Neural Representations of Non-native Speech Reflect Proficiency and Interference from Native Language Knowledge.

Learning to process speech in a foreign language involves learning new representations for mapping the auditory signal to linguistic structure. Behavioral experiments suggest that even listeners that are highly proficient in a non-native language experience interference from representations of their native language. However, much of the evidence for such interference comes from tasks that may inadvertently increase the salience of native language competitors. Here we tested for neural evidence of proficiency and native language interference in a naturalistic story listening task. We studied electroencephalography responses of 39 native speakers of Dutch (14 male) to an English short story, spoken by a native speaker of either American English or Dutch. We modeled brain responses with multivariate temporal response functions, using acoustic and language models. We found evidence for activation of Dutch language statistics when listening to English, but only when it was spoken with a Dutch accent. This suggests that a naturalistic, monolingual setting decreases the interference from native language representations, whereas an accent in the listener's own native language may increase native language interference, by increasing the salience of the native language and activating native language phonetic and lexical representations. Brain responses suggest that such interference stems from words from the native language competing with the foreign language in a single word recognition system, rather than being activated in a parallel lexicon. We further found that secondary acoustic representations of speech (after 200 ms latency) decreased with increasing proficiency. This may reflect improved acoustic-phonetic models in more proficient listeners.Significance Statement Behavioral experiments suggest that native language knowledge interferes with foreign language listening, but such effects may be sensitive to task manipulations, as tasks that increase metalinguistic awareness may also increase native language interference. This highlights the need for studying non-native speech processing using naturalistic tasks. We measured neural responses unobtrusively while participants listened for comprehension and characterized the influence of proficiency at multiple levels of representation. We found that salience of the native language, as manipulated through speaker accent, affected activation of native language representations: significant evidence for activation of native language (Dutch) categories was only obtained when the speaker had a Dutch accent, whereas no significant interference was found to a speaker with a native (American) accent.

Inverse priority effects: A role for historical contingency during species losses.

Communities worldwide are losing multiple species at an unprecedented rate, but how communities reassemble after these losses is often an open question. It is well established that the order and timing of species arrival during community assembly shapes forthcoming community composition and function. Yet, whether the order and timing of species losses can lead to divergent community trajectories remains largely unexplored. Here, we propose a novel framework that sets testable hypotheses on the effects of the order and timing of species losses-inverse priority effects-and suggests its integration into the study of community assembly. We propose that the order and timing of species losses within a community can generate alternative reassembly trajectories, and suggest mechanisms that may underlie these inverse priority effects. To formalize these concepts quantitatively, we used a three-species Lotka-Volterra competition model, enabling to investigate conditions in which the order of species losses can lead to divergent reassembly trajectories. The inverse priority effects framework proposed here promotes the systematic study of the dynamics of species losses from ecological communities, ultimately aimed to better understand community reassembly and guide management decisions in light of rapid global change.

Native Plant Diversity Generates Microbial Legacies That Either Promote or Suppress Non-Natives, Depending on Drought History.

Diverse native plant communities resist non-native plants more than species-poor communities, in part through resource competition. The role of soil biota in diversity-invasibility relationships is poorly understood, although non-native plants interact with soil biota during invasions. We tested the responses of non-native plants to soil biota generated by different native plant diversities. We applied well-watered and drought treatments in both conditioning and response phases to explore the effects of 'historical' and 'contemporary' environmental stresses. When generated in well-watered soils, the microbial legacies from higher native diversity inhibited non-native growth in well-watered conditions. In contrast, when generated in drought-treated soils, the microbial legacies from higher native diversity facilitated non-native growth in well-watered conditions. Contemporary drought eliminated microbial legacy effects on non-native growth. We provide a new understanding of mechanisms behind diversity-invasibility relationships and demonstrate that temporal variation in environmental stress shapes relationships among native plant diversity, soil biota and non-native plants.

The disruption of birds' double mutualistic interactions in novel ecosystems.

