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Invasions of non-native species are considered major threats to biodiversity in urban waterbodies. We compared macroinvertebrate richness, density, and community composition among three urban lakes with varying macrophyte covers: One dominated by the invasive macrophyte species Elodea nuttallii, one by the native species Myriophyllum spicatum, and the third one by the native Phragmites australis. We also monitored substrate parameters and water quality. Canonical correspondence analysis combined with hierarchical and variation partitioning confirmed that macrophytes were the most different feature among the lakes and that dominant macrophytes of each lake best explained differences in invertebrate communities, followed by water quality and substrate type. Macrophyte growth form could be linked to certain invertebrate taxa: emergent macrophytes supported abundant shredders (Gammarus sp. and Asellus aquaticus); and submerged macrophytes favored certain predators (Hemiptera, e.g., Plea leachi). Our data also show that the invasive species E. nuttallii supports similar richness and density of invertebrates as the native macrophyte M. spicatum. Overall, our findings indicate a positive effect of E. nuttallii on the richness and density of invertebrates in the studied urban lakes. Future studies should analyze how the structural complexity of macrophytes can be managed in urban water bodies to improve macroinvertebrate diversity. [ABSTRACT FROM AUTHOR]

Climate change and intensified human activities have disrupted the natural hydrological regime and rhythm of river-connected lakes, extending the dry season, increasing water loss, and exposing previously submerged lake floors. This exposure has led to significant sediment hardening, which directly impacts submerged macrophytes. However, strategies to mitigate the negative effects of hardened sediments and promote the growth and development of submerged macrophytes remain largely unexplored. In this study, we selected typical hardened sediment from Dongting Lake to investigate the response of different growth forms of submerged macrophytes to multiple sediment remediation measures (loosening and litter addition) using a mesocosm experiment. The results indicated that loosening alone uniformly benefited all submerged macrophytes by increasing total biomass, relative growth rate (RGR), and the root/shoot ratio. Additionally, loosening altered the root traits of submerged macrophytes, promoting maximum root length (MRL) while reducing average root diameter (ARD). Moreover, different submerged macrophytes exhibited species-specific responses to the combination of loosening and litter addition. Notably, the combination of loosening and adding Miscanthus lutarioriparius litter had an antagonistic effect on the growth of Potamogeton wrightii and Myriophyllum spicatum. The response of functional traits of submerged macrophytes with similar growth forms to the same treatment was consistent. Our findings suggest that future sediment remediation efforts should consider matching specific treatments with the growth forms of submerged macrophytes to achieve optimal outcomes. [ABSTRACT FROM AUTHOR]

Efforts to prevent the spread of aquatic invasive species (AIS) have been widely implemented to mitigate economic and environmental harms. Boater education, watercraft inspection, and hot water decontamination are popular strategies for preventing AIS spread through recreational boating. However, few studies have quantified the effectiveness of these strategies under field conditions. We estimated the effectiveness of AIS preventions based on the performances of boaters, watercraft inspectors, and hot water decontaminators. Participants (n = 144) were recruited at public water access sites in Minnesota (n = 56) and Wisconsin (n = 1). Each participant was asked to inspect and remove AIS from a boat consistently staged with macrophytes in the same six locations, adult zebra mussels in two locations, spiny water flea in one location, and residual water in one location. The types and amounts of AIS removed were used to estimate the effectiveness of each prevention method. We observed that removal rates varied by type of AIS and location – the locations with macrophytes were most commonly removed by all participant types. There were also regional (within or outside of the Minneapolis/Saint Paul metro area) differences for some species, such as spiny water flea, perhaps due to regionally specific outreach campaigns. Hot water decontamination had the highest percentage of intervention effectiveness (mean = 84.4%), but was not significantly better than watercraft inspection (mean = 79.2%). Our results suggest boaters are less effective (mean = 56.4%) at removing AIS than both trained professional groups in this study, but nevertheless play an important role in AIS prevention. Furthermore, we identified areas of the boat that were often overlooked (e.g., winch, bow line, transducer) by boaters and could be incorporated into future outreach campaigns. We observed high variability in the actions (i.e., time spent, places looked, methods used) taken among individuals from each participant group, revealing opportunities for standardizing outreach and professional training to maximize effectiveness. This was particularly evident among decontaminators, who often made risk-based decisions to modify the protocol and relied on equipment that often failed to reach minimum temperature thresholds for lethal exposure. This study can better inform AIS managers as they weigh the cost-benefit of each prevention strategy to meet their management objectives. [ABSTRACT FROM AUTHOR]

The recovery of submerged macrophytes is crucial for lake restoration. However, Myriophyllum spicatum usually shows an overgrowth and inhibits the growth of Vallisneria denseserrulata via light shading in many restored shallow lakes after the plant transplantation. So far, harvesting M. spicatum is the primary method to alleviate these shading effects in post-restoration lakes. Nevertheless, the effects of harvesting on the growth of V. denseserrulata and water quality are poorly elaborated. In this study, we conducted a mesocosm experiment, including both monoculture and polyculture groups, to investigate the response of V. denseserrulata growth, light climate, and nutrient concentrations in the water with M. spicatum harvesting. Moreover, the growth and morphology of M. spicatum were also examined. We hypothesized that M. spicatum harvesting would enhance the growth of V. denseserrulata and improve both the light climate and water quality. Our results showed that harvesting M. spicatum in the polyculture mesocosms substantially enhanced the relative growth rate (RGR) of V. denseserrulata compared to the non-harvesting controls. Moreover, harvesting M. spicatum reduced the light attenuation coefficient at 30 cm depth; however, the concentrations of chlorophyll-a, total nitrogen, and total phosphorus did not change significantly. As for M. spicatum, harvesting inhibited the growth of main stem and root but did not significantly affect the cumulative weight and RGR of M. spicatum. In contrast, the presence of V. denseserrulata decreased cumulative weight and RGR while promoting the root parameters of M. spicatum. Our findings imply that harvesting overgrowth nuisance submerged macrophyte species (e.g., M. spicatum) can improve the light climate and reduce its root growth, thereby enhancing the growth of target macrophyte species like V. denseserrulata without changes in the water quality which provides valuable insights for post-restoration lake management. [ABSTRACT FROM AUTHOR]

This study investigates the inhibitory and hormetic effects of Myriophyllum spicatum extract on Microcystis aeruginosa in a controlled, continuous culture environment. To address the global challenge posed by harmful algal blooms, we used a range of extract concentrations to delineate the growth response patterns. At very low concentrations (6.25 and 12.5 mg/L), the addition of M. spicatum extract shows no discernible reduction in M. aeruginosa cell density or growth rate; instead, a slight increase is observed during exposure, suggesting a hormetic effect. However, at higher concentrations (75 and 100 mg/L), there is a drastic reduction of more than 50% in cell density and growth rate at 75 mg/L, with complete inhibition at 100 mg/L, leading to pronounced oxidative stress, damage to antioxidant defense systems, and increased cell mortality. Increased levels of malondialdehyde, catalase, and superoxide dismutase activities indicate the involvement of these enzymes in combating oxidative stress. Furthermore, intracellular and extracellular microcystins were significantly decreased at higher extract concentrations (50, 75, and 100 mg/L) in a dose-dependent manner. Our results indicate a dose-dependent response and provide insight into the potential application of natural water treatment solutions. Implications for ecological management and future research directions are discussed. [ABSTRACT FROM AUTHOR]

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Introduction: Freshwater ecosystems are susceptible to invasion by alien macrophytes due to their connectivity and various plant dispersal vectors. These ecosystems often experience anthropogenic nutrient enrichment, favouring invasive species that efficiently exploit these resources. Propagule pressure (reflecting the quantity of introduced individuals) and habitat invasibility are key determinants of invasion success. Moreover, the enemy release hypothesis predicts that escape from natural enemies, such as herbivores, allows alien species to invest more resources to growth and reproduction rather than defense, enhancing their invasive potential. Yet, the combined impact of propagule pressure, herbivory, and nutrient enrichment on the competitive dynamics between invasive alien macrophytes and native macrophyte communities is not well understood due to a paucity of studies. Methods: We conducted a full factorial mesocosm experiment to explore the individual and combined effects of herbivory, nutrient levels, propagule pressure, and competition on the invasion success of the alien macrophyte Myriophyllum aquaticum into a nativemacrophyte community comprising Vallisneria natans, Hydrilla verticillata, and Myriophyllum spicatum. This setup included varying M. aquaticum densities (low vs. high, simulating low and high propagule pressures), two levels of herbivory by the native snail Lymnaea stagnalis (herbivory vs no-herbivory), and two nutrient conditions (low vs. high). Myriophyllum aquaticum was also grown separately at both densities without competition from native macrophytes. Results: The invasive alien macrophyte M. aquaticum produced the highest shoot and total biomass when simultaneously subjected to conditions of high-density intraspecific competition, no herbivory, and low-nutrient availability treatments. Moreover, a high propagule pressure of M. aquaticum significantly reduced the growth of the native macrophyte community in nutrient-rich conditions, but this effect was not observed in nutrient-poor conditions. Discussion: These findings indicate that M. aquaticum has adaptive traits enabling it to flourish in the absence of herbivory (supporting the enemy release hypothesis) and in challenging environments such as intense intraspecific competition and low nutrient availability. Additionally, the findings demonstrate that when present in large numbers, M. aquaticum can significantly inhibit the growth of native macrophyte communities, particularly in nutrientrich environments. Consequently, reducing the propagule pressure of M. aquaticum could help control its spread and mitigate its ecological impact. Overall, these findings emphasize that the growth and impacts of invasive alien plants can vary across different habitat conditions and is shaped by the interplay of biotic and abiotic factors. [ABSTRACT FROM AUTHOR]

