Ismael Soto

Freshwater ecosystems harbour a substantial proportion of global biodiversity yet face intense pressure from multiple stressors. Historical models indicate that Türkiye has served as a crucial hub of fish diversification since the Late Miocene, although projections suggest that freshwater biodiversity faces escalating threats. This study investigates the past, present and future distribution dynamics of 14 species belonging to the Alburnoides genus in Türkiye using an ensemble species distribution modelling (SDM) approach. Habitat suitability was assessed under present conditions and future climate scenarios (SSP1–2.6 and SSP5–8.5) by integrating species records with climatic, hydrological and environmental variables. The results show that temperature and precipitation are the dominant limiting factors determining habitat suitability for the genus Alburnoides , with species thriving in well‐oxygenated, rapidly flowing streams within a temperature range of 7°C–20°C. Future projections indicate a substantial contraction of suitable habitats across Türkiye, particularly under the high‐emission scenario (SSP5–8.5). However, a select few species are anticipated to experience range expansion as newly suitable habitats emerge under future climate scenarios. These findings highlight the necessity of formulating basin‐wide and climate change‐adaptive management methods for the preservation of biodiversity in Turkish inland water ecosystems.

The use of freshwater fish as biological control agents has been widely implemented to manage populations of perceived nuisance species, ranging from disease vectors to aquatic weeds. While these introductions are often intended as a management tool, they can have unintended and severe ecological, economic, and social consequences. This review assesses the risks associated with using non‐native fish for biological control, emphasising the challenges presented by their persistence, adaptability, and interactions with native species and ecosystems. Key case studies illustrate how species such as mosquitofishes ( Gambusia spp.), grass carp ( Ctenopharyngodon idella ), and tilapias (mainly Oreochromis spp.) have inadvertently contributed to biodiversity loss, habitat degradation, trophic disruptions, and disease transmission, while often failing to effectively control the target species. We further explore the limitations of biocontrol strategies, including the context‐dependent nature of species interactions and deferred negative impacts. Given the complexity and unpredictability of biological control interventions, rigorous impact assessments and long‐term monitoring programmes are needed before and after introducing non‐native fish as control agents, embedded within an adaptive management framework that allows for responsive decision‐making based on observed ecological outcomes. Precautionary policies should prioritise habitat restoration and native species‐based solutions over the introduction of non‐native species to support more sustainable and ecologically responsible management decisions.

This study provides the first confirmed record of Xironogiton victoriensis Gelder & Hall, 1990 (Clitellata: Branchiobdellida), the original ectosymbiont of invasive signal crayfish Pacifastacus leniusculus (PL) in the Czech Republic, thereby expanding its known non-native distribution in Europe. Available records indicate that X. victoriensis has already been reported from multiple sites across Europe and from a single site in Japan, suggesting that it may be the most widely distributed North American branchiobdellidan species. Field observations showed that X. victoriensis can reach high abundances on PL (up to 946 individuals found on a single crayfish), with abundance increasing according to the host size. Additionally, molting state and claw condition were additional significant predictors of X. victoriensis abundance—recently molted PL and those with missing or regenerating chelae carried significantly fewer ectosymbionts. In addition, a laboratory experiment indicated that branchiobdellidan infestation success and short-term survival depend on host species, with the European native noble crayfish Astacus astacus appearing to be a significantly less suitable host than PL. Our current findings suggest that the establishment of branchiobdellidans on novel crayfish hosts may be more limited by host-specific biological factors than implied by the numerous reports of novel crayfish–branchiobdellidan associations.

1. The invasion success of a species often hinges on its capacity to adapt to novel environments and outcompete native species for available resources, such as shelter and food (McMahon, 2002; Saka...

Appendage loss in crayfish can cause physiological stress or fitness consequences, or be fatal. While the ecological importance of chelipeds (claws) is well documented, the impact of losing other appendages remains understudied. Furthermore, there are almost no records of injury rates for other appendages in stocking conditions. This study evaluated the frequency of appendage injuries in a laboratory stock of marbled crayfish (Procambarus virginalis) and experimentally tested their effects on oviposition performance. First, we assessed stock individuals for appendage injuries, body size, and reproductive stage. Second, we conducted a controlled experiment in which we removed one or both fifth pereiopods to analyze the effects on ovulation timing, fecundity, and spatial egg distribution along the pleon. In stock analysis, claw status, rather than body size, was significantly associated with appendage status. The loss of one or both claws initiated a vulnerability cycle, increasing injury rates, especially in the antennae and the fourth and fifth walking leg pairs. Injury rates also fluctuated within reproductive stages. In the experiment, the loss of the fifth pereiopod did not significantly impair fecundity or delay ovulation, while effects on egg distribution were minor and inconsistent. Compensatory behaviors likely maintain successful egg attachment and distribution despite fifth-pereiopod loss.

Crayfish are freshwater macroinvertebrates with prominent ecological roles (Füreder and Reynolds, 2003; Kouba et al., 2016). Their ecological impacts are shaped by activity patterns and driven by f...