Non-native trees disrupt ecological processes vital to native plant communities. We studied how forests dominated by Acacia dealbata and Eucalyptus globulus affect the role of birds as dual pollinators and seed dispersers in a region heavily impacted by these two non-native species. We compared bird-plant interactions in the native and in the two non-native forest types. We constructed a multilayer regional network for each forest type and evaluated differences in network dissimilarity between networks. We also calculated the bird's importance in connecting processes and variables associated with module diversity. To determine how the networks react to changes in species richness, we did a simulation of species richness gradient and link percentage for each forest type. The number of birds acting both as pollinators and seed dispersers was higher in native than in non-native forests. However, birds in non-native forests still play a crucial role in maintaining the ecological services provided to native plant communities. However, the eucalyptus network exhibited a concerning simplification, forcing bird species to fully exploit the few remaining resources, leaving little room for structural adjustments and limiting the ecosystem's ability to withstand further species loss. These findings highlight how non-native trees may trigger cascading effects across trophic levels.

Bacterial microcompartments as a next-generation metabolic engineering tool: utilizing nature's solution for confining challenging catabolic pathways.

Advancements in synthetic biology have facilitated the incorporation of heterologous metabolic pathways into various bacterial chassis, leading to the synthesis of targeted bioproducts. However, total output from heterologous production pathways can suffer from low flux, enzyme promiscuity, formation of toxic intermediates, or intermediate loss to competing reactions, which ultimately hinder their full potential. The self-assembling, easy-to-modify, protein-based bacterial microcompartments (BMCs) offer a sophisticated way to overcome these obstacles by acting as an autonomous catalytic module decoupled from the cell's regulatory and metabolic networks. More than a decade of fundamental research on various types of BMCs, particularly structural studies of shells and their self-assembly, the recruitment of enzymes to BMC shell scaffolds, and the involvement of ancillary proteins such as transporters, regulators, and activating enzymes in the integration of BMCs into the cell's metabolism, has significantly moved the field forward. These advances have enabled bioengineers to design synthetic multi-enzyme BMCs to promote ethanol or hydrogen production, increase cellular polyphosphate levels, and convert glycerol to propanediol or formate to pyruvate. These pioneering efforts demonstrate the enormous potential of synthetic BMCs to encapsulate non-native multi-enzyme biochemical pathways for the synthesis of high-value products.

Genetic tools for the electrotroph Sporomusa ovata and autotrophic biosynthesis.

Sporomusa ovata is a Gram-negative acetogen of the Sporomusaceae family with a unique physiology. This anerobic bacterium is a core microbial catalyst for advanced CO2-based biotechnologies including gas fermentation, microbial electrosynthesis, and hybrid photosystem. Until now, no genetic tools exist for S. ovata, which is a critical obstacle to its optimization as an autotrophic chassis and the acquisition of knowledge about its metabolic capacities. Here, we developed an electroporation protocol for S. ovata. With this procedure, it became possible to introduce replicative plasmids such as pJIR751 and its derivatives into the acetogen. This system was then employed to demonstrate the feasibility of heterologous expression by introducing a functional ß-glucuronidase enzyme under the promoters of different strengths in S. ovata. Next, a recombinant S. ovata strain producing the non-native product acetone both from an organic carbon substrate and from CO2 was constructed. Finally, a replicative plasmid capable of integrating itself on the chromosome of the acetogen was developed as a tool for genome editing, and gene deletion was demonstrated. These results indicate that S. ovata can be engineered and provides a first-generation genetic toolbox for the optimization of this biotechnological workhorse.IMPORTANCES. ovata harbors unique features that make it outperform most microbes for autotrophic biotechnologies such as a capacity to acquire electrons from different solid donors, a low H2 threshold, and efficient energy conservation mechanisms. The development of the first-generation genetic instruments described in this study is a key step toward understanding the molecular mechanisms involved in these outstanding metabolic and physiological characteristics. In addition, these tools enable the construction of recombinant S. ovata strains that can synthesize a wider range of products in an efficient manner.