The invasive red swamp crayfish Procambarus clarkii (Girard, 1852) can affect freshwater ecosystems, their macrophyte communities in various ways. To examine the effects of red swamp crayfish on clearwater macrophyte-dominated lakes, we performed a 28-day mesocosm experiment, without and with presence of red swamp crayfish, with or without access to sediments using netting. All in the presence of one of the following three different submerged macrophytes: Myriophyllum spicatum L., Vallisneria denseserrulata (Makino) Makino, or Hydrilla verticillate (L.f.) Royle. This experimental design allowed a partial separation of the effects of disturbing the sediment using netting from other factors such as excretion and direct harm of the plants. Nutrients and total suspended solids concentrations were lower in the crayfish-with-net than in the crayfish-without-net treatments but had similar concentrations in the crayfish-with-net and crayfishless-without-net treatments. Compared to the crayfish-with-net treatment, there were more broken leaves in the crayfish-without-net treatments for V. denseserrulata and H. verticillata, while no difference was found for M. spicatum, likely reflecting their different growth forms. Our results suggest that the sediment disturbance by the crayfish was more important than their plant handling/consumption and nutrient excretion for an observed water quality change from clear to turbid. [ABSTRACT FROM AUTHOR]

Eutrophication due to nutrient addition can result in major alterations in aquatic ecosystem productivity. Foundation species, individually and interactively, whether present as invasive species or as instruments of ecosystem management and restoration, can have unwanted effects like stabilizing turbid eutrophic states. In this study, we used whole-pond experimental manipulations to investigate the impacts of disturbance by nutrient additions in the presence and absence of two foundation species: Dreissena polymorpha (a freshwater mussel) and Myriophyllum spicatum (a macrophyte). We tracked how nutrient additions to ponds changed the prokaryotic and eukaryotic communities, using 16S, 18S, and COI amplicon sequencing. The nutrient disturbance and foundation species imposed strong selection on the prokaryotic communities, but not on the microbial eukaryotic communities. The prokaryotic communities changed increasingly over time as the nutrient disturbance intensified. Postdisturbance, the foundation species stabilized the prokaryotic communities as observed by the reduced rate of change in community composition. Our analysis suggests that prokaryotic community change contributed both directly and indirectly to major changes in ecosystem properties, including pH and dissolved oxygen. Our work shows that nutrient disturbance and foundation species strongly affect the prokaryotic community composition and stability, and that the presence of foundation species can, in some cases, promote the emergence and persistence of a turbid eutrophic ecosystem state. [ABSTRACT FROM AUTHOR]

The deterioration of water quality caused by human activities has triggered significant impacts on aquatic ecosystems. Submerged macrophytes play an important role in freshwater ecosystem restoration. Understanding the relative contributions of the sources and environment to the adaptive strategies of submerged macrophytes is crucial for freshwater restoration and protection. In this study, the perennial submerged macrophyte Myriophyllum spicatum was chosen as the experimental material due to its high adaptability to a variable environment. Through conducting reciprocal transplant experiments in two different artificial environments (oligotrophic and eutrophic), combined with trait network and redundancy analysis, the characteristics of the plant functional traits were examined. Furthermore, the adaptive strategies of M. spicatum to the environment were analyzed. The results revealed that the plant source mainly influenced the operational pattern among the traits, and the phenotypic traits were significantly affected by environmental factors. The plants cultured in high-nutrient water exhibited a higher plant height, longer leaves, and more branches and leaves. However, their physiological functions were not significantly affected by the environment. Therefore, the adaptation strategy of M. spicatum to the environment mainly relies on its phenotypic plasticity to ensure the moderate acquisition of resources in the environment, thereby ensuring the stable and efficient operation of plant physiological traits. The results not only offered compelling evidence on the adaptation strategies of M. spicatum in variable environments but also provided theoretical support for the conservation of biodiversity and sustainable development. [ABSTRACT FROM AUTHOR]

The Albufera of Valencia, a Mediterranean coastal lagoon, has been in a turbid state since 1974, with only four episodes of temporary water transparency in spring. Despite its average depth of 1 m and oligohaline waters, excessive turbidity, fish grazing, and toxic compounds have inhibited submerged macrophyte growth. In spring 2018, a significant area of Myriophyllum spicatum emerged and exhibited significant density until its complete disappearance in August 2018. Using Sentinel-2 and Landsat-8 imagery, we monitored water quality variables and vegetation density during these months. Our study revealed the first unique occurrence of M. spicatum in more than 40 years. A period of increased transparency from summer 2017 compared to previous years seems to be the cause of this appearance, while high summer temperatures caused its disappearance. While improving water quality may help restore submerged macrophyte meadows, our results suggest that summer maximum temperatures may inhibit recovery. Remote sensing, particularly the NDVI index, proved successful in monitoring aquatic vegetation and understanding species-environment relationships. This methodology can enhance future monitoring efforts for macrophyte colonization and expand knowledge of their occurrence and causes of disappearance in this and other similar areas. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the effects of sediment types and planting density on the functional traits, growth and community stability of submerged plants, particularly Myriophyllum spicatum. An indoor cultivation experiment was conducted, where different planting densities (1 plant/pot, 10 plants/pot) and sediment types (mud, upper sand + lower mud, sand, upper mud + lower sand) were evaluated for their impact on the species. The findings are as follows: (1) Both sediment types and planting density had significant effects on the morphological characteristics and biomass of M. spicatum; (2) Morphological characteristics: the growth of M. spicatum displayed superior results in all low-density planting conditions compared to high-density; (3) Biomass: planting density had limited impact on biomass allocation patterns within the same sediment type; however, there was a significantly higher in areas with sediment heterogeneity compared to homogeneity. The high morphological plasticity of M. spicatum enables it to adapt to heterogeneous habitats, which likely contribute to its importance as a pioneer species in water restoration projects. These results provide valuable insights for the technical research and development of screening, expansion, colonization and construction, as well as the regulation and management of submerged plant. Moreover, they offer technical support for aquatic ecosystem restoration engineering. [ABSTRACT FROM AUTHOR]

The biogenic synthesis of copper oxide nanoparticles was explored using the Myriophyllum spicatum plant through a process involving co-precipitation and was utilized as an effective photocatalyst for the reduction of Cr(VI) and Pb(II) ions in an aqueous solution. The plant-mediated CuO nanoparticles were characterized using microscopic techniques (TEM and SEM), FT-IR, and XRD analyses. The amount of the reduced metal ions was determined by UV–visible and Atomic Absorption (AA) spectrophotometers. The analyses of the functional group present in the leaf extract revealed the type of bioactive molecules that were involved in the formation of copper oxide nanoparticles. The nanoparticles were used in the photo-enhanced reduction of hexavalent Cr and divalent Pb ions, and the impact of solution pH, initial metal concentrations, and photocatalyst dosage was investigated to establish the optimal performance of the CuO nanoparticles. Results revealed a direct association between the reduction of metal ions and catalyst dosage in both cases. A maximum percentage reduction of 89.2% and 79.1% was achieved for Cr(VI) and Pb(II), respectively, using 3 g of the CuO nanoparticles. This confirms that the CuO nanoparticles exhibited higher efficiency for Cr(VI) reduction as compared to Pb(II) reduction and indicates that CuO nanoparticles are a promising photocatalyst that is capable of reducing these metal ions into less toxic products. [ABSTRACT FROM AUTHOR]

