Biological Invasions最新文献

Understanding societal interest in invasive species is crucial as greater public attention can support the success of conservation efforts. One of the main challenges in monitoring societal interest to support conservation is the absence of near-real-time indicators to track large-scale spatiotemporal dynamics of public attention. However, the digital revolution has opened up new opportunities to develop such indicators in support of invasive species research and management. Here, we aim to evaluate public awareness and interest in the invasive lionfish (Pterois miles) in the Mediterranean Sea and investigate spatiotemporal patterns of public interest in the species along its invasion front by using Google search volumes as a proxy for public attention. We implemented topic searches for the lionfish to download Google search volumes from 2013 to 2022 and used these data to test two hypotheses: (1) countries experiencing lionfish invasion exhibit higher public attention than those without lionfish, and (2) in invaded countries, public attention peaks around the arrival year, followed by a decline to baseline levels. Our study confirmed the first hypothesis, showing higher public attention in invaded countries. However, temporal patterns of attention did not fully align with the year of lionfish arrival, suggesting that the socio-political complexity of the region (e.g., cultural trends or internet accessibility), may be a key aspect to consider in future studies. Overall our study shows that digital data sources provide a unique opportunity to monitor social aspects of biological invasions with low associated costs and quick access to a great amount of data generated by internet users.

Invasive alien plants (IAPs) represent a major challenge to biodiversity and ecosystem functioning, especially those transformer species. Litter chemistry and decomposition rates are relevant factors to understand the invasion process due to its influence on nutrient cycling and ecosystem dynamics. Here, we present the results of a litterbag mesocosm comparing the decomposition dynamics of litter produced by two common IAPs (Acacia dealbata and Carports edulis) with similar amounts of native litter from invaded ecosystems (shrubland and coastal dunes invaded by A. dealbata and C. edulis, respectively), and how this different leaf litter origin further affects soil community function and the growth of seedlings of different native species. After 12 months of incubation, plant litter decayed at a rate of between 54 and 36% (C. edulis litter > dune litter and Shrub litter > A. dealbata litter) with slight changes in nutrient composition (C, N, C:N, and P content) at the end of the assay. Whereas the effect of the litterbag content (native vs. non-native plant litter) was rather limited, the incubation time significantly affected physico-chemical parameters. Thus, extracellular enzymatic activities (EAs, including acid and basic phosphatase, β-glucosidase, urease) varied depending on the litterbag content (native and non-native) for both decomposing species (A. dealbata or C. edulis). The correspondence analysis (CA) based on the community level physiological profile (CLPPs) showed a similar trend of data clustering regardless of the IAP considered. In both cases, different decomposition times were more relevant than litter origin to discriminate the soil functional activity. Finally, seedlings of different native species were grown in soils previously used for the litter incubation experiment. Here, seedlings of native species growing in soils from the mesocosm (previously covered with native or invasive litter) showed a species-dependent response. At the end of the assay, slight differences were found between the invasive and native plant litter. The results of the decomposition rates between litter of different origin, the effect of litter origin on soil nutrient content, on extracellular EAs, on the functional profile of soil communities, and also on the performance of native seedlings can be considered as limited. These results suggest that litter chemistry might not be as relevant as previously suggested—at least not relevant to explain ecosystem-level alterations—while highlighting the importance of assessing invasion thresholds rather than litter chemical composition.

Knowledge on the distribution of non-native fishes is critical to assess the current status of biological invasions and prevent further spread and impacts. This study aims to synthesize current distributional data of the non-native catfish, Hemibagrus wyckioides, an emerging invader in Peninsular Malaysia. We collected occurrence data from Facebook groups created by anglers and freshwater fish enthusiasts, which were used to map the distribution of the species. A total of 106 occurrences of H. wyckioides were recorded in five states, with three major invasion hotspots identified—Selangor, Pahang and Perak. Given the scarcity of distributional data for this species within the published literature, social media platforms provided invaluable information on the current distribution of this emerging invader, highlighting their potential utility in early detection and monitoring of poorly-known non-native fishes.

