Nutrient enrichment and artificial light at night synergistically confer a competitive advantage to alien aquatic species over natives

93 Nutrient enrichment and artificial light at night synergistically confer a competitive advantage to alien aquatic species over natives Jin Zhang1, Yilin Nie1, Fukang Li1, Yidan Zhang1, Haihao Yu1, Chunhua Liu1 1 The National Field Station of Freshwater Ecosystem of Liangzi Lake, College of Life Science, Wuhan University, Wuhan 430072, China Corresponding authors: Chunhua Liu ([email protected]); Haihao Yu ([email protected]) Copyright: © Jin Zhang et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0). Research Article Abstract Many freshwater ecosystems are currently facing the dual challenges of artificial light at night (ALAN) and nutrient enrichment. How these simultaneously acting environmental factors affect competitive outcomes between alien and native aquatic plants has not been thoroughly investigated. Here, we conducted a greenhouse experiment to quantify the competitive outcomes and their determinants of nine pairs of alien and native aquatic plant species in China under fully crossed factorial combinations of ALAN (Ambient vs. ALAN) and nutrient enrichment (Low vs. High). Nutrient enrichment significantly affected competitive outcomes. Specifically, native species tended to have more biomass under low-nutrient conditions, while the reverse was true under high-nutrient, although the trends were not significant. This pattern was even more pronounced in the presence of ALAN. Differential effects of nutrient enrichment and ALAN on interspecific competition of alien and native species may be responsible for variation in competitive outcomes. We found that nutrient enrichment tended to increase the interspecific competition coefficients for native species, whereas an opposite trend for alien species was observed, this effect being most prominent in the presence of ALAN. Our findings suggest that nutrient enrichment and ALAN could synergistically confer a competitive advantage to alien species over native species. Therefore, intervention measures are necessary to minimise nutrient enrichment of freshwater habitats, especially in habitats exposed to light pollution resulting from ALAN. Key words: Artificial light at night, competitive outcome, freshwater ecosystem, intraand interspecific competition, intrinsic growth rates, nutrient availability, plant invasion Introduction The Anthropocene is characterised by the widespread invasion of alien plants, posing threats to local biodiversity, disrupting ecosystem services and causing substantial economic losses (Vilà et al. 2011; Schaffner et al. 2020; Diagne et al. 2021; Zhang et al. 2023b). The success of these invasions hinges on competitive interactions between alien and native species (Funk and Vitousek 2007; Pearse and Altermatt 2013; Wang et al. 2017). It is hypothesised that alien species are generally more competitive than native species, a notion supported by meta-analyses primarily focusing on interspecific competition intensity (Kuebbing and Nuñez 2016; Golivets and Wallin 2018). However, intrinsic growth rates and intraspecific competition intensity also significantly affect the competitive outcomes (Chesson 2000; Hart et al. 2018). Thus, predicting co-existence dynamics between native and alien species requires consideration of all three determinants: intrinsic growth Academic editor: Pedro Anastácio Received: 26 November 2024 Accepted: 21 April 2025 Published: 7 October 2025 Citation: Zhang J, Nie Y, Li F, Zhang Y, Yu H, Liu C (2025) Nutrient enrichment and artificial light at night synergistically confer a competitive advantage to alien aquatic species over natives. In: Anastácio P, Ribeiro F, Chainho P (Eds) Invasions in Aquatic Systems. NeoBiota 102: 93–108. https://doi.org/10.3897/ neobiota.102.142791 NeoBiota 102: 93–108 (2025) DOI: 10.3897/neobiota.102.142791 Advancing research on alien species and biological invasions A peer-reviewed open-access journal NeoBiota 94 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species rates, intraand interspecific competition. Yet, studies integrating these factors comprehensively remain limited (but see Godoy et al. (2014); Godoy and Levine (2014); Chu and Adler (2015); Zhang and van Kleunen (2019)). In theory, species with higher intrinsic growth rates and lower intraand interspecific competition intensity are expected to outcompete others (Zhang and van Kleunen 2019). However, in reality, these determinants may not operate independently. Alien species often exhibit higher intrinsic growth rates, but this can coincide with stronger intraspecific competition (Dostál et al. 2019). Furthermore, there is a trade-off between intraand interspecific competitive abilities, observed in some alien plant species (Lankau and Strauss 2007; Lankau 2009). For instance, in environments where an alien species faces intense intraspecific