Chlorostoma rustica is an economically important species that thrives in rocky intertidal zones and is frequently exposed to salinity fluctuations. In this study, RNA sequencing and metabolomic profiling were performed on foot muscle tissues from C. rustica exposed to four salinity levels (18, 23, 28 control, and 38 psu) for 6 and 24 h to profile transcriptional and metabolic responses, respectively. A total of 93.18 Gb of high-quality clean reads were generated, resulting in 130,291 unigenes with N50 = 1113 bp and a mean length of 890.64 bp. Compared with the control group, the high-salinity group demonstrated 3370 and 3468 differentially expressed genes (DEGs) at 6 and 24 h, respectively. In the low-salinity Group 1 (18 psu), 3522 and 3489 DEGs were identified at 6 and 24 h, respectively. In the low-salinity Group 2 (23 psu), 3103 and 4293 DEGs were detected at 6 and 24 h, respectively. KEGG analysis showed that DEGs in low- and high-salinity groups were significantly enriched in core immune response and apoptosis-related pathways. ABCA3, MAP3K7IP2, and CLEC4G were identified as key genes in terms of salinity adaptation. Six DEGs were randomly selected for quantitative RT-PCR validation, confirming the reliability of the transcriptomic data. Metabolomic profiling identified 488 differential metabolites (DMs) in low-salinity group 1 (18 psu), mainly enriched in lipid and amino acid metabolism pathways. In the high-salinity group (38 psu), 363 DMs were detected, primarily enriched in amino acid metabolism and nutrient absorption-related pathways. In low-salinity group 2 (23 psu), 308 DMs were identified; however, no metabolic pathways were significantly enriched. Integrative transcriptomic and metabolomic analyses revealed coordinated changes in pathways related to osmotic regulation, energy metabolism, membrane lipid metabolism, and oxidative stress responses. These findings indicate that salinity induces the stress response of C. rustica by regulating osmotic balance (e.g., L-proline, spermine), lipid metabolism (e.g., acylcarnitines, sphingolipids), and transport systems. Overall, this study provides valuable insights into the molecular mechanisms underlying salinity tolerance in intertidal gastropods.

The Asian paddle crab, Charybdis japonica, is a commercially and ecologically important marine species. Discerning the population genetic structure and connectivity of C. japonica in a dynamic marine environment is crucial for implementing sustainable management practices. This study investigated the population genetics of C. japonica in the Bohai, Yellow, and East China Seas using 104 mtDNA control-region sequences; a total of 26 haplotypes were identified. High haplotype but low nucleotide diversity were detected among five populations. The frequency of the dominant haplotype H4 declined along the Chinese coast from the southern regions (Taizhou and Zhoushan) to the northern regions (Lianyungang, Yantai, and Dalian). The relatively abundant H1 haplotype exhibited a higher localized frequency in the south than in the north. A Neighbor-Joining phylogenetic tree was constructed from these sequences; two distinct lineages (A and B) with remarkable differences in their geographic distribution frequencies were detected. The proportion of lineage A individuals declined along the Chinese coast from south to north, and lineage B members were mainly found in the Dalian population. AMOVA and pairwise FST values showed statistically significant genetic differences among five populations, with the Dalian population differing most from the other four. The Mantel test results indicated that coastal distance may hinder gene flow between Dalian and the other four populations. Thus, our results suggest that five C. japonica populations along the Chinese coast can be considered separate fishery management units. These findings can help guide the design of future C. japonica management practices applicable to this region of China’s coastal waters.