Divergent temporal responses of native macroinvertebrate communities to biological invasions.

Biological invasions pose a major threat to biodiversity, ecosystem functioning, and human well-being. Non-native species can have severe ecological impacts that are transformative, affecting ecosystems across both short-term and long-term timescales. However, few studies have determined the temporal dynamics of impact between these scales, impeding future predictions as invasion rates continue to rise. Our study uses a meta-analytical approach to dissect the changing taxonomic and functional impacts of biological invasions on native macroinvertebrate populations and communities in freshwater ecosystems across Europe, using a recently collated European long-term time series spanning several decades. Our findings reveal a complex temporal pattern: while initial stages of invasions (i.e. five years after the first record of non-native species) often exhibited benign impacts on macroinvertebrate abundance, richness, or functional diversity, the long-term (i.e. the period following the early invasion) effects became predominantly negative. This pattern was consistent between taxonomic and functional metrics for impacts at both the population and species level, with taxonomic metrics initially positively affected by invasions and functional metrics being more stable before also declining. These results suggest that even initially benign or positively perceived impacts could be eventually superseded by negative consequences. Therefore, understanding the magnitude of invasion effects increasingly requires long-term studies spanning several years or decades to offer insights into effective conservation strategies prioritising immediate and future biodiversity protection efforts. These findings also highlight the importance of integrating multiple taxonomic, functional and temporal components to inform adaptive management approaches to mitigate the negative effects of current and future biological invasions.

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.

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

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

Landscape change and alien invasions drive shifts in native lady beetle communities over a century.

Understanding causes of insect population declines is essential for the development of successful conservation plans, but data limitations restrict assessment across spatial and temporal scales. Museum records represent a source of historical data that can be leveraged to investigate temporal trends in insect communities. Native lady beetle decline has been attributed to competition with established alien species and landscape change, but the relative importance of these drivers is difficult to measure with short-term field-based studies. We assessed distribution patterns for native lady beetles over 12 decades using museum records, and evaluated the relative importance of alien species and landscape change as factors contributing to changes in communities. We compiled occurrence records for 28 lady beetle species collected in Ohio, USA, from 1900 to 2018. Taxonomic beta-diversity was used to evaluate changes in lady beetle community composition over time. To evaluate the relative influence of temporal, spatial, landscape, and community factors on the captures of native species, we constructed negative binomial generalized additive models. We report evidence of declines in captures for several native species. Importantly, the timing, severity, and drivers of these documented declines were species-specific. Land cover change was associated with declines in captures, particularly for Coccinella novemnotata which declined prior to the arrival of alien species. Following the establishment and spread of alien lady beetles, processes of species loss/gain and turnover shifted communities toward the dominance of a few alien species beginning in the 1980s. Because factors associated with declines in captures were highly species-specific, this emphasizes that mechanisms driving population losses cannot be generalized even among closely related native species. These findings also indicate the importance of museum holdings and the analysis of species-level data when studying temporal trends in insect populations.

Mimicking functional elements of the natural flow regime promotes native fish recovery in a regulated river.

Streamflow regimes that maintain vital functions and processes of aquatic ecosystems are critical to sustaining ecosystem health. In rivers with altered flow regimes, restoring components of the natural flow regime is predicted to conserve freshwater biodiversity by supporting ecological functions and geomorphological processes to which native communities are adapted. However, the effectiveness of environmental flow restoration is poorly understood because of inadequate monitoring and uncertainty in ecological responses to managed changes in specific, quantifiable aspects of the annual streamflow regime. Here, we used time series models to analyze 25 years of fish assemblage data collected before and after environmental flow implementation in a dammed river in California, USA. We examined the response of the fish community to changes in individual components of the flow regime known to support ecosystem functions. We found that as functional flow components shifted toward their predicted natural range, the quasi-extinction risk (likelihood of population declines of >80%) decreased for the native fish assemblage. Following environmental flow implementation, observed changes toward natural ranges of dry season duration, fall pulse flow magnitude, and wet season timing each reduced quasi-extinction risk by at least 40% for the native assemblage. However, functional flow components that shifted away from their predicted natural range, including lower spring recession flows and higher dry season baseflow, resulted in greater quasi-extinction risk for native species. In contrast, non-native species decreased in abundance when flow components shifted toward predicted natural ranges and increased when components shifted away from their natural range. Although most functional flow components remained outside of their natural range following environmental flow implementation, our results indicate that even moderate shifts toward a natural flow regime can benefit native and suppress non-native fish species. Overall, this study provides the most compelling evidence to date of the effectiveness of functional environmental flows in supporting native fish recovery in a highly regulated river.

