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The soft-shell clam Mya japonica (Jay, 1857) is a commercially important fishery resource. In this study, we identified the complete mitochondrial genome of M. japonica and performed a phylogenetic analysis to explore its genetic relationship with Mya arenaria. The genome is 21,396 bp in length and contains 13 protein-coding genes (PCGs), 23 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and 5 D-Loop control regions. The atp8 gene was annotated in Myidae for the first time. Notably, the genome contains an additional trnM, consistent with M. arenaria. The length of the cox2 gene is 1,947 bp, which is 513 bp longer than that in M. arenaria. Its base composition is 29.14% A, 37.26% T, 10.89% C, and 22.71% G. Phylogenetic analysis based on 12 PCGs and 2 rRNAs indicates that M. japonica and M. arenaria form a sister group. In this study, the identification and phylogenetic analysis of the complete mitochondrial genome of M. japonica provide significant information for future taxonomic and evolutionary research of the genus Mya.

Aeromonas hydrophila (Family: Aeromonadaceae) is a traditional aquatic animal pathogen. It has been widely prevalent in our country since the 1980s and 1990s, causing diseases in a series of freshwater fish, leading to serious economic losses. It has been confirmed to be one of the main pathogens in freshwater aquaculture worldwide. The American shad (Alosa sapidissima) is one of the biggest shad in the world and grows much faster than other shad. Because of its delicious taste as reeves shad (Tenualosa reevesii), American shad were introduced into China from the USA by the Shanghai Fisheries Research Institute for local farming in 1998 and is widely welcomed in Shanghai, Jiangsu, and Zhejiang Provinces. In recent years, with the rapid development of the American shad culturing, fish diseases have become a major threat to fish farming. However, because most of the American shad are cultured in extensive ponds, few diseases have been reported in China. In this study, we reported a case of A. hydrophila infection in American shad. In 2021, the disease outbreak was observed in American shad cultured in Linyi City, Shandong Province, with severe mortality. The daily mortality could be up to 2.5%. The fish were cultured in indoor ponds for breeding and outdoor ponds when fish reached 300 g. The American shad were cultured with underground water and water was changed 1–3 times daily. The water temperature was 18–20 ℃. The fish were fed largemouth bass (Micropterus salmoides) commercial feed, and the daily feeding rate was approximately 2%. The disease broke out in the indoor ponds first, and then in outdoor ponds. The cumulative mortality was approximately 90% in 2 months. Enrofloxacin was administered orally, but no effects were observed and the disease continued to progress. The typical disease symptoms in the American shad were furunculosis or ulceration, with shedding scales and surface bleeding, especially on the tail, sometimes swollen and pus-filled. In autopsies of the diseased fish, ascites were found in the fish abdomen, and dark red necrosis on the liver, with sepsis and enteritis. The liver, spleen, and kidney of American shad with typical symptoms were collected and cut into about 1 cm3 tissue blocks, immersed in Davidson's Fixative (Davidson's AFA) for 24 h, and preserved in 70% ethanol. The tissues were mounted onto glass slides with hematoxylin and eosin staining for histological analysis. Histopathological results showed swollen liver cells, vacuolar degeneration, basophilia, and diffuse necrosis; the spleen showed hemorrhagic anemic necrosis, nuclear rupture, and