Microplastics (MPs) are widely studied as marine contaminants, yet their ecological roles in microbial systems remain incompletely understood. Conventional toxicological frameworks, largely developed for multicellular organisms, emphasize acute stress and cellular damage but capture only a limited subset of microbial responses. Here, we propose a stage-structured framework in which MPs function primarily as selective substrates rather than as conventional toxicants. Plastisphere assembly is governed by dynamically shifting selection across three stages: initial physicochemical filtering, substrate- and metabolism-driven selection, and biofilm-mediated spatial adaptation. Central to this process is the coupling between substrate transformation and reactive oxygen species (ROS) dynamics. Extracellular ROS arise from interfacial reactions of weathered plastic compounds, while intracellular ROS are generated during microbial carbon assimilation. These processes are mechanistically linked: plastic-derived compounds act as both substrates and stressors, and extracellular ROS further transform them into more bioavailable forms, reinforcing intracellular constraints. Biofilms introduce spatial organization that redistributes metabolic and oxidative burdens, enabling metabolic cooperation, stress partitioning, and HGT, allowing selection to operate at both individual traits and spatially organized community levels. Together, this framework shifts the perspective from toxicity-based interpretations toward a selection paradigm that integrates substrate availability, metabolic constraints, and spatial organization, providing a mechanistic basis for linking microscale microbial processes to broader ecological and biogeochemical dynamics.

In recent decades, species distribution models have emerged as essential tools for analyzing the potential effects of climate change on species distributions. This study employed an ensemble model to predict future changes in the distributions of small yellow croaker (Larimichthys polyactis) across seasons for the years 2030, 2050, and 2100 under the SSP1-2.6 and SSP2-4.5 climate scenarios of the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6). The species distribution model results indicated that the integrated model’s true skill statistics and area under the curve values of the receiver operating characteristic exceeded 0.95. The model demonstrates good predictive performance. Among the four seasons, summer habitat showed a notable reduction, and losses ranged from 14.945% (SSP1-2.6) to 29.080% (SSP2-4.5) by the 2100s. Habitat reduction occurred mainly in the offshore waters of the Bohai, Yellow, and East China Seas. The center of gravity of the species’ distribution shifted to higher latitudes and exhibited notable seasonal variation. The findings establish a predictive framework for the development of this species, and the prediction results based on scientific analysis will support the optimization of fishery management strategies in the context of climate change and thereby facilitate the sustainable use of fishery resources.

Halogenated organic compounds (HOCs) are pervasive in marine environments, yet their molecular diversity, vertical distribution, and fate in deep-sea ecosystems remain largely uncharted. Here, we integrated non-targeted analysis, geochemical profiling, and metagenomics to systematically analyze a 500-cm sediment core from the Haima deep-sea cold seep, deciphering these key aspects and their controlling factors. Non-targeted analysis identified 669 HOCs (at molecular formula level), predominantly of marine origin with saturated structures. The highest HOC diversity was found in the oxic/suboxic (OS) zone, where 73.4% of the frequently detected HOCs reached their peak abundance. Concurrently, a marked decrease in organochlorines was observed at the OS-suboxic/anoxic (SA) interface, followed by level stabilization below this transition, suggesting regulation by abrupt redox shifts. Correlation analyses revealed co-regulation of HOC distribution by geochemical (e.g., depth, pH, and SO42-) and microbial (e.g., reductive and hydrolytic dehalogenases) factors. Metagenomics combined with redundancy analysis further demonstrated significant interactions between HOCs and dehalogenating microbial community along the vertical profile. In summary, this study provided an integrated perspective on the biogeochemical cycling of HOCs in the deep-sea cold seep, linking their removal at redox boundaries, long-term burial, and spatial organization to underlying microbial and geochemical drivers.

