Nutrient enrichment, propagule pressure, and herbivory interactively influence the competitive ability of an invasive alien macrophyte Myriophyllum aquaticum.

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 native macrophyte 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 nutrient-rich 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.

Adaptive responses and transgenerational plasticity of a submerged plant to benthivorous fish disturbance.

Submerged macrophytes play a key role in the restoration of shallow eutrophic lakes. However, in some subtropical lakes, benthivorous fishes dominate the fish assemblages and influence the growth of submerged plants. A comprehensive understanding of the direct and indirect effects of benthivorous fishes on submerged plants is important. We conducted mesocosm experiments to examine the effects of three densities of benthivorous fish, Misgurnus anguillicaudatus, on the water properties, the growth, asexual reproduction, and the germination of turions of Potamogeton crispus L. Our results showed that fish disturbance increased TN, TP, PO4-P, NH4-N, and NO3-N of the water, raising the extinction coefficient K, Chl a, and the periphyton biomass. Benthivorous fish disturbance reduced the total biomass, root length, relative growth rate (RGR), and branching number while increasing the plant height of P. crispus. The P stoichiometric homeostasis coefficient (H P) (except turions) and H N was lower in plant tissues due to fish disturbance. Benthivorous fish disturbances promoted turions formation (e.g., increased turions total numbers and biomass) of P. crispus. Moreover, P. crispus exhibited transgenerational plasticity for benthivorous fish affecting turion emergence. The maximum final germination rate occurred only when fish density in the mother plant grow experiment matched that in the turion germination experiment. Turions generated by P. crispus disturbed by low-density fish exhibited increased germination rates. Our findings suggest that controlling benthivorous fish reduces its indirect and direct effects on submerged vegetation, facilitating the successful restoration of these plants.

Community structure and function of epiphytic bacteria attached to three submerged macrophytes.

In aquatic ecosystems, large amounts of epiphytic bacteria living on the leaf surfaces of submerged macrophytes play important roles in affecting plant growth and biogeochemical cycling. The restoration of different submerged macrophytes has been considered an effective measure to improve eutrophic lakes. However, the community ecology of epiphytic bacteria is far from well understood for different submerged macrophytes. In this study, we used quantitative PCR, 16S rRNA gene high-throughput sequencing and functional prediction analysis to explore the structure and function of epiphytic bacteria in an aquatic ecosystem recovered by three submerged macrophytes (Hydrilla verticillata, Vallisneria natans and Potamogeton maackianus) during two growth periods. The results showed that the community compositions and functions of epiphytic bacterial communities on the submerged macrophyte hosts were different from those of the planktonic bacterial communities in the surrounding water. The alpha diversity of the epiphytic bacterial community was significantly higher in October than in July, and the community compositions and functions differed significantly in July and October. Among the three submerged macrophytes, the structures and functions of the epiphytic bacterial community exhibited obvious differences, and some specific taxa were enriched on the biofilms of the three plants. The alpha diversity and the abundance of functions related to nitrogen and phosphorus transformation were higher in the epiphytic bacteria of P. maackianus. In summary, these results provide clues for understanding the distribution and formation mechanisms of epiphytic bacteria on submerged macrophyte leaves and their roles in freshwater ecosystems.

Prevalence and clinical correlates for depression in women with urinary incontinence: a cross-sectional study.

INTRODUCTION AND HYPOTHESIS: The coexistence of urinary incontinence (UI) and depression has been intensively examined in women. This study aimed to investigate the prevalence and some clinical correlates of depression in women with UI. METHODS: The National Health and Nutrition Examination Survey (NHANE) 2005-2018 was used in this cross-sectional study, and a total of 7250 UI patients were included. Patientss were defined as having UI if they answered "yes" to the UI screening question. Depression symptoms were measured by Personal Health Questionnaire (PHQ-9). RESULTS: The age-standardized prevalence of depression in women with UI was 13.7 (95% CI: 12.5-14.9). Multiple logistic regression showed that being younger (age <60 years), widowed, divorced or separated and having lower income, lower education level, more severe incontinence and mixed UI were associated with an increased likelihood of depression. CONCLUSIONS: This population-based study suggested that the prevalence of depression in women with UI was high. The main clinical correlates for depression were younger age (<60 years), lower education level, lower income, being widowed, divorced or separated, and having more severe incontinence and mixed UI.

Conductivity-difference-enhanced DC dielectrophoretic particle separation in a microfluidic chip.