atrophy. Glomerular atrophy of the renal corpuscle, cells in the proximal and distal tubules cytoarchitectural loss, and necrosis and shedding of kidney lymphocytes was also observed. No parasite was found on the fish surface, fins, in the gills, or internal organs with the naked eye and a light microscope. Freshwater viruses, such as Cyprinus herpesvirus type 2, largemouth bass ranavirus, megalocytivirus, and rhabdovirus, were checked by polymerase chain reaction (PCR), and no viruses were detected. The liver, spleen, and kidney of the diseased fish were sampled and cultured in tryptic soy agar medium (TSA) and Luria-Bertani agar medium (LB) plate medium at 28 ℃ for 24 h. Several pure and dominant colonies with the same morphology were observed on all the plates. These colonies were purified and cultured. The 16S rRNA gene sequencing results of all the purified colonies showed that the dominant strains were of the same species. The typical isolate was purified and named AS-AH2101. The results of biochemical identification with Biolog GenⅢ showed that the isolate AS-AH2101 was negative to gentiobiose, stachyose, D-raffinose, α-D-lactose, D-melibiose, 3-methyl glucose, D-fucose, D-sorbitol, D-arabitol, and Myo-inositol, while positive to dextrin, D-maltose, D-trehalose, D-cellobiose, sucrose, D-turanose, and β-methyl-D-glucoside. According to the Biolog GenⅢ identification system database, the biochemical characterization of AS-AH2101 was similar to that of A. hydrophila, with a confidence of 0.999. The 16S rRNA gene sequence of AS-AH2101 was submitted to GenBank databases under the accession number OP787967 and blasted in GenBank and EzTaxon. Comparison of the 16S rRNA gene sequences showed 99%−100% identity with those of A. hydrophila. The phylogenetic tree was constructed using Mega 7 with the Aeromonas typical strains 16S rRNA gene sequences obtained from GenBank, and the phylogenetic analysis also clustered AS-AH2101 with A. hydrophila. Thus, the molecular analysis results identified the SC18032201 strains as A. hydrophila, and the phenotype also supported this result. Because of the strong stress response of American shad, it is difficult to perform the experimental culturing and infection in the laboratory. As a classic pathogenic infection model organism in aquatic animals, blue gourami (Trichogaster trichopterus) is a traditional model for fish pathogen study and has been widely used in the research of A. hydrophilia and E. piscicida. Therefore, in this study, blue gouramis were used as the model organism for virulence evaluation of AS-AH2101 in the experimental infection. The results of the challenge experiment showed that the death of the blue gourami infected via intramuscular injection was observed on the third day post infection. The infected fish showed redness, bleeding, and scale shedding at the injection site, congestion or bleeding at the base of the fin, abdominal ascites, and liver necrosis, which were similar to the naturally infected American shad. The isolate strain AS-AH2101 showed high virulence to blue gouramis, with the median lethal dose (LD50) of 3.23×104 CFU/fish. The virulence genes of A. hydrophilia were also detected by PCR, and results indicated that AS-AH2101 possessed six virulence genes, including aerolysin (aerA), hemolysin (hlyA), extracellular protease (ahpA), anti-metalloproteinases (ast), enterotoxin (altA), and quorum sensing gene (luxS). Antibiotic sensitivity studies showed that AS-AH2101 was resistant to cefradine, amoxicillin, ampicillin, and erythromycin. These results provided important information for disease control and A. hydrophila prevention and control of American shad culturing in China.