Based on previous studies and the ecological characteristics of Portunus trituberculatus, we hypothesized that climate change could substantially reshape its suitable habitat in Zhoushan fishing ground. Under present-day climate conditions (2010-2020), P. trituberculatus exhibits a distinct seasonal distribution pattern in this region. However, its potential spatial response to future climate change, and whether suitable habitat will remain available, remains poorly understood. To address this gap, we combined species occurrence records with environmental variables from the Bio-ORACLE v3.0 database, including benthic temperature, benthic salinity, benthic current velocity, primary productivity, bathymetry, topographic slope, and topographic aspect, to develop a maximum entropy (MaxEnt) model and predict the potential distribution of suitable habitat for P. trituberculatus under present-day conditions and future SSP1-2.6 and SSP2-4.5 scenarios for 2030-2040, 2040-2050, and 2090-2100. Model performance was high across all seasons, with area under the curve values exceeding 0.80. Primary productivity and benthic temperature were the dominant environmental predictors, highlighting the joint influence of trophic conditions and thermal constraints on habitat suitability. Future projections revealed pronounced seasonal reorganization of suitable habitat rather than a uniform range shift. Spring suitable habitat expanded consistently under both scenarios, with the magnitude of expansion increasing toward the end of the century and reaching 46.9% by 2100 under SSP2-4.5, likely because warming relaxed low-temperature limitation during the early seasonal transition. In contrast, suitable habitat in autumn and winter generally contracted. Autumn losses were moderate but persistent, ranging from 5.4% to 16.4%, whereas the strongest declines occurred in winter, particularly under SSP2-4.5, where habitat reductions exceeded 30% after mid-century. These contractions were likely associated with cumulative thermal stress and related environmental changes under continued warming. Summer responses were scenario-dependent, showing weak gains or net declines under SSP1-2.6 but substantial expansion under SSP2-4.5 after mid-century, reaching up to 23.6% by 2050, suggesting that habitat suitability in this season is shaped by interactions among thermal conditions, trophic support, and habitat characteristics. Overall, these findings reveal strong seasonal asymmetry in habitat responses to climate change and provide a scientific basis for seasonally adaptive management of P. trituberculatus resources in Zhoushan fishing ground.

The giant African snail (Achatina fulica), a globally invasive mollusk, poses a serious threat to agricultural production and the ecological environment. However, few studies have focused on the feeding preference and growth performance of A. fulica on different plants, with especially few reports on the correlation between the nutrient content of plants and its growth performance. In this study, 10 plant species, including lettuce, stem lettuce, spinach, Chinese cabbage, cabbage, rape, apple, pear, banana, and pitaya, were selected as food sources to explore their effects on the feeding and growth performance of A. fulica. The results showed that A. fulica had the highest selection rate for lettuce and the lowest for rape. Feeding consumption (FC), daily body growth (DBG), daily increase in shell diameter (DISD), daily increase in shell length (DISL), relative consumption rate (RCR), and relative growth rate (RGR) of snails feeding on lettuce were significantly higher than those in the other nine groups. FC, DBG, DISD, DISL, RCR, and RGR were significantly correlated with the nutrient contents (protein, carbohydrate) of the 10 plants and with the protein-to-carbohydrate (P:C) ratio. Finally, based on the correlation between the macronutrient content of plants and the growth performance of A. fulica, we determined that these snails exhibit the optimal growth performance when fed food with the relative balanced P:C ratios (0.41-0.66) while having poor growth performance when fed plants with extremely imbalanced P:C ratios (rape: 2.45 or fruits: 0.04-0.13). Our study shows that A. fulica may cause potential economic losses for many cultivated plants, particularly lettuce, and provides a foundation for certain research values for agricultural prevention and ecological environment protection.

The large yellow croaker (Larimichthys crocea) is a flagship marine fish in China given its extreme commercial value and golden-yellow coloration. However, the genetic mechanisms underlying golden-yellow coloration remain unclear. Here, we construct a telomere-to-telomere gap-free genome assembly (T2T-Larcro_1.0) spanning 716.87 Mb, with a contig N50 of 31.75 Mb. Compared to the current reference genome (L_crocea_2.0), T2T-Larcro_1.0 incorporates 112.70 Mb of previously unassembled regions and 2368 newly anchored genes. This assembly facilitates comparative genomics analyses in sciaenids by identifying several candidate genes (e.g., OPNVA, nNOS, RDH13) potentially involved in evolution of golden-yellow coloration. Transcriptomic analyses further confirm expression of OPNVA-encoded vertebrate ancient opsin (VA opsin) in skin tissues of the large yellow croaker, suggesting its role as an extraretinal photoreceptor regulating localized golden-yellow coloration. Integrating genomics and transcriptomics results, we uncover the triggering effect of VA opsin linking skin and neural photoreception to physiological regulation of body color change (golden-yellow to silvery-white) in L. crocea. Collectively, our findings provide molecular evidence that elucidate the underlying evolutionary mechanism of golden-yellow coloration in L. crocea. This high-quality genome assembly also serves as an improved resource for biological evolution, genetic improvement, and selective breeding of L. crocea.

