factors that drive variation in vital rates among populations is a prerequisite to understanding a species' population biology and, ultimately, to developing effective conservation strategies. This is especially true for imperiled species like the golden-winged warbler (Vermivora chrysoptera) that exhibit strong spatial heterogeneity in demography and responds variably to conservation interventions. Habitat management actions recommended for breeding grounds conservation include timber harvest, shrub shearing, and prescribed fire that maintain or create early successional woody communities. Herein, we assessed variation in the survival of nests [n = 145] and fledglings [n = 134] at 17 regenerating timber harvest sites within two isolated populations in Pennsylvania that differed in productivity and response to habitat management. Although the overall survival of nests and fledglings was higher in the eastern population than the central population, this was only true when the nest phases and fledgling phases were considered wholly. Indeed, survival rates of nestlings and recently fledged young (1-5 days post-fledging) were lower in the central population, whereas eggs and older fledglings (6-30 days post-fledging) survived at comparable rates in both populations. Fledglings in the central population were smaller (10% lower weight) and begged twice as much as those in the eastern population, suggesting food limitation may contribute to lower survival rates. Fledgling survival in the central population, but not the eastern, also was a function of habitat features (understory vegetation density [positive] and distance to mature forest [negative]) and individual factors (begging effort [negative]). Our findings illustrate how identifying how survival varies across specific life stages can elucidate potential underlying demographic drivers, such as food resources in this case. In this way, our work underscores the importance of studying and decomposing stage-specific demography in species of conservation concern.

Rural Households' Demand Status for Mitigation of Prosopis juliflora (Sw.) DC Invasion and Its Determinant Factors in Ethiopia: Empirical Evidence from Afar National Regional State

Ethiopia is among the world's poorest nations, and its economy is growing extremely slowly; thus, the government's budget to manage environmental amenities is not always sufficient. Thus, for the provision of environmental management services such as the eradication of Prosopis juliflora, the participation of local households and other stakeholders is crucial. This study is therefore initiated with the objective of assessing rural households' demands for mitigating Prosopis juliflora invasion in the Afar Region of Ethiopia. A multistage sampling technique was employed to obtain the 313 sample rural households that were used in the analysis, and those sample households were selected randomly and independently from the Amibara and Awash Fentale districts of Afar National Regional State, Ethiopia. In doing this, a seemingly unrelated bivariate probit model was used to determine factors affecting rural households' demands for mitigating Prosopis juliflora invasion. Consequently, as per the inferential statistical results, there was a significant mean/percentage difference between willing and nonwilling households for the hypothesized variables, except for some variables such as farm experience; years lived in the area, distance from the market, and dependency ratio. Furthermore, the seemingly unrelated bivariate probit model result indicates that sex, family size, tenure security, livestock holding, frequency of extension contact, and years lived in the area were important factors influencing the willingness to participate in Prosopis juliflora management practices positively, whereas age, off-farm/nonincome, and bid value affected willingness to pay negatively and significantly. Hence, to improve the participation level of households, policymakers should target these variables.

Risks posed by invasive species to the provision of ecosystem services in Europe

Invasive species significantly impact biodiversity and ecosystem services, yet understanding these effects at large spatial scales remains a challenge. Our study addresses this gap by assessing the current and potential future risks posed by 94 invasive species to seven key ecosystem services in Europe. We demonstrate widespread potential impacts, particularly on outdoor recreation, habitat maintenance, crop provisioning, and soil and nitrogen retention. Exposure to invasive species was higher in areas with lower provision of ecosystem services, particularly for regulating and cultural services. Exposure was also high in areas where ecosystem contributions to crop provision and nitrogen retention were at their highest. Notably, regions vital for ecosystem services currently have low invasion suitability, but face an average 77% increase in potential invasion area. Here we show that, while high-value ecosystem service areas at the highest risk represent a small fraction of Europe (0-13%), they are disproportionally important for service conservation. Our study underscores the importance of monitoring and protecting these hotspots to align management strategies with international biodiversity targets, considering both invasion vulnerability and ecosystem service sustainability.

Global introductions and environmental impacts of freshwater megafish

Freshwater megafish species, such as sturgeons, salmonids, carps, and catfishes, have a maximum reported weight ≥30 kg. Due to their charisma and economic value, they have been widely introduced outside of their native ranges. Here, we provide a comprehensive overview of the introduction of freshwater megafish and an assessment of their environmental impacts. Of the 134 extant freshwater megafish species, 46% have been introduced to new environments, and of these, 69% have established self-sustaining alien populations. These introductions affect 59% of the world's main basins, with the USA and western Europe being particular hotspots of megafish introductions. The common carp (Cyprinus carpio) is the most widely introduced species. Using the Environmental Impact Classification for Alien Taxa (EICAT and EICAT+) frameworks, we assessed the severity and type of negative and positive impacts posed by alien megafish on native species. Alien megafish caused negative impacts through nine different mechanisms, with predation being the most frequently reported mechanism, followed by herbivory and competition. Moreover, 58% of the alien megafish species with sufficient data to evaluate the severity of their impacts caused declining populations of native species, or worse, extirpations of native species populations. The positive environmental impacts of alien megafish were far less frequently documented. They include biotic interactions that benefit native species, and the provision of trophic resources or habitats. Widely introduced or extensively studied species are more likely to have documented severe impacts on native species. There is a clear trade-off between the economic benefits associated with megafish introductions and the severe adverse impacts they have on native biodiversity. Our study highlights the need for comprehensive risk assessments to evaluate the potential environmental impacts of megafish. More research and long-term monitoring schemes are required to inform management actions to protect biodiversity, particularly in the Global South.

