Search Results (855)

Biological invasions and environmental gradients are major drivers of biodiversity change in wetland ecosystems, but their associations on native plant diversity in Central Asian riverine wetlands remain poorly understood. We surveyed 158 wetland plant communities across 54 transects in the Ertix River Basin to examine how environmental gradients (elevation, mean annual temperature [MAT], and mean annual precipitation [MAP]) and non-native plant establishment jointly related to native plant importance values and alpha diversity indices. Non-native plants were classified according to invasion stage—non-naturalized, naturalized, and invasive—to elucidate how the associations between alien plants and native communities shift dynamically along the invasion continuum. Elevation emerged as the dominant predictor, explaining 82% (individual R² = 0.15) of the variance in native species richness and 63.37% (individual R² = 0.1) of the variance in the Shannon–Wiener diversity index, while MAT and MAP were not retained as significant predictors in the optimal models. Native plant importance values, richness, and diversity all increased with elevation. Unexpectedly, naturalized plant richness and abundance were positively associated with native diversity metrics, contrasting with the negative associations of all non-native categories (non-naturalized, naturalized, and invasive) on native importance values, partly reflecting the compositional nature of this metric. Our results reveal positive co-occurrence patterns between early-stage naturalized species and native species, but native dominance may eventually decline as invasion intensity increases. These findings highlight the importance of considering invasion stage when predicting wetland biodiversity responses to biological invasions under environmental heterogeneity. Full article

The increasing spread of invasive alien species (IAS) represents one of the major causes of biodiversity loss, making containment practices necessary. In this regard, the circular economy framework proposes to reuse the biomass from IAS in growing sectors such as aquaculture, in which more sustainable practices are required. This study evaluated the possibility of using biomass derived from two widespread freshwater IAS, Procambarus clarkii and Silurus glanis, as dietary ingredients for Oncorhynchus mykiss. Experimental diets were formulated by incorporating 20% of IAS-derived muscle powder into a commercial feed, and their effects were assessed through a 35-day feeding trial. Chemical analyses confirmed the nutritional suitability of the formulated diets and the absence of antibiotic residues. No mortality or significant differences in growth performance were observed among treatments. Blood biochemical parameters showed limited variations, remaining within physiological ranges, while oxidative stress biomarkers indicated only minor, diet-specific responses without evidence of oxidative damage. An increase in Hsp70 expression suggested adaptive physiological responses rather than pathological stress. Histological analyses of liver and gut tissues revealed no structural alterations across experimental groups. Overall, the results demonstrate that the inclusion of IAS-derived biomass at 20% is well tolerated by O. mykiss and does not impair fish health. These findings support the potential of invasive species valorization as a sustainable strategy for aquaculture feed production, contributing to both resource efficiency and ecosystem management. Full article

With over 140 species of primary freshwater fish, including 73 that are endemic, Greece is recognized as a biodiversity hotspot in Europe. However, like freshwater systems worldwide, these ecosystems face serious threats, particularly from the introduction of non-native species. This ongoing increase in invasive species has heightened scientific and policy-maker awareness, as such introductions can lead to population declines and even extinctions of native fish. In response to this growing concern, various risk assessment tools have been developed to evaluate the potential hazards posed by non-native species, both those already established and those likely to be introduced. These tools are critical for informing policy decisions and managing biological invasions effectively. In the current study, a new tool, the Hellenic Risk Assessment (HeRA), is proposed. Unlike its predecessors, HeRA places greater emphasis on assessing the biological traits of introduced species and incorporates region-specific considerations tailored to the Mediterranean basin. Its scoring system evaluates both the likelihood of a species establishing itself and its potential environmental impact, making it a valuable resource for stakeholders in prioritizing management actions and making informed decisions regarding the import of live fish species. Full article

