Temperature is a crucial factor affecting the physiological processes of aquatic plants. It influences respiration, photosynthesis, nitrogen metabolism, and oxidative metabolism. These processes are fundamental for plant growth, energy production, and stress responses, directly linking to the plant’s ability to tolerate and remediate environmental contaminants.

As temperatures rise, respiration rates generally increase to an optimum point, enhancing metabolic activity and energy production and facilitating greater uptake and detoxification of contaminants. For example, a temperature increase of 2.5°C is expected to boost respiration and primary production by 31% and 28%, respectively [30], and rising temperatures could even increase potential species richness in certain lake types [31]. However, temperatures exceeding the optimal range can lead to increased respiration that surpasses photosynthesis, resulting in a net loss of carbon and energy [32] (Table 1). Excessive temperatures can cause Rubisco deactivation and reduce chloroplast electron transport rates, co-limiting photosynthesis [33]. This imbalance impairs growth and reduces phytoremediation efficiency. Similarly, optimal temperatures enhance enzymatic activities involved in the Calvin cycle, leading to increased photosynthetic rates and biomass production (Table 1), critical for phytoremediation. However, temperatures above the optimum range can cause photoinhibition and damage to photosystem II, reducing the efficiency of light energy conversion and carbon fixation [34]. Elevated temperatures can also accelerate nitrogen uptake and assimilation [35,36], enhancing plants’ growth and detoxification abilities. However, extreme temperatures can disrupt nitrogen metabolism [35], accumulating toxic ammonium and reducing the synthesis of essential proteins and enzymes. Moreover, increased temperatures can indirectly affect plant nutrition by altering nutrient cycles. For instance, Kramer et al. [37] observed that temperatures from 29°C to 30°C promote cyanobacterial growth but suppress nitrogen fixation rates in lake communities. Temperature increases are also predicted to accelerate litter decomposition rates, potentially impacting carbon sequestration and affecting plant nutrition [38]. Temperature-induced oxidative stress is another significant challenge for aquatic plants. Elevated temperatures may increase the production of reactive oxygen species (ROS), causing oxidative damage to cellular components [39]. However, some plants counteract this by upregulating antioxidant enzymes, which may improve the plants’ tolerance and contaminant-removal capacity [40].

Aquatic plants have evolved various mechanisms to adapt to temperature fluctuations, such as changes in membrane fluidity, enzyme activity, and gene expression [41]. These adaptations enable some species to thrive in a broader range of temperature conditions, enhancing their effectiveness in phytoremediation under varying climatic conditions. For instance, an increase in temperature from 20°C to 30°C favored the harmful effects of the antibiotic Cipro on the mitochondrial activity of Ricciocarpus natans. However, it also enhanced the activity of antioxidant enzymes, preventing Cipro-induced oxidative stress and resulting in increased uptake of Cipro by the plants [42]. Similarly, in response to rising temperatures, aquatic plants modify pigment and membrane lipid composition, increasing membrane fluidity and, thus, cell permeability to water contaminants [43]. Understanding the complex interplay between temperature and plant physiology is crucial for designing and optimizing aquatic phytoremediation systems that can effectively remove contaminants in a changing climate.

Temperature changes have several secondary effects on the aquatic environment, which can further influence aquatic plants’ physiology and phytoremediation capabilities. For instance, increased temperatures accelerate evaporation rates, leading to higher water salinity. Elevated salinity levels impose osmotic stress on aquatic plants, disrupting ion balance and water uptake mechanisms [4] (Table 1). This osmotic stress can alter the plants’ physiological pathways, potentially enhancing their tolerance and uptake of specific contaminants, such as metals and pharmaceuticals (Fig. 1). For instance, heightened antioxidant enzyme activities under osmotic stress may improve the phytoremediation capacity of plants by mitigating oxidative damage from contaminants [55]. However, increased salinity can also result in decreased remediation ability by aquatic plants, as seen for metals (Cu, Zn, cadmium (Cd), and Pb) in E. canadensis and Potamogeton natans [50].