Effects of the control of an invasive tree on the structure of a plant-frugivore network.

Invasive non-native species are one of the main causes of degradation of ecosystems worldwide. The control of invasive species is key to reducing threats to ecosystem viability in the long term. Observations of structural changes in ecological interaction networks following invasive species suppression can be useful to monitor the success of ecological restoration initiatives. We evaluated the structure of plant-bird frugivory interaction networks in a plant community invaded by the guava tree (Psidium guajava L.) by comparing network metrics before and after control actions. Psidium guajava was relevant in all metrics for the unmanaged network in this study, with high degree centrality and high nestedness contribution. Based on the asymmetry of species interactions, we found that birds were highly dependent on the invasive plant before suppression. Once P. guajava trees were eliminated, bird and plant species richness, total number of interactions, and modularity increased, whereas nestedness and interaction strength asymmetry decreased. The diet of the bird community became more diversified once P. guajava was no longer available and relevant species roles in community structure emerged. Our results corroborate the fact that ecological restoration interventions should include the control of non-native plant species that attract frugivorous animals in order to diversify plant-frugivore interactions and thus maintain biodiversity in natural ecosystems.

Conservation priorities for functionally unique and specialized terrestrial vertebrates threatened by biological invasions.

Invasive non-native species (INS) continue to pose a significant threat to biodiversity, including native population declines, which can ultimately disrupt ecosystem processes. Although there is growing evidence of the impacts of INS on functional diversity, most of the existing approaches to prioritization of species for conservation still focus on taxonomic diversity, neglecting the ecological role of species. We developed the functionally unique, specialized, and endangered by invasive non-native species (FUSE INS) score to fill this gap by combining functional irreplaceability (i.e., uniqueness and specialization) of species with their extinction risk due to INS. We calculated this score for 3642 terrestrial vertebrates exposed to INS by assessing how INS affected them based on the IUCN Red List and by evaluating their specialization and uniqueness in a multidimensional functional space. Thirty-eight percent of native species were both at high extinction risk because of INS and functionally unique and specialized, making them priority species for INS impact mitigation. Priority species of amphibians concentrated in Central America and Madagascar and of lizards in the Caribbean islands, northern Australia, New Zealand, and New Caledonia. Priority bird and mammal species were more widespread (birds, mostly in coastal areas, on Pacific islands, and in northern India and New Zealand; mammals, in southwestern Europe, Central Africa, East Africa, Southern Africa, Southeast Asia, and eastern Australia). Seventy-eight species were also highly irreplaceable but not yet threatened by INS, suggesting that preventive conservation measures may help protect these species. For the 50 birds of the highest priority, 64% required conservation actions to mitigate the INS threat. The FUSE INS score can be used to help prioritize indigenous species representing large amounts of functional diversity. Incorporating functional diversity into the conservation prioritization of species and associated areas is key to accurately reducing and mitigating the impacts of INS on native biodiversity.