The greenfin horse-faced filefish (Thamnaconus septentrionalis) and rockfish (Sebastes schlegeli) occupy important positions in the offshore net fishery in Shandong Province. Interest in their mariculture has been developing rapidly in recent years as candidates for submerged cage open-sea aquaculture. With the development of breeding techniques and the expansion of large- scale farming, fish disease may become a serious constraint that limits sustainable aquaculture and leads to great economic losses. Epidemiological investigation is the basis of disease control and should be carried out throughout the culture process. In this study, we describe the diseases of T. septentrionalis and S. schlegeli caused by Aeromonas salmonicida subsp. masoucida. In November 2018, an outbreak of T. septentrionalis disease was observed in a farm located in Penglai, Shandong Province, and an outbreak of S. schlegeli disease occurred in the same farm in April 2019, with daily mortalities of 0.4%~1% and about 1%, respectively. The main symptoms in the diseased fish were ulcers, redness, swelling, and bleeding in the mouth. Most diseased fish in the ponds showed "red mouth". No parasites were observed by the naked eye or light microscope. From the liver, spleen, and kidney of all the diseased fish, many homogeneous colonies were observed after three days incubation on TSA and 2216E agar plates. All strains had the same shape, color, and size, and the 16S rRNA genes of all strains were the same, with high identity with A. salmonicida. The virulence of the isolates was tested experimentally via injection with T. septentrionalis (infected by 2018TS-1) and S. schlegeli (infected by 2019SS-1) in the laboratory to calculate the median lethal dose (LD50). The results showed that the LD50 of 2018TS-1 to T. septentrionalis was 1.78×105 CFU/fish, and that of 2019SS-1 to S. schlegeli was 0.89×105 CFU/fish. The dead fish of the experimentally infected group showed ulcers and red mouth, the same symptoms as in naturally infected fish. Dominant colonies isolated from experimentally infected fish were all identified as A. salmonicida by 16S rRNA gene sequencing, which indicated that 2018TS-1 and 2019SS-1 were the pathogens of T. septentrionalis and S. schlegeli, respectively. Bacterial identification was carried out by 16S rRNA gene analysis and Biolog Gen Ⅲ characterization. The 16S rRNA gene sequences of 2018TS-1 and 2019SS-1 (Gene Bank: OK258319 and OK258320) isolated from T. septentrionalis and S. schlegeli were analyzed using MEGA5, and the phylogenetic tree derived from 16S rRNA gene sequences clustered the isolates with A. salmonicida. Among the Biolog Gen Ⅲ tests, 31 produced positive reactions or weak positive reactions for both strains (Dextrin, D-Maltose, D-Trehalose, D-Cellobiose, Sucrose, β-Methyl-D-Glucoside, D-Salicin, α-D-Glucose, D-Mannose, D-Fructose, D-Mannitol, Glycerol, Gelatin, Glycyl-L-Proline, L-Arginine, D-Gluconic Acid, Methyl Pyruvate, L-Malic Acid, Bromo-Succinic Acid, Tween 40, α-Keto-Butyric Acid, Acetoacetic Acid, Propionic Acid, Acetic Acid, pH 6, 1% NaCl, 1% Sodium Lactate, L-Aspartic Acid, L-Glutamic Acid, L-Histidine, and L-Serine), and two weak positive reactions for 2019SS-1, while the others were negative. According to the Biolog database, both strains were identified as A. salmonicida. Based on the molecular analysis of 16S rRNA genes and Biolog Gen Ⅲ phenotype results, the isolates were identified as A. salmonicida. The vapA gene, which encodes the outer membrane protein (A-layer protein) and causes the auto-aggregation of bacteria, is a conserved gene with some variation region in A. salmonicida. vapA gene typing is an effective and important method for classifying the molecular types and subspecies of this fish. vapA gene typing was also used in this study to identify subspecies of strains isolated from T. septentrionalis and S. schlegeli. The vapA gene sequences of 2018TS-1 and 2019SS-1 (Gene Bank: OK300094 and OK300095) were analyzed using MEGA5 with type strains obtained from Gene Bank. The phylogenetic tree derived from the vapA gene sequences clustered 2018TS-1 and 2019SS-1 with type strain ATCC 27013, indicating that the strains isolated from T. septentrionalis and S. schlegeli belonged to A. salmonicida subsp. masoucida, similar to the A-layer type Ⅶ strains, which are all from the northeast Asian and Canadian coasts in the Pacific Ocean. Based on the experimental infection, 16S rRNA sequence analysis, Biolog Gen Ⅲ characterization, and vapA gene typing, we confirmed that A. salmonicida subsp. masoucida is the pathogen of T. septentrionalis and S. schlegeli, and the cause of these two diseases on the farm. This is the first report of T. septentrionalis and S. schlegeli infected by A. salmonicida in industrial aquaculture, as well as the first report of a disease of T. septentrionalis in culture. It has been reported that A. salmonicida subsp. masoucida can infect Atlantic salmon (Salmo salar), turbot (Scophthalmus maximus), sablefish (Anoplopoma fimbria), and tongue sole (Cynoglossus semilaevis) cultured in Shandong Province. In this study, we expanded the host list of A. salmonicida subsp. masoucida to include two new species in aquaculture, T. septentrionalis and S. schlegeli, on the same farm, indicating that A. salmonicida subsp. masoucida may translate and adapt to a new host in a short period. Considering the increasing host and economic losses caused by A. salmonicida in fish culture, the prevention of A. salmonicida subsp. masoucida should be an important objective for mariculture in the future.