Changes in precipitation patterns and water availability due to rising temperatures can also affect hydrological regimes, impacting the distribution and concentration of contaminants in aquatic environments [52,53]. Increases in rainfall and extreme weather events can lead to higher contaminant loads in waterways, and the interactive effects between rising contaminant concentrations and temperature in water are difficult to predict. For instance, increased temperature and nitrogen loading have significantly boosted cyanobacterial growth rates in lakes. However, this also impairs nitrogen fixation, contributing to nitrogen limitation in these ecosystems, which can profoundly affect plant communities, including the phytoremediation capacities of macrophytes. Nutrients such as nitrogen, phosphorus, and sulfur are crucial for a plant’s ability to cope with contaminants, modulating their phytoremediation capacity [56,57]. Fluctuating water levels can lead to drought and flooding, each presenting unique challenges and opportunities for phytoremediation. Drought conditions might concentrate pollutants, increasing the burden on plants, while flooding can disperse contaminants, potentially reducing their bioavailability but increasing the spatial extent of contamination. Moreover, increasing temperatures are closely linked to rising sea levels, contributing to the salinization of coastal and freshwater environments [58]. This salinization exacerbates osmotic stress on aquatic ecosystems, further influencing plant’s capacity for phytoremediation.

Climate-induced shifts in pest and disease patterns may also lead to increased use of pesticides and herbicides, contributing to higher levels of these contaminants in water bodies [59,60]. The emerging threat of insect pests driven by rising global temperatures is a clear example of this issue. A study on the sweet potato whitefly (Bemisia tabaci) in the southeastern United States found that warmer temperatures were associated with earlier and more abundant whitefly activity, particularly in areas with higher insecticide use [61]. The study suggests that frequent insecticide applications, driven by these climate-induced pest outbreaks, may disrupt biological control mechanisms, resulting in even more persistent pest problems. This creates a potential feedback loop, or “pesticide treadmill,” where increased temperatures and pest abundance lead to further pesticide use, exacerbating the contamination of water bodies as global climate change accelerates [62]. These chemicals can interact with the physiological responses of aquatic plants, affecting their growth and contaminant uptake capacities. For example, certain pesticides can inhibit or enhance specific metabolic pathways involved in phytoremediation, complicating predictions of plant performance under climate change scenarios. In E. canadensis, Roundup (a glyphosate-based herbicide) inhibits the activity of cytochrome P450, thereby decreasing the metabolism and uptake of the antibiotic Enro by plants. However, the presence of Enro in water increased glyphosate uptake and toxicity [21].

Studies have explored the impacts of temperature on the phytoremediation capabilities of aquatic plants. Huynh et al. [44] investigated the removal of trace elements (Cd, As, Pb, Zn, and Cu) by water hyacinth (Eichornia crassipes) under different temperature regimes. Their findings showed that temperatures exceeding 33°C stifle plant development and decrease trace element-removal capacity. Similarly, Haris et al. [63] observed that temperature significantly affects the remediation capacity of water hyacinth, with optimal nutrient removal occurring at 30°C. Higher temperatures increased phosphorus release from organic matter, reducing the plant’s remediation efficiency. In contrast, increasing temperature from 11°C to 32°C enhanced the cyanide metabolism rate of weeping willows (Eleocharis acicularis), an emergent macrophyte, by 46% for every 10°C increase due to higher enzyme activity without causing increased cyanide accumulation or toxicity [64]. However, higher temperatures also improved the remediation capacity of E. acicularis for As-contaminated leachate. The absorption of As by E. acicularis was higher at an average temperature of 20.5°C (0.8% of total As absorbed) compared to 4.2°C (0.3% of total As absorbed) [65].

Fritioff et al. [50] observed increased metal (Cu, Zn, Cd, Pb) accumulation in E. canadensis and P. natans when the temperature was raised from 5°C to 20°C. Additionally, the Cu-remediation capacity of Typha latifolia improved with increasing temperatures from 18°C to 32°C [66]. A recent review by Pang et al. [67] reported that the metal-remediation capacity of macrophytes generally increases with temperature up to an optimal range of 20°C–30°C. Beyond 30°C, remediation capacity can decrease due to plant stress, with maximum removal observed around 25°C–30°C for the metals studied. Similarly, increased temperature (from 20°C to 30°C) favored ciprofloxacin (Cipro) uptake by Ricciocarpus natans [42]. However, increased temperature (from 12°C to 28°C) had little effect on the bioaccumulation of the herbicide isoproturon in freshwater macrophytes Egeria densa and Ludwigia natans. Still, it increased the herbicide burden in E. densa [68].