Forest disturbance increases functional diversity but decreases phylogenetic diversity of an arboreal tropical ant community

Tropical rainforest trees host a diverse arthropod fauna that can be characterised by their functional diversity (FD) and phylogenetic diversity (PD). Human disturbance degrades tropical forests, often coinciding with species invasion and altered assembly that leads to a decrease in FD and PD. Tree canopies are thought to be particularly vulnerable, but rarely investigated. Here, we studied the effects of forest disturbance on an ecologically important invertebrate group, the ants, in a lowland rainforest in New Guinea. We compared an early successional disturbed plot (secondary forest) to an old-growth plot (primary forest) by exhaustively sampling their ant communities in a total of 852 trees. We expected that for each tree community (1) disturbance would decrease FD and PD in tree-dwelling ants, mediated through species invasion. (2) Disturbance would decrease ant trait variation due to a more homogeneous environment. (3) The main drivers behind these changes would be different contributions of true tree-nesting species and visiting species. We calculated FD and PD based on a species-level phylogeny and 10 ecomorphological traits. Furthermore, we assessed by data exclusion the influence of species, which were not nesting in individual trees (visitors) or only nesting species (nesters), and of non-native species on FD and PD. Primary forests had higher ant species richness and PD than secondary forest. However, we consistently found increased FD in secondary forest. This pattern was robust even if we decoupled functional and phylogenetic signals, or if non-native ant species were excluded from the data. Visitors did not contribute strongly to FD, but they increased PD and their community weighted trait means often varied from nesters. Moreover, all community-weighted trait means changed after forest disturbance. Our finding of contradictory FD and PD patterns highlights the importance of integrative measures of diversity. Our results indicate that the tree community trait diversity is not negatively affected, but possibly even enhanced by disturbance. Therefore, the functional diversity of arboreal ants is relatively robust when compared between old-growth and young trees. However, further study with higher plot-replication is necessary to solidify and generalise our findings.

Multiple invasions and predation: The impact of the crayfish Cherax quadricarinatus on invasive and native snails

The pace of biological invasions has increased in recent decades, leading to multiple invasions and the potential dominance of invasive species, destabilizing local ecological networks. This provides opportunities to study new ecological species interactions, including predation. Tropical freshwaters have been particularly concerned by aquatic invasions and we focused here on the Martinique island (Lesser Antilles). We examined the predator-prey relationships involving invasive Thiarid snails (Tarebia granifera and Melanoides tuberculata) and the native Neritina punctulata, both confronted with a newcomer predator, the redclaw crayfish (Cherax quadricarinatus). We conducted several mesocosm experiments to assess the impact of crayfish predation on snail survival and the passive and active antipredator responses of snails. A first experiment indicated snail survival rates between 50% and 80%, depending on crayfish size and sex. Notably, there was a negative correlation between snail survival and male crayfish size and the predation method (shell crushing vs. "body sucking") varied with crayfish size. The second experiment suggested no refuge size for snails, with both very small (<5 mm) and very large (>5 mm) unable to escape predation, regardless of crayfish size (from 77 to 138 mm) or sex. Finally, we investigated the escape behavior of Thiarids regarding three crayfish cues. Melanoides tuberculata tend to bury in the substrate and T. granifera to climb up aquarium walls, what was expected from their shell morphologies, and both responding to crayfish cues within minutes. Overall, C. quadricarinatus proves to be an efficient snail predator with limited escape options for snails, potentially contributing to the decline of certain snail populations in Martinique. This omnivorous predator might impact other native species across different groups, including shrimps and fish. Our study underscores the urgent need for monitoring efforts, solidifying the redclaw crayfish reputation as a dangerous invasive species for freshwater macrobenthic faunas worldwide.

Using the IUCN Environmental Impact Classification for Alien Taxa to inform decision-making

The Environmental Impact Classification for Alien Taxa (EICAT) is an important tool for biological invasion policy and management and has been adopted as an International Union for Conservation of Nature (IUCN) standard to measure the severity of environmental impacts caused by organisms living outside their native ranges. EICAT has already been incorporated into some national and local decision-making procedures, making it a particularly relevant resource for addressing the impact of non-native species. Recently, some of the underlying conceptual principles of EICAT, particularly those related to the use of the precautionary approach, have been challenged. Although still relatively new, guidelines for the application and interpretation of EICAT will be periodically revisited by the IUCN community, based on scientific evidence, to improve the process. Some of the criticisms recently raised are based on subjectively selected assumptions that cannot be generalized and may harm global efforts to manage biological invasions. EICAT adopts a precautionary principle by considering a species' impact history elsewhere because some taxa have traits that can make them inherently more harmful. Furthermore, non-native species are often important drivers of biodiversity loss even in the presence of other pressures. Ignoring the precautionary principle when tackling the impacts of non-native species has led to devastating consequences for human well-being, biodiversity, and ecosystems, as well as poor management outcomes, and thus to significant economic costs. EICAT is a relevant tool because it supports prioritization and management of non-native species and meeting and monitoring progress toward the Kunming-Montreal Global Biodiversity Framework (GBF) Target 6.