In this study, the complete mitochondrial genome sequence of the New Guinea tiger fish Datnioides campbelli (Whitley 1938) (Lobotiformes: Datnioididae) was sequenced by next-generation sequencing method. The assembled mitochondrial genome consists of 13 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes, with a length of 16,416 bp. The total base composition of the mitogenome of D. campbelli was 29.31% for A, 29.02% for C, 15.14% for G and 26.54% for T. A phylogenetic tree based on 13 protein-coding genes (PCGs) provides important molecular data for further phylogeographic and evolutionary analysis of Lobotiformes.

Comaster schlegelii, belonging to the family Comatulidae, is a variable feather star distributed in the Pacific Ocean. The complete mitochondrial genome of this species was 15,887 bp in length, consisting of 13 protein-coding genes, 22 transport RNA genes, two ribosomal RNA genes and one control region. The whole mitochondrial genome of C. schlegelii had a high AT content of 72.73%. The phylogenetic relationship was reconstructed with 16 relevant echinoderms, which revealed C. schlegelii was closely clustered with Anneissia pinguis in the family Comatulidae.

Salinity can affect the physiological and productive characteristics of bivalves. The razor clam Sinonovacula constricta naturally distributing in intertidal zones and estuarine waters is extensively cultured in China. High-salinity is a serious threat to its culture, especially in pond culture model. Here, we investigated the effects of high-salinity on the survival, gill tissue, enzyme activity and free amino acid content of S. constricta. Individuals were randomly divided into six groups treated with different salinities of 20, 25, 30, 35, 40, and 45 ppt. The median lethal salinity calculated by linear regression and probit analysis methods were similar, with 46.61, 43.17, 36.99, 35.99, and 34.99 ppt by linear regression, while 44.63, 42.87, 38.45, 37.32, and 36.17 ppt by probit analysis at 72, 96, 120, 144, and 168 h, respectively. Furthermore, paraffin section revealed that the gill of razor clam shrunk quickly under high-salinity and dissolved at 48 h under salinity of 40 ppt, but not under 30 ppt. In addition, the activities of three enzymes including Na+-K+-ATPase, acid phosphatase and alkaline phosphatase changed significantly under high-salinity. Besides, the contents of total free amino acids (TFAAs) in the gill tissues were 61.25 ± 1.58, 89.36 ± 4.18, and 111.98 ± 1.46 mg⋅g–1 at salinity of 20, 30, and 40 ppt, respectively, indicating increasing TFAA contents with salinity. Notably, several amino acid species including taurine, alanine, proline, glycine and glutamic showed significantly changed contents in response to salinity variation, suggesting these amino acids might play an important role in razor clam’s adaptation to salinity stress. Combining all these results, it was referred that razor clams may adapt to moderately high-salinity of 30 ppt in a short time through osmotic adjustment. Although a small proportion of individuals could survive under the salinity of 35 ppt, the death of most individuals still suggested it can hardly be accepted in aquacultural production. Notably, living under a salinity of 40 ppt for more than 48 h could cause great damage to razor clams. Therefore, the seawater salinity is recommended to be lower than 30 ppt for S. constricta aquaculture. Overall, this study provides guidance for the culture and breeding of high-salinity tolerant razor clams.

The Chinese razor clam (Sinonovacula constricta) is an important for Chinese aquaculture marine bivalve that naturally occurs across intertidal and estuarine areas subjected to significant changes in salinity level. However, the information on the molecular mechanisms related to high salinity stress in the species remain limited. In this study, nine gill samples of S. constricta treated with 20, 30, and 40 ppt salinity for 24 h were used for whole-transcriptome RNA sequencing, and a regulatory network of competing endogenous RNAs (ceRNAs) was constructed to better understand the mechanisms responsible for adaptation of the species to high salinity. A total of 83,262 lncRNAs, 52,422 mRNAs, 2890 circRNAs, and 498 miRNAs were identified, and 4175 of them displayed differential expression pattern among the three groups examined. The KEGG analyses of differentially expressed RNAs evidenced that amino acid synthesis and membrane transport were the dominant factors involved in the adaptation of the Chinese razor clam to acute salinity increase, while lipid metabolism and signaling played only a supporting role. In addition, lncRNA/circRNA-miRNA-mRNA regulatory networks (ceRNA network) showed clearly regulatory relationships among different RNAs. Moreover, the expression of four candidate genes, including tyrosine aminotransferase (TAT), hyaluronidase 4 (HYAL4), cysteine sulfinic acid decarboxylase (CSAD), and ∆1-pyrroline-5-carboxylate synthase (P5CS) at different challenge time were detected by qRT-PCR. The expression trend of TAT and HYAL4 was consistent with that of the ceRNA network, supporting the reliability of established network. The expression of TAT, CSAD, and P5CS were upregulated in response to increased salinity. This might be associated with increased amino acid synthesis rate, which seems to play an essential role in adaptation of the species to high salinity stress. In contrast, the expression level of HYAL4 gene decreased in response to elevated salinity level, which is associated with reduction Hyaluronan hydrolysis to help maintain water in the cell. Our findings provide a very rich reference for understanding the important role of ncRNAs in the salinity adaptation of shellfish. Moreover, the acquired information may be useful for optimization of the artificial breeding of the Chinese razor clam under aquaculture conditions.