Although the sublethal effects of botanical pesticides are critical for pest management, their role in modifying insect behaviour is frequently overlooked. In a laboratory bioassay utilising powder prepared from the leaf, stem, and root of the invasive alien plants (IAPs) Gleditsia triacanthos, Chromolaena odorata, and Schinus terebinthifolia, this study evaluated the behavioural reactions, notably repellence and locomotion, of Spodoptera frugiperda larvae. For repellence, six second instar larvae of S. frugiperda were individually placed in 30 mL vial that remained unsealed to allow larvae to exit freely if repelled and were exposed to 22% of leaf, stem and root powders of all three plant species over a 12 h period before recording the number of repelled insects. For locomotion, ten-second instar larvae were directly coated with different powder quantity 1.5 g and 2.5 g of leaf, stem, and root of all three IAPs, then released and allowed to move for 60 s on a 90 × 60 cm whiteboard. The running speed was calculated as the distance travelled per unit time. All plant-part powder exhibited significantly higher repellence than the control (0%). Gleditsia triacanthos leaf, root and stem powders showed minimal repellence, with values of 16%, 29% and 21%, respectively. However, higher rates were observed for C. odorata and S. terebinthifolia. Specifically, C. odorata stem powder achieved the highest overall repellence at 54%, whereas S. terebinthifolia performed best with its root powder at 45%. Compared to the control group, the running speed of the insects experienced a substantial reduction, decreasing by 60 to 80% when exposed to powders derived from all parts of the three IAPs. Our results suggest that the IAP powders used in this study both repel S. frugiperda and strongly limit their ability to move, highlighting their potential for behaviour-based pest control strategies. Full article

The invasion of the marine alien gastropod Rapana venosa (Valenciennes, 1846) across different basins is investigated through a spatiotemporal analysis of distribution patterns, aggregation processes, and spatial structure. Occurrence data from scientific literature and citizen science were integrated with GIS-based spatial statistics to compare invasion dynamics in the Black Sea, the Mediterranean Sea, and Northwest Europe. The Black Sea represents the most advanced invasion stage, characterized by extensive distribution, multiple aggregation zones, and strong associations with brackish, nutrient-rich areas influenced by major river outflows. In the Mediterranean, the invasion has progressed from a prolonged establishment phase to a recent acceleration, with the Adriatic Sea acting as the historical core of expansion. Here, persistent populations are concentrated near the Po River delta and lagoon systems, where reduced salinity and high nutrient loads favor both settlement and long-term persistence. In Northwest Europe, R. venosa remains in the establishment phase, forming a compact and localized nucleus along the French Atlantic coast without evidence of broad spatial expansion. Our analyses suggest that environmental factors, particularly salinity gradients and riverine inputs, are possibly related to the observed invasion patterns. Transitional coastal environments emerge as important areas for establishment and subsequent spread, suggesting that monitoring efforts should prioritize these environments. Full article

Introduction: Longlines are traditional fishing gear and are widely used in marine systems for both quantitative and qualitative sampling of large predators like tuna, swordfish, sailfish, marlin or sharks. This highly selective method has been applied for the sampling of European catfish (Silurus glanis), the largest freshwater fish in Europe. This apex predator is a highly valuable fish species in its native localities of Central and Eastern Europe (commercial fishing, anglers’ trophy fishing, biomanipulation purposes) but a dangerous alien invasive species in South and Western Europe. Objective: The efficiency and selectivity of longlines for European catfish sampling were compared with more traditional fishing methods like gillnets and electrofishing. Methodology: European catfish were sampled in native areas (Římov, Žlutice, Vrchlice, Hubenov, Lipno, Želivka reservoirs; Czech Republic) and areas of invasion (Lakes Campagna, Avigliana Grande, Maggiore; Italy; Belver, Meimoa, Cedillo reservoirs; Portugal; Iznajar, Mequinenza reservoirs; Spain) following the protocols of best catfish (Silurus glanis) capture methodologies in small and large lakes and reservoirs established for the current needs of the European Commission within the LIFE PREDATOR project. Results: The longline efficiency expressed as the proportion of individual hooks catching catfish (live baits exposed overnight) was from low to medium (5–25%; Czech reservoirs, Italian lakes, Meimoa reservoir) to very high (up to over 50%; Portuguese and Spanish reservoirs). In many water bodies, specifically in areas of invasion, catfish represented 100% of the longline catch (Campagna, Maggiore, Cedillo, Iznajar, Mequinenza). In the rest of the water bodies, the by-catch ranged from 2 to 20% with the highest values occurring in its native localities (due to the presence of large individuals of Northern pike, Esox lucius, another predatory fish in these systems). In areas of invasion, the inconsiderable by-catch was composed of other non-native predatory fish species like pikeperch (Sander lucioperca), European perch (Perca fluviatilis) or channel catfish (Ictalurus punctatus). Both the efficiency and selectivity of longlines were higher compared to gillnets and electrofishing, and longlines also caught larger catfish individuals. Conclusions: Longlines represent an efficient and extremely selective method for European catfish sampling, reduction and even eradication, especially in areas of invasion. Their usage, however, requires specific equipment, skills and also baits. Full article