Temperature increases can also enhance selenium (Se) accumulation by giant reed (Arundo donax) by altering microbial activity, affecting selenium’s mobility, bioavailability, and volatility [69]. Indeed, temperature increases can modulate microbial activity in bioremediation, impacting the efficacy of natural biodegradation or the injection of biological materials [70]. For example, higher summer temperatures were associated with increased Pb and Co remediation capacity of Pistia stratiotes, likely due to lower dissolved oxygen levels and bacterial abundance, compared to lower winter remediation capacity [71]. Weirich et al. [72] observed increased nitrogen removal efficiency by P. stratiotes and E. crassipes during summer. Additionally, constructed wetlands planted with aquatic macrophytes showed increased denitrification rates as water temperatures rose from 12°C to around 26°C [73]. Temperature also influences the remediation capacity of both T. domingensis and Pontederia parviflora. Temperatures above 20°C, in the mesophilic range, allowed for optimal microbial and plant metabolism, leading to high removal efficiencies for chemical oxygen demand (COD) and suspended solids. Conversely, temperatures below 20°C, in the psychrophilic range, reduced the metabolism of microorganisms and aquatic plants, leading to lower remediation capacity. Large temperature fluctuations, with drops of over 10°C in a single day, negatively impacted the stability and performance of these systems [54].

Climate change can also influence the distribution and prevalence of aquatic plant species, affecting their availability and suitability for phytoremediation. Studies have shown that certain floating species, such as L. minor, exhibit greater tolerance to high temperatures than other morphotypes of macrophytes [29]. Increased temperatures and freshwater salinization favor the growth of floating macrophytes and phytoplankton [74] while decreasing the metal remediation capacity of submerged macrophytes like E. canadensis [50]. However, the metal (Mn and Fe) removal capacity of phytoplanktonic species such as Synechococcus elongatus (Cyanobacteria) and Chlorococcum infusionum (Chlorophyta) remains unaffected under these conditions [75]. These findings suggest that floating macrophytes, such as duckweed species, may be more suitable for phytoremediation under warmer and more saline conditions. Nevertheless, compared to submerged macrophytes, floating plants have proven to be less effective in removing some contaminants, such as the antibiotic erythromycin [76], which could result in lower overall effectiveness of phytoremediation programs. A potential solution is the use of mixed cultures of floating macrophytes. For example, more excellent growth rates were observed for both L. minor and S. molesta when grown together in water contaminated with the antibiotics Cipro and sulfamethoxazole (Sulfa), compared to systems with each plant growing separately. This co-culture approach resulted in more excellent removal of Cipro and Sulfa in the mixed system [77].

In summary, temperature impacts on aquatic phytoremediation are multifaceted and require a comprehensive understanding of plant physiology, environmental interactions, and system-level optimization (Fig. 1; Table 2).

Light is a fundamental factor affecting the physiological processes of aquatic plants. Changes in light conditions due to climate alterations can significantly impact these processes [7]. Light intensity directly influences photosynthetic rates and the growth patterns of aquatic plants (Table 1). Optimal light conditions enhance the efficiency of photosystem II and the Calvin cycle, leading to increased carbon fixation and biomass production [78], which are essential for phytoremediation. Conversely, low light conditions can lead to etiolation, reduced growth rates, and lower biomass [78], compromising phytoremediation efficiency. Moreover, reduced light penetration due to increased water turbidity from extreme weather events can limit photosynthesis [79], reducing the energy available for growth and contaminant uptake, especially in submerged plants [80]. Underwater darkening can also alter the ecological dynamics of ecosystems, particularly impacting plants with notable phytoremediation capacities. For example, a study conducted in East China examined the effects of light attenuation on the growth and photosynthetic traits of native phytoremediator plants like water thyme (Hydrilla verticillata) and Eurasian watermilfoil (Myriophyllum spicatum) compared to the invasive Carolina fanwort (Cabomba caroliniana). The study found that while light attenuation inhibits the growth of native submerged plants, it facilitates the growth of invasive species like C. caroliniana, which exhibited superior growth and photosynthetic traits under low underwater light conditions [80]. Using native species in phytoremediation programs is crucial to avoid introducing exotic species with potential ecological impacts. Changes in light conditions will affect the success of these programs, particularly in environments susceptible to underwater darkening.

On the other hand, excessive light intensity can also induce stress responses, such as the production of ROS [81,82], which can damage plant tissues and compromise their phytoremediation capabilities [55]. Light intensity can also affect the plant’s accumulation and distribution of contaminants by affecting their growth. Higher light levels may stimulate the production of chelating compounds, such as phytochelatins and metallothioneins, which can sequester and compartmentalize metals, enhancing their removal from the environment [83]. For instance, higher light intensities in the terrestrial metal hyperaccumulator plant Noccaea caerulescens increased biomass production and metal accumulation, improving phytoremediation efficiency [84]. However, caution is necessary, as hyperaccumulators may mobilize metals but only accumulate some, potentially increasing the risk of metal leaching [84].

