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Seasonal precipitation distribution determines ecosystem CO<sub>2</sub> and H<sub>2</sub>O exchange by regulating spring soil water-salt dynamics in a brackish wetland
No full text1. The intensification of the global hydrological cycle is anticipated to increase the variability of precipitation patterns. Brackish wetlands respond to changes in precipitation patterns by regulating the absorption and release of CO2 and H2O to maintain the stability of ecosystem functions. However, there is limited understanding of how the inter-seasonal precipitation distribution (SPD) affects ecosystem CO2 and H2O exchange compared with annual precipitation totals. 2. Here, we conducted four consecutive years of field experiments in a brackish wetland, manipulating the proportion of precipitation across different seasons while maintaining a constant annual precipitation total. We utilized five inter-SPD proportions (+73%, +56%, control (CK), -56%, -73%) to examine the effects of SPD on ecosystem CO2 and H2O exchange. 3. Our findings revealed that the annual ecosystem CO2 and H2O fluxes showed a trend of decreasing with the decrease in spring precipitation distribution. Among them, the annual net ecosystem CO2 exchange, evapotranspiration, carbon use efficiency and water use efficiency were shown to be more sensitive to decrease in spring precipitation distribution and increase in summer and autumn precipitation distribution. This negative asymmetric response pattern suggests that annual ecosystem CO2 and H2O exchange is primarily governed by seasonal precipitation variability, with spring soil water-salt dynamics identified as the key driver. Therefore, this association can be explained by the fact that drought of the early growth stage exacerbates soil salinization and inhibits vegetation colonization and growth, thereby greatly impairing the annual CO2-H2O exchange capacity of brackish wetlands. 4. Our results emphasized that the spring extreme precipitation-induced soil water-salt conditions will greatly influence CO2 and H2O exchange in brackish wetlands in the future. These findings are crucial for improving predictions of the carbon sequestration and water-holding capacity of brackish wetlands. Read the free Plain Language Summary for this article on the Journal blog
Activity Pattern and Habitat Use of Shorebirds in an Artificial Wetland Complex: A Case Study of Breeding Pied Avocet in the Yellow River Delta, China
No full textWith the loss of substantial natural wetlands in coastal zones, artificial wetlands provide alternative habitats for many shorebirds. Scientific management of artificial wetlands used by shorebirds plays an important role in maintaining the stability of shorebird population. Satellite tracking technique can obtain high-precision location information of individuals day and night, providing a good technical support for the study of quantitative relationship between waterfowls and their habitats. In this study, satellite tracking method, Remote Sensing (RS) and Geographic Information System (GIS) technology were used to analyze the activity pattern and habitat utilization characteristics of Pied Avocet during breeding period in an artificial wetland complex in the Yellow River Delta (YRD), China. The results showed that the breeding Pied Avocets had a small range of activity, with a total core and main home range of 33.10 km2 and 216.30 km2, respectively. This species tended to forage in the pond and salt pan during the day and night, respectively, with an unfixed staying time in the breeding ground. The distance between breeding ground and feeding ground was less than 6 km. It is emphasized that in addition to improving the conditions of the remaining natural habitats, effective managing artificial habitats is a priority for shorebird conservation. This research could provide reference for the management of artificial wetlands in coastal zones and supply technique support for the protection of shorebirds and their habitats, and alleviate human-bird conflicts and sustainable development of coastal zones
Transcriptomic profiling of the thermal tolerance in two subspecies of the bay scallop Argopecten irradians