Paraleyrodes minei is an invasive alien species in China, representing a new record for Yunnan Province and a new sugarcane pest. The mitochondrial genome of P. minei was sequenced using the Illumina NovaSeq 6000 sequencing platform. The genome sequence was assembled and annotated, and its structural characteristics and nucleotide composition were analyzed. A phylogenetic tree of 18 species in the family Aleyrodidae was constructed using maximum likelihood (ML) and Bayesian inference (BI) methods to analyze the phylogenetic relationship of P. minei within the family Aleyrodidae. The results indicated that the mitochondrial genome of P. minei was 18,774 bp in length and contained 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and 1 non-coding control region. The A+T content of the mitochondrial genome of P. minei was 80.93%, indicating a marked A+T preference. ATN was used as the start codon for the PCGs, and TAA, TAG, TA, and T were used as the stop codons. In the secondary structure of tRNA, the TΨC arm was missing in trnA, trnC, and trnG, and the DHU arm was missing in trnS1 and trnS2, with G-U base mismatches present. The phylogenetic tree revealed that the 18 species of 10 genera in the two subfamilies of the family Aleyrodidae clustered into two major branches: the subfamilies Aleyrodinae and Aleurodicinae. All 10 genera were monophyletic groups; among them, the genus Paraleyrodes and the genus Aleurodicus formed a sister relationship, and both belonged to the subfamily Aleurodicinae. This study represents the first successful sequencing of the mitochondrial genome of P. minei, as well as the first mitochondrial genome of the genus Paraleyrodes, laying the foundation for the control of P. minei and the analysis of phylogenetic relationships among various genera of the family Aleyrodidae. Full article

Mediterranean rivers experience various pressures that cause native fish populations to decline. This is the case of Achondrostoma asturicense, a threatened endemic species recently classified as "endangered" (EN) by the Portuguese Red Book. In northeastern Portugal, the main populations occur in the Carvalhais (Tua basin), Maçãs, and Angueira (Sabor basin) rivers. This study aimed to evaluate the effect of small weirs on the distribution, abundance, and habitat use of A. asturicense populations along the longitudinal gradient of River Angueira. Three river zones (Z1 to Z3) affected by small weirs were selected along the watercourse. In each zone, four sampling sites were distributed relative to the weir, as follows: A1—200 m downstream; A2—immediately downstream; A3—under the influence of the reservoir; and A4—200 m upstream (reference). Sampling was carried out in three seasons: winter, spring, and summer 2025. Physical–chemical (water), hydromorphological (habitats), and biological (fish) elements were assessed in accordance with the protocols of the Water Framework Directive. The results revealed the worst water quality in the summer season due to flow reduction, dissolved oxygen depletion, elevated conductivity, and high nutrient (N, P) concentrations, leading to eutrophication phenomena. The distribution and abundance of A. asturicense were negatively influenced by the presence of small weirs, which were dominated by the non-native species Lepomis gibbosus. PERMANOVA analysis (two-way, p < 0.05) identified significant differences (Pseudo-F = 28.349, p < 0.05) between sampling sites and river zones, and paired similarity analysis tests (ANOSIM; one-way, p < 0.05) confirmed that these differences occur only between the weir reservoir (A3) and the remaining sampling sites. A. asturicense showed a maximum length (Lmax) of 135 mm, isometric growth only in the upstream zone (Z1), and significant differences in body condition (0.75 < K < 0.84). This species showed a preference for rheophilic habitats, with coarse substrate and diversity of currents and distinct cover mainly guaranteed by submerged aquatic macrophytes. A. asturicense populations are severely affected in the River Angueira by habitat fragmentation, riparian degradation, pollution, invasive alien species (e.g., L. gibbosus, P. clarkii, N. vison), and climate change, justifying the development of mitigation and restoration measures for the conservation of natural habitats and native threatened species. Full article