Development and application of a second-generation multilingual tool for invasion risk screening of non-native terrestrial plants

Under the increasing threat to native ecosystems posed by non-native species invasions, there is an urgent need for decision support tools that can more effectively identify non-native species likely to become invasive. As part of the screening (first step) component in non-native species risk analysis, decision support tools have been developed for aquatic and terrestrial organisms. Amongst these tools is the Weed Risk Assessment (WRA) for screening non-native plants. The WRA has provided the foundations for developing the first-generation WRA-type Invasiveness Screening Kit (ISK) tools applicable to a range of aquatic species, and more recently for the second-generation ISK tools applicable to all aquatic organisms (including plants) and terrestrial animals. Given the most extensive usage of the latter toolkits, this study describes the development and application of the Terrestrial Plant Species Invasiveness Screening Kit (TPS-ISK). As a second-generation ISK tool, the TPS-ISK is a multilingual turnkey application that provides several advantages relative to the WRA: (i) compliance with the minimum standards against which a protocol should be evaluated for invasion process and management approaches; (ii) enhanced questionnaire comprehensiveness including a climate change component; (iii) provision of a level of confidence; (iv) error-free computation of risk scores; (v) multilingual support; (vi) possibility for across-study comparisons of screening outcomes; (vii) a powerful graphical user interface; (viii) seamless software deployment and accessibility with improved data exchange. The TPS-ISK successfully risk-ranked five representative sample species for the main taxonomic groups supported by the tool and ten angiosperms previously screened with the WRA for Turkey. The almost 20-year continuous development and evolution of the ISK tools, as opposed to the WRA, closely meet the increasing demand by scientists and decision-makers for a reliable, comprehensive, updatable and easily deployable decision support tool. For terrestrial plant screening, these requirements are therefore met by the newly developed TPS-ISK.

River ecological status is shaped by agricultural land use intensity across Europe

Agriculture impacts the ecological status of freshwaters through multiple pressures such as diffuse pollution, water abstraction, and hydromorphological alteration, strongly impairing riverine biodiversity. The agricultural effects, however, likely differ between agricultural types and practices. In Europe, agricultural types show distinct spatial patterns related to intensity, biophysical conditions, and socioeconomic history, which have been operationalised by various landscape typologies. Our study aimed at analysing whether incorporating agricultural intensity enhances the correlation between agricultural land use and the ecological status. For this, we aggregated the continent's agricultural activities into 20 Areas of Farming-induced Freshwater Pressures (AFFP), specifying individual pressure profiles regarding nutrient enrichment, pesticides, water abstraction, and agricultural land use in the riparian zone to establish an agricultural intensity index and related this intensity index to the river ecological status. Using the agricultural intensity index, nearly doubled the correlative strength between agriculture and the ecological status of rivers as compared to the share of agriculture in the sub-catchment (based on the analysis of more than 50,000 sub-catchment units). Strongest agricultural pressures were found for high intensity cropland in the Mediterranean and Temperate regions, while extensive grassland, fallow farmland and livestock farming in the Northern and Highland regions, as well as low intensity mosaic farming, featured lowest pressures. The results provide advice for pan-European management of freshwater ecosystems and highlight the urgent need for more sustainable agriculture. Consequently, they can also be used as a basis for European Union-wide and global policies to halt biodiversity decline, such as the post-2027 renewal of the Common Agricultural Policy.

Past and recent anthropogenic pressures drive rapid changes in riverine fish communities

Understanding how and why local communities change is a pressing task for conservation, especially in freshwater systems. It remains challenging because of the complexity of biodiversity changes, driven by the spatio-temporal heterogeneity of human pressures. Using a compilation of riverine fish community time series (93% between 1993 and 2019) across the Palaearctic, Nearctic and Australasia realms, we assessed how past and recent anthropogenic pressures drive community changes across both space and time. We found evidence of rapid changes in community composition of 30% per decade characterized by important changes in the dominant species, together with a 13% increase in total abundance per decade and a 7% increase in species richness per decade. The spatial heterogeneity in these trends could be traced back to the strength and timing of anthropogenic pressures and was mainly mediated by non-native species introductions. Specifically, we demonstrate that the negative effects of anthropogenic pressures on species richness and total abundance were compensated over time by the establishment of non-native species, a pattern consistent with previously reported biotic homogenization at the global scale. Overall, our study suggests that accounting for the complexity of community changes and its drivers is a crucial step to reach global conservation goals.