Prioridades de conservación de los vertebrados terrestres especialistas y con funciones únicas amenazados por las invasiones biológicas Resumen Las especies exóticas invasoras (EEI) todavía representan una amenaza importante para la biodiversidad, incluido el declive de las poblaciones nativas, el cual puede perturbar los procesos ambientales. Aunque cada vez hay más pruebas del impacto de las EEI en la diversidad funcional, la mayoría de los enfoques existentes para priorizar la conservación de las especies sigue centrada en la diversidad taxonómica, lo que ignora el papel ecológico de las especies. Desarrollamos la puntuación FUEA EEI (funcionalmente únicas, especializadas y amenazadas por especies exóticas invasoras) para llenar este vacío mediante la combinación de la funcionalidad irremplazable (es decir, la singularidad y la especialización) de las especies con su riesgo de extinción causado por las EEI. Calculamos esta puntuación para 3,642 vertebrados terrestres expuestos a las EEI y analizamos cómo les afectan con base en la Lista Roja de la UICN y en la evaluación de su especialización y singularidad en un espacio funcional multidimensional. Treinta y ocho por ciento de las especies nativas estaban en alto riesgo de extinción debido a las EEI y eran funcionalmente únicas y especializadas, lo que las convertía en especies prioritarias para la mitigación de los impactos de las EEI. Las especies prioritarias de anfibios se concentraron en Centroamérica y Madagascar, y las de lagartos en las islas del Caribe, el norte de Australia, Nueva Zelanda y Nueva Caledonia. Las especies prioritarias de aves y mamíferos estaban más extendidas (aves, sobre todo en zonas costeras, islas del Pacífico y norte de la India y Nueva Zelanda; mamíferos, en el suroeste de Europa, África central, oriental y meridional, sureste asiático y este de Australia). Setenta y ocho especies también eran altamente irremplazables pero aún no estaban amenazadas por las EEI, lo que sugiere que las medidas preventivas de conservación pueden ayudar a proteger estas especies. Para las 50 aves de mayor prioridad, el 64% requería acciones de conservación para mitigar la amenaza de las EEI. La puntuación FUEA EEI puede utilizarse para priorizar las especies nativas que representan alta diversidad funcional. La incorporación de la diversidad funcional a la priorización de la conservación de especies y áreas asociadas es clave para reducir y mitigar con precisión los impactos de las EEI sobre la biodiversidad autóctona.

Do community changes persist after irruptive population dynamics? A case study from an invasive species boom and bust.

Irruptive or boom-and-bust population dynamics, also known as 'outbreaks', are an important phenomenon that has been noted in biological invasions at least since Charles Elton's classic book was published in 1958. Community-level consequences of irruptive dynamics are poorly documented and invasive species provide excellent systems for their study. African Jewelfish (Rubricatochromis letourneuxi, "jewelfish") are omnivores that demonstrate opportunistic carnivory, first reported in Florida in the 1960s and in Everglades National Park (ENP) in 2000. Twelve years after invasion in ENP, jewelfish underwent a 25-fold increase in density in one year. By 2016, jewelfish represented 25-50% of fish biomass. Using a 43-year fish community dataset at two sites (1978-2021), and a 25-year dataset of fish and invertebrate communities from the same drainage (1996-2021), with additional spatial coverage, we quantified differences in fish and invertebrate communities during different phases of invasion. During jewelfish boom, abundant, native cyprinodontiform fishes decreased in density and drove changes in community structure as measured by similarity of relativized abundance. Density of two species declined by > 70%, while four declined by 50-62%. Following the jewelfish bust, some species recovered to pre-boom densities while others did not. Diversity of recovery times produced altered community structure that lagged for at least four years after the jewelfish population declined. Community structure is an index of ecological functions such as resilience, productivity, and species interaction webs; therefore, these results demonstrate that irruptive population dynamics can alter ecological functions of ecosystems mediated by community structure for years following that population's decline.

Clonality contributes to the spread of Avrainvillea lacerata (Bryopsidales, Chlorophyta) in Hawai'i.