European catfish, an invasive alien species (IAS) that inhabits the Tagus River in Extremadura, is a threat to freshwater biodiversity and the local economy. As a freshwater mega-predator, it eats all kinds of fish, impacting local ichthyofauna as well as sport-recreational angling, a major economic driver in Extremadura, with 100,000 angling licenses issued by the Extremadura local government and more than 1000 annual bank fishing competitions. The introduction of Silurus glanis into Tagus basin is recent, dating to the 20th century, but it has rapidly spread. Although this expansion is driven by anglers, boat anglers account for only two per thousand anglers in the region, and even among them European catfish anglers are scarce, as fishing for this species is prohibited in the region and local anglers and anglers associations are against European catfish expansion. Efforts to control catfish in Extremadura have been based on studies of selective capture methods, such as trammel nets, gill nets, long lines, fish traps, and electrofishing combined with nets in areas where barbel congregate during their spawning migration. The most effective and selective methods for European catfish, avoiding bycatch, are trammel nets and electrofishing. Therefore, a combination of these methods and collaboration between local government and anglers are proposed for its control in reservoirs. In cases of recent introductions into standing water, rapid actions have been taken, involving complete drainage of the water body, rescue of native fish and removal of European catfish. These measures are feasible in reservoirs up to 10 hectares and can be combined with sediment management to improve water quality. Deterrence and control measures have been implemented in response to the promotion of catfish angling in regional media and on social media. To control European catfish expansion, collaborative actions involving public agencies, local government, angler associations and public awareness are essential. Full article

Marine biological invasions are rapidly reshaping Mediterranean ecosystems, with growing consequences for biodiversity and fisheries. This study investigates recent changes in the composition of commercially important crustacean assemblages along the south-eastern coast of Sicily (central Mediterranean), focusing on penaeid shrimps (Penaeus aztecus and Penaeus kerathurus) and stomatopods (Erugosquilla massavensis and Squilla mantis). Field surveys were conducted during the fishing seasons of 2021 and 2025 at major landing sites and markets (Portopalo di Capo Passero, Syracuse and Catania), using standardized subsampling protocols applied to catches obtained by trammel nets and bottom trawls. Species composition was quantified through repeated sampling events, and temporal differences were analyzed using non-parametric tests and binomial generalized linear models, incorporating year and fishing gear as explanatory variables. Quantitative data were complemented by local ecological knowledge derived from structured interviews with professional fishers. Across the four-year interval, both taxonomic groups exhibited a pronounced shift in species dominance. The proportion of the invasive shrimp P. aztecus increased from approximately 20% in 2021 to over 80% in 2025, while the invasive stomatopod E. massavensis rose from about 2% to nearly 90% of total landings. These changes were statistically significant and independent of fishing gear. Fishers’ perceptions closely mirrored the quantitative trends, confirming the rapid replacement of native species by non-indigenous taxa and highlighting emerging socio-economic implications for local fisheries. Our findings document a rapid shift in the composition of commercial crustacean landings in Sicilian coastal waters, with invasive species becoming the dominant component of catches within a few years. This study underscores the need for adaptive fisheries management and integrated monitoring frameworks capable of responding to accelerating biological invasions in Mediterranean marine ecosystems. Full article