Non-native, invasive plants are increasingly common in Eastern North American forests, but their impact on soil fungi remains unclear. We used DNA metabarcoding to investigate the effects of nativity, plant mycorrhizal type and soil factors on root-associated fungal communities. We focused on understory woody plants in a deciduous forest tract in central New York state, and included three plant types, invasive arbuscular mycorrhizal (AM), native AM, and native ectomycorrhizal (EM), each represented by 3–5 species. We found lower fungal operational taxonomic unit (OTU) diversity in EM than AM plants, but no OTU diversity difference between native and invasive AM species. Pathogen OTU richness and relative abundance were not distinct between plant types. OTU composition was influenced by host mycorrhizal type and by AM plant nativity, with mycorrhizal fungi being important drivers in both cases. The relationships of soil characteristics (e.g., pH) with OTU composition were independent of plant nativity and mycorrhizal type. Specific root length of native AM species was lower than that of invasive AM plants, while EM plants were intermediate. Irrespective of plant type, OTU composition was distinct among plant species, particularly in fungal communities associated with the invader Rhamnus cathartica. These results suggest that invasive AM plants may shift fungal composition relative to native AM and EM plants, with potential long-term consequences for soil biodiversity.

The Galápagos Archipelago, a unique and ever-changing natural experiment, has seen an increase in introduced species due to increased human mobility. Among these, introduced ants represent a significant concern given their potential to reach high densities and displace native fauna. This study analyzed the diet of six Galápagos lava lizard species (Microlophus spp.) through the examination of 177 fecal pellets collected over two seasons. We identified 7084 food items across 39 categories, with ants predominating, making up 65% of occurrences and 90% of the total abundance. Notably, introduced ants constituted 57.1% of these occurrences and 79.4% of the total abundance, indicating a significant prevalence of introduced prey. This finding suggests a substantial shift in the islands’ ecological dynamics away from their natural state (i.e., without introduced ants). We also explore the dietary breadth of each lizard species and their similarity. Finally, we discuss the possible direct and indirect effects of the high prevalence of ants in the diet of Galápagos lava lizards, report interesting findings in their diet, and advocate for the use of feces as a non-invasive method to monitor for invasive ants. Our study highlights the ecological changes underway on these islands, underscoring the need for targeted conservation strategies to mitigate the impact of invasive species and preserve Galápagos biodiversity.

Although the impacts of single-species invasions on resident communities have been widely studied, the ecological effects of co-invasion (simultaneous invasion by multiple alien species) remain largely unexplored. In this study, using an analytical framework, we investigate the individual and combined effects of two global plant invaders (Leucanthemum vulgare and Lupinus polyphyllus) on the aboveground vegetation (plant richness, diversity and biomass) and belowground soil variables (pH, salinity, electrical conductivity, total dissolved solids, organic carbon [OC], phosphorous, and potassium) of grassland communities in the Himalaya. We studied these ecological variables in comparable plots under the following four scenarios: both invaders absent (i.e. uninvaded), either of the two invaders present (i.e. single species invasion), and both invaders present (i.e., co-invasion). Our results show invasion effects vary with the invasion scenarios and the studied variables. The single species invasion plots had lower mean plant richness and diversity but higher mean soil OC than the uninvaded plots. The co-invasion plots had significantly increased mean plant biomass and soil OC, but had a non-significant effect on plant richness and diversity compared to the uninvaded plots. The overall combined effect of species’ co-invasion was additive in nature, but the effect varied significantly with choice of the response variable. We found synergistic effects of co-invasion on species richness and diversity, antagonistic effects on soil pH, and additive effects on the remaining response variables when compared with the predicted additive effect of the two invaders. Our findings suggest that further spread of L. polyphyllus will impact the resident plant community more severely when co-invading with L. vulgare than when invading alone, thereby lending support to the invasional meltdown hypothesis. Nevertheless, antagonistic and additive impacts for soil pH and other response variables respectively hint towards other alternate mechanisms at play. Overall, our study showcases a proof-of-concept to empirically estimate the additive, antagonistic and synergistic impacts of plant co-invasions, and also provides a model for designing co-invasion studies on other taxa/systems/scales elsewhere. Finally, based on the insights gained from this study, we highlight priority areas of future research in species’ co-invasions.