Due to the unique microstructure and diverse opsin genes of the trinocular compound eye, stomatopoda possess an extraordinary ability to perceive multiple properties of light. They not only can detect natural light (NL) and linearly polarized light (LPL), but also are the only animals capable of recognizing circularly polarized light (CPL). Here, we integrated single-cell RNA sequencing, previously published Illumina data, and in-situ hybridization (ISH) to quantify and localize functional opsin genes in Oratosquilla oratoria, a common stomatopoda species in the China Sea. A total of high-quality 31 777 cells were captured for the first time in the O. oratoria compound eye, which were classified into 25 cell subpopulations, and hypothesized that cluster 22 is a critical cell subpopulation responsible for light (whether NL, LPL, or CPL) response in O. oratoria. Furthermore, we propose that the long-wavelength-sensitive opsin gene (lws) gene family, retinol dehydrogenase (rdh), voltage-gated ion channel (vgic), arrestin (arr), and myosin (myo) collectively mediate the light response in O. oratoria. Considering that very few vision-related opsin genes show differential expression in right-handed CPL (RCPL) -vs.- dark (DL), which provides additional evidence that stomatopoda cannot recognize RCPL. Meanwhile, we believe that UV-stimulated scaffold protein A (uvssa) and red pigment concentrating hormone (rpch) play special contributions in the left-handed CPL (LCPL) environment response. ISH revealing that 16 lws, 6 middle-wavelength-sensitive (mws), and 2 ultraviolet (uv) opsin genes were expressed in the photoreceptors of the O. oratoria compound eye. Although the inability to determine the functional types of cell subpopulations limits the resolution of opsin genes, these findings systematically elucidate the specific expression patterns of opsin genes in O. oratoria and represent a significant step toward refining the visual ecological theory of O. oratoria and other stomatopod species.

This research identified functional genes and regulatory pathways of salinity stress in red claw crab Uca arcuata, which a globally distributed intertidal species inhabiting saline ecosystems, providing data and theoretical basis for the protection and utilization of U. arcuata in global climate change. In this study, we performed RNA sequencing on U. arcuata gill tissues exposed to salinity gradients (15‰, 25‰ control, and 35‰) to profile transcriptional responses. A total of 63.83 GB of high-quality clean reads were generated, yielding 125,462 unigenes with robust assembly metrics (N50 = 969 bp; mean length = 688 bp). The transcriptome analysis predicted 101,280 coding sequences (CDSs) and 52,706 simple sequence repeats (SSRs). Compared with the control group, the high-salinity group obtained 52 differentially expressed genes (DEGs), with 36 upregulated and 16 downregulated genes. The low-salinity group obtained 1,035 DEGs, with 780 upregulated and 255 downregulated genes. GO analysis showed a significant enrichment of DEGs in signal transduction, enzymatic activity, and binding. KEGG analysis showed that most DEGs were associated with signaling pathways and metabolism. APOA1, APOA2, GPX and GST were specific genes related to salinity adaptation. Five DEGs were randomly selected for quantitative RT-PCR validation, and the results demonstrated that the transcriptome data are highly reliable. However, we did not delve into the key functional genes and their regulatory mechanisms. Joint analysis of the genome and transcriptome of U. arcuata should conduct in the future, and comprehensively elucidate its adaptation mechanism to salinity fluctuations.