Aquatic plants have developed various adaptive strategies to cope with fluctuations in light intensity. Some species, such as water hyacinth and duckweed, exhibit a high degree of phenotypic plasticity, allowing them to acclimate to a wide range of light conditions [83]. Other plants may allocate resources to specific physiological processes, such as increased production of light-harvesting pigments or antioxidant enzymes, to mitigate the effects of excessive or limited light [85].

Increased water turbidity, a consequence of climate-induced extreme weather events [3], reduces light penetration in aquatic environments. As discussed above, this reduced light availability affects photosynthesis and growth, decreasing phytoremediation efficiency. Turbidity also impacts the distribution of pollutants, potentially increasing their bioavailability in the water column [86] (Table 1). Climate change can also alter seasonal light patterns, affecting the timing and duration of light availability [87]. These changes can disrupt the phenology of aquatic plants, such as flowering and growth cycles, leading to mismatches between peak light availability and periods of active growth. Such disruptions can reduce phytoremediation efficiency, as plants may not be in their optimal growth phase when contaminants are most prevalent.

Understanding the relationship between light intensity, biomass production, and phytoremediation is crucial for developing effective strategies to enhance the removal of contaminants from aquatic environments. By optimizing light conditions and selecting plant species with high phenotypic plasticity or other adaptive traits, we can improve the efficiency of phytoremediation systems, making them more resilient to the impacts of climate change.

Light significantly influences the growth and physiology of aquatic macrophytes, which in turn impacts their phytoremediation capabilities. Photosynthetic rates increase with light intensity up to a certain point, beyond which photoprotective mechanisms are activated to prevent damage [88]. Light-induced changes in the cellular redox environment play a crucial role in metabolic regulation, affecting various pathways, including carbon, nitrogen, and secondary metabolism [89], all of which are intrinsically involved in the phytoremediation capacity of macrophytes [55]. For instance, under low-light conditions, such as those caused by increased turbidity due to climate events, biomass production is reduced, and nutrient uptake in submerged species is adversely affected [90]. In submerged macrophytes like Potamogeton crispus, shaded conditions (42% and 11% of full sunlight) lead to reduced tissue soluble protein, soluble carbohydrates (SC) contents, and the SC/free amino acid (FAA) ratio, while increasing FAA concentrations, and promoting the activity of antioxidant enzymes, such as superoxide dismutase and guaiacol peroxidase. This results in aggravated carbon and nitrogen consumption and oxidative stress, disrupting the plant’s capacity for nutrient removal and contributing to the decline of submerged macrophytes in eutrophic lakes [91]. Conversely, intermediate light levels (around 30%–50% shade) are optimal for the phytoremediation potential of M. aquaticum, as this light regime promotes the greatest plant biomass and growth [92]. Light availability also affects the toxicity of herbicides to aquatic plants. For example, the herbicide atrazine decreased shoot length in E. canadensis grown under low-light conditions. Still, not biomass, while under optimal light conditions, atrazine significantly decreased both shoot length and biomass [93]. In Lemna sp. and Spirogyra sp., increases in light intensity have been shown to enhance the plant’s ability to remove pharmaceuticals and endocrine-disrupting chemicals from wastewater. The highest removal efficiencies were achieved in uncovered planted systems [94]. Similarly, increased light intensity enhanced the removal of diclofenac and Sulfa in wetlands. However, this enhancement was attributed to the photodegradation of the contaminants [95] rather than improved plant performance. Many organic pollutants, including pharmaceuticals, are particularly susceptible to photodegradation [96,97]. Therefore, even moderate increases in light intensity could potentially enhance remediation by facilitating the cleavage of these molecules. However, this process may also lead to the generation of intermediary metabolites, which could exhibit a higher level of toxicity to plants compared to their parent compounds [98], thereby compromising the plant’s performance in contaminant uptake.

Despite its importance, there are relatively few studies on the effect of light on the remediation capacity of macrophytes. It appears that changes in the light environment due to climate change predominantly affect submerged species of macrophytes due to increased water turbidity and decreased light availability. In contrast, floating and emerging plants seem tolerant to increased light intensity and regimes (Fig. 1). Understanding these light-dependent mechanisms is crucial for improving phytoremediation strategies and deserves more attention in future research.

Elevated CO₂ levels have been shown to increase the phytoremediation efficiency of Noccaea caerulescens by enhancing biomass production and metal accumulation and reducing oxidative damage [115]. Similarly, CO₂ enrichment stimulates the accumulation of sediment-derived minerals like Al, Fe, P, and N in the submerged macrophyte Vallisneria americana, with the effects being more pronounced at a lower pH of 5 compared to a higher pH of 7.3 [116]. This suggests that CO₂ levels, in combination with pH, can significantly influence the nutrient uptake and overall health of aquatic plants.

