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Preliminary Performance Assessment of the Wave Parameter Retrieval Algorithm from the Average Reflected Pulse
No full textTo obtain new information about surface waves, it is proposed to use an underwater acoustic wave gauge, and an assessment of its effectiveness can be performed using a numerical simulation and field experiment. A new device, an underwater acoustic wave gauge named "Kalmar", was developed by the Institute of Applied Physics of the Russian Academy of Sciences for long-term, all-weather monitoring of wind waves. The instrument uses ultrasound to probe the water surface from underwater and can be used to verify remote sensing data. In this work, the capabilities of the device are tested and compared with ADCP data. Two independent methods for processing underwater acoustic wave gauge data are discussed and compared. One of them is completely new for acoustic measurements and is based on the analysis of the shape of the reflected acoustic pulse averaged over space and time. The other allows processing individual reflected pulses and calculating the time implementation of the distance to the water surface. It is shown that two independent methods of significant wave height retrieval from the acoustic wave gauge measurements are highly correlated. The "Kalmar" acoustic wave gauge and the RDI WH-600 acoustic Doppler current profiler operated simultaneously at the test site in Gelendzhik from 1 February to 10 February 2020. The significant wave heights measured by the two instruments are in good agreement
The pollution characteristics and risk assessment of microplastics in mollusks collected from the Bohai Sea
No full textMicroplastics (MPs) pollution in the marine environment has become a global problem. In this study, a number of 21 mollusk species (n = 2006) with different feeding habits were collected from 11 sites along the Bohai Sea for MPs uptake analysis. The MPs in mollusk samples were isolated and identified by micro-Fourier Transform Infrared Spectroscopy (mu-FTIR), and an assessment of the health risks of MPs ingested by mollusk consumption is also conducted. Approximately 91.9 % of the individuals among all the collected species inhaled MPs, and there was an average abundance of 3.30 +/- 2.04 items & sdot;individual- 1 or 1.04 +/- 0.74 items & sdot;g- 1 of wet weight. The shape of MPs was mainly fiber, and a total number of 8 polymers were detected, of which rayon had the highest detection rate (58.3 %). The highest abundance, uptake rate and polymer composition of MPs was observed in creeping types, suggesting that they might ingest these MPs from their food. The gastropod Siphonalia subdilatata contains the highest levels of MPs, which may increase the risk of human exposure if consumed whole without removing the digestive gland. The polymer risk level of MPs in these mollusks was Level III (H = 299), presenting harmful MPs such as polyvinyl chloride. In terms of human exposure risk, the average risk of human exposure to MPs through consumption of Bohai mollusks is estimated to be 3399 items & sdot;(capita & sdot;year)-1 (424-9349 items & sdot; (capita & sdot;year)-1). Overall, this study provides a basis for the ecological and health Risk assessment of MPs in mollusks collected from the coastline of China
New insights into estimation of bioavailable inorganic phosphorus in natural coastal seawater
No full textConsidering the impact of the high salinity and high turbidity of coastal seawater on phosphorus forms, a new method was proposed to determine bioavailable inorganic phosphorus (BIP). The phosphorus most relevant to eutrophication is BIP, and traditional analysis methods may underestimate the degree of eutrophication. In this study, a microelectrode of multigold (Au mu E) was fabricated for direct voltammetric determination of BIP without filtration, and BIP environmental characteristics including distribution and correlation relationships with environmental factors in typical coastal seawater of Northern China were analyzed. The proposed Au mu E showed a low detection limit of 0.03 mu M. The surface and bottom BIP concentrations ranged from 1.00 to 2.13 and from 0.88 to 2.05 mu M, respectively. BIP dominated the total P (TP) accounting for 48.5-67.5 % in the surface layer samples, and 32.6-92.7 % in the bottom layer samples, respectively. The concentrations of BIP were obviously higher than those of DIP, indicating that DIP may underestimate the probability of eutrophication occurring. And BIP was positively correlated with dissolved oxygen (DO) (P < 0.05). BIP may be a promising indicator of eutrophication potential in coastal areas with high salinity and high turbidity. The proposed reliable voltammetry method provides a new indicator for environmental assessment and represents a significant step in the comprehensive analysis of P species
Reproductive biology of <i>Hemitripterus villosus</i> in the Bohai Strait, China