Human-mediated redistribution of organisms has reshaped global ecosystems, leading to the increasing homogenization of biotic communities. Among invasive taxa, vertebrates, including mammals, birds, reptiles, amphibians, and fishes,are recognised as among the most harmful groups due to their high establishment rates and strong top-down pressures. Despite their known consequences, a systematic global synthesis explicitly linking these impacts to specific mechanisms across all vertebrate classes has been lacking. We addressed this gap by leveraging InvaPact v1.0, a global database containing over 99,000 impact records extracted via fine-tuned large language models. Ecological impacts were quantified using an expanded Environmental Impact Classification for Alien Taxa (EICAT) framework, which assigns impact scores based on the severity and level of biological organisation affected. We analysed the spatial and temporal distribution of these impacts, compared vertebrate impacts to those of invertebrates, and assessed taxonomic representativeness. Our analysis reveals that ecological harm is concentrated within a limited subset of taxa. The most impactful species identified include wild boars ( Sus scrofa ), domestic cats ( Felis catus ), rabbits ( Oryctolagus cuniculus ), and black rats ( Rattus rattus ). Predation emerged as the dominant mechanism of impact, particularly for Mammalia and Actinopterygii, primarily driving declines in native population sizes and changes in assemblage structure. Spatially, the highest impact magnitudes were recorded in Australia and the United States, with significantly higher impacts observed in island ecosystems compared to mainland ecosystems. Furthermore, we found that vertebrates generally have a greater impact across all habitat types than invertebrates. These findings highlight that invasive vertebrate impacts are uneven across taxa and space, often driven by a few high-impact "worst" invaders. The high vulnerability of island biota to predation-mediated extinctions underscores the need for prioritised management and eradication programs in these regions. Additionally, our representativeness analysis suggests research biases toward charismatic or well-known invaders, such as mammals, which may influence global reporting patterns.

Biological invasions have become a major component of global change, yet the processes governing secondary spread after initial introductions remain insufficiently resolved. A specific and central gap is the lack of a spatially explicit and temporally dynamic quantification of colonisation pressure, despite its presumed importance for establishment and spread in connected river systems. Identifying whether and where previously established non‐native populations generate the momentum to further facilitate dispersal is essential for separating spread processes from local environmental suitability Using long‐term freshwater macroinvertebrate monitoring data from Germany, we describe colonisation pressure for the zebra mussel Dreissena polymorpha as a distance‐weighted function of previously colonised sites across a river‐network framework and subsequently link it to first detections, establishment probability and several site‐level predictors. We found that colonisation pressure increased through time as the invaded range expanded and that it was consistently highest along the Rhine River, with newly colonised sites generally experiencing higher colonisation pressure in their year of first detection than uninvaded sites. At the same time, colonisation pressure did not explain observed abundances at first detection and was negatively associated with establishment probability, while variation in colonisation pressure itself was better explained by anthropogenic and invasion‐related factors than by local climatic, hydrological or topographic conditions. While several questions remain, our results position colonisation pressure as a useful mechanistic descriptor of invasion momentum in riverine systems, with direct relevance for surveillance and risk prioritisation and with potential applicability to climate‐driven range shifts, species reintroductions and the expansion of commercially or conservation‐relevant taxa in spatially structured landscapes.

Biological invasions pose major threats to ecosystems, with aquatic habitats particularly vulnerable due to high connectivity and biodiversity. The Ponto‐Caspian region is widely recognised as a major source of highly invasive non‐native aquatic species, yet a global synthesis of their spatial, taxonomic and temporal invasion patterns has been lacking. Here, we provide the first global review of the taxonomic diversity of non‐native aquatic Ponto‐Caspian species from published literature and biodiversity records, including information on invasion pathways, spatial distribution and temporal reporting trends. Our analysis of 146 non‐native aquatic Ponto‐Caspian species revealed a strong taxonomic bias, with arthropods (53%) and fishes (23%) accounting for over three‐quarters of recorded taxa, while crustaceans (Malacostraca) were markedly over‐represented relative to global non‐native aquatic taxa. Canal‐mediated connectivity among European waterbodies remained the dominant invasion pathway, whereas ballast water has been the primary pathway to North America. Geographically, invasions were concentrated in Europe and the Laurentian Great Lakes, with few records from other continents. From a temporal perspective, reporting showed fluctuating trends associated with canal construction, management actions and growing scientific attention. Overall, our findings suggest that invasion risks from Ponto‐Caspian species are largely context‐dependent, mainly affecting Europe and North America, but increasing trends highlight the need for strengthened prevention, control and international cooperation under ongoing environmental change.

Artificial light at night is an emerging environmental stressor with significant implications for aquatic ecosystems, influencing species’ behaviour and physiological processes. We examined the effects of artificial light at night on the routine metabolic rate of two widespread, invasive crayfish species, red swamp, Procambarus clarkii (Girard, 1852) and signal, Pacifastacus leniusculus (Dana, 1852). Crayfishes were exposed to light intensities mimicking urban nighttime lighting (20 lux) and natural daylight (1000 lux) to assess species-specific metabolic responses to artificial light at night. The results revealed distinct patterns: P. clarkii displayed no significant metabolic change (P = 0.331), suggesting a lower sensitivity to artificial light at night, whereas P. leniusculus showed a significant (P < 0.0001) reduction in routine metabolic rate under artificial light at night, likely due to behavioural adaptations related to reduced activity. Both species exhibited higher nocturnal routine metabolic rate compared to diurnal measurements, regardless of treatment, with routine metabolic rate of P. clarkii remaining elevated longer than that of P. leniusculus. These findings underscore the species-specific metabolic responses to artificial light at night, with potential ecological implications for their roles within aquatic ecosystems. The study enhances our understanding of invasion ecology by demonstrating how species-specific responses to environmental stressors like artificial light at night may influence their competitive dynamics and ecological impacts.