A conductivity-difference-based method for increasing dielectrophoretic (DEP) force for particle separation in a microfluidic chip is presented in this paper. By applying a direct-current (DC) voltage across two immiscible electrolyte solutions with a conductivity difference, an enhanced electric field gradient is generated at the liquid-liquid interface. Theoretical analysis based on equivalent circuit theory found that the gradient of the electric field squared increases with the decrease in the conductivity ratio of the two liquids (main channel to the side channel). As a result, the particle separation distance (an indicator of DEP force) increases with the decrease in the conductivity ratio, which is both numerically predicted and experimentally verified. Numerical simulations also show that the separation distance increases with the increase in the magnitude of the electric field and the decrease in the width of the orifice. The method presented in this paper is simple and advantageous for increasing DEP force without applying higher DC voltages or fabricating smaller orifices.

The spatiotemporal characteristics of water quality and phytoplankton community in a shallow eutrophic lake: Implications for submerged vegetation restoration.

One of the most serious consequences of eutrophication in shallow lakes is deterioration of water quality, proliferation of phytoplankton and disappearance of submerged macrophytes. After removing herbivorous and plankti-benthivorous fish, submerged macrophyte restoration was utilized at the entire lake (82.7 km2) to combat eutrophication and improve water quality in the shallow subtropical aquaculture of Lake Datong. We conducted two years of monitoring, from March 2018 to February 2020. During the first year of restoration, 80% of the area of Lake Datong (approximately 60 km2) was successfully recovered by submerged vegetation, and the water quality was improved. For example, the phosphorous (P) content (including total P (TP), dissolved reactive P (DRP) and total dissolved P (TDP)) and turbidity decreased, and the Secchi depth (SD) increased. However, the submerged vegetation disappeared from autumn 2019 in the intermittent recovery area (MN), while the continuous recovery area (DX) continued to recover with an abundance of submerged vegetation. During the second year, the water quality continued to improve significantly in the DX area, with high biomass and coverage of submerged vegetation. In the MN area, although turbidity and ammonia nitrogen (NH4+-N) increased significantly and SD decreased significantly, the P content (TP, TDP, and DRP) still continued to decrease. The restoration of submerged macrophytes could significantly decrease the density of phytoplankton. Over time, there was a regime shift in Lake Datong. The structural equation model (SEM) results illustrated that the water level and submerged plant coverage were the primary drivers that triggered changes in the state of the lake ecosystem. Our results highlight the potential of restoring submerged vegetation to control water eutrophication at the whole-lake scale. However, the water level in spring was the primary driver that triggered changes in the state of the lake ecosystem. Water level management should be emphasized during the early stages of recovery of submerged plants.

Stable and Reversible Photoluminescence from GaN Nanowires in Solution Tuning by Ionic Concentration.

We report response of photoluminescence (PL) from GaN nanowires without protection in solutions. The distinct response is not only toward pH but toward ionic concentration under same pH. The nanowires appear to be highly stable under aqueous solution with high ionic concentration and low pH value down to 1. We show that the PL has a reversible interaction with various types of acidic and salt solutions. The quantum states of nanowires are exposed to the external environment and have a direct physical interaction which depends on the anions of the acids. As the ionic concentration increases, the PL intensity goes up or down depending on the chemical species. The response results from a competition of change in surface band bending and charge transfer to redox level in solution. That of GaN films is reported for comparison as the effect of surface band bending can be neglected so that there are only slight variations in PL intensity for GaN films. Additionally, such physical interaction does not impact on the PL peaks in acids and salts, whereas there is a red shift on PL when the nanowires are in basic solution, say NH4OH, due to chemical etching occurred on the nanowires.

Secrecy Enhancing Scheme for Spatial Modulation Using Antenna Selection and Artificial Noise.

In this paper, we present a new secrecy-enhancing scheme for the spatial modulation (SM) system, by considering imperfect channel state information (CSI). In the proposed scheme, two antennas are activated at the same time. One of the activated antennas transmits information symbols along with artificial noise (AN) optimized under the imperfect CSI condition. On the other hand, the other activated antenna transmits another AN sequence. Because the AN are generated by exploiting the imperfect CSI of the legitimate channel, they can only be canceled at the legitimate receiver, while the passive eavesdropper will suffer from interference. We derive the secrecy rate of the proposed scheme in order to estimate the performance. The numerical results demonstrated in this paper verify that the proposed scheme can achieve a better secrecy rate compared to the conventional scheme at the same effective data rate.