Ecosystems worldwide are increasingly being invaded by multiple species, and the rate of biological invasion is accelerating, leading to more interactions among invasive species. One such interaction that has received little attention is the phenomenon of ‘serial replacement’ or ‘over-invasion’, where an established invasive species is supplanted by a second invasive species. Understanding this interaction is important as controlling the second species could inadvertently lead to an increase in the abundance of the first species. We used a hierarchical state-space model to analyse changes in annual abundances (commercial catch-per-unit-effort) of three invasive fish species, tench (Tinca tinca), common carp (Cyprinus carpio) and redfin perch (Perca fluviatilis), in the Murray-Darling River system (MDRS), Australia between 1954–2002. Tench were present at low abundances until the mid-1970 s, before declining to the point of no commercial catch post-1989. This rapid decline coincided with a significant increase in carp abundance, suggesting that carp may have driven the tench decline through habitat modification (particularly the destruction of aquatic plants), consistent with findings from European studies that show the disappearance of tench from ponds with intensive carp farming. Redfin perch populations, were inferred to be much less impacted by the invading carp population. While carp were present in the MDRS for the duration of the study, the rapid increase in carp abundance in the early 1970 s coincided with the introduction of a specific genetic lineage—the “Boolarra strain”. Our analysis provides compelling evidence of serial replacement of long-established tench by invading common carp triggered by the introduction of a novel carp strain.

Hakea decurrens subsp. physocarpa is an invasive fire-adapted shrub of Australian origin that is quickly expanding in Portugal with potential impacts on fire behavior and fire regime. In this study we examined the effects of H. decurrens on fire hazard by assessing fire behavior indicators at the landscape scale, using a modeling and simulation approach. Six fuel models for H. decurrens were developed through fuel characterization and experimental fires. The fuel models correspond to combinations of developmental stages of H. decurrens populations (Early, Intermediate and Mature) and management (Standing and Slashed fuels). These combinations were used with three levels of H. decurrens invasion, corresponding to 25%, 50% and 75% of cover of the landscape, applied to five real landscapes in northern Portugal (replicates) under three fuel moisture conditions (Low, Medium and High), used as surrogates of weather severity. Fire behavior simulations were conducted with FlamMap software. The relationships between fire behavior indicators (flame length, rate of spread and burn probability) at the landscape level and the four factors tested were analyzed using Generalized Linear Mixed Models. Standing fuels were found to be more hazardous than slashed fuels. Fire-hazard increased with H. decurrens stand maturity and slash, regardless of moisture conditions. The results of this study indicate that H. decurrens expansion might negatively affect the fire regime in the north of Portugal. Our findings add to other known negative impacts of the species on native ecosystems, calling for the need to reinforce its control.

The invasive shrub, Russian olive (Elaeagnus augustifolia), is widely established within riparian areas across North America and eastern Europe. Limited information on its distribution and invasion dynamics in northern regions has hampered understanding and management efforts. Given this lack of spatial and ecological information we worked with local stakeholders and developed two main objectives: (1) map the distribution of Russian olive along the Powder River (Montana and Wyoming, United States) as of 2020 with field data and remote sensing; and (2) relate that distribution to environmental variables to understand its habitat suitability and community/invasion dynamics. Field data showed Russian olive has reached near equal canopy cover (18.3%) to native Plains cottonwood (Populus deltoides; 19.1%) and has a broader distribution. At the watershed scale, we modeled Russian olive distribution using field surveys, ocular sampling of aerial imagery, and spectral variables from Sentinel-2 MultiSpectral Instrument using a random forest model (RMSE = 15.42, R² = 0.64). A statistical model linking the resulting Russian olive percent cover detection map to environmental variables for the entire watershed indicated Russian olive cover increased with flow accumulation and decreased with elevation, and was associated with poorer soil types. We attribute the success of Russian olive to its broad habitat suitability combined with changing hydrologic conditions favoring it over natives. The maps of Russian olive cover along the Powder River and its main tributaries in northern Wyoming and southern Montana revealed regions of the watershed with high and low cover, which can guide landscape-scale management prioritization. This study provides a repeatable Russian olive detection method due to the use of Sentinel-2 imagery that is available worldwide and provides insight into Russian olive’s ecological relationships and success with relevance for management across areas with similar environmental conditions.