In soil environments, elevated CO₂ generally enhances rhizoremediation and phytoextraction of metals by increasing biomass and microbial activity in the rhizosphere, while elevated O₃ has the opposite effect [48]. High O₃ levels decrease the inputs of assimilates to the rhizosphere, negatively impacting decomposition processes, rhizoremediation, and metal phytoextraction efficiency. Elevated O₃ also adversely affects microbial biomass, reducing the effectiveness of phytoremediation [48]. Increased CO₂ significantly enhances the abundance of bacterial and functional genes related to CO₂ assimilation and carbon decomposition, promoting photoautotrophy, hydrocarbon degradation, and cellulolysis [47]. However, elevated CO₂ levels reduce the abundance of chemoautotrophic bacteria, including nitrifying bacteria. Culturing E. crassipes under elevated CO₂ conditions decreases photosynthetic bacteria. Still, it increases bacteria involved in complex carbon decomposition due to root exudates. These interactions can decrease bacterial diversity and the abundance of CO₂-assimilating, nitrifying, and certain carbon-degrading bacteria with denitrifying properties. Consequently, the interactions between aquatic plants and the bacterial community in eutrophic waters under elevated CO₂ can benefit the environment and help mitigate the greenhouse effect [47]. Conversely, rising concentrations of CO₂ and O₃ have been shown to decrease the removal of polycyclic aromatic hydrocarbon (PAH) pollutants in grassland soils. This reduction in PAH degradation is linked to shifts in soil microbial community structure, specifically a reduction in gram-positive bacteria essential for soil enzyme production and PAH degradation [49]. These findings highlight the complex interplay between CO₂, O₃, and pH levels and their effects on phytoremediation. While elevated CO₂ can enhance biomass production and microbial activity, thus improving phytoremediation efficiency, elevated O₃ can negate these benefits by reducing microbial biomass and nutrient inputs to the rhizosphere. Additionally, changes in pH due to increased CO₂ levels can further complicate these interactions, affecting nutrient availability and metal solubility.

Aquatic macrophytes respond differently to environmental factors such as CO₂, O₃, and pH. Floating and emerging macrophytes are most resilient to elevated CO₂, showing notable enhancements in photosynthesis and biomass production [117]. This is attributed to their superior carbonic anhydrase activity, which is related to their higher carbonic anhydrase activity and bolsters their phytoremediation capacity in scenarios of increased CO₂. In contrast, water acidification may adversely affect submerged macrophytes [117]. These plants are highly sensitive to pH fluctuations; optimal pH levels facilitate healthy growth and nutrient uptake, while extreme pH levels can decrease nutrient availability and enhance the solubility of toxic metals, thereby compromising phytoremediation efficiency. Emergent macrophytes can tolerate a broader range of pH levels than submerged types [118]. However, extreme pH levels can still affect nutrient availability and microbial activity, potentially reducing their effectiveness. Floating macrophytes are generally less sensitive to pH fluctuations than submerged types [117]. They may tolerate a broader range of pH levels, maintaining phytoremediation capabilities even under varying conditions. However, extreme pH levels can still impact nutrient uptake and microbial interactions. Regarding O₃, submerged macrophytes are generally less affected by elevated O₃, as atmospheric O₃ does not readily dissolve in water, meaning their phytoremediation capacity is not significantly impacted. On the other hand, emergent macrophytes are more exposed to atmospheric O₃, which can cause oxidative stress, reduce photosynthesis, and impair growth. Chronic exposure to high O₃ levels can decrease phytoremediation efficiency by damaging plant tissues and reducing assimilated inputs to the rhizosphere. Floating macrophytes are directly exposed to atmospheric O₃, which can cause oxidative damage and impair growth. While they exhibit high phenotypic plasticity and can adapt to varying O₃ levels, chronic exposure may still reduce their effectiveness in phytoremediation (Fig. 1).

Despite the growing body of research on terrestrial systems, there is a notable lack of information regarding the impacts of CO₂, O₃, and pH fluctuations on aquatic phytoremediation. However, possible scenarios can be inferred. For instance, pharmaceuticals can be cleaved by ozonation and pH changes [119,120]. Thus, increased atmospheric CO₂ (leading to water acidification) and higher O₃ levels could enhance the degradation of organic contaminants, potentially aiding in their removal from water bodies. This suggests that elevated CO₂ and O₃ may affect plant health and growth; they could also contribute to the breakdown of certain pollutants, offering a mixed but potentially beneficial impact on phytoremediation in aquatic environments.