A fast-analytical method using simplified extraction has been developed for the simultaneous determination of 42 compounds from 4 different classes of veterinary drugs (amphenicols, triphenylmethane, fluoroquinolones, and sulfonamides) in fish by reverse phase liquid chromatography-tandem mass spectrometry. The selection of extraction reagents was optimized using different types of microfiltration membrane, mobile phase, and LC column. Samples were extracted using 0.4% hydrochloric acid in acetonitrile and ethyl acetate and then were cleaned up using solid-phase extraction Cleanert Alumina N columns (500 mg) and Oasis hydrophilic-lipophilic balance (HLB) cartridges. The chromatographic separation was performed on a XR-ODS C8 column using a mobile phase of (A) 0.1% formic acid and 2 mM ammonium acetate and (B) 0.1% formic acid acetonitrile at a flow rate of 0.25 mL·min−1. The results indicated 67.7–112.8% recovery of 42 compounds with an intra- and interday relative standard deviations less than 10%. The limits of quantification for analytes were in the range of 0.3–1.0 μg kg−1 for samples which were satisfactory to support future surveillance monitoring. The method applicability was checked by analyzing 30 fish samples collected from local markets. Two fish samples surpassed the established MRL of 100 μg kg−1 with values of 104 μg kg−1 and 112 μg kg−1.

Red rot disease is one of the notorious algal diseases that threaten the cultivation of Pyropia in China, and two Pythium pathogens, i.e., Pythium porphyrae and P chondricola, have been reported as causative agents. To monitor the pathogens, a fluorescent quantitative polymerase chain reaction (PCR) method was developed to quantitatively detect their abundance. Using overlapping PCR and pathogen-specific primer pairs, two pathogen-specific fragments were concatenated to construct an internal standard plasmid, which was used for quantification. For zoospores of known numbers, the results showed that this method can detect as less as 100 and 10 zoospores mL-1 in a 200 mL solution for P porphyrae and P chondricola, respectively. Using monthly collected seawater at 10 sites in Haizhou Bay, a typical aquaculture farm in China, a significantly higher temperature and a significantly lower salinity were determined in December 2021. P. porphyrae was determined to be more abundant than P. chondricola, though with similar temporal distribution patterns from December 2021 to February 2022. When a red rot disease occurred in December 2021, the two pathogens were significantly more abundant at two infected sub-sites than the uninfected sub-site within both seawater and sediment, though they were all significantly more enriched in sediment than in seawater. The present method provides the capability to quantify and compare the abundance of two pathogens and also has the potential to forecast the occurrence of red rot disease, which is of much significance in managing and controlling the disease. [ABSTRACT FROM AUTHOR]

Magnetic holes are magnetic depression structures that exist widely in many plasma environments. The magnetic holes with durations of >1 s in the solar wind at Mercury’s orbit have drawn much attention, but the properties of the magnetic holes with shorter durations are still unclear. Here, we investigate the magnetic holes with durations of 0.1–100 s in the upstream region of Mercury’s bow shock based on observations by the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft. They can be divided into two groups according to the distribution of their duration: small-duration magnetic holes (SDMHs, 0.6 s). The duration of each group approximately obeys a log-normal distribution with a median of ~0.25 s and 3 s, respectively. Approximately 1.7% (32.6%) of the SDMHs (LDMHs) reduce the magnetic field strength by more than 50%. For both groups, some structures have a linear or quasi-linear polarization, whereas others have an elliptical polarization. The magnetic hole events in both groups tend to have a higher rate of occurrence when the interplanetary magnetic field strength is weaker. Their occurrence rates are also affected by Mercury’s foreshock, which can increase (decrease) the occurrence rate of the SDMHs (LDMHs). This finding suggests that Mercury’s foreshock might be one source of the SDMHs and that the foreshock can destroy some LDMHs. These observations suggest that a new group of magnetic holes with durations of

Geomagnetic storms can result in large magnetic field disturbances and intense currents in the magnetosphere and even on the ground. As an important medium of momentum and energy transport among the solar wind, magnetosphere, and ionosphere, field-aligned currents (FACs) can also be strengthened in storm times. This study shows the responses of FACs in the plasma sheet boundary layer (PSBL) observed by the Magnetospheric Multiscale (MMS) spacecraft in different phases of a large storm that lasted from May 27, 2017, to May 29, 2017. Most of the FACs were carried by electrons, and several FACs in the storm time also contained sufficient ion FACs. The FAC magnitudes were larger in the storm than in the quiet period, and those in the main phase were the strongest. In this case, the direction of the FACs in the main phase showed no preference for tailward or earthward, whereas the direction of the FACs in the recovery phase was mostly tailward. The results suggest that the FACs in the PSBL are closely related to the storm and could be driven by activities in the tail region, where the energy transported from the solar wind to the magnetosphere is stored and released as the storm is evolving. Thus, the FACs are an important medium of energy transport between the tail and the ionosphere, and the PSBL is a significant magnetosphere–ionosphere coupling region in the nightside.