No full textTo understand the reproductive biology of Hemitripterus villosus in the Bohai Strait, and fill the key knowledge gap in verifying reproductive seasonality and documenting gonadotropin dependent reproductive cycle of this species, a year-round detail study was conducted for the first time. In total, 263 individuals were randomly sampled off the coasts of the Bohai Strait. Results show that and the overall female-to-male ratio (1.35:1) did not differ significantly from the 1:1 sex ratio. The length and weight relationship for females and males were regressed, depicting an isometric growth for both sexes. Four reproductive phases of the complete gonadotropin dependent reproductive cycle in both sexes were identified. The monthly variations in the gonadosomatic and hepatosomatic indexes for both sexes further indicated that this species spawns a single batch of eggs per year and the peak spawning period is from October to December. The average diameter of eggs ranged from 2.10 to 3.57 mm. The length at first sexual maturity was 224.87 mm for females and 241.26 mm for males. Significant positive relationships between absolute fecundity and fish size, and also gonadal weight were observed. H. villosus from the Bohai Strait exhibited smaller body size, smaller egg diameter, lower gonadosomatic index, lower absolute fecundity, and higher population extinction risk than the other populations' studied previously. Our findings contribute to understanding the status of this isolated westernmost population, and we emphasize that more efficient protection measures for the species and control measures are urgently required to improve the coastal environment in the Bohai Strait
The optimal realized niches of the diatom<i> Paralia</i><i> sulcata</i> in the Yellow Sea and its environmental implication
No full textThe observational and paleo-ecological records on some shelves (e.g., North Sea, Yellow Sea) have indicated that the proportion of Paralia sulcata in the diatom community has been increasing since the 1980s. Because of its heavily-silicified frustules, this species is considered as an important siliceous organism, which can impact the recycling efficiency of biogenic silicon in the ocean. However, the specific environmental factors driving the increase of P. sulcata remain unclear. In this study, based on seasonal in-situ observations and historical literature in the Yellow Sea, we statistically assessed the importance of different environmental factors in determining P. sulcata abundance. Further, we quantified its optimal realized niches, using the maximum entropy and generalized additive models to predict the fate of this species. P. sulcata indicates a preference for environments with cold temperatures and high nutrient levels. The contribution of sea temperature on cell abundance reaches up to 37.2 %, which is higher than that of the nutrient concentrations (-20.5 %) and salinity (-17.1 %). The optimal realized niches are defined as sea temperature at 6.25 +/- 3.50 degrees C, salinity at 32.8 +/- 0.52, the concentrations of dissolved inorganic nitrogen, phosphorus, and silicate at 8.38 +/- 5.42 mu M, 0.42 +/- 0.29 mu M, and 5.87 +/- 3.53 mu M, respectively, and ammonium/nitrate ratio at 1.32 +/- 0.19. Based on the multivariate statistical methods, the optimal realized niches indicate that the increased sea temperatures in winter and spring, combined with nitrogen enrichment, especially ammonium enrichment, are key environmental drivers for P. sulcata proliferation in the Yellow Sea
Interactive effects of multiple antibiotic residues and ocean acidification on physiology and metabolome of the bay scallops Argopecten irradians irradians
No full textCoastal areas are confronted with compounding threats arising from both climatic and non-climatic stressors. Antibiotic pollution and ocean acidification are two prevalently concurrent environmental stressors. Yet their interactive effects on marine biota have not been investigated adequately and the compound hazard remain obscure. In this study, bay scallops Argopecten irradians irradians were exposed to multiple antibiotics (sulfamethoxazole, tetracycline, oxytetracycline, norfloxacin, and erythromycin, each at a concentration of 1 mu g/L) combined with/without acidic seawater (pH 7.6) for 35 days. The single and interactive effects of the two stressors on A. irradians irradians were determined from multidimensional bio-responses, including energetic physiological traits as well as the molecular underpinning (metabolome and expressions of key genes). Results showed that multiple antibiotics predominantly enhanced the process of DNA repair and replication via disturbing the purine metabolism pathway. This alternation is perhaps to cope with the DNA damage induced by oxidative stress. Ocean acidification mainly disrupted energy metabolism and ammonia metabolism of the scallops, as evidenced by the increased ammonia excretion rate, the decreased O:N ratio, and perturbations in amino acid metabolism pathways. Moreover, the antagonistic effects of multiple antibiotics and ocean acidification caused alternations in the relative abundance of neurotransmitter and gene expression of neurotransmitter receptors, which may lead to neurological disorders in scallops. Overall, the revealed alternations in physiological traits, metabolites and gene expressions provide insightful information for the health status of bivalves in a natural environmental condition under the climate change scenarios
Structural framework for the understanding spectroscopic and functional signatures of the cyanobacterial Orange Carotenoid Protein families