competition due to high abundance, individuals may prioritise enhancing intraspecific competitive ability, potentially at the expense of reduced competitive ability against other species (Lankau 2008). Therefore, accurately predicting species co-existence remains a significant challenge. Ecosystems worldwide are currently undergoing unprecedented environmental changes driven by factors such as nutrient enrichment (Sinha et al. 2017). Nutrient enrichment can potentially amplify the competitive advantage of alien plant species over native ones. For example, garden experiments with individual plants have demonstrated that alien species derive greater benefits from increased resource availability compared to native species (Liu and van Kleunen 2017; Kawawa Abonyo and Oduor 2024; Shan et al. 2024). Therefore, nutrient enrichment may alter competitive outcomes by impacting the disparity in intrinsic growth rates between alien and native species. Studies also indicate that nutrient enrichment reduces the competitive effects of native species on aliens (Barger et al. 2003; Eller and Oliveira 2017; Sun et al. 2023), although this often reflects changes in relative differences between intraand interspecific competition (but see Slate et al. (2022)). Additionally, nutrient enrichment significantly reduces intraspecific competition intensity for alien species, while increasing it for native species (Ba and Facelli 2022). It remains unclear whether this pattern persists in the presence of interspecific competition. Integrating intrinsic growth rates, intraand interspecific competition provides deeper insights into how nutrient enrichment influences competitive outcomes between alien and native species. In addition, the current understanding of these effects of nutrient enrichment is mainly from terrestrial ecosystems, while little is known about the situation in aquatic habitats. Artificial light at night (ALAN) imposes significant anthropogenic pressure on natural biological systems (Falchi et al. 2016; Kyba et al. 2017; Sanders et al. 2021). ALAN affects not only animal behaviour, physiology and life histories, but also alters plant community composition and phenology (Bennie et al. 2016; Liu et al. 2022). Recent field surveys by Murphy et al. (2021) have found a positive correlation between the presence of the invasive plant Bromus tectorum L. and streetlights, suggesting that ALAN may differently influence alien and native species, thereby affecting their competitive outcomes. However, Speißer et al. (2021) found no evidence that ALAN enhances the dominance of alien species in communities. Moreover, they observed a trend of decreased fitness of alien species under ALAN compared to ambient light conditions when grown individually. Conversely, another study suggested that ALAN tended to promote the growth of alien species under monocultures (Liu et al. 2022). Intraspecific interactions may partially explain the discrepancies between these studies’ results. Overall, our understanding of how ALAN impacts the performance of invasive and native species, as well as their intraand interspecific interactions, remains limited. 95 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species A large number of exotic aquatic plants have been consciously introduced for ecological restoration and landscape creation and many aquatic habitats have suffered severe plant invasions as a result (Hussner et al. 2021; Wang et al. 2024). In addition, freshwater ecosystems are particularly susceptible to ALAN because lighting road networks, urban development and industrial infrastructure are often located along rivers, lakes and coasts (Reid et al. 2019; Segrestin et al. 2021), while industrial wastewater and storm-water runoff from urban areas simultaneously contribute to nutrient enrichment (Maharjan et al. 2022; Kawawa Abonyo and Oduor 2024). Thus, aquatic habitats provide an ideal site for us to test the interactive effects of ALAN and nutrient enrichment. Here, we conducted experiments using a freshwater model system with seven alien and six native species. Employing a response surface design (Inouye 2001) in which we varied the density of both species of a pair independently, we planted 4320 individuals, describing competitive relationships between nine pairs of alien and native aquatic species under fully crossed factorial combinations of ALAN and nutrient enrichment treatments, each at two levels. We tested: (1) whether alien aquatic species are more competitive than native species and (2) how nutrient enrichment and ALAN affect competitive outcomes between alien and native aquatic species. Materials and methods Study species To examine the effects of ALAN and nutrient enrichment on competitive outcomes between alien and native aquatic plants, we selected seven alien and six native species to create nine species pairs (Suppl. material 1: table S1). The alien species we used in the experiment included