The Mars Orbiter MAGnetometer (MOMAG) is a scientific instrument onboard the orbiter of China’s first mission for Mars — Tianwen-1. Since November 13, 2021, it has been recording magnetic field data from the solar wind to the magnetic pile-up region surrounding Mars. Here we present its in-flight performance and first science results, based on its first one and one-half months’ data. Comparing these early MOMAG observations to the magnetic field data in the solar wind from NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we report that the MOMAG magnetic field data are at the same level in magnitude, and describe the same magnetic structures with similar variations in three components. We recognize 158 clear bow shock (BS) crossings in these MOMAG data; their locations match well statistically with the modeled average BS. We also identify and compare five pairs of datasets collected when Tianwen-1’s orbiter and the MAVEN probe made simultaneous BS crossings. These BS crossings confirm the global shape of modeled BS, as well as the south-north asymmetry of the Martian BS. Two cases presented in this paper suggest that the BS is probably more dynamic at flank than near the nose. So far, MOMAG performs well, and provides accurate magnetic field vectors. MOMAG is continuously scanning the magnetic field surrounding Mars. Data from MOMAG’s measurements complement data from MAVEN and will undoubt edly advance our understanding of the plasma environment of Mars.

Abstract The Martian bow shock stands as the first defense against the solar wind and shapes the Martian magnetosphere. Previous studies showed the correlation between the Martian bow shock location and solar wind parameters. Here we present direct evidence of solar wind effects on the Martian bow shock by analyzing Tianwen‐1 and MAVEN data. We examined three cases where Tianwen‐1 data show rapid oscillations of the bow shock, while MAVEN data record changes in solar wind plasma and magnetic field. The results indicate that the bow shock is rapidly compressed and then expanded during the dynamic pressure pulse in the solar wind, and is also oscillated during the IMF rotation. The superposition of variations in multiple solar wind parameters leads to more intensive bow shock oscillation. This study emphasizes the importance of joint observations by Tianwen‐1 and MAVEN for studying the real‐time response of the Martian magnetosphere to the solar wind.

Transient current sheets (CSs) are common magnetic structures in the solar wind that can significantly disturb the planetary space environment and cause space weather phenomena. This study focuses on their properties in the Martian space environment and investigates their transformations caused by the Martian bow shock. Based on 14 months of data from the Mars Atmosphere and Volatile Evolution mission during similar solar activity, 786 CSs with directional changes greater than 90° and magnetic field depression were automatically identified, including 256 events in the upstream solar wind and 530 events in the Martian magnetosheath. After crossing the bow shock, the duration and thickness of the CSs decrease, while their current density and occurrence rate significantly increase. In the Martian magnetosheath, CSs located on the dayside exhibit stronger current density, a relatively lower occurrence rate, and a smaller ${B}_{x}/{B}_{T}$ than CSs located on the nightside. From the dayside to the nightside, the predominant magnetic field component of CSs changes to ${B}_{x}$ due to the draping process. Moreover, a clear dawn–dusk asymmetry in CS properties emerges from the foreshock to the downstream region of the Martian bow shock. Our results reveal the properties and evolution of solar wind CSs in the Martian space environment.

We present two multipoint interplanetary coronal mass ejections (ICMEs) detected by the Tianwen-1 and Mars Atmosphere and Volatile Evolution spacecraft at Mars and the BepiColombo (0.56 au ∼0.67 au) upstream of Mars from 2021 December 5 to 31. This is the first time that BepiColombo is used as an upstream solar wind monitor ahead of Mars and that Tianwen-1 is used to investigate the magnetic field characteristics of ICMEs at Mars. The Heliospheric Upwind Extrapolation time model was used to connect the multiple in situ observations and the coronagraph observations from STEREO/SECCHI and SOHO/LASCO. The first fast coronal mass ejection event (∼761.2 km s ^−1 ), which erupted on December 4, impacted Mars centrally and grazed BepiColombo by its western flank. The ambient slow solar wind decelerated the west flank of the ICME, implying that the ICME event was significantly distorted by the solar wind structure. The second slow ICME event (∼390.7 km s ^−1 ) underwent an acceleration from its eruption to a distance within 0.69 au and then traveled with the constant velocity of the ambient solar wind. These findings highlight the importance of background solar wind in determining the interplanetary evolution and global morphology of ICMEs up to Mars distance. Observations from multiple locations are invaluable for space weather studies at Mars and merit more exploration in the future.