Atrogin-1, a muscle-specific ubiquitin ligase, is integral to the regulation of protein degradation and plays a pivotal role in the targeted degradation of critical muscle signaling proteins, which can lead to skeletal muscle dysfunction. High salt stress is known to induce muscle atrophy and alter the physical and chemical properties of muscle in cultured fish. Conversely, an optimal salinity level can enhance muscle quality. The Russian sturgeon ( Acipenser gueldenstaedtii), an anadromous species of significant economic value, is potentially adaptable to brackish water environments, yet the underlying regulatory mechanisms remain elusive. To elucidate the regulatory mechanism of Atrogin-1 in response to high salt stress in Russian sturgeon, we conducted cDNA cloning and expression analysis. The cDNA encoding the Russian sturgeon protein Atrogin-1 was successfully cloned, comprising 1472 bp and encoding 353 amino acid residues (with an open reading frame of 1062 bp). Utilizing the sequence of Russian sturgeon atrogin-1, we designed novel primers and a specific anti-peptide antibody for our study, confirming that atrogin-1 is selectively expressed in skeletal muscle and heart tissues. The sturgeons were then allocated into four experimental groups for salt stress exposure; one control group was maintained in freshwater, while the others were subjected to salinities of 8 %o, 16 %o, and 24 %o, respectively. Quantitative PCR (qPCR) and western blot analysis were employed to assess Atrogin-1 expression levels under high salt stress. A significant upregulation of atrogin-1 mRNA was observed at salinities of 16 %o and 24 %o compared to the control group. Similarly, protein expression levels of Atrogin-1 were markedly elevated under the same salinity conditions. Our findings indicate that the modulation of Atrogin-1 expression is a sensitive indicator of the response to high salt stress. This research is anticipated to inform aquaculture practices and shed light on the selection of germplasm resources for the development of salt-tolerant Russian sturgeon strains.

Deep-sea cold seeps harbor a rich and diverse repertoire of reductive dehalogenase-encoding genes (rdhA), yet their potential for reductive dehalogenation remains largely unexplored. In this study, we investigated the microbial debromination of 2,4,6-tribromophenol (TBP) in cold seep sediment microcosms. By optimizing culture conditions with different nutrient sources and substrate concentrations, we established a highly efficient debrominating microbial consortium capable of completely degrading 50 μM TBP within 72 h. Metagenomic analysis revealed Bin3, a novel bacterium affiliated with Peptococcaceae, as a key dehalogenator harboring multiple rdhA genes. Microbial community analysis demonstrated that nutrient availability significantly influenced beta diversity (community composition) but had only a minor effect on alpha diversity. Through degradation kinetics, co-occurrence network analysis, normalized stochasticity ratio analysis, and metagenomic quantification, we found that supplementing lactate along with 0.05 % yeast extract significantly enhanced TBP degradation efficiency and facilitated the targeted enrichment of key dehalogenating microbes (with relative abundance increasing from <1 % to 32 %). Comparative genomic analysis indicated that Bin3 has undergone specific adaptations through expansion of gene families involved in pili formation, cell motility, nutrient acquisition, and diverse metabolic pathways, potentially enhancing its competitiveness in deep-sea cold seep environments. This study advances our understanding of deep-sea dehalogenating microbiomes and their adaptation to extreme environments, providing insights into their ecological significance and potential applications in pollutant bioremediation.

17α-methyltestosterone (MT) is known for its ability to suppress ovaries and induce spermatogenesis; yet, its effects in crustaceans are underexplored. This study investigates the impact of varying MT concentrations on the gonadal development and intestinal microbiota of juvenile Macrobrachium rosenbergii. Feeds containing different MT doses were provided, and the sex ratios, histological observations, reproductive gene expression, and intestinal microbial composition were analyzed. The results revealed short-term feeding (60 days) of 1000 mg/kg MT resulted in the highest male ratio, while long-term feeding (150 days) of 500 mg/kg MT achieved the same outcome. Conversely, long-term feeding of 1500 mg/kg MT led to the lowest male ratio and retarded male germ cell development. An intestinal microbiota analysis showed that MT supplementation significantly increased microbial abundance and altered the intestinal microbial community structure. Additionally, MT suppressed the expression of female reproductive-related genes. This study provides insights into the effects of MT on reproductive development and gut microbiota in juvenile prawns, offering a valuable reference for the application of MT in crustacean aquaculture.