Ammonium toxicity in macrophytes reduces growth and development due to a disrupted metabolism and high carbon requirements for internal ammonium detoxification. To provide more molecular support for ammonium detoxification in the above-ground and below-ground parts of Myriophyllum spicatum, we separated (using hermetic bags) the aqueous medium surrounding the below-ground from that surrounding the above-ground and explored the genes in these two regions. The results showed an upregulation of asparagine synthetase genes under high ammonium concentrations. Furthermore, the transcriptional down and/or upregulation of other genes involved in nitrogen metabolism, including glutamate dehydrogenase, ammonium transporter, and aspartate aminotransferase in above-ground and below-ground parts were crucial for ammonium homeostasis under high ammonium concentrations. The results suggest that, apart from the primary pathway and alternative pathway, the asparagine metabolic pathway plays a crucial role in ammonium detoxification in macrophytes. Therefore, the complex genetic regulatory network in M. spicatum contributes to its ammonium tolerance, and the above-ground part is the most important in ammonium detoxification. Nevertheless, there is a need to incorporate an open-field experimental setup for a conclusive picture of nitrogen dynamics, toxicity, and the molecular response of M. spicatum in the natural environment. [ABSTRACT FROM AUTHOR]

In alpine Lake Bohinj, which is an LTER site and a part of the national park, the occurrence and depth distribution of submerged and emerged aquatic macrophytes were analyzed. Nine submerged and one emergent macrophyte taxa were found in the lake: Myriophyllum spicatum, Chara virgata, Chara aspera, Potamogeton lucens, Potamogeton alpinus, Potamogeton crispus, Potamogeton perfoliatus, Potamogeton pusillus, Ranunculus circinatus with the synonym Batrachium foeniculaceum and the emergent species Phragmites australis. The depth of the vegetation zones was measured using a depth meter and their coordinates were recorded using a GNSS antenna with RTK receiver. These data were used along with a DEM of lake depths to accurately map the potential zone of macrophyte growth, which was based on the depths of macrophyte distribution. The potential zone of macrophyte growth consisted of 28 different transects and covered 240.14 ha of the lake. The macrophytes covered 5.55 ha. The most common and abundant species was M. spicatum. A significant difference in macrophyte cover was found between the south and north shores of the lake, with the south shore having more patches with a larger total area. A clear difference in macrophyte cover was also noted between the main inflow and outflow of the lake. The presence of macrophytes and their diversity varied in different parts of the lake due to differences in slope, depth and type of substrates. [ABSTRACT FROM AUTHOR]

The bioturbation effect of the typical zoobenthos freshwater worm Limnodrilus hoffmeisteri on the allelopathic cyanobacterial inhibition of the submerged macrophyte Myriophyllum spicatum was investigated. Different worm densities induced different stress responses and affected the allelopathic profile of M. spicatum. Coculture of L. hoffmeisteri and M. spicatum initially led to increases in the turbidity of the water column and in total nitrogen, total phosphorus, and NH4+-N contents. After 14 days of coculture, the growth and photosynthesis rate in M. spicatum significantly decreased compared with the control. The bioturbation effect of L. hoffmeisteri on cyanobacterial inhibition and the concentration of allelochemicals in M. spicatum also depended on the duration of coculture and worm density. Analysis of the culture filtrate obtained a various time points (7–28 days) after initiating coculture of the worm and macrophyte revealed that the inhibitory rates followed the order of worm density of medium density > high density > low density > control. The cyanobacterial inhibitory effects of the tissue extracts varied according to coculture duration among the four treatments, with the medium density treatment having the greatest inhibitory effects after coculture for 14 days. In addition, the concentrations of three allelochemicals, namely, palmitic acid, stearic acid, and cis-9-octadecenoic acid, in the culture filtrates or in M. spicatum tissue extracts were affected by L. hoffmeisteri, where the effects depended on worm density and length of coculture time. Among the four treatments, the contents of the individual allelochemicals were highest in the medium density treatment and the contents increased with increasing coculture time. Moderate stress under a medium worm density after coculture for 14–21 days significantly enhanced the cyanobacterial suppression of M. spicatum and allelochemical production. These results suggest that restoring M. spicatum and L. hoffmeisteri to a reasonable ratio could facilitate cyanobacterial control in eutrophic water bodies. [ABSTRACT FROM AUTHOR]

Macrophytes are one of the important indicators used in assessing the anthropic impact on aquatic ecosystems. The structure of macrophyte communities of two rivers were compared by species composition, dominant species and projective cover using statistical methods. It is shown that the influence of storm runoff on these rivers is manifested in the form of a change in the dominant species composition. Based on the statistical analysis carried out, it can be argued that, despite the peculiarities of the flora composition of each of the rivers, the influence of storm runoffs largely neutralizes this specificity, determining the situation in local areas immediately below the runoff. In the area of the effluent discharge the dominance of individual species and an increase in the area overgrown with macrophytes was observed. In the area of stormwater discharge on the Psel River, species were usually present: Nuphar lutea, Ceratophyllum demersum, Myriophyllum spicatum and on the Bystrica River--Glyceria maxima, Sagitaria sagittiformis, Stuckenia pectinata and Potamogeton crispus. The use of the NMDS method has been found to provide good insight into the structural rearrangements in macrophyte communities affected by runoff from stormwater systems. [ABSTRACT FROM AUTHOR]

Outbreaks of Microcystis blooms can affect growth of submerged plants, which in turn can inhibit cyanobacterial growth. Microcystin (MC)-producing and non-MC-producing Microcystis strains typically coexist in Microcystis-dominated blooms. However, the interaction between submerged plants and Microcystis at strain level is not clear. This study was aimed at assessing the effects of a submerged macrophyte Myriophyllum spicatum on one MC-producing versus one non-MC-producing strains of the cyanobacterium Microcystis using plant-Microcystis co-culture experiments. The impacts of Microcystis on M. spicatum were also examined. It showed that the MC-producing Microcystis strain had a higher resistance to negative impacts by the cocultured submerged plant M. spicatum than the non-MC-producing strain. By contrast, the plant M. spicatum was impacted more by the MC-producing Microcystis than the non-MC-producer. The associated bacterioplankton community was affected more by the MC-producing Microcystis than the cocultured M. spicatum. The MC cell quotas were significantly higher in the coculture treatment (the PM + treatment, p < 0.05), indicating that the production and release of MCs might be a key factor responsible for the reduced impact of M. spicatum. The higher concentrations of dissolved organic and reducing inorganic compounds might eventually exacerbate the recovering capacity of coexisting submerged plants. Overall, this study indicated that the capacity to produce MCs, as well as the density of Microcystis, should be taken into account when attempting to reestablish submerged vegetation to undertake remediation works. [ABSTRACT FROM AUTHOR]

Accelerated lakes eutrophication is one of the greatest challenges nowadays. To counteract its negative effects, large-scale restoration treatments are carried out worldwide. However, research in this field is mainly focused on the process effectiveness and there is a scarcity of studies concerning the impact of restoration treatments on water organisms and ecosystem homeostatsis. Our microcosm study presents the effects of a phosphorus coagulant (iron [III] chloride) on functional traits changes, oxidative stress and macro- and microelement stoichiometry disturbances in macrophyte Myriophyllum spicatum, a model species inhabiting eutrophic waters. Application of the coagulant to experimental vessels influenced the physicochemical and optical parameters of water and led to significant changes in biogeochemistry. Stoichiometric alterations were reflected by disturbances in the relative contents of macro- (C, N, P, Ca, Mg) and microelements (Fe, Zn, Cu, Co) and induced luxury consumption of available ions. Physicochemical and stoichiometric changes mutually exerted negative influence on M. spicatum functional traits. The parameters of oxidative stress remained at low levels, comparable to the untreated control whereas stoichiometric analysis revealed the activation of mechanisms responsible for minimizing low light stress. The ability of M. spicatum to maintain homeostasis of Cu and Co under simulated chemical water restoration was closely related to high concentrations of Fe and Zn ions, which simultaneously were not subjected to homeostasis control. Thus, chemical lake restoration treatments based on phosphorus coagulants are not as environmentally safe as previously considered and may have far-reaching consequences for the biogeochemical cycle and food web functioning. [ABSTRACT FROM AUTHOR]