all of China’s invasive submerged and floating plants, except for Azolla filiculoides Lam. (Wang et al. 2019; Wu and Ding 2019), which increased the generalisability of the results (van Kleunen et al. 2014). Species pairs were chosen, based on their co-occurrence in habitats and differences in growth forms. Hydrocharis dubia (Blume) Backer, Pistia stratiotes L., Cabomba caroliniana A.Gray, Egeria densa (Planch.) Casp., Elodea nuttallii (Planch.) H.St. John and Pontederia crassipes Mart. were sourced from commercial plant traders, while the remaining species were collected from pools of water from cement tanks at the National Field Station of Freshwater Ecosystems of Liangzi Lake, Hubei Province, China (30°15'N, 114°33'E)(hereafter referred to as the “Liangzi Lake Station”). Before starting the experiment, we selected 240 individuals of similar size for each species. As three species were used in multiple pairs, the actual number of individuals was 240*n, where n represents the number of repetitions. Experimental set-up The experiment was conducted in the greenhouse at the Liangzi Lake Station, China. For each alien-native species pair, we transplanted individual plants according to a response-surface experimental design (Inouye 2001). This design included 15 different density combinations, with total densities of 4, 8 or 12 plants per pot and the frequency of each species from 0 via 0.25, 0.5 and 0.75 to 1. Each density combination for each species pair was replicated 4 times and then randomly assigned to a fully crossed factorial combination of ALAN and nutrient enrichment treatments at two levels each (Fig. 1). 96 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species Due to differences in growth periods and growth forms amongst different species, the experimental duration and the type of containers were varied. On 12, 13 March 2024, we transplanted the individuals of the first six species pairs into soilfilled plastic pots (top diameter: 18 cm, bottom diameter: 13 cm, height: 12.5 cm) according to the experimental design. The soil (TN: 0.60 ± 0.005 g kg−1, TP: 0.58 ± 0.03 g kg−1, mean ± standard error (SE), n = 3) was obtained from the Liangzi Lake Station and meticulously sieved to eliminate stones, plants and animal remnants. We opted for terrestrial topsoil as opposed to lake-bottom silt, in order to mitigate the potential for the emergence of unwanted macrophytes stemming from an aquatic plant seed bank (Yan et al. 2024). We then placed six pots of the same density combination and treatment in a specific order in a rectangular aquarium (length × width × height: 105 × 50 × 60 cm), arranged in three rows and two columns and filled the aquarium with lake water to a depth of 50 cm. On 4 April 2024, we placed the individuals of the 7th and 8th species pairs in cylindrical stainless-steel tanks (50 cm diameter, 60 cm height) with lake water depth of 50 cm according to the experimental design. On the same day, we placed the individuals of the 9th species pair in circular flower pots (70 cm top diameter, 50 cm bottom diameter, 40 cm height) with a water depth of 30 cm. After three days of transplanting the individuals, we started different experimental treatments. We used LED strips fixed above the three types of containers to simulate ALAN. The LED strips (6 W/m, IP 180 lm/m, warm white 3300K-5000K; NVC, Figure 1. Graphical illustration of the response-surface design used for each pair of alien and native aquatic plant species. Each pair is treated with different nutrient (N− vs. N+) and ALAN (ALAN− vs. ALAN+) conditions. 97 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species China) were positioned 10 cm above the water surface for the rectangular aquarium, 56 cm for the cylindrical stainless-steel tanks and 40 cm for the circular flower pots. The containers were arranged in rows, with the plastic pots in the rectangular aquarium also arranged in rows. Therefore, the LED strips fixed in the middle of the two rows of cylindrical stainless-steel tanks, the two rows of circular flower pots and the single row of rectangular aquariums provided uniform illumination for each container. At night, the control group remained in darkness, while the ALAN group was continuously exposed to light at an intensity of 16 ± 3.5 lux. During the experiment, the LED lights were switched on at 6:30 pm and off at 6:30 am the next day. We controlled the nutrient levels by varying the amount of slow-release fertiliser (Osmocote Plus 15N-9P-12K+2MgO+TE, Everris). Specifically, we added 2.3 g of fertiliser to half of the rectangular aquariums for high nutrient treatment, leaving the other half without fertiliser for low nutrient treatment. For the cylindrical stainless-steel tanks and circular flower pots, the high nutrient treatment involved adding 7 g and 1.6 g of fertiliser, respectively, while the low nutrient treatment involved adding 2.5 g and 0.7 g, respectively. The controlled