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In order to improve the species composition and structural characteristics of fish in the southern sea area of Zhoushan, the environmental DNA technology was used to detect the fish diversity. By collecting water samples, filtering, extracting environmental DNA, PCR amplification and sequencing, 8 environmental DNA samples were obtained from 6 stations in the southern sea area of Zhoushan, and 9 species of common fish in Zhoushan sea area were detected, including 1 species of cartilaginous fish, 8 species of radial fin fish, and Harpadon nehereus was the dominant species. The results show that, although the environmental DNA technology can not completely replace the traditional methods of fish resources investigation, it can be used as a supplementary means of fish resources investigation and spatial distribution. Combined with bottom trawl data, it provides a basis for the seasonal changes of fish composition and community structure in the southern sea area of Zhoushan.

Quinolone antibiotics (QNs) contamination in the aquatic environment is a global public health issue considering their resistance and mobility. In this study, a simple, efficient, and sensitive method was developed for the accurate quantification of fifteen QNs in water using automated disk-based solid-phase extraction (SPE) coupled with ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). By utilizing a 3M SDB-XC disk to enrich QNs from a 1000 mL water sample, the detection limits were improved to 0.008–0.055 ng/L due to the satisfactory enrichment factors of 897−1136, but only requiring about 60 min per six samples. The linearity of the method ranged from 0.05 to 100 μg/L for the 15 QNs, with correlation coefficients of 0.9992–0.9999, and the recoveries were in the range of 81–114%, with relative standard deviations of 0.2–13.3% (n = 6). The developed method was applicable for the quantification of trace QNs at low ng/L levels in drinking and environmental waters. The results showed that no QNs were detected in tap water, while three and four QNs were detected in the river water of Zhoushan and the seawater of Daiquyang and Yueqing Bay, East China, respectively, with a total concentration of 1.600–8.511 ng/L and 1.651–16.421 ng/L, respectively. Among the detected QNs, ofloxacin (OFL) was the predominant compound in river water, while enrofloxacin (ENR) was predominant in seawater. The risk quotient (RQ) results revealed that QNs posed a low risk to crustaceans and fish, but a low-to-medium risk to algae, and OFL presented the main ecological risk factor in river water, while ENR and CIP in seawater. Overall, the proposed automated disk-based SPE–UPLC–MS/MS method is highly efficient and sensitive, making it suitable for routine analysis of QNs in drinking and environmental waters. [ABSTRACT FROM AUTHOR]

Majority of macrozooplankton have a wider dietary niche breadth and utilize small invertebrates, microzooplankton and mesozooplankton, so effect on primary production might be through trophic cascading effect. To better understand the ecosystem structure of benthic oyster-macroalgae reefs, we analyzed zooplankton community structure before (July 2016) and after (from September 2016 to October 2017) the construction of benthic reefs in the 2 km2 sea ranch area in Xiangyun Cove, Tangshan, China. We identified 57 zooplankton species, including the 12 cnidarian (e.g., Clytia hemisphaerica Linnaeus and Eirene ceylonensis Browne), 1 ctenopharyngodon (Pleurobrachia globosa Moser), 24 crustacean (e.g., Calanus sinicus Brodsky, Paracalanus parvus Claus, Labibocera euchaeta Glesbrecht, Labibocera bipinnata Tanaka, Calanopia thompsoni Scott, and Centropages dorsispinatus Thompson), 1 chaetognath (Sagitta crassa Tokioka), 1 urochordate species (Oikopleura dioica Fol), and 18 species of planktonic polychaete and gastropod larvae. The zooplankton density and biomass values before reef construction were 266.14 ind/m3 and 2.72 mg/m3, respectively, and those after reef construction were 138.06 ind/m3 and 32.91 mg/m3, respectively. The biomass trend was as follow: October 2017 (89.08 mg/m3) > August 2017 (70.97) > September 2016 (3.17) > July 2016 (2.72) > June 2017 (0.86) > May 2017 (0.44). The common dominant organisms were crustaceans and chaetognaths. According to the RDA ranking results, water temperature was positively correlated with the Shannon-Wiener diversity index and Margalef's richness indexes. With the increasement of Margalef's richness index, the value of dissolved oxygen content showed a significant negative correlation with zooplankton abundance. The results of this study are applicable to sustainable development and management strategies of coastal reef ecosystems and provide a basis for further surveys of secondary productivity in the sea ranch area. [ABSTRACT FROM AUTHOR]