Background: Flavonoid natural dyes have gained attention because they are nontoxic and eco-friendly. However, they do not work effectively with artificial fibers and require the use of mordants, which are considered as hazardous chemicals. Laccase enzyme catalyzes the oxidation of phenols, forming phenoxyl radicals that undergo a further polymerization process. So, laccase can oxidize flavonoid dyes, and it can be used instead of harmful mordants in flavonoid dye fixation on cotton fabrics. Laccases also are involved in a variety of metabolic processes, and they have anti-proliferative effects toward HepG2 and MCF-7 tumor cells. Results: Among fifteen fungal isolates, the fungus Ceratorhiza hydrophila isolated from the submerged plant Myriophyllum spicatum was selected as the most potent laccase producer. Optimization of the production medium resulted in a 9.9-fold increase in laccase productivity. The partially purified Ceratorhiza hydrophila laccase could successfully improve the affinity of cotton fabrics toward quercetin (flavonoid) dye with excellent color fastness properties. The partially purified laccase also showed anti-proliferative activity against HepG2 and MCF-7 tumor cells. However, high laccase concentration is required to estimate IC50. Conclusions: Ceratorhiza hydrophila MK387081 is an excellent laccase producer. The partially purified laccase from Ceratorhiza hydrophila can be used in textile dyeing and printing processes as a safer alternative to the conventional hazardous mordants. Also, it can be used in preparation of cancer treatment drugs. However, further studies are needed to investigate IC50 for both cell types at higher laccase concentrations. [ABSTRACT FROM AUTHOR]

Background: Resource translocation among interconnected ramets can improve the growth performance of the recipient ramets and influence soil properties and microbial communities in the rooting zone. However, scanty attention has been paid to the effect of this clonal integration on soil biotic and abiotic characteristics of neighboring species around the recipient ramets. Methods: We conducted a soil heterogeneous experiment in which the mother ramet of the ramet pair for Vallisneria natans was planted in a high-nutrient patch, and the daughter ramet was planted in a low-nutrient patch with conspecific neighbors V. natans or heterospecific neighbors Myriophyllum spicatum. The stolons between ramet pairs were severed or left intact. Results: Our results showed that effects of clonal integration on growth of the daughter ramet depend on the identity of neighboring species. Overall growth of neighbors V. natans was not affected by clonal integration, while growth of neighbors M. spicatum was greatly reduced. Soil properties and microbial community composition (especially bacteria) in the rhizosphere of neighboring plants were significantly influenced by clonal integration, and these effects were more obvious in the rhizosphere of neighbor V. natans than those in the rhizosphere of neighbors M. spicatum. Conclusion: Our study suggests that clonal integration may play a vital role in facilitating nutrient cycling, modifying habitat heterogeneity and affecting interspecific interactions and even the community structure. [ABSTRACT FROM AUTHOR]

This research aimed to verify the identification and distribution of Myriophyllum sibiricum in Lithuania. The study was based on a revision of available herbarium specimens and information from archival materials and literature sources. A total of 134 herbarium specimens of Myriophyllum, mainly initially identified as Myriophyllum spicatum, were examined. After revision of herbarium specimens, 101 of these were identified as Myriophyllum sibiricum. The remaining 33 herbarium specimens were tentatively determined as hybrids Myriophyllum sibiricum × Myriophyllum spicatum. None of the specimens were identified as Myriophyllum spicatum. The distribution of Myriophyllum sibiricum is related mainly to standing waters of upland regions, while localities of putative hybrid scattered throughout the area and associated with upland lakes and river stretches. The morphological features of the leaves (number of segments pairs and its angle with the central axis, occurrence of glands at the base of young leaves and in axils of leaves segments) are helpful to distinguish typical specimens of Myriophyllum sibiricum from Myriophyllum spicatum, however useless for their separation from the hybrid. This study revealed that further research on Myriophyllum sibiricum, Myriophyllum spicatum and their putative hybrid must apply morphological and molecular methods. [ABSTRACT FROM AUTHOR]

We examined the response of Eurasian watermilfoil (Myriophyllum spicatum) coverage on Manistee Lake, Michigan (U.S.A.) in the presence of milfoil weevils (Euhrychiopsis lecontei). Among 150 sites, milfoil presence declined from 2008 levels of 34 (23%) sites to 2 (1%) sites by 2015 coincident with cumulative stocking of 259,500 weevils from 2007 to 2014. Severe winter temperatures also were associated with milfoil declines. Each 1°C decline in average low temperature during the preceding winter was associated with 3.4 (95% CI 0.8–6.1) fewer sites with milfoil. Impacts of weevil herbivory on watermilfoil may be accentuated by severe winter temperatures. Lake managers should, when possible, integrate weather conditions with weevil stocking regimes to control Eurasian watermilfoil. [ABSTRACT FROM AUTHOR]

Disturbance regimes related to water level fluctuation play an important role in the structuring of aquatic macrophyte communities. In managed systems, winter water level drawdowns have shown promise in controlling populations of nuisance macrophytes, however, drawdowns may have unintended negative consequences on erosion, fauna, and non-target plant species. The Chippewa Flowage, located in Sawyer County, WI, has implemented targeted winter water level drawdowns with the goal of reducing nuisance levels of Myriophyllum spicatum. To evaluate the effects of water level drawdowns on Myriophyllum spicatum and the native macrophyte community, we conducted repeated full lake surveys of aquatic macrophytes at 2018 points under drawdown and normal water level management in 2005/06, 2015, and 2017. We supplemented these efforts with downscaled surveys in 2007, 2010, and 2016. Surveys revealed a statistically significant decline in both Myriophyllum spicatum occurrence and abundance, and average macrophyte abundance during active drawdown management. Kernel distributions of change in point-specific c-value between the two time periods showed a significant increase under drawdown conditions, and a decrease under normal management (D = 0.41, P ≤0.0001). Drawdown management appeared to successfully control Myriophyllum spicatum abundance and allowed for improvements in the floristic quality of the macrophyte community but resulted in reduced macrophyte abundance overall. [ABSTRACT FROM AUTHOR]

Cultural eutrophication is the main cause of the decline of submerged plants in freshwater ecosystems. While many studies have focused on the nutrient uptake by the roots of these plants, less attention has been given to the effects of eutrophication on root structure. We designed a mesocosm experiment with Eurasian watermilfoil (Myriophyllum spicatum), a submerged plant indigenous to the Eurasian continent. The responses of plant functional traits, including growth traits, morphological traits and root topological indices, to different nitrogen (N) and phosphorus (P) concentrations were elucidated. We found that high P concentrations suppressed all the morphological traits and reduced the root topological traits, whereas N concentrations had a comparatively minor effect. Although the root branching of M. spicatum did not change, its root topology became more dichotomous with fewer exterior root links being formed in nutrient-rich habitats, and the root form changed from deep and thin to shallow and dense with increasing P concentrations. The root nutrient absorption ability of M. spicatum may decrease with cultural eutrophication, and this change most likely reduces its anchoring ability and increases its sensitivity to dislodge from the sediment if disturbed by hydraulic forces. • The responses of plant traits of Myriophyllum spicatum to different nutrient concentrations were studied. • M. spicatum did not change its root architecture with increasing P concentrations. • Nutrient addition may reduce the anchoring ability of M. spicatum. [ABSTRACT FROM AUTHOR]

To address the issues of submerged vegetation restoration in the deep-water area of Baiyangdian Lake, a type of suspended ecological bed was developed, which was constructed with aquatic plants, ropes and supporting poles. The depth of a suspended ecological bed could be adjusted based on the water level. From July to November 2019, the phytoplankton community structure in the water around the suspended beds was continually monitored, and the effects of the submerged plants present in the suspended beds on the phytoplankton community structure in the deep-water area of the lake were studied. The results showed that Myriophyllum spicatum L. grew well in the suspended beds, with 95% survival after 60 d. The maximum biomass was reached in 55 d, and the water surface coverage reached 23%. There were 71 species of phytoplankton belonging to seven phyla in the water surrounding the suspended ecological beds. Over half (36 species) were members of Prochlorophyta, and the average density and biomass of phytoplankton gradually decreased month by month. The proportion of cyanobacteria in the community showed a downwards trend, while the proportions of other phytoplankton phyla showed upwards trends. The annual average Shannon–Wiener diversity index was 0.88, the annual average Pielou evenness index was 0.32, and the annual average Margalef richness index was 1.21. The Shannon–Wiener diversity index and Pielou's evenness index both showed increasing trends. This comprehensive analysis shows that planting submerged plants in suspended beds can improve the phytoplankton community structure of the surrounding water and increase the biodiversity of phytoplankton, making this an effective measure for restoring submerged vegetation in algae-dominated northern lakes. [ABSTRACT FROM AUTHOR]

Eurasian watermilfoil (Myriophyllum spicatum) is an invasive submersed macrophyte that has infested many waters in North America since its introduction. Eurasian watermilfoil has the ability to alter the structure and function of the ecosystems that it invades. Eurasian watermilfoil was first surveyed in the Clark Fork River, MT in 2008, alongside the native northern watermilfoil (Myriophyllum sibiricum). Three reservoirs (Cabinet Gorge, Noxon Rapids and Thompson Falls) on the lower Clark Fork River had entire lake surveys conducted using the point intercept method. Morphological data from these surveys showed that only Eurasian watermilfoil and northern watermilfoil were present during the time of the surveys in 2008. The results of the morphological identification were supported by molecular identification at three different laboratories. In 2015, a genetic survey of watermilfoil species was conducted on the Noxon Rapids Reservoir and found that hybrid watermilfoil (Myriophyllum spicatum × sibiricum) was present. This hybridization event poses a number of issues for aquatic plant management. Hybrid watermilfoil is much more difficult to identify morphologically than its parent types. The hybrid is also more invasive and may be differentially susceptible to some herbicides than the parental type Eurasian watermilfoil.