The relative rates of sexual versus asexual reproduction influence the partitioning of genetic diversity within and among populations. During range expansions, asexual reproduction often facilitates colonization and establishment. The arrival of the green alga Avrainvillea lacerata has caused shifts in habitat structure and community assemblages since its discovery in 1981 offshore of O'ahu, Hawai'i. Field observations suggest this species is spreading via vegetative reproduction. To characterize the reproductive system of A. lacerata in Hawai'i, we developed seven microsatellite loci and genotyped 321 blades collected between 2018 and 2023 from three intertidal sites at Maunalua Bay and 'Ewa Beach. We observed one to four alleles at multiple loci, suggesting A. lacerata is tetraploid. Each site was characterized by high genotypic richness (R > 0.8). However, clonal rates were also high, suggesting the vegetative spread of A. lacerata plays a significant role. The importance of clonal reproduction for the persistence of A. lacerata in Hawai'i is consistent with the ecological data collected for this species and observations of other abundant macroalgal invaders in Hawai'i and other regions of the world. These data demonstrate the necessity for implementing appropriate population genetic methods and provide insights into the biology of this alga that will contribute to future studies on effective management strategies incorporating its reproductive system. This study represents one of the few that investigate green algal population genetic patterns and contributes to our understanding of algal reproductive system evolution.

Speaker-listener neural coupling reveals a right-lateralized mechanism for non-native speech-in-noise comprehension.

While the increasingly globalized world has brought more and more demands for non-native language communication, the prevalence of background noise in everyday life poses a great challenge to non-native speech comprehension. The present study employed an interbrain approach based on functional near-infrared spectroscopy (fNIRS) to explore how people adapt to comprehend non-native speech information in noise. A group of Korean participants who acquired Chinese as their non-native language was invited to listen to Chinese narratives at 4 noise levels (no noise, 2 dB, -6 dB, and - 9 dB). These narratives were real-life stories spoken by native Chinese speakers. Processing of the non-native speech was associated with significant fNIRS-based listener-speaker neural couplings mainly over the right hemisphere at both the listener's and the speaker's sides. More importantly, the neural couplings from the listener's right superior temporal gyrus, the right middle temporal gyrus, as well as the right postcentral gyrus were found to be positively correlated with their individual comprehension performance at the strongest noise level (-9 dB). These results provide interbrain evidence in support of the right-lateralized mechanism for non-native speech processing and suggest that both an auditory-based and a sensorimotor-based mechanism contributed to the non-native speech-in-noise comprehension.

Automatic mental simulation in native and non-native speakers.

Pictures of objects are verified faster when they match the implied orientation, shape, and color in a sentence-picture verification task, suggesting that people mentally simulate these features during language comprehension. Previous studies had an unintended correlation between match status and the required response, which may have influenced participants' responses by eliciting strategic use of this correlation. We removed this correlation by including color-matching filler trials and investigated if the color-match effect was still obtained. In both a native sample (Experiment 1) and a non-native sample (Experiment 2), we found strong evidence for a color-match advantage on median reaction time and error rates. Our results are consistent with the view that color is automatically simulated during language comprehension as predicted by the grounded cognition framework.

Tissue damage, antioxidant capacity, transcriptional and metabolic regulation of red drum Sciaenops ocellatus in response to nanoplastics exposure and subsequent recovery.

Nanoplastics are recognized as emerging contaminants that can cause severe toxicity to marine fishes. However, limited researches were focusing on the toxic effects of nanoplastics on marine fish, especially the post-exposure resilience. In this study, red drum (Sciaenops ocellatus) were exposed to 5 mg/L polystyrene nanoplastics (100 nm, PS-NPs) for a 7-day exposure experiment, and a 14-day recovery experiment that followed. The aim was to evaluate the dynamic alterations in hepatic and branchial tissue damage, hepatic antioxidant capacity, as well as hepatic transcriptional and metabolic regulation in the red drum during exposure and post-exposure to PS-NPs. Histopathological observation found that PS-NPs primarily triggered hepatic lipid droplets and branchial epithelial liftings, a phenomenon persistently discernible up to the 14 days of recovery. Although antioxidant capacity partially recovered during recovery periods, PS-NPs resulted in a sustained reduction in hepatic antioxidant activity, causing oxidative damage throughout the entire exposure and recovery phases, as evidenced by decreased total superoxide dismutase activities and increased malondialdehyde content. At the transcriptional and metabolic level, PS-NPs primarily induced lipid metabolism disorders, DNA damage, biofilm disruption, and mitochondrial dysfunction. In the gene-metabolite correlation interaction network, numerous CcO (cytochrome c oxidase) family genes and lipid metabolites were identified as key regulatory genes and metabolites in detoxification processes. Among them, the red drum possesses one additional CcO6B in comparison to human and zebrafish, which potentially contributes to its enhanced capacity for maintaining a stable and positive regulatory function in detoxification. This study revealed that nanoplastics cause severe biotoxicity to red drum, which may be detrimental to the survival of wild populations and affect the economics of farmed populations.