Planetary bow shocks noncollisionally dissipate the incident bulk flow energy of solar wind into some other forms. To what extent and how solar wind disturbances affect the energy dissipation processes at the bow shocks on different planets remain unclear. With the Chinese Tianwen-1 and American Mars Atmosphere and Volatile EvolutioN missions, we present the first observation of significant modifications by a solar wind stream interaction region to the Martian foreshock waves, which are an important energy dissipation product of the bow shock. After the stream interface hitting Mars, an unusual band of foreshock waves emerged, with a central frequency of ∼0.4 Hz and frequency width of ∼0.2 Hz. These waves exhibited highly distorted waveforms, with peak-to-peak amplitudes of 10–25 nT in contrast to a background magnetic field of 6–9 nT. They were approximately elliptically polarized with respect to the wavevector and propagated highly obliquely to the background magnetic field. These waves reported here differed greatly from the commonly known Martian foreshock “30 s waves” and “1 Hz waves,” but resembled, to some extent, the less frequently occurring terrestrial foreshock “3 s waves.” Our present findings may imply an unexpected energy dissipation pattern of the Martian bow shock to the disturbed solar wind, which needs further observational, theoretical, and numerical investigations.

Small-scale magnetic holes are common magnetic structures with a spatial scale always smaller than one thermal proton gyroradius (ρi) in the turbulent planetary magnetosheath. However, the contribution of small-scale MHs to dissipating energy and transporting particles in turbulent plasmas is still unclear. In this work, we investigate magnetic fluctuations around small-scale MHs in the Martian magnetosheath and compute their spectral indices in the kinetic frequency range. Our statistical results show that the spectral index value gradually decreases from the bow shock to the induced magnetosphere boundary at the nightside of Mars. Small-scale MHs have an obvious influence on the spectral indices of the magnetic fluctuations by their high-frequency components. For most events, these MHs lead to a variation in the spectral index in the kinetic range, and such a variation can be very significant in more than 20% of events. Our results indicate that because of the existence of MHs, using the spectral index alone as a diagnostic sometimes is not enough convincing during the analysis of turbulence in planetary environments.

With Venus Express magnetic field measurements at 32 Hz from 2006 to 2012, we investigate statistically the magnetic fluctuations in the near-Venusian space. The global spatial distribution of their spectral scaling features is presented in MHD and kinetic regimes. It can be observed that turbulence is a common phenomenon in the solar wind in both regimes. The solar wind MHD turbulence is modified at the Venusian bow shock; MHD turbulence is absent in the Venusian magnetosheath but present at the magnetosheath boundary layer. Pre-existing kinetic turbulence from the far upstream solar wind is modified in the near solar wind region, while kinetic turbulence can be extensively observed throughout the Venusian magnetosheath and in some regions of the induced magnetosphere. Our results reveal that, in the near-Venusian space, energy cascade can be developed at the boundary between magnetosheath and wake, and the turbulence-related dissipation of magnetic energy occurs extensively in the magnetosheath and the induced magnetosphere.

Interplanetary coronal mass ejections (ICMEs) are solar transients that have significant effects on the upper atmosphere and ionosphere of Mars. The simultaneous spacecraft observations from Tianwen-1/MOMAG in solar wind and multiple instruments on board the Mars Atmosphere and Volatile Evolution (MAVEN) in the Martian upper atmosphere are used to study the response of Mars to an ICME. The ICME was observed at Mars by Tianwen-1 and MAVEN at 00:00 UT on 2021 December 10, which was earlier observed by BepiColombo upstream of Mars at 22:32 UT on 2021 December 6. During 2021 December 6–15, MAVEN measured the nightside ionosphere and Tianwen-1 measured the dayside ionosphere while both were inside the Martian bow shock. The rapid drop in densities of ionospheric ions and electrons, which is typically identified as the end of the ionosphere at altitudes between 300–800 km, is known as the ionopause. The altitude of the Martian ionopause location was lowered by the high dynamic pressure of the solar wind during the ICME passage. The depletion of the plasma density in the topside Martian ionosphere on the nightside reveals the presence of substantial ion and electron escape to space through the interaction between the ICME and Mars. The column abundance of plasma dramatically decreased, with 34% e ^− , 61% ${{\rm{O}}}_{2}^{+}$ , and 73% O ^+ reduced. This study highlights the significant impact of the space weather associated with the intense magnetic field and high dynamic pressure of the ICME on Mars’s atmosphere, which is particularly important for future human exploration missions to Mars.