Epiphytic bacteria develop complex interactions with their host macrophytes and play an important role in the ecological processes in freshwater habitats. However, how dominant and rare taxa respond to elevated atmospheric CO2 remains unclear. A manipulated experiment was carried out to explore the effects of elevated CO2 on the diversity or functional characteristics of leaf epiphytic dominant and rare bacteria from a submerged macrophyte. Three levels (high, medium, normal) of dissolved inorganic carbon (DIC) were applied to the overlying water. The physicochemical properties of the overlying water were measured. Elevated atmospheric CO2 significantly decreased the pH and dissolved oxygen (DO) of overlying water. Proteobacteria, Cyanobacteria, Bacteroidetes, Planctomycetes, and Actinobacteria are the dominant phyla of leaf epiphytic bacteria from Myriophyllum spicatum, occupying over 90% of the accumulated relative abundances. The aquatic DIC level and further pH significantly drove the epiphytic community composition differences among the three DIC levels. For dominant epiphytic bacteria, the functional potential of nutrient processes and mutualistic relationships were strongly affected by a high DIC level, while responses of rare epiphytic bacteria were more related to trace element processes, pathogens, and defense strategies under a high DIC level. Our results showed the responses of epiphytic bacteria to elevated CO2 varied across dominant and rare taxa. [ABSTRACT FROM AUTHOR]

The synergy between climate change, eutrophication, and biological invasion is threatening for native submerged plants in many ways. The response of submerged plants to these changes is a key factor that determines the outcome of biological invasion. In order to explain the invasion successes, we investigated the combined effects of climate change and eutrophication‐related environmental factors (temperature, light, and nutrients) on the trait responses of a native (Myriophyllum spicatum) and an alien (Cabomba caroliniana) submerged species. In a factorial design, we cultivated the two species in aquaria containing low (0.5 mg N L−1, 0.05 mg P L−1) and high (2 mg N L−1, 0.2 mg P L−1) nutrient concentrations, incubated at four light intensities (average 25, 67, 230, and 295 μmol m−2 s−1 PAR photon flux density) under two temperature levels (21.5 and 27.5 ± 0.5°C). We used four invasion‐related functional traits (relative growth rate (RGR), specific leaf area (SLA), leaf dry matter content (LDMC), and nitrogen to carbon ratio (N:C molar ratio)) to measure the environmental response of the species. We calculated plasticity indexes to express the trait differences between species. Cabomba caroliniana showed significantly higher RGR and SLA than M. spicatum especially under low light intensity indicating that Cabomba is much more shade tolerant. Elevated temperature resulted in higher SLA and reduced LDMC for C. caroliniana indicating that Cabomba may have higher invasion success. Myriophyllum showed higher LDMC than C. caroliniana. Chemical analyses of the plant tissue revealed that although M. spicatum showed significantly higher N:C molar ratio, nonetheless, the daily nitrogen uptake of C. caroliniana was more than three times faster than that of M. spicatum. Results supported the idea that due to its higher shade tolerance and nitrogen uptake capacity, Cabomba likely has greater invasion success with increasing temperature combined with low light levels. [ABSTRACT FROM AUTHOR]

To explore how decomposed Microcystis-dominant cyanobacterial blooms affect submerged macrophytes, the submerged plant Myriophyllum spicatum was exposed to cell extracts from microcystin (MC)- and non-MC-producing Microcystis strains in a laboratory experiment. Results showed that both Microcystis cell extracts exerted obvious damages to plant biomass, photosynthesis, primary and secondary metabolism measures, and resistance of plant antioxidant systems, with MC-producing Microcystis having stronger effects due to the presence of MCs. Cyanotoxins other than MCs responsible for the negative effects from both Microcystis strains needs further identification. The Shannon diversity and Chao1 indices of epiphytic and planktonic bacteria were decreased by the cell extracts from both Microcystis strains. However, epiphytic and planktonic bacterial communities responded differently to Microcystis cell extracts at the genus level. The dominant genera of planktonic bacteria including Enterobacter, Pseudomonas, and Novosphingobium from phylum Proteobacteria, Chryseobacterium from phylum Bacteroidetes, and Microbacterium from Actinobacteriota in the treatments with cell extracts were previously reported to have strains with algicidal and MC-degrading capabilities. Bacterial genes associated with energy production and conversion, amino acid transport and metabolism, and inorganic ion transport and metabolism, were more abundant in both treatments than the control for planktonic bacteria, but less abundant for epiphytic bacteria. We speculate that planktonic bacterial communities have the potential to use and degrade substances derived from Microcystis cell extracts, which may be beneficial for M. spicatum to alleviate damages from Microcystis. Further research is needed to verify the structure and function dynamics of epiphytic and planktonic bacteria in the interaction between cyanobacteria and submerged macrophytes. [ABSTRACT FROM AUTHOR]

Considering the vital role of rooted macrophytes in the aquatic ecosystem, validating assumptions on the interactive effects of herbicides with different modes of action at an environmentally relevant mixture ratio is necessary. We investigated the effects of diflufenican (a carotenoid biosynthesis inhibitor) and iodosulfuron‐methyl‐sodium (IMS; an acetolactate synthase inhibitor) in a 14‐day growth inhibition experiment with Myriophyllum spicatum, wherein single compounds and their combination were tested in parallel (n = 84). The assessment was done using three different methods: significance testing, model deviation ratio (MDR), and mixture interaction factor (MIF). Interactions relative to both concentration addition and independent action were assessed via significance testing. This revealed that diflufenican and IMS acted antagonistically relative to both models for fresh weight and total shoot length (p < 0.05) and that there was slight synergism for the number of side shoots (p < 0.001) relative to concentration addition. The MDR and MIF can only assess interactions relative to the concentration addition model. According to MDR, the mixture appeared to show no interaction (neither antagonistic nor synergistic), whereas the MIF method revealed that the compounds acted antagonistically for fresh weight and that there was a slight synergism for total shoot length and number of side shoots. We conclude that inferences about mixture toxicity interactions are method‐ and endpoint‐dependent, which can have implications for regulatory mixtures assessment. Environ Toxicol Chem 2022;41:2209–2220. © 2022 SETAC [ABSTRACT FROM AUTHOR]

Myriophyllum spicatum, more commonly known as Eurasian watermilfoil (EWM), is one of the most invasive aquatic plants in North America, causing negative ecological and economic impacts in ecosystems where it proliferates. Many control strategies have been developed and implemented to mitigate EWM growth and spread, although the results are mixed and there is no consensus on lake‐specific strategies. Here, we describe the development of a predictive model using a support vector technique, that predicts the success of biological pest control using Euhrychiopsis lecontei (the milfoil weevil), a milfoil specialist, to reduce EWM in lakes. Such a model is informed by lake characteristics (limnological and landscape) and augmentation strategies. To develop our predictive model, we performed a metadata analysis from 133 published peer‐reviewed literature and professional reports of milfoil weevil augmentation field experiments that contained information on lake characteristics. The predictive model's algorithm uses a support vector machine (SMV) to learn patterns among lake characteristics, along with the recorded augmentation strategy and the reported success of each study, where success is a measure of EWM change over a season and is recorded in a variety of ways (e.g., EWM biomass change, EWM percent change, EWM visual change, etc.,). Overall, the model results suggests that shallower lakes, more frequent weevil augmentations, and larger weevil overwintering habitat are the most important predictors for EWM reduction success by weevil augmentation. Although watermilfoil weevil augmentation is a promising mitigation strategy, it may not work for all lakes. However, in terms of suggesting weevil augmentation, our model is a valuable tool for lake stakeholders and resource managers, who can use it to determine whether milfoil weevil augmentation, which can be very costly due to the difficulties in finding and raising milfoil weevils, will be a useful and sustainable approach to control EWM in their lake community. [ABSTRACT FROM AUTHOR]