Fulgoraria rupestris is a predatory marine gastropod belonging to Neogastropoda and possessing considerable taxonomic significance. However, research on this species remains limited. We acquired the complete mitochondrial genome of F. rupestris through second-generation sequencing and conducted an analysis of its genome structural features. The mitochondrial genome of F. rupestris spans a total length of 16,223 bp and encompasses 37 genes (13 protein-coding genes (PCGs), 22 transfer RNAs, and 2 ribosomal RNAs). Notably, most tRNAs exhibit the typical cloverleaf structure, but there is an absence of the Dihydrouridine (DHU) arm in the trnS1 and trnS2 genes. The A + T content is 68.67%, indicating a pronounced AT bias. Additionally, we conducted a selection pressure analysis on the mitochondrial genomes of four species within Volutidae, revealing that all PCGs are subjected to purifying selection. In comparison to other species within Neogastropoda, F. rupestris shares an identical gene arrangement. Additionally, based on mitochondrial genome sequences of the 13 PCGs from 50 species within Neogastropoda, we constructed a phylogenetic tree. The phylogenetic tree indicates F. rupestris forms a clade with species within the family Volutidae (Cymbium olla, Neptuneopsis gilchristi, and Melo melo). This study serves as a valuable reference for future research on F. rupestris, offering insights for the upcoming phylogenetic and taxonomic classification within Neogastropoda. Furthermore, the findings provide valuable information for the development of genetic resources in this context. [ABSTRACT FROM AUTHOR]

In this study, a comparison of the concentrations of eight heavy metals (including Fe, Mn, Cu, Zn, Cr, As, Cd, and Hg) was conducted between wild and cultured Oplegnathus fasciatus. Significant differences in the concentrations of Zn, Cd, As, and Hg were observed between wild and cultured Oplegnathus fasciatus. The results showed that the mean Zn concentration was significantly higher in cultured Oplegnathus fasciatus (3.051 ± 0.738 mg/kg) when compared to its wild counterpart (2.512 ± 0.407 mg/kg). In contrast, the mean Cd concentration was found to be lower in the cultured Oplegnathus fasciatus (0.001 ± 0.0007 mg/kg) than in the wild ones (0.003 ± 0.003 mg/kg). Likewise, the wild samples demonstrated a higher mean As concentration (1.494 ± 0.659 mg/kg) than the cultured samples (0.594 ± 0.215 mg/kg). Lastly, it was noted that the mean Hg concentration was considerably higher in the cultured Oplegnathus fasciatus (0.042 ± 0.016 mg/kg) than in the wild specimens (0.014 ± 0.011 mg/kg). Pollution levels and health risks were evaluated using the single-factor pollution index (SFI), metal pollution index (MPI), and health risk assessment methods. The results showed that, for Cu, Zn, Cr, and Cd, both wild and cultured Oplegnathus fasciatus had SFI values below 1 compared to the marine organism quality standards. The MPI values for wild and cultured Oplegnathus fasciatus were 0.188 ± 0.051 and 0.172 ± 0.054, respectively, both far below the safety limit of 2 for pollution-free aquatic products. The Hazard Index (HI) for wild and cultured Oplegnathus fasciatus were below 1, indicating no health risks from long-term consumption. A discriminant analysis, based on Zn, Cd, As, and Hg concentrations, distinguished wild from cultured Oplegnathus fasciatus with a 96.0% accuracy, remaining stable at over 94.9% upon cross-validation. These findings accurately evaluate that there is no risk to human health from consuming Oplegnathus fasciatus, which is significant in safeguarding public health. [ABSTRACT FROM AUTHOR]