The Tianwen-1 spacecraft is China's first Mars exploration mission. The Mars Orbiter Magnetometer (MOMAG) is a scientific instrument on board the Tianwen-1 mission that is designed to study magnetic fields at Mars, including the solar wind to the magnetosheath and the ionosphere. Using the first Tianwen-1/MOMAG data that is publicly available, we present an interplanetary coronal mass ejection (ICME) and stream interaction region (SIR) list based on in situ observations at Mars between 2021 November 16 and 2021 December 31. We compared the magnetic field intensity and vector magnetic field measurements from Tianwen-1/MOMAG and Mars Atmospheric Volatile EvolutioN (MAVEN)/Magnetometer (MAG) during the ICME and SIR interval and found a generally good consistency between them. Due to MAVEN's orbital adjustment since 2019, the Tianwen-1/MOMAG instrument is almost unique in its status as an interplanetary magnetic field monitor currently at Mars. The observations indicate that the MOMAG instrument on Tianwen-1 is performing well and can provide accurate measurements of the vector magnetic field in the near-Mars solar wind space. The multipoint observations combining MOMAG, MINPA, and MEPA on board Tianwen-1 with MAG, SWIA, and STATIC on board MAVEN will help develop systematic studies of the characteristics of ICMEs and SIRs at Mars, and their influences on the Martian atmosphere and ionosphere.

Like 1 Hz waves occurring in the upstream of various celestial bodies in the solar system, 1 Hz narrowband whistler-mode waves are often observed around the Moon. However, wave properties have not been thoroughly investigated, which makes it difficult to proclaim the generation mechanism of the waves. Using 5.5 yr wave data from ARTEMIS, we perform a detailed investigation of 1 Hz waves in the near-lunar space. The amplitude of lunar 1 Hz waves is generally 0.05–0.1 nT. In the geocentric solar ecliptic coordinates, the waves show no significant regional differentiation pattern but show an absence inside the magnetosphere. Correspondingly, in the selenocentric solar ecliptic coordinates, the waves can occur extensively at ∼1.1–12 R _L , while few events are observed in the lunar wake due to a lack of interaction with the solar wind. Furthermore, the wave distributions exhibit modest day–night and dawn–dusk asymmetries but less apparent north–south asymmetry. Compared with the nightside, more intense waves with lower peak wave frequency are present on the dayside. The preferential distribution of 1 Hz waves exhibits a moderate correlation with strong magnetic anomalies. The waves propagate primarily at wave normal angles

In this paper, we present a new tool to investigate the interaction of the solar wind with Venus with the approach of a global multifluid magnetohydrodynamics (MHD) model. The continuity, momentum, and energy equations for H ^+ , O ^+ , ${{\rm{O}}}_{2}^{+}$ , and ${\mathrm{CO}}_{2}^{+}$ are solved self-consistently together with Faraday’s law. The photochemistry of ionospheric ions are considered as the source term in the density, momentum, and energy equations for each ion. We found that the simulated ionospheric density, temperature, and the bow shock location are consistent with previous observations and simulations for both the solar maximum and minimum. The simulated magnetic fields also agree well with the Venus Express observations. Meanwhile, the high-resolving power and low numerical diffusion makes the model capable of capturing the fine structures of the Venusian-induced magnetosphere, such as the Kelvin–Helmholtz instability and the nightside wake. The escape rates have also been estimated and the results are similar to previous estimations. The high-resolution model could be an efficient tool for the exploration of the fine structures of the Venusian space environment system, and also for the application to other unmagnetized planets.

The effects of dietary protein (DP) levels on the growth, digestibility, digestive enzyme activity and stress tolerance of Litopenaeus vannamei (Boone, 1931) were investigated in high-density (375 m) tank trials. Shrimps (6.2 ± 0.2 g) were fed diets with five different protein levels (31%, 35%, 39%, 43% and 47%) for 60 days. The results showed that variations in DP significantly ( P<0.05) influenced the growth performance, digestibility, enzyme activity and their ability to tolerate stress. Weight gain showed a linear increase in relation to crude protein (CP) up to 43% and showed a slight decrease with a further increase to 47%. Feed conversion ratio was observed to be the lowest in CP 43%: 2.53. A higher protein efficiency ratio was observed with the low-protein diet CP31 (1.07); however, it was not significantly different from the rest of the dietary treatments. Protein digestibility was the highest (75.71%) in CP47 and the lowest (71.94%) in CP31. Protease activity ranged between 63.7 and 70.2 (U Protein), and showed a positive correlation with the DP levels. Shrimp fed CP43 well tolerated a sudden decline in salinity and survived for 548.3 min in fresh water. Observations from this study indicate that a DP level around 43% could be optimum for L. vannamei in high-density culture systems in the absence of natural productivity. [ABSTRACT FROM AUTHOR]