release fertiliser was placed in a mesh bag at the bottom of the container. For the rectangular aquariums, the nutrient concentrations in the water column under low and high nutrient treatments were 0.758 ± 0.025 mg l−1 and 0.967 ± 0.022 mg l−1 for TN, 0.014 ± 0.001 mg l−1 and 0.030 ± 0.001 mg l−1 for TP, respectively. For the cylindrical stainless-steel tanks and circular flower pots, the nutrient concentrations in the water column under low and high nutrient treatments were 1.236 ± 0.077 mg l−1 and 1.476 ± 0.080 mg l−1 for TN, 0.141 ± 0.016 mg l−1 and 0.222 ± 0.030 mg l−1 for TP, respectively. Data represent mean values ± standard error, n = 18. These two water quality indices were significantly different between the two nutrient levels. The concentration of nutrients in the high nutrient treatment was within the range of nutrient enrichment in freshwater lakes across China (Huo et al. 2013). Measurements On 5 May 2024, we harvested all plants from the rectangular aquarium, dried each individual (including roots) to a constant weight at 70 °C and weighed them to the nearest milligram. On 20 May 2024, we harvested, dried and weighed the remaining plants in the same manner. Statistical analyses Intrinsic growth rates and competition coefficients To describe the competition between alien and native species pairs, we fitted our data on the biomass of individual plants to a linearised version of a modified Ricker competition model (Ricker 1954) by taking the natural log of both sides of the equation: ln(Bi,t) = ln(λi) – αii Ni,t – αij Nj,t In the equation, Bi,t is the individual biomass of species i in year t. Ni,t and Nj,t are the number of individuals of species i and j in year t, respectively. λi is the intrinsic growth rate of species i, which represents the expected biomass of an individual in the absence of conspecific and heterospecific neighbours. αii represents 98 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species the per capita effect of species i on itself (the intraspecific competition coefficient) and αij represents the per capita effect of species j on species i (the interspecific competition coefficient). Positive values of competition coefficients indicate competition amongst individuals and negative values indicate facilitation. Bi,t,Ni,t and Nj,t were measured directly during the experiment, while λi, αii and αij were estimated by fitting the linearised model. Although the subscript t typically denotes a time step (e.g. in years), here it refers only to the single time point of harvest at the end of the experiment and does not represent inter-annual dynamics. For each species pair under the four different experimental conditions, we fitted a linear mixed-effects model. We used total biomass of each individual at the end of the experiment. We included the number of conspecific and heterospecific competitors as fixed effects, with container as a random effect to account for non-independence of individuals within the same container. We used the number of individuals at the end of experiment rather than at the beginning of the experiment. Next, we used linear mixed-effects models to test the effects of species status, nutrient enrichment and ALAN on intrinsic growth rates and intraspecific competition coefficients. We included species status, nutrient enrichment, ALAN and their interactions as fixed factors, with identity (nested within family) of target species as random effects. We also tested the effects of species status, nutrient enrichment and ALAN on interspecific competition coefficients. In this mixed-effects linear model, we included species status, nutrient enrichment, ALAN and their interactions as fixed factors, with target species and competitor species (nested within their respective families) as random effects. In all models, we included the inverse of variance as weights. Competitive outcomes Based on population-level biomass, we calculated lnRRk, the competitive outcome between alien and native plants in each of the biculture containers (k) as: ln RRk = ln(TBk_a) – ln (TBk_n) where TBk_a and TBk_n are the total biomass of alien and native species, respectively, in the biculture container k. Subsequently, for each pair of species in different conditions, we used a linear model with lnRRk as the response variable and an intercept as the only explanatory variable. Therefore, a positive intercept value fitted for a pair signifies that, on average, the alien species in that pair exhibited higher biomass than the native species across a broad range of density combinations (indicating greater competitiveness of the alien species), whereas a negative intercept value indicates the opposite. To test how nutrient enrichment and ALAN affect competitive outcomes between alien and native species, we fitted a linear mixed-effects model. The model included nutrient enrichment, ALAN and their interactions as fixed factors, with identity (nested within