Variation in the timing and duration of autumn leaf phenology among temperate deciduous trees, native shrubs and non-native shrubs.

The timing and duration of autumn leaf phenology marks important transitions in temperate deciduous forests, such as, start of senescence, declining productivity and changing nutrient cycling. Phenological research on temperate deciduous forests typically focuses on upper canopy trees, overlooking the contribution of other plant functional groups like shrubs. Yet shrubs tend to remain green longer than trees, while non-native shrubs, in particular, tend to exhibit an extended growing season that confers a competitive advantage over native shrubs. We monitored leaf senescence and leaf fall (2017-2020) of trees and shrubs (native and non-native) in an urban woodland fragment in Wisconsin, USA. Our findings revealed that, the start of leaf senescence did not differ significantly between vegetation groups, but leaf fall started (DOY 273) two weeks later in shrubs. Non-native shrubs exhibited a considerably delayed start (DOY 262) and end of leaf senescence (DOY 300), with leaf-fall ending (DOY 315) nearly four weeks later than native shrubs and trees. Overall, the duration of the autumn phenological season was longer for non-native shrubs than either native shrubs or trees. Comparison of the timing of spring phenophases with the start and end of leaf senescence revealed that when spring phenology in trees starts later in the season senescence also starts later and ends earlier. The opposite pattern was observed in native shrubs. In conclusion, understanding the contributions of plant functional groups to overall forest phenology requires future investigation to ensure accurate predictions of future ecosystem productivity and help address discrepancies with remote sensing phenometrics.

Characterizing spring phenology in a temperate deciduous urban woodland fragment: trees and shrubs.

Phenological research in temperate-deciduous forests typically focuses on upper canopy trees, due to their overwhelming influence on ecosystem productivity and function. However, considering that shrubs leaf out earlier and remain green longer than trees, they play a pivotal role in ecosystem productivity, particularly at growing season extremes. Furthermore, an extended growing season of non-native shrubs provides a competitive advantage over natives. Here, we report spring phenology, budburst, leaf-out, and full-leaf unfolded (2017-2021) of a range of co-occurring species of tree (ash, American basswood, red oak, white oak, and boxelder) and shrub (native species: chokecherry, pagoda dogwood, nannyberry, American wild currant and Eastern wahoo, and non-native species: buckthorn, honeysuckle, European privet, and European highbush cranberry) in an urban woodland fragment in Wisconsin, USA, to determine how phenology differed between plant groups. Our findings show that all three spring phenophases of shrubs were 3 weeks earlier (p < 0.05) than trees. However, differences between shrubs groups were only significant for the later phenophase; full-leaf unfolded, which was 6 days earlier (p < 0.05) for native shrubs. The duration of the spring phenological season was 2 weeks longer (p < 0.05) for shrubs than trees. These preliminary findings demonstrate that native shrubs, at this site, start full-leaf development earlier than non-native species suggesting that species composition must be considered when generalizing whether phenologies differ between vegetation groups. A longer time series would be necessary to determine future implications on ecosystem phenology and productivity and how this might impact forests in the future, in terms of species composition, carbon sequestration, and overall ecosystem dynamics.