Myriophyllum spicatum is a sediment‐rooted, aquatic macrophyte growing submerged, with a wide geographical distribution and high ecological relevance in freshwater ecosystems. It is used in testing and risk assessment for pesticides in water and sediment. Population models enable effects measured under laboratory conditions to be extrapolated to effects expected in the field with time‐variable environmental factors including exposure. These models are a promising tool in higher‐tier risk assessments. However, there is a lack of data on the seasonal dynamics of M. spicatum, which is needed to test model predictions of typical population dynamics in the field. To generate such data, a two‐year study was set up in outdoor experimental systems from May 2017 to May 2019. The growth of M. spicatum was monitored in 0.2025 m2 plant baskets installed in an experimental ditch. Parameters monitored included biomass (fresh weight [FW] and dry weight [DW]), shoot length, seasonal short‐term growth rates of shoots, relevant environmental parameters, and weather data. The results showed a clear seasonal pattern of biomass and shoot length and their variability. M. spicatum reached a maximum total shoot length (TSL) of 279 m m−2 and a maximum standing crop above‐ground DW of 262 g m−2. Periodical growth rates reached up to 0.072, 0.095, and 0.085 day−1 for total length, FW, and DW, respectively. Multivariate regression revealed that pH (as a surrogate for the availability of carbon species) and water temperature could explain a significant proportion of the variability in M. spicatum growth rates (p < 0.05). This study has provided an ecologically relevant data set on seasonal population dynamics representative of shallow freshwater ecosystems, which can be used to test and refine population models for use in chemical risk assessment and ecosystem management. Integr Environ Assess Manag 2022;18:1375–1386. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: This study has generated a time‐series of seasonal dynamics for the growth of M. spicatum over two years under environmental conditions found in temperate regions to be used to develop and test population models for Myriophyllum spicatum.Myriophyllum spicatum showed a clear seasonal pattern of biomass and shoot length and of their variability (increasing in summer and decreasing in winter).Multiple regression modeling revealed that water temperature and pH (the latter as surrogate for the available carbon species) explained a significant part of the variability in Myriophyllum growth rates (p‐values < 0.05).Over the first four experimental months in summer, exponential functions yielded a better fit for the growth of Myriophyllum spicatum than linear growth functions. [ABSTRACT FROM AUTHOR]

2,4-Dichlorophenoxyacetic acid (2,4-D) is commonly used to control invasive aquatic macrophytes, including Eurasian watermilfoil (Myriophyllum spicatum) (EWM). Potential influences of 2,4-D on non-target organisms are poorly understood; however, research has suggested the possibility of lethal effects on certain fish species. Lake Ellwood, Wisconsin was treated with 2,4-D to control EWM annually during 2003–2012. Fish surveys following treatment revealed natural recruitment failures of several regionally thriving species, including largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus). We hypothesized that these species had been negatively influenced by the chemical treatments. We monitored the post-chemical treatment fish community and aquatic ecosystem for responses during 2013–2019. Similar data were collected from Cosgrove (EWM absent) and Seidel lakes (EWM present, no chemical treatment) as reference systems. Limnological and submersed aquatic vegetation conditions did not change on Lake Ellwood post-chemical treatment. Total zooplankton density increased immediately post-chemical treatment on Lake Ellwood and then stabilized, whereas total zooplankton density did not change on the reference lakes over time. Analyses indicated immediate increases in recruitment post-chemical treatment for largemouth bass, smallmouth bass (Micropterus dolomieu), bluegill, and yellow perch (Perca flavescens). Back calculation of year class strength confirmed failures occurred during treatment for northern pike (Esox lucius), largemouth bass, bluegill, and black crappie (Pomoxis nigromaculatus). Our results provide evidence to suggest long-term 2,4-D treatments may negatively influence fish through lethal and sublethal mechanisms. Thus, there remains a critical need for directed research on whole-lake herbicide treatment side-effects. [ABSTRACT FROM AUTHOR]

The phase inversion technique was used to successfully immobilize a submerged aquatic plant called Myriophyllum spicatum L. onto hybrid polymeric beads of Polyacrylonitrile/Polyvinylpyrrolidone (PAN/PVP). The surface morphology of the fabricated beads exhibited a porous structure with a homogeneous morphology. While their thermogram demonstrated a positive impact of PVP incorporation. In this study, the fabricated hybrid beads were tested against Safranin O as a dye adsorption model. Thus, the various parameters affecting Safranin O dye uptake onto the synthesized beads, such as time of contact, initial Safranin O concentration, adsorbent dose, and pH have been investigated and optimized using statistical response surface methodology (RSM). The results revealed that within 4 h, the fabricated PAN/PVP-M. spicatum beads showed a maximum adsorption capacity towards Safranin O dye of up to 217 mg g−1 using 0.3 g of the fabricated beads. The adsorption isotherm results were also fit to the Langmuir, Freundlich, and Temkin models, with the Langmuir model performing the best. The kinetic studies, on the other hand, obeyed the pseudo-second-order, and the fabricated PAN/PVP-M. spicatum beads showed appropriate reusability in the uptake of Safranin O dye from wastewater. Finally, the newly developed fabricated (PAN/PVP-M. spicatum) hybrid beads pave the way for the use of low-cost, efficient natural materials for wastewater treatment in the textile industry. [ABSTRACT FROM AUTHOR]

Ammonium (NH4-N) produces a paradoxical effect on submersed macrophytes because it is not only the preferred nitrogen source for the growth of plants but also threatens the growth of plants at high concentration. Whether short-term and smallscale physiological toxicity experiments at an individual level can reflect the effects of high ammonium on populations of submersed macrophytes in natural conditions is still unclear. In this study, an 18-month experiment was conducted in six 600 m2 ponds subjected to different levels of ammonium loading. The effects of high ammonium on populations of canopy-forming Myriophyllum spicatum and rosette-forming Vallisneria natans were explored. The results showed that M. spicatum and V. natans populations can develop high cover and height at high ammonium concentration (7 mg/L) at shortterm exposures, and V. natans may be tolerant to 18 mg/L ammonium concentration. However, the cover of M. spicatum and the height of both species were inhibited at 2.4 mg/L at long-term exposures. The height of M. spicatum was two to six times higher than that of V. natans across all treatments and control by the end of the experiment, and the cover of M. spicatum was 7-11 times higher than that of V. natans in most NH4-N loading treatments, except the cover of M. spicatum in the highest NH4-N loading treatment with 18 mg/L NH4-N. The rosette-forming V. natans resists ammonium stress by slow growth (shoot elongation) to reduce consumption, while canopy-forming species resist ammonium stress by shoot elongation and canopy development to capture light. Although increasing ammonium concentration may induce severe stress on M. spicatum, the morphological characteristics of this species may, to some extent, release the plants from this stress. Our present study indicates that the negative effects of ammonium stress on the development of populations increased with exposure duration, and the submersed macrophyte community with stronger ability for light capture and dispersal may resist high ammonium stress. Nevertheless, in strongly ammonium-enriched systems, competition and succession cannot be neglected. [ABSTRACT FROM AUTHOR]

Trait‐based methods are key to understanding the biodiversity–productivity relationship (BPR) of macrophyte communities. Community‐weighted mean traits (i.e., community trait structure) have been proven to have more influence on macrophyte community productivity than species richness. However, the underlying mechanism by which community trait structure variation affects macrophyte community productivity along an environmental gradient is still not well understood.A mesocosm experiment was used to investigate how community trait structure shapes macrophyte community productivity along the water depth gradient. Three submerged macrophyte species (Myriophyllum spicatum, Vallisneria natans and Potamogeton malaianus) were assembled into all possible combinations (one, two and three species per community) at three different water depths (1, 2.5 and 4 m). We fitted the relationships between community‐weighted mean traits and community productivity, and between species richness and community productivity as a comparison. We compared functional traits under different water depths and species composition at the species and community levels and disentangled the community trait structure into species turnover and intraspecific trait variability effects.The results showed that community trait structure had various influences on macrophyte community productivity, which was based on traits per se. However, species richness had a non‐significant impact on macrophyte community productivity. Water depth had a significant impact on most traits of the three species at the species level, whereas both water depth and species composition had significant impacts on community trait structure which was mainly affected by intraspecific trait variability along the water depth gradient.Our findings highlight the importance of considering intraspecific trait variability and species turnover under water depth gradients to understand the relationship between trait‐based biodiversity and productivity. [ABSTRACT FROM AUTHOR]