No full textThe Orange Carotenoid Protein (OCP) is a unique photoreceptor crucial for cyanobacterial photoprotection. Best studied Synechocystis sp. PCC 6803 OCP belongs to the large OCP1 family. Downregulated by the Fluorescence Recovery Protein (FRP) in low-light, high-light-activated OCP1 binds to the phycobilisomes and performs non -photochemical quenching. Recently discovered families OCP2 and OCP3 remain structurally and functionally underexplored, and no systematic comparative studies have ever been conducted. Here we present two first crystal structures of OCP2 from morphoecophysiologically different cyanobacteria and provide their comprehensive structural, spectroscopic and functional comparison with OCP1, the recently described OCP3 and all-OCP ancestor. Structures enable correlation of spectroscopic signatures with the effective number of hydrogen and discovered here chalcogen bonds anchoring the ketocarotenoid in OCP, as well as with the rotation of the echinenone's beta-ionone ring in the CTD. Structural data also helped rationalize the observed differences in OCP/ FRP and OCP/phycobilisome functional interactions. These data are expected to foster OCP research and applications in optogenetics, targeted carotenoid delivery and cyanobacterial biomass engineering
An inversion model of microplastics abundance based on satellite remote sensing: a case study in the Bohai Sea
No full textNowadays, microplastics (MPs) as emerging contaminants have posed great risks to marine ecosystems and human health. However, non-continuous field sampling data makes it difficult to meet the needs of scientific research and pollution control of marine MPs. Consequently, the development of rapid monitoring techniques for marine MPs to achieve efficient acquisition of data is increasingly essential. Remote sensing technology provides a convenient and effective tool for monitoring and mapping marine MPs pollution. Therefore, we established an inversion model based on multiple regression by combining the remote sensing data and the measured data to predict the MPs pollution status in the Bohai Sea. The feature variables of a model are crucial to the prediction, and we proposed three methods of variable selection, namely successive projections algorithm (SPA), band combination method, and remote sensing index method. By comparing accuracy evaluation metrics, an approach based on SPA was selected to analyze the abundance and spatio-temporal distribution of MPs in the Bohai Sea in 2022. The determination coefficient of the SPA model is 0.75, and the root mean square error is 0.38 items/m3. The error of the model is within an acceptable range. It was found that the MPs abundance on the sea surface of the Bohai Sea varied significantly in different seasons and regions. This study indicates that satellite remote sensing technology has great potential in monitoring marine MPs
Design and Synthesis of Fluorine-Containing Embedded Carbon Dots Stationary Phase for Separation of Versatile Analytes
No full textThus far, numerous new stationary phases have been developed. A fluorine-containing embedded carbon dots (F3-CDs-SiO2) stationary phase was first designed and synthesized. The resulting F3-CDs-SiO2 stationary phase was characterized carefully by scanning electron microscopy, transmission electron microscopy, elemental analysis, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller experiment. The F3-CDs-SiO2 stationary phase was slurry packed into the HPLC column (150 x 2.1 mm) for evaluation. Furthermore, the F3-CDs-SiO2 column was successfully used for separation of pesticides, nucleosides, sulfonamides, alkaloids, and alkylbenzenes. The retention mechanism (including hydrophobic interaction, F-F, hydrogen bond interaction, ion-exchange, dipole-dipole interaction, electrostatic interaction, etc.) was investigated carefully. Meanwhile, the F3-SiO2 stationary phase was synthesized and used to evaluate the role of CDs. Furthermore, various commercial stationary phases (including amino-SiO2, diol-SiO2, C18-SiO2, and PFP-SiO2) were used for comparison. Moreover, the F3-CDs-SiO2 column possessed good repeatability, reproducibility, and stability in separation of versatile analytes
Spatio-seasonal variations in functional trait composition and diversity patterns of marine fish communities in coastal waters
No full textDespite the consensus that the distribution of functional traits within a community provides insights into community assembly and maintenance mechanisms, few studies have explored spatio-seasonal variations in the functional patterns of marine fish communities. Seven functional traits within the context of 2 distinct groups-habitat use and trophic niche-were selected to assess functional richness (FRic), functional evenness (FEve), and functional dispersion (FDis) across various spatio-seasonal scales. Community-weighted mean redundancy analysis (CWM-RDA) was used to identify the impact of environmental factors on dominant traits. We found seasonal and spatial variations in dominant traits of the fish community, notably influenced by the latitudinal-depth gradient (from shallower stations in the north to deeper stations in the south), east-west (longitudinal) dynamics, and temperature gradient. Latitude was negatively correlated with the CWM values of most functional trait categories. FRic showed more pronounced seasonal variations than other indices, with higher values observed in autumn. Fish assemblages displayed more similarity in functional traits in winter than in other seasons, with lower FRic, higher FEve, and lower FDis. Overall, our findings illustrate that fish assemblages undergo continuous formation and dissolution across different seasons and zones, resulting in various forms of functional diversity patterns