In this paper, a W-band waveguide bandpass filter with a standard fourth-order Chebyshev response is proposed based on the computer numerical control (CNC)-milling technology. The harmonics-staggered technique and orthogonal coupling method are incorporated into this waveguide filter design without increasing the complexity of the filter structure in order to suppress the intrinsic spurious responses near the passband. Furthermore, the proposed filter design maintains a simple construction, which can be conveniently fabricated using CNC milling. The fabricated waveguide filter exhibits an average insertion loss of 0.9 dB and a return loss of above 20 dB in a 3 dB fractional bandwidth (FBW) of 5.5% centered at 85 GHz. The excellent spurious suppression property can reach better than −25 dB up to 165 GHz. The wide stopband performance of the proposed W-band filter is very competitive compared with the reported waveguide filters. [ABSTRACT FROM AUTHOR]

Background: Despite the Caridean shrimps' vast species richness and ecological diversity, controversies persist in their molecular classification. Within Caridea, the Pandalidae family exemplifies significant taxonomic diversity. As of June 25, 2023, GenBank hosts only nine complete mitochondrial genomes (mitogenomes) for this family. The Plesionika genus within Pandalidae is recognized as polyphyletic. To improve our understanding of the mitogenome evolution and phylogenetic relationships of Caridea, this study introduces three novel mitogenome sequences from the Plesionika genus: P. ortmanni, P. izumiae and P. lophotes. Methods: The complete mitochondrial genomes of three Plesionika species were sequenced utilizing Illumina's next-generation sequencing (NGS) technology. After assembling and annotating the mitogenomes, we conducted structural analyses to examine circular maps, sequence structure characteristics, base composition, amino acid content, and synonymous codon usage frequency. Additionally, phylogenetic analysis was performed by integrating existing mitogenome sequences of true shrimp available in GenBank. Results: The complete mitogenomes of the three Plesionika species encompass 37 canonical genes, comprising 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs), and one control region (CR). The lengths of these mitogenomes are as follows: 15,908 bp for P. ortmanni, 16,074 bp for P. izumiae and 15,933 bp for P. lophotes. Our analyses extended to their genomic features and structural functions, detailing base composition, gene arrangement, and codon usage. Additionally, we performed selection pressure analysis on the PCGs of all Pandalidae species available in Genbank, indicating evolutionary purification selection acted on the PCGs across Pandalidae species. Compared with the ancestral Caridea, translocation of two tRNA genes, i.e., trnP or trnT, were found in the two newly sequenced Plesionika species—P. izumiae and P. lophotes. We constructed a phylogenetic tree of Caridea using the sequences of 13 PCGs in mitogenomes. The results revealed that family Pandalidae exhibited robust monophyly, while genus Plesionika appeared to be a polyphyletic group. Conclusions: Gene rearrangements within the Pandalidae family were observed for the first time. Furthermore, a significant correlation was discovered between phylogenetics of the Caridea clade and arrangement of mitochondrial genes. Our findings offer a detailed exploration of Plesionika mitogenomes, laying a crucial groundwork for subsequent investigations into genetic diversity, phylogenetic evolution, and selective breeding within this genus. [ABSTRACT FROM AUTHOR]

Environmental enrichment has the potential to improve the welfare and post‐release survival of hatchery fish stocked for conservation purposes. However, the effectiveness of environmental enrichment is partly dependent on the fish species, life stage, and specific enrichment structure used. To enhance the effectiveness of environmental enrichment, it is crucial to focus on characteristic differences in enrichment structures, such as type and level. This study investigated how differences in enrichment type and level affected physiological and behavioral aspects of the welfare of pre‐release juvenile rock bream Oplegnathus fasciatus by evaluating growth performance, basal and stressed cortisol levels, antioxidant enzyme activities, and exploratory behaviors regarding anxiety and flexibility. Fish were reared for 4 weeks in different enrichment treatments: barren, low‐level cover structure, high‐level cover structure, low‐level interference structure (LI), and high‐level interference structure (HI). The results revealed that fish reared with the LI treatment showed less anxiety and greater flexibility with respect to exploratory behaviors, without oxidative damage being detected. Despite exhibiting less anxiety as well, fish reared in the HI treatment had oxidative damage, indicated by lower superoxide dismutase activity, compared to those in the barren treatment. In addition, none of these enrichment structures enhanced growth performance or mitigate chronic and acute stress responses. Overall, the low‐level interference structure may be more favorable in promoting the behavioral welfare of the fish. Application of this type and level of enrichment may increase the survival of the hatchery fish after release, which is critical to stocking success. [ABSTRACT FROM AUTHOR]