Freshwater resources are hotspot areas for sustainable water use. Surface sediment samples from four stations in Terme River were collected seasonally between April 2019 and January 2020. Sample collection from 0 to 10 cm depth of the riverbed was carried out with an Ekman Dredge Grab. Cu, Pb, Zn, Ni, Mn, Fe, Co, As, Cr, Cd, and Al concentrations were determined with an inductively coupled plasma-mass spectrometry (ICP-MS). The percentage of organic matter in the sediment was evaluated by the combustion method. pH measurements were made with a pH meter. The concentrations of elements measured are listed in descending order as follows: Fe > Al > Mn > Cr > Cu > Zn > Ni > Co > Pb > As > Cd. Enrichment factor (EF), contamination factor (CF), and geo-accumulation index (Igeo) are the most commonly used tools to determine whether elements are of natural origin or anthropogenic origin. According to average EF values, the metals are listed as follows: Cd > Cu > Co > Fe > Cr > Pb > Mn > Zn > Al > Ni > As. The CF and Igeo values are listed as follows: Cd > Cu > Co > Fe > Cr > Pb > Mn > Zn > Al > Ni > As. According to EF results, Cd and Cu originate from human activities. The CF and Igeo indicate minimal enrichment for all metals. Potential ecological risk (PERI), pollution load (PLI), modified hazard quotient (mHQ), ecological contamination (ECI), and toxic risk indices (TRI) indicate low risk in the region. Human health risk indices also show that carcinogenic and noncarcinogenic risks are low. In the bioaccumulation evaluation performed on Myriophyllum spicatum species, it was determined that the plant accumulated Mn, Co, Ni, Cu, Zn, As, and Cd. These results show that Myriophyllum spicatum can be used as a bioindicator. [ABSTRACT FROM AUTHOR]

Aquatic plants and algae are the primary producers in lake ecosystems, providing the organic matter and oxygen necessary for the nutrients and energy of most organisms. Climatic and environmental changes may have irreversible impacts on aquatic plants and algae communities, while direct observation and experiments can only provide a short-term perspective. As a record of the long-term variation of the ecosystem, sedimentary ancient DNA (sedaDNA) could offer evidence about aquatic plants and algae change over extended time scales and improve the taxonomic resolution than the traditional morphology methods such as pollen and macrofossil. In this study, we employed metagenomics in sedaDNA from Luanhaizi Lake (northeastern Tibetan Plateau) since 8.2 cal kyr BP, to characterize the aquatic plant and algae communities' response to the climatic and environmental change over an extended historical timeline. The results demonstrate that during 8130–4620 cal yr BP, pondweed (Stuckenia) was the dominating aquatic plant in Luanhaizi Lake, with a generally low diversity of aquatic plants and algae. During 3670–2290 cal yr BP, Luanhaizi Lake had an increased diversity and triggered a shift from Stuckenia to Eurasian watermilfoil (Myriophyllum). During 1810–50 cal yr BP, with the warming process, cyanobacteria appeared and diversity peaked. Correlation and redundancy analyses show that this process might be related to climatic and environmental changes, such as decreased salinity, increased temperature, and higher water levels. Our results signify that aquatic plants and algae communities are sensitive to paleoclimatic and environmental change, in the context of global warming, the studies on the past dynamics of aquatic plants and algae will help predict the potential changes of the lake ecosystem on the northeastern Tibetan Plateau in the future. • SedaDNA records can provide an effective approach to studying long-term aquatic plant and algae changes in lakes. • Since 8.2 cal kyr BP, Luanhaizi Lake had an increased diversity and triggered a shift from Stuckenia to Myriophyllum. • These changes might be related to decreased salinity, increased temperature, and higher water levels. [ABSTRACT FROM AUTHOR]

Wind‐induced turbulence can strongly impact ecological processes in shallow lake ecosystems. The creation of shelter against wind can be expected to affect both primary producers and herbivores in aquatic food webs. Shelter may benefit particular primary producers more than others by changing relative resource availabilities for different primary producers. Herbivore community compositions may be affected either directly or indirectly as a consequence of changes in their food quantity and quality that, in turn, may affect the transfer efficiency between primary producers and herbivores. A reduction in trophic transfer efficiency resulting from wind‐induced turbulence potentially can lead to declines of higher trophic levels, but is generally understudied.Here, we focus on the impact of wind on aquatic primary producers and trophic transfer efficiency. We hypothesised that reducing wind‐induced turbulence will stimulate higher trophic production in shallow lakes. However, the multitude of impacts of wind‐induced turbulence on aquatic food webs make it challenging to predict the direction of change when creating sheltered conditions.We tested our hypothesis in the shallow waters of a newly constructed archipelago named Marker Wadden in lake Markermeer in the Netherlands. Lake Markermeer has experienced declining numbers of birds and fish. These declines have been related to wind‐induced sediment resuspension that potentially limits primary production and trophic transfer efficiency. Marker Wadden is a large‐scale restoration project that aims to add sheltered and heterogeneous habitat to the otherwise mostly homogeneous lake, thus targeting the potential problems associated with wind‐induced turbulence.We executed a 2‐month manipulative field mesocosm experiment in the shallow waters of Marker Wadden to study the effect of reduced wind‐induced turbulence (i.e., shelter) on aquatic food webs. Specifically, we studied the effects on primary producers, trophic transfer efficiency between phytoplankton and zooplankton (using zooplankton biomass divided by phytoplankton Chl a as a proxy), and benthic fauna. The experiment consisted of three treatments: no shelter, shelter without macrophytes and shelter with submerged macrophytes (Myriophyllum spicatum) present at the start of the experiment.Our results clearly showed that under unsheltered conditions phytoplankton was the dominant primary producer, whereas in sheltered conditions submerged macrophytes became dominant. Interestingly, submerged macrophytes appeared rapidly in the sheltered treatment where first no macrophytes were visibly present; hence, at the end of the experiment, there was little difference among the sheltered treatments with and without initial presence of submerged macrophytes. Despite that phytoplankton concentrations were 23‐fold higher under the unsheltered conditions, this did not result in higher zooplankton biomass. This can be explained by a five‐fold greater trophic transfer efficiency between phytoplankton and zooplankton under the sheltered conditions. Furthermore, under the sheltered conditions the Gastropoda density reached 746 individuals m−2, whereas no Gastropoda were found under the no shelter treatment.These findings indicate that for shallow lakes that are negatively affected by wind‐induced turbulence, measures aimed at ameliorating this stressor can be effective in facilitating submerged macrophyte recovery, increasing Gastropoda densities and restoring trophic transfer efficiency between phytoplankton and zooplankton. Ultimately, this may support higher trophic levels such as fish and water birds by increasing their food availability in shallow lake ecosystems. [ABSTRACT FROM AUTHOR]

The 6 different genera Canna indica L., Eichhornia crassipes, Nelumbo nucifera, Iris pseudacorus L., Ceratophyllum demersum L., and Myriophyllum spicatum L. were selected as experimental plants. All genera could remove cobalt (Co) from water, and E. crassipes showed the highest removal efficiency of 94.86%. C. demersum L. showed the strongest enrichment ability with a maximum comprehensive enrichment coefficient of 4214.08. For different aquatic plant species, the best harvest time should be considered, and different harvesting methods should be adopted to avoid secondary pollution caused by the decomposition of aquatic plants. In combination with the landscape effect of aquatic plants, the floating plants, E. crassipes and C. demersum L., can be considered potential species for the remediation of Co-polluted water body. [ABSTRACT FROM AUTHOR]

The submerged plant species Carolina fanwort (Cabomba caroliniana) has become a dominant invasive aquatic plant in the Lake Taihu Basin (LTB) in China. Introduced species may escape their original specialist enemies and encounter fewer enemies in their new environment. They were assumed to have suffered less herbivory than native species as they are relatively unpalatable (the enemy release hypothesis [ERH]). The objective of this study was to compare the responses of C. caroliniana with those of co-occurring native species to herbivory from native herbivores. We conducted a mesocosm experiment to record the responses of C. caroliniana and two commonly co-occurring native submerged plant counterparts, water thyme (Hydrilla verticillata) and Eurasian watermilfoil (Myriophyllum spicatum), to herbivory by two native generalist gastropod snails, Radix swinhoei and Sinotaia quadrata. Plant morphological traits (total biomass, shoot/root [S/R] biomass ratio and relative growth rate [RGR]) and physiological traits (leaf total nonstructural carbohydrate [TNC], lignin, and cellulose) were recorded. The snail S. quadrata rarely influenced the plant traits of the three submerged plants. With the increasing numbers of R. swinhoei treatments, most of the plant traits of H. verticillata and M. spicatum changed, while those of C. caroliniana showed a relatively stable fluctuation. This result indicates that C. caroliniana is more resistant to herbivory by the snail R. swinhoei , which is consistent with the ERH hypothesis. This finding indicates that herbivorous snail species contributes to the invasion of C. caroliniana , which potentially alters the species composition of submerged plants in the plant community. [ABSTRACT FROM AUTHOR]