No full textThe bay scallop is a eurythermal species with high economic value and now represents the most cultured bivalve species in China. Two subspecies of the bay scallop, the northern subspecies Argopecten irradians irradians Korean population (KK) and the southern subspecies Argopecten irradians concentricus (MM), exhibited distinct adaptations to heat stress. However, the molecular mechanism of heat resistance of the two subspecies remains unclear. In this study, we compared the transcriptomic responses of the two subspecies to heat stress and identified the involved differentially expressed genes (DEGs) and pathways. More DEGs were found in the KK than in the MM when exposed to high temperatures, indicating elevated sensitivity to thermal stress in the KK. Enrichment analysis suggests that KK scallops may respond to heat stress more swiftly by regulating GTPase activity. Meanwhile, MM scallops exhibited higher resistance to heat stress mainly by effective activation of their antioxidant system. Chaperone proteins may play different roles in responses to heat stress in the two subspecies. In both subspecies, the expression levels of antioxidants such as GST were significantly increased; the glycolysis process regulated by PC and PCK1 was greatly intensified; and both apoptotic and anti-apoptotic systems were significantly activated. The pathways related to protein translation and hydrolysis, oxidoreductase activity, organic acid metabolism, and cell apoptosis may also play pivotal roles in the responses to heat stress. The results of this study may provide a theoretical basis for marker -assisted breeding of heat -resistant strains
Root Disturbance Effects of Four Halophytes on Soil Physiochemical Characteristics in Intertidal Ecotone of the Yellow River Estuary (vol 44,77, 2024)
No full textShining light on carbon dots: Toward enhanced antibacterial activity for biofilm disruption
No full textIn spite of tremendous efforts dedicated to addressing bacterial infections and biofilm formation, the post-antibiotic ear continues to witness a gap between the established materials and an easily accessible yet biocompatible antibacterial reagent. Here we show carbon dots (CDs) synthesized via a single hydrothermal process can afford promising antibacterial activity that can be further enhanced by exposure to light. By using citric acid and polyethyleneimine as the precursors, the photoluminescence CDs can be produced within a one-pot, one-step hydrothermal reaction in only 2 h. The CDs demonstrate robust antibacterial properties against both Gram-positive and Gram-negative bacteria and, notably, a considerable enhancement of antibacterial effect can be observed upon photo-irradiation. Mechanistic insights reveal that the CDs generate singlet oxygen (1O2) when exposed to light, leading to an augmented reactive oxygen species level. The approach for disruption of biofilms and inhibition of biofilm formation by using the CDs has also been established. Our findings present a potential solution to combat antibacterial resistance and offer a path to reduce dependence on traditional antibiotics.
Shining carbon dots (CDs) produced by a single-step hydrothermal method can afford enhanced antibacterial activity against both Gram-positive and Gram-negative bacteria. Mechanistic insights reveal that the CDs generate singlet oxygen (1O2) under light irradiation, contributing to an augmented ROS level, facilitating disruption of biofilms and inhibition of biofilm formation. imag
Ship Emissions as the Largest Contributor to Coastal Atmospheric Black Carbon at a Receptor Island in Southern China
No full textAtmospheric black carbon (BC) over coastal regions poses a threat in terms of both climate change and human health. However, the provenance of aerosol BC, particularly its subfractions (char-BC and soot-BC, which have different physicochemical properties), is poorly constrained. Here, we apportioned the sources of char-BC and soot-BC in year-round PM2.5 samples from a coastal receptor island off southern China. Char-BC dominated, accounting for 88.6 +/- 13.2% of the total BC. The two BC subfractions exhibited distinct seasonal variation patterns, which may be attributed to differences in their sources and hydrophilicity. Combustion of liquid fossil fuels, including bunker fuel, diesel, and gasoline, contributed more highly to soot-BC (71.4%) than to char-BC (53.9%). Conversely, combustion of solid fuels, including biomass and coal, contributed more highly to char-BC (44.6%) than to soot-BC (6.7%). Bunker fuel combustion, the dominant portion of ship emissions, was the largest contributor to total BC (46.0%), char-BC (45.2%), and soot-BC (56.4%). This indicates that marine ship emissions, rather than land-based sources including biomass and coal combustion, were the dominant source of atmospheric BC in coastal areas, highlighting the importance of controlling maritime ship emissions
Potential threats of microplastics and pathogenic bacteria to the immune system of the mussels <i>Mytilus galloprovincialis</i>