family) of native species as random effects. We also included identity of alien species as random effects and we allowed each alien species to respond differently to the nutrient treatments (i.e. we included random slopes). We included the inverse of variance of competition outcomes as weights. Considering potential differences between species combinations, we also fitted a linear model using the gls function. This model included nutrient enrichment, ALAN, identity of species pair and their interactions as fixed factors. Additionally, it allowed for different variances for each species pair. 99 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species All analyses were conducted using the lme4 package (Bates et al. 2015) and nlme package (Pinheiro et al. 2023) in R 4.2.0 (Team 2022). Results were visualised using the plot function or the ggplot function from the ggplot2 package (Wickham 2016). Results Compared with native aquatic species, alien species tended to have higher intrinsic growth rates, but the difference was not statistically significant (Table 1, Fig. 2a). The intrinsic growth rate was also not affected by the interaction between status and nutrient enrichment or the interaction between status and ALAN (Table 1, Fig. 2a). Alien species tended to have lower intraspecific competition coefficients compared with native aquatic species, but the difference was not statistically significant (Table 1, Fig. 2b). The intraspecific competition coefficients were also not affected by the interaction between status and nutrient enrichment or the interaction between status and ALAN (Table 1, Fig. 2b). Overall, there was no difference in interspecific competition coefficients between alien and native species (Table 1, Fig. 2c). However, nutrient enrichment affected the interspecific competition coefficients of alien and native species significantly differently (Table 1). Specifically, nutrient enrichment tended to increase the interspecific competition coefficients for native species, whereas an opposite trend was observed for alien species (Suppl. material 1: fig. S1), this effect being most pronounced in the presence of ALAN (a marginally significant three-way interaction between status, nutrient and ALAN in Table 1, Fig. 2c). Overall, when grown together, alien species and native species exhibited similar biomass (Fig. 3). Competitive outcomes between alien and native species were significantly affected by nutrient enrichment (Table 2). Specifically, under low-nutrient conditions, native species tended to have higher biomass, while under high-nutrient conditions, alien species tended to have higher biomass (Fig. 3). However, these trends were not statistically significant. This pattern was more pronounced Table 1. Effects of status of target species (native vs. alien), nutrient enrichment (low-nutrient vs. high-nutrient levels), ALAN treatment (ambient vs. ALAN) and their interaction on intrinsic growth rates (λi) and intraand interspecific competition coefficients (αii and αij). Significant (P < 0.05) effects are in bold. Marginally significant (0.05 ≤ P < 0.10) effects are shown in italics. The significance of fixed effects was assessed with likelihood-ratio tests by comparing models with and without the effect of interest. λi; χ2Pαii; χ2Pαij; χ2P Status (S) 1.521 0.217 1.902 0.168 0.613 0.433 Nutrient (N) 0.542 0.462 1.137 0.286 1.688 0.193 ALAN (L) 1.305 0.253 0.014 0.906 0.765 0.381 S × N 1.439 0.23 1.479 0.224 5.503 0.018 S × L 0.821 0.364 0.063 0.802 0.578 0.446 N × L 4.653 0.031 2.831 0.093 0.389 0.532 S × N × L 1.031 0.309 1.399 0.237 3.385 0.065 Random effects SD SD SD Species of target 0.906 0.000 0.009 Family of target 0.503 0.019 0.013 Species of competitor - - 0.019 Family of competitor - - 0.002 Residual 0.407 0.450 0.280 R2 mR2 cR2 mR2 cR2 mR2 c 0.080 0.877 0.001 0.003 0.003 0.011 100 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species Figure 2. Mean intrinsic growth rates (a λi) and intraand interspecific competition coefficients (b αii; c αij) for alien and native aquatic plant species under different experimental treatments. Positive values of αii and αij indicate competitive interactions. Error bars represent 95% confidence intervals. Intrinsic growth rates (λi), whose unit is milligram, was natural log-transformed. Figure 3. Mean values of competitive outcomes between alien and native plant species (i.e. mean values of lnRRk) under different experimental treatments. Error bars represent 95% confidence intervals. Table 2. Effects of nutrient enrichment (low-nutrient vs. high-nutrient levels), ALAN treatment (ambient vs. ALAN) and their interaction on competitive outcomes (i.e. which species have higher biomass in bicultures across different density combinations). Significant (P < 0.05) effects are in bold. Marginally significant (0.05 ≤ P < 0.10) effects are shown in italics. The significance of fixed effects was assessed with likelihood-ratio tests by comparing models with and without the effect of interest. χ2P Nutrient (N) 4.524 0.033 ALAN (L) 0.255 0.614 N × L 4.008 0.045 Random effects SD Alien species 1.050 (0.260)a Native species 0.457 Family of native 1.231 Residual 0.211 R2 mR2 c 0.022 0.984 aHere, the standard deviations (SD) are given for the random intercepts (corresponding to the values in the high nutrient treatment) and random slopes (corresponding to the effects of the low nutrient treatment) of species of alien. The values in brackets represent the SDs of the random slopes. 