Invasive alien species (IAS) threaten coastal wetland ecosystems, and smooth cordgrass (Spartina alterniflora) is among the most damaging invaders along the coast of China. We compiled occurrence records from the invaded range (China) and native range (United States) and retained 358 and 291 spatially thinned occurrences after quality control and definition of coastal-accessible areas. We assembled climatic, topographic, land use, soil and anthropogenic predictors and fitted species distribution models using the biomod2 ensemble-modeling framework, complemented by an ecospat-based comparison of native and invaded niche spaces. The ensemble model (EM) showed high predictive accuracy (China: AUC = 0.98, TSS = 0.99; USA: AUC = 0.99, TSS = 0.94). Elevation (73.6%) and human influence (6.0%) were the strongest predictors, highlighting the role of intertidal geomorphology and human-mediated propagule pressure. Niche overlap between ranges was low (Schoener’s D = 0.13), and the invaded niche showed substantial unfilling (0.36), indicating additional environmental space at risk of colonization in China. The current suitable habitat forms a continuous coastal belt from the Bohai Rim through the Yellow Sea–East China Sea to the South China Sea. Projections under future climate change suggest predominantly stable suitable areas with localized expansions but potential contractions in some periods. Our results may support the early warning, surveillance prioritization, and adaptive management of S. alterniflora under climate change. Full article

Introduction: Studying the structure and dynamics of living communities is essential from both ecological and wildlife management perspectives. Objective: The main objective of this study was to analyze the fish community structure inhabiting different river sections across several basins in the Mediterranean area. The data collected here contributed to: (i) creating a regional and national reference inventory to assess ichthyological biodiversity; (ii) generating digital cartographic information on species distribution and potential habitats; and (iii) providing scientific data to update national legal protection for governments. Methodology: Fish assemblages were monitored using electrofishing, which ensures reproducible data and long-term comparability. The study period extended until autumn 2025, with intensive sampling at 30 sites across major water bodies in the Valencian Community and selected rivers in Mijares, Turia, Jucar and Palancia basins. Results: The results reveal notable ichthyological richness in the studied basins (Turia, Júcar, Palancia, Mijares), with 12 native species identified. Cyprinidae and Leuciscidae were the most representative families, both in species number and spatial distribution, consistent with their dominance in Mediterranean river systems. Areas with the highest species richness corresponded to the middle and lower river sections and to ecologically valuable coastal wetlands. However, the study also detected 10 invasive alien species, representing 45% of the total fish fauna recorded. This high proportion reflects the significant ecological alteration affecting rivers and wetlands in these basins and underscores the urgent need for management actions to limit the spread of invasive species and reduce their impact on native biodiversity. The most widespread IAS were the bleak (A. alburnus), mainly in the Júcar basin, and the mosquitofish (G. holbrooki), predominantly in coastal wetlands. Conclusions: This study contributes directly to updating the Atlas of Ichthyofauna of the Valencian Community, providing a robust and current information base to support environmental decision-making at regional and national levels. The findings highlight the importance of strengthening proactive conservation measures, particularly in areas where biodiversity is most vulnerable. Full article