Simple Summary: The mitochondrial COI gene as a molecular marker is widely used in genetic diversity and population genetic diversity analysis. In this study, mitochondrial COI was used to analyze the genetic diversities of eight populations of Nerita yoldii along the coast of China. The results showed that N. yoldii has a high level of genetic diversity, with genetic structure differences observed between the Xiapu population and six other populations, excluding the Taizhou population. The results of neutral tests and nucleotide mismatch analyses indicate a historical demographic expansion in the N. yoldii population. Our study results provide foundational data for the conservation and sustainable utilization of N. yoldii resources. Nerita yoldii is a euryhaline species commonly found in the intertidal zone. To investigate the genetic diversity of 233 N. yoldii individuals from eight locations along the coast of China, we utilized the mitochondrial COI gene as a molecular marker. A total of 34 haplotypes were detected, exhibiting a mean haplotype diversity (Hd) of 0.5915 and a mean nucleotide diversity (Pi) of 0.0025, indicating high levels of genetic diversity among all populations. An analysis of molecular variance (AMOVA) indicated that the primary source of genetic variation occurs within populations. In addition, neutral tests and mismatch analyses suggested that N. yoldii populations may have experienced bottleneck events. Moderate genetic differentiation was observed between Xiapu and other populations, excluding the Taizhou population, and may be attributed to the ocean currents. Intensively studying the genetic variation and population structure of N. yoldii populations contributes to understanding the current population genetics of N. yoldii in the coastal regions of China. This not only provides a reference for the study of other organisms in the same region but also lays the foundation for the systematic evolution of the Neritidae family. [ABSTRACT FROM AUTHOR]

Sepiella maindroni was once one of the four traditional marine products in our country. In order to evaluate the ecological capacity of Sepiella maindroni in the sea area of Zhongjieshan Islands, this study used Ecopath with Ecosim 6.5 (EwE) software to construct an Ecopath model composed of 17 functional groups in the sea area of Zhongjieshan Islands. The nutrient structure and energy flow characteristics of the sea area of Zhongjieshan Islands are analyzed from the ecosystem level, and the reasonable ecological capacity of the sea area of Zhongjieshan Islands is estimated by the model.The results show that the trophic level of each functional group in the marine ecosystem of the Zhongjieshan Islands is between 1-4.648, total primary production/total respiration is 4.539, the system Connectance Index is 0.478, the System Omnivory Index is 0.389, The trophic level of Sepiella maindroni is 3.562, and the Ecotrophic Efficiency is 0.306, indicating that the Ecotrophic Efficiency of each trophic level in the system is low and the energy is not fully utilized. There is still room for breeding and exile for the Sepiella maindroni. The model estimates that the ecological capacity of Sepiella maindroni is about 2t·km2.

This article aims to improve the synthesis efficiency and radiation performance of large ultra-wideband (UWB) rotationally symmetric sparse circular planar arrays by using a modified differential evolution algorithm (MDEA). In the proposed MDEA, we adopt a new encoding mechanism in which an individual represents an element position expressed in polar coordinates. Importantly, such an encoding mechanism can facilitate the multiplication calculation for the array factor in the individual being updated while making it easier to meet the given minimum element spacing constraint. Moreover, to cater to the new encoding mechanism, some low-dimensional evolution operators are introduced to avoid the prematurity. In particular, the UWB rotationally symmetric sparse planar array synthesis problem is transformed into the sidelobe suppression problem of the array pattern at the highest frequency under the given array aperture, and the minimum spacing constraints is used to guarantee enough space to place physical UWB antenna elements. Two synthesis examples of UWB sparse planar arrays based on rotationally symmetric structures are presented. The results show that the peak sidelobe level (PSL) obtained by the proposed MDEA is significantly lower than the results obtained by some existing algorithms in an acceptable CPU time, which proves the effectiveness and superiority of the proposed MDEA. [ABSTRACT FROM AUTHOR]