101 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species in the presence of ALAN, demonstrated by a significant ALAN × nutrient enrichment interaction (Table 2, Fig. 3). We also found that competitive outcomes were significantly affected by species combination (Suppl. material 1: table S2, fig. S2). Moreover, the effect (Suppl. material 1: table S2, fig. S2) and determinants (Suppl. material 1: figs S3–S5) of nutrient enrichment on competitive outcomes varied amongst different species combinations. Discussion While alien species are often perceived as more competitive than native counterparts (Vilà and Weiner 2004; Pearse et al. 2019), our study did not find significant differences in competitive ability between them (Fig. 3). Similarly, Zhang and van Kleunen (2019) found in their study quantifying competition outcomes amongst 48 pairs of native and naturalised alien plants in Germany that alien and native species generally exhibited comparable competitive abilities. However, their research indicated that common alien plants were more competitive than rare natives. Previous studies into alien-native competition may have been skewed towards using rare native species (Vilà and Weiner 2004), potentially contributing to variable outcomes. The native aquatic species in our study are widely distributed in China and some are recognised as invasive in other regions worldwide (e.g. Myriophyllum spicatum L. (Marko et al. 2008; Martin and Coetzee 2014), Potamogeton crispus L. (Fleming et al. 2015), Hydrilla verticillata (L.f.) Royle (Louback-Franco et al. 2020; Mormul et al. 2020). A meta-analysis previously indicated no significant trait disparities between invasive alien and native species known to be invasive elsewhere (Van Kleunen et al. 2010). Thus, our findings, alongside existing research, suggest that alien species do not inherently possess a competitive advantage over commonly encountered natives. Growth and intraspecific competition may exhibit a trade-off relationship, where larger and faster-growing species typically face stronger resource competition and greater negative density dependence (Dostál et al. 2019). However, our study did not observe this trade-off pattern. Instead, we found that alien species generally displayed higher intrinsic growth rates coupled with lower, rather than higher, levels of intraspecific competition (Fig. 2a, b). Future research should investigate the prevalence and mechanisms underlying this relationship between growth and intraspecific competition. In contrast to findings from several meta-analyses (Kuebbing and Nuñez 2016; Golivets and Wallin 2018), we did not find evidence that alien species consistently exhibit lower interspecific competition coefficients compared to natives (Fig. 2c). Potential explanations include the smaller sample size of species pairs in our study compared to meta-analyses, resulting in reduced statistical power. Moreover, the intensity of interspecific competition between alien and native species may vary depending on environmental conditions (e.g. nutrient availability), a factor that our study’s limited environmental scope may not fully capture. Last, data from several meta-analyses may have been derived primarily from terrestrial ecosystems, whereas the subjects of our study were submerged and floating aquatic plants. Previous empirical studies examining the effects of nutrient enrichment on competitive outcomes have produced mixed results. While some studies indicate positive effects (Zhang et al. 2017; Uddin and Robinson 2018; Ren et al. 2019), others suggest that in the presence of common natives, nutrient enrichment may not affect or could even diminish the competitive advantage of alien species (Going et al. 2009; 108 NeoBiota 102: 93–108 (2025), DOI: 10.3897/neobiota.102.142791 Jin Zhang et al.: Nutrient-ALAN synergy favors alien species Zhang Z, van Kleunen M (2019) Common alien plants are more competitive than rare natives but not than common natives. 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Journal of Applied Ecology 60(11): 2425–2436. https://doi. org/10.1111/1365-2664.14505 Supplementary material 1 Supplementary information Authors: Jin Zhang, Yilin Nie, Fukang Li, Yidan Zhang, Haihao Yu, Chunhua Liu Data type: docx Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited. Link: https://doi.org/10.3897/neobiota.102.142791.suppl1