System-scale restoration efforts within the Upper Mississippi River National Wildlife and Fish Refuge have included annual monitoring of submersed aquatic vegetation (SAV) since 1998 in four representative reaches spanning ∼ 440 river kilometers. We developed predictive models relating monitoring data (site-scale SAV abundance indices) to diver-harvested SAV biomass, used the models to back-estimate annual standing stock biomass between 1998 and 2018, and compared biomass estimates with previous abundance measures. We modeled two morphologically distinct groups of SAV with differing sampling efficiencies and estimated each separately: the first category included only wild celery Vallisneria americana, which has long, unbranched leaves and dominates lotic environments, while the second category included 17 branched morphology species (e.g., hornwort Ceratophyllum demersum and Canadian water weed Elodea canadensis) and dominates lentic environments. Wild celery accounted for approximately half of total estimated total biomass in the four reaches, combined branched species accounted for half, and invasive species (Eurasian watermilfoil Myriophyllum spicatum and curly-leaf pondweed Potamogeton crispus), a fraction of the branched species, accounted for < 1.5%. Site-scale SAV estimates ranged from 0 to 535 g·m−2 (dry mass). We observed increases in biomass in most areas between 1998 and 2009 and substantial increases (e.g., from < 10 g·m−2 to ∼ 125 g·m−2) in wild celery in extensive impounded areas between 2002 and 2007. Analyses also indicate a transitional period in 2007–2010 during which changes in biomass trajectories were evident in all reaches and included the start of a 9-y, ∼ 70% decrease in wild celery biomass in the southernmost impounded area. Biomass estimates provided new insights and illustrated scales of change that were not previously apparent using traditional metrics. The ability to estimate biomass from Long Term Resource Monitoring data improves conservation efforts through better understanding of changes in habitat and food resources for biota, improved goal setting for restoration projects and improved quantification of SAV-mediated structural effects such as anchoring of sediments and feedbacks with water quality. [ABSTRACT FROM AUTHOR]

The jute mattings of two different densities were tested to control growth of Elodea canadensis Michx. and Myriophyllum spicatum L. in the Velký Bolevecký pond (West Bohemia, Czechia) during fourteen months. Both jute densities prove to be effective, permeable and stayed intact for one year. Results showed significant interaction among species, jute density and date in both abundance and length of Elodea and Myriophyllum fragments. When tested separately, we found the significant difference between abundance of Elodea and Myriophyllum fragments on the jute mattings, among the sites, and in time, but not between the two jute densities. Elodea dominated the sites due to spread of fragments from mowing that continued at the pond. However, the fragment length of given species varied between the two jute densities. They might easier root, but it could be also explained by the variability of sampled quadrats. Fragment lengths of Elodea and Myriophyllum were also changing in time but the length did not significantly differ between the two species or among the sites. Although Elodea and Myriophyllum dominated the jute mattings by the end, their progress was slower than in control sites. This study proved the positive effect of jute mattingson growth control of native and invasive macrophytes in shallow clear-water ponds. Result also showed significant interaction among jute density and time on abundance and length of Elodea and Myriophyllum fragment. [ABSTRACT FROM AUTHOR]

Remote sensing approaches that could identify species of submerged aquatic vegetation (SAV) and measure their extent in lake littoral zones would greatly enhance SAV study and management, especially if these approaches can provide faster or more accurate results than traditional field methods. Remote sensing with multispectral sensors can provide this capability, but SAV identification with this technology must address the challenges of light extinction in aquatic environments where chlorophyll, dissolved organic carbon, and suspended minerals can affect water clarity and the strength of the sensed light signal. Here, we present an uncrewed aerial system (UAS)-enabled methodology to identify the extent of the invasive SAV species Myriophyllum spicatum (Eurasian watermilfoil, or EWM), primarily using a six-band Tetracam multispectral camera, flown over sites in the Les Cheneaux Islands area of northwestern Lake Huron, Michigan, USA. We analyzed water chemistry and light data and found our sites clustered into sites with higher and lower water clarity, although all sites had relatively high water clarity. The overall average accuracy achieved was 76.7%, with 78.7% producer's and 77.6% user's accuracy for the EWM. These accuracies were higher than previously reported from other studies that used remote sensing to map SAV. Our study found that two tested scale parameters did not lead to significantly different classification accuracies between sites with higher and lower water clarity. The EWM classification methodology described here should be applicable to other SAV species, especially if they have growth patterns that lead to high amounts of biomass relative to other species in the upper water column, which can be detected with the type of red-edge and infrared sensors deployed for this study. [ABSTRACT FROM AUTHOR]

The goal of the present study was to investigate the antibacterial properties, enzyme production, and metabolic profiling of a new Ceratorhiza hydrophila strain isolated from the submerged aquatic plant Myriophyllum spicatum. Furthermore, the fungus' morphological characterization and DNA sequencing have been described. The fungus has been identified and submitted to the GenBank as Ceratorhiza hydrophila isolate EG19 and the fungus ID is MK387081. The enzyme analyses showed its ability to produce protease and cellulase enzymes. According to the CSLI standard, the ethyl acetate extract of C. hydrophila showed intermediate antibacterial activity against Streptococcus pneumonia, Micrococcus luteus, and Staphylococcus aureus. Metabolic profiling has been carried out using 700 MHz NMR spectroscopy. Based on the 1H and 1H-13C heteronuclear single quantum coherence (HSQC) NMR data and NMR databases, 23 compounds have been identified. The identified metabolites include 31% amino acids, 9% sugars, 9% amines, 4% sugar alcohols, and 4% alkaloids. This is the first report for the metabolic characterization of C. hydrophila, which gave preliminary information about the fungus. It is expected that our findings not only will pave the way to other perspectives in enormous applications using C. hydrophila as a new promising source of antimicrobial agents and essential metabolites, but also it will be valuable in the classification and chemotaxonomy of the species. [ABSTRACT FROM AUTHOR]

Nitellopsis obtusa was first reported in North America in 1974. The overall ecological threat that N. obtusa poses towards freshwater ecosystems in its non‐native range is thought to be similar to other invasive macrophyte species. However, few studies have evaluated the impacts to aquatic communities upon successful establishment of this species in North America. Despite N. obtusa being a non‐native invasive species in North America, it is considered a beneficial macrophyte within its native range in EurasiaWe evaluated the impacts associated with the non‐native invasive charophyte N. obtusa on the lower aquatic food web (LAFW) communities (phytoplankton, macroinvertebrates, and macrophytes) in a large, shallow lake in Ontario, Canada. To tease apart abiotic and biotic factors that influence LAFW species assemblages, a generalised linear latent variable model (GLLVM) was used.Over the course of the 4‐year study period, N. obtusa abundance significantly increased throughout the lake (pairwise comparison, p < 0.001) and notable shifts in community composition occurred across years (PERMANOVA, p < 0.001), especially for the phytoplankton and macrophyte communities.Nitellopsis obtusa was also found to be associated with a decline in diversity, where Simpson's diversity indices across all LAFW communities decreased as a function of increasing N. obtusa biomass. The GLLVM analysis revealed significant negative associations between N. obtusa and the majority of LAFW taxa. Most notably, there was a significant (p < 0.001) negative relationship between Myriophyllum spicatum, a previously established non‐native invasive macrophyte, and N. obtusa. The GLLVM model also demonstrated that N. obtusa had positive co‐occurrence relationships with other members of the macrophyte community including Utricularia vulgaris, Najas flexilis, Potamogeton crispus, and Stuckenia pectinata.These results show for the first‐time significant impacts to the LAFW in an invaded ecosystem, which raises major concerns for fish communities that depend on the LAFW for food and habitat. Further studies are necessary to confirm the extent of these impacts in other invaded lakes. [ABSTRACT FROM AUTHOR]

In this study, six hydrophyte species (Ceratophyllum demersum, Canna indica, Iris pseudacorus, Pistia stratiotes, Myriophyllum spicatum, and Eichhornia crassipes) were selected to investigate the effects of different Cd concentrations on the growth and water purification rates in order to identify species with the best Cd remediation effects. Additionally, a kinetic model of Cd adsorption by aquatic plants was determined using a regression method. The survival rate of the six species of aquatic plants under Cd stress was 100%. However, Cd stress inhibited the accumulation of biomass and nutrient elements in aquatic plants. Cd was mainly concentrated in the roots of aquatic plants. The simulation result of the kinetic model revealed that the exponential function model was most suitable for describing Cd removal, indicating that this model can be used to predict the degree of Cd purification by aquatic plants. The species E. crassipes and P. stratiotes were highly efficient in Cd removal, with an average removal rate above 88%. Thus, E. crassipes and P. stratiotes are species with potential for use in the remediation of Cd-polluted water in constructed wetlands and floating beds. [ABSTRACT FROM AUTHOR]