Monodonta labio is exposed to prolonged periods of air exposure due to the complexity and variability of the intertidal environment, particularly the cyclical rise and fall of the tides. However, current research tends to focus on changing temperature and salinity rather than atmospheric exposure. In this study, RNA sequencing (RNA-seq) was used to analyze gene expression levels at different times of air exposure in the intertidal mollusc M. labio. Transcriptome analysis of nine individuals yielded 420.81 Mb of clean data, and the number of clean reads mapped to the genome ranged from 62.91% to 90.96%. In comparison with the control group, the 2 days and 5 days air exposure stress group groups showed 50 and 940 differentially expressed genes (DEGs), respectively. Gene Ontology (GO) enrichment analysis revealed that the DEGs were significantly enriched in enzyme activity, catalytic activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment revealed that the DEGs were significantly enriched in immune response, Apoptosis. Several key genes (BRAF, RAN, COL6A, DNAJA1) were related to air exposure. Among them, RAN, COL6A, DNAJA1 were differentially expressed on 2 day air exposure compared to 5 day air exposure, and BRAF was differentially expressed in all three groups. Eight differentially expressed genes were randomly selected for qRT-PCR validation, and the results showed that the transcriptomic data were of high confidence.

The assembly of complete and circularized mitochondrial genomes (mitogenomes) is essential for population genetics, phylogenetics and evolution studies. Recently, Song et al. developed a seed-free tool called MEANGS for de novo mitochondrial assembly from whole genome sequencing (WGS) data in animals, achieving highly accurate and intact assemblies. However, the suitability of this tool for marine fish remains unexplored. Additionally, we have concerns regarding the overlap sequences in their original results, which may impact downstream analyses. In this Letter to the Editor, the effectiveness of MEANGS in assembling mitogenomes of cartilaginous and ray-finned fish species was assessed. Moreover, we also discussed the appropriate utilization of MEANGS in mitogenome assembly, including the implementation of the data-cut function and circular detection module. Our observations indicated that with the utilization of these modules, MEANGS efficiently assembled complete and circularized mitogenomes, even when handling large WGS datasets. Therefore, we strongly recommend users employ the data-cut function and circular detection module when using MEANGS, as the former significantly reduces runtime and the latter aids in the removal of overlapped sequences for improved circularization. Furthermore, our findings suggested that approximately 2x coverage of clean WGS data was sufficient for MEANGS to assemble mitogenomes in marine fish species. Moreover, due to its seed-free nature, MEANGS can be deemed one of the most efficient software tools for assembling mitogenomes from animal WGS data, particularly in studies with limited species or genetic background information.

Global climate change has caused rapid temperature changes in marine environments. Understanding how marine organisms respond to temperature changes can help predict their richness of future biodiversity. In this study, we examined the gene expression levels and the difference in the pathways that are responsive to acute temperature stress in low- and high-latitude populations of the shore swimming crab, Charybdis japonica. The two populations of C. japonica were exposed to low- and high-temperature stresses (15°C and 28°C) and used for transcriptome sequencing. Genetic regulatory ability changes were compared to determine the diverse response of the two crab populations to temperature change. The gene expression levels and functional enrichment analysis showed that the low-latitude crab regulated more genes (938) that were mainly enriched in DNA replication and metabolic pathways, whereas the high-latitude crab regulated less genes (309) that were mainly enriched in genetic information processing at low-temperature stress. Furthermore, the low-latitude crab regulated less genes (33) that were mainly enriched in genetic information processing, whereas the high-latitude crab regulated more genes (280) that were mainly enriched in signal transduction and cellular process at high-temperature stress. These results implied that the low-latitude population was more resilient to high-temperature stress, while the high-latitude population was more resilient to low-temperature stress. This study enhances our understanding of how different geographic C. japonica populations respond to varying temperature environments in their living zone, which could be helpful for predicting future biodiversity trends of intertidal crustaceans under global climate change.