No full textAs one of the main components of marine pollution, microplastics (MPs) inevitably enter the mussel aquaculture environment. At the same time, pathogenic bacteria, especially pathogens such as Vibrio, can cause illness outbreaks, leading to large-scale death of mussels. The potential harm of MPs and pathogenic bacteria to bivalve remains unclear. This study designed two experiments (1) mussels (Mytilus galloprovincialis) were exposed to 100 particles/L or 1,000 particles/L polymethyl methacrylate (PMMA, 17.01 +/- 6.74 mu m) MPs and 1 x 107 CFU/mL Vibrio parahaemolyticus at the same time (14 days), and (2) mussels were exposed to 100 particles/L or 1,000 particles/L MPs for a long time (30 days) and then exposed to 1 x 107 CFU/mL V. parahaemolyticus to explore the effects of these two stresses on the mussel immune system. The results showed that after the combined exposure of V. parahaemolyticus and MPs, the lysosomal membrane stability of hemocytes decreased, lysozyme activity was inhibited, and hemocytes were induced to produce more lectins and defensins to fight pathogenic invasion. Longterm exposure to MPs caused a large amount of energy consumption in mussels, inhibited most of the functions of humoral immunity, increased the risk of mussel infection with pathogenic bacteria, and negatively affected mussel condition factor, the number of hemocytes, and the number of byssuses. Mussels may allocate more energy to deal with MPs and pathogenic bacterial infections rather than for growth. Above all, MPs exposure can affect mussel immune function or reduce its stress resistance, which in turn has an impact on mollusk farming
The influences of Yellow River input and nutrient dynamics on colloidal Fe migration in the Bohai Sea, China
No full textThe coupling relationship between the <1 kDa, 1-3 kDa, 3-10 kDa, 10-100 kDa, and 100 kDa-0.45 mu m Fe fractions and the environmental factors in the Bohai Sea (BS) was investigated. The 1-100 kDa Fe in the surface water exhibited a non-conservative phenomenon during the river-sea mixing process, which was related to the removal of colloidal Fe via flocculation during this process. For the bottom water, the ligands released by the sediments may form additions to the <100 kDa Fe. The COC and DOC were mainly closely related to the behavior of the Fe in the bottom water. The <1 and 3-10 kDa Fe was mainly significantly positively correlated with the DOC, while the <100 kDa-0.45 mu m Fe was significantly negatively correlated with the DOC. <100 kDa LMW colloidal Fe exhibited more synergistic behavior with easily absorbed ammonium salts
Glutamate, glycine, and especially the secretions of Ruditapes phillipinarum induce efficient foraging by juvenile Rapa whelks
No full textChemical signals are known to influence interactions within and among species of aquatic organisms, including gastropods. However, despite the indispensable roles of chemical signals in species interactions, little is known about their effectiveness, especially in gastropods. The rapa whelk Rapana venosa (Valenciennes, 1846) is an ecologically and economically important gastropod, but it has also become a global invasive species. Currently, bottlenecks exist in the breeding of R. venosa related to foraging behaviour and efficiency in juveniles, while significant problems also exist in controlling invasive populations of the gastropod. Here, we aimed to identify chemical signaling molecules that could effectively improve their foraging behaviour and efficiency and potentially solve the bottlenecks in aquaculture production and control the invasiveness of R. venosa. The foraging behaviour of R. venosa during the search phase was evaluated in response to various signaling molecules as to activity time, motion path, and successful perception rate, and a standard scoring metric was proposed. The results showed that bivalve (Ruditapes philippinarum) secretion and glutamic acid and glycine, could effectively induce foraging behaviour in R. venosa. In contrast, 4-dodecylbenzene sulfonic acid and dodecyl sulfate, did not induce significant foraging behaviour. The induced foraging behaviour by a single amino acid was less effective than that of the entire bivalve secretion. These findings could be helpful in improving breeding efficiency, efficient trapping, and controlling invasive populations of aquatic gastropods
Chronopotentiometric Nanopore Sensor Based on a Stimulus-Responsive Molecularly Imprinted Polymer for Label-Free Dual-Biomarker Detection
No full textThe development of sensors for detection of biomarkers exhibits an exciting potential in diagnosis of diseases. Herein, we propose a novel electrochemical sensing strategy for label-free dual-biomarker detection, which is based on the combination of stimulus-responsive molecularly imprinted polymer (MIP)-modified nanopores and a polymeric membrane chronopotentiometric sensor. The ion fluxes galvanostatically imposed on the sensing membrane surface can be blocked by the recognition reaction between the target biomarker in the sample solution and the stimulus-responsive MIP receptor in the nanopores, thus causing a potential change. By using two external stimuli (i.e., pH and temperature), the recognition abilities of the stimulus-responsive MIP receptor can be effectively modulated so that dual-biomarker label-free chronopotentiometric detection can be achieved. Using alpha fetoprotein (AFP) and prostate-specific antigen (PSA) as model biomarkers, the proposed sensor offers detection limits of 0.17 and 0.42 ng/mL for AFP and PSA, respectively