Hyblaea puera is a major pest of teak and mangroves. Reliable RT-qPCR normalization requires stable reference genes, none of which have been validated in H. puera. In this study, we assessed the expression stability of ten candidate reference genes under different experimental conditions. Stability was evaluated using the ΔCt method, BestKeeper, NormFinder, and geNorm, and a comprehensive stability ranking was generated using the RefFinder online tool. Our results indicated that amplification efficiencies ranged from 91.67% to 100.82%, with R² values exceeding 0.9901. The optimal reference gene combinations varied by condition: Ribosomal Protein L27 (RPL27) and Ribosomal Protein L10 (RPL10) for temperature treatments; Actin and RPL10 for larval instars; Ribosomal protein S5 (RPS5) and Elongation factor-1α (EF-1a) for adult sexes; RPL10 and EF-1a for tall developmental stages; RPL10 and RPS5 for tissues; as well as EF-1α and Actin for all combined conditions. Finally, the expression profiles of target gene Lethal were evaluated, and the outcomes further confirm the importance of selecting fitting reference genes for normalization of qRT-PCR data. These results provide the evaluated reference gene sets for H. puera, facilitating more accurate RT-qPCR normalization in future molecular studies of host plant adaptation (teak vs. mangroves), temperature tolerance, and larval development in this pest. Full article

This study utilized the age-stage, two-sex life table method to evaluate the toxic effects of polyethylene microplastics (PE, 300 mg/kg) and cadmium (Cd, 30 mg/kg), both individually and combined, on Leptinotarsa decemlineata. Compared to controls, all treatments significantly prolonged larval development and reduced survival, lifespan, and fecundity. The combined exposure (PE + Cd) exerted the strongest inhibition: the total pre-adult developmental duration (TPOP) increased by 18.8% (38.00 days), while the intrinsic growth rate ($r$) dropped by 59.0% to 0.0273 d⁻¹. Additionally, the net reproduction rate ($R_0$) and fecundity fell to their lowest levels (5.08 and 19.06, respectively), significantly lower than in single-treatment groups. Age-stage life expectancy analysis confirmed severe survival pressure in the combined group, evidenced by a 30% reduction in first-instar survival and a 14-day shortened adult lifespan. These findings demonstrate the synergistic toxicity of PE and Cd co-contamination, providing critical data for ecological risk assessment in the “soil–plant–herbivore” system and integrated pest management strategies. Full article

Introduction: Freshwater ecosystems are increasingly threatened by river fragmentation caused by the accumulation of small barriers such as weirs. These structures disrupt longitudinal connectivity and hinder fish movements, restricting access to essential habitats (e.g., spawning) and affecting biodiversity and ecological river functions. Though many of these structures are obsolete and their removal is increasingly promoted as a river restoration measure under the EU Biodiversity Strategy and the Nature Restoration Law, the ecological implications of barrier removal are not totally positive. One of the most pressing concerns is the unintended spread of Invasive Alien Species (IAS), which may expand upstream once a barrier is eliminated. In this context, selective barriers are gaining attention as a promising management tool to balance ecological restoration goals with IAS control. By carefully designing or adjusting hydraulic features such as head drops, it may be possible to allow passage for native species while restricting the movement of invasive fish. However, despite its potential, selective barrier design remains underexplored. Objective: This research aims to address this gap by testing how head drops influence the upstream movement of Iberian straight-mouth nase (Pseudochondrostoma polylepis), a native leuciscid, and the European perch (Perca fluviatilis), an IAS rapidly expanding across the Iberian Peninsula. Methodology: Laboratory experiments were conducted in an indoor ecohydraulic flume (6.5 × 0.7 × 0.7 m) at the Hydraulics Laboratory of IST. A single weir structure whose downstream water level was adjusted to create three distinct head drops—11, 18, and 25 cm (configurations A, B, and C, respectively)—was tested. Tests were performed using one specimen of each species that were allowed 15 min acclimation to the flume conditions followed by a 60 min trial. The number of approaches, attempts and successful upstream passages were recorded. Additionally, the flow-field characterization was performed using an Acoustic Doppler Velocimeter (ADV; Nortek-AS Vectrino 10 MHz). Results: Preliminary results indicate a strong capability of the native nase to overcome two of the tested head drops, with four and two successful passages recorded for configurations A and B, respectively. In contrast, the invasive species showed no successful passages under these conditions. For configuration C, no successful passages were observed for either species. Conclusions: These results highlight the potential of selective weir designs to promote river connectivity for native species while helping prevent the upstream expansion of invasive fish. Full article