Meghimatium bilineatum is a notorious pest land slug used as a medicinal resource to treat ailments in China. Although this no-model species is unique in terms of their ecological security and medicinal value, the genome resource of this slug is lacking to date. Here, we used the Illumina, PacBio, and Hi-C sequencing techniques to construct a chromosomal-level genome of M. bilineatum. With the Hi-C correction, the sequencing data from PacBio system generated a 1.61 Gb assembly with a scaffold N50 of 68.08 Mb, and anchored to 25 chromosomes. The estimated assembly completeness at 91.70% was obtained using BUSCO methods. The repeat sequence content in the assembled genome was 72.51%, which mainly comprises 34.08% long interspersed elements. We further identified 18631 protein-coding genes in the assembled genome. A total of 15569 protein-coding genes were successfully annotated. This genome assembly becomes an important resource for studying the ecological adaptation and potential medicinal molecular basis of M. bilineatum.

The gut microbiota plays a crucial role in food webs, carbon cycling, and related elements. Exopalaemon annandalei and Exopalaemon carinicauda are two important forage species in the Yangtze River estuary with extremely similar living habits and morphological characteristics. Exploring the microorganisms in the guts of these two shrimp species can help us understand the survival status of forage species and gut microbiota in the Yangtze River estuary. Therefore, this study analyzed the similarities and differences in the intestinal flora of E. annandalei and E. carinicauda through high-throughput sequencing of 16S rRNA gene amplicons. The results showed that the dominant bacteria in the intestinal flora of E. annandalei and E. carinicauda at the phylum level were Proteobacteria and Firmicutes, respectively. At the genus level, the intestinal flora had higher concentrations of Psychrobacter, Bacillus, Pseudomonas, Acinetobacter, and Macrococcus. In both shrimp species, the contents of Acinetobacter and Macrococcus were higher in spring than in winter. The most important potential functions of the intestinal microbiota were amino acid metabolism and purine metabolism. Additionally, the functions of metabolism and diseases in the intestinal microbiota of E. annandalei were greatly influenced by the season. Furthermore, the experimental results indicated that a lower ratio of Firmicutes to Bacteroidetes was associated with a larger body weight in shrimp. Overall, this study provides a theoretical reference for understanding the intestinal bacterial community of shrimp in estuaries and the healthy cultivation of E. annandalei and E. carinicauda.

For marine invertebrates, the disruption of organismal physiology and behavior by nanoplastics (NPs) has been extensively reported. Heat shock proteins (Hsps) are important for redundant protein breakdown, environmental changes, and intracellular protein transport. An exhaustive identification of Hsp70 genes and an experiment where different concentrations of NPs were stressed were performed to study how Hsp70 genes respond to NPs stress in Monodonta labio. Our results identified 15 members of Hsp70 within the genome of M. labio and provided insights into their responses to different concentrations of acute NP stress. Phylogenetic analyses revealed extensive amplification of the Hsp70 genes from the Hsc70 subfamily, with gene duplication events. As a result of NP stress, five of fifteen genes showed significant upregulation or downregulation. Three Hsp70 genes were highly expressed at an NP concentration of 0.1 mg/L, and no genes were downregulated. At 10 mg/L, they showed significant upregulation of two genes and significant downregulation of two genes. At 1 mg/L treatment, three genes were significantly downregulated, and no genes were significantly upregulated. Moreover, a purifying selection was revealed using a selection test conducted on duplicate gene pairs, indicating functional redundancy. This work is the first thorough examination of the Hsp70s in Archaeogastropoda. The findings improve knowledge of Hsp70s in molluscan adaptation to NP stress and intertidal living and offer essential data for the biological study of M. labio.