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Volume 39 ， Issue 3 ， 2021
- Abstract：The feedback induced by mesoscale wind stress-SST coupling to the ocean in the western coast of South America was studied using the Regional Ocean Modeling System (ROMS). To represent the feedback, an empirical mesoscale wind stress perturbation model was constructed from satellite observations, and was incorporated into the ocean model. Comparing two experiments with and without the mesoscale wind stress-SST coupling, it was found that SST in the mesoscale coupling experiment was reduced in the western coast of South America, with the maximum values of 0.5 ℃ in the Peru Sea and 0.7 ℃ in the Chile Sea. A mixed layer heat budget analysis indicates that horizontal advection is the main term that explains the reduction in SST. Specifically, the feedback induced by mesoscale wind stress-SST coupling to the ocean can enhance vertical velocity in the nearshore area through the Ekman pumping, which brings subsurface cold water to the sea surface. These results indicate that the feedback due to the mesoscale wind stress-SST coupling to the ocean has the potential for reducing the warm SST bias often seen in the large-scale climate model simulations in this region.Keywords：mesoscale air-sea coupling;western coast of South America;ocean model simulations;cooling effect;warm bias5|0|0Updated：2023-05-20
- Abstract：The Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data were used to analyze the temporal and spatial distribution characteristics of water clarity (Zsd) in the Jiaozhou Bay, Qingdao, China, in the Yellow Sea from 2000 to 2018. Zsd retrieval models were regionally optimized using in-situ data with coincident MODIS images, and then were used to retrieve the Zsd products in Jiaozhou Bay from 2000-2018. The analysis of the Zsd results suggests that the spatial distribution of relative Zsd spatial characteristics in Jiaozhou Bay was stable, being higher Zsd in the southeast and a lower Zsd in the northwest. The annual mean Zsd in Jiaozhou Bay showed a significant upward trend, with an annual increase of approximately 0.02 m. Water depth and wind speed were important factors affecting the spatial distribution and annual variation of Zsd in Jiaozhou Bay, respectively.Keywords：water clarity;Jiaozhou Bay;Moderate Resolution Imaging Spectroradiometer (MODIS);spatial distribution12|0|3Updated：2023-05-20
Physics
- Abstract：To reconstruct the paleoenvironment, the petrography and geochemical compositions of the upper Permian Dalong Formation (Fm) (P3d) sandstones in the Central Uplift, South Yellow Sea Basin, was investigated, after which the provenance, tectonic setting, weathering conditions, and diagenetic history were determined. The Dalong Fm is mainly composed of sandstones with a few mudstones and limestones. The petrographic analysis showed that the P3d sandstones are in low maturity and could be classified into feldspar sandstone and lithic sandstone on average framework composition of Q63F16L21. The major and trace element results show that Dalong Fm sandstones are enriched in Rb and depleted in Cr and Ni compared with the upper continental crust (UCC). The chemical weathering intensity is weak to low moderate in the source area as indicated by the chemical index of alteration (CIA) and other results from a variety of methods. The diagenetic process included three main stages: eodiagenesis, mesodiagenesis, and telodiagenesis. Tectonic discrimination plots show that the source areas were an active continental margin (ACM) and a passive continental margin (PCM), which may have been related to the northward movement of the Lower Yangtze Plate (LYP) and the collision between the LYP and the North China Plate (NCP).Keywords：rock geochemistry;rock weathering;tectonic setting;evolution of rock;South Yellow Sea Basin5|0|2Updated：2023-05-20
Geology
- Abstract：A cruise covering two transects in the Changjiang (Yangtze) estuary in July 2017 was conducted, aiming to explore the sources for riverine NO3- and identify reactions involved in the NO3- transformations along the transport of the Changjiang diluted water (CDW). In the river water, NO3- was fundamentally contributed by chemical fertilizer leakage in the watershed according to isotope signals. Sewage discharge may also be significant on riverine NO3- inventory, while the isotope signal was masked by nitrification. Together with the transport of the CDW, NO3- production was observed in waters with low salinities (< 20) and high turbidities. Nitrification resulted from the mineralization of riverine organic nitrogen; therefore, the high turbidity was linked to active production. In the outer plume, coupled with stratification, a significant decrease in NO3- concentration was observed in the surface water. In parallel, enrichment in δ15N-NO3- and δ18O-NO3- was found, indicating biological consumption by phytoplankton. The difference in the stratification intensity between two transects led to variations in NO3- concentrations and isotope compositions. In the benthic water, denitrification (sediment-water interface) and nitrification (bottom water) coexisted. Furthermore, accumulations of NH4+ and dissolved organic nitrogen in the bottom water were observed, indicating that nitrification was constrained by oxidant (mainly dissolved oxygen) supplies.Keywords：Changjiang diluted water (CDW);denitrification and nitrification;estuary;production and removal;stable isotope4|0|4Updated：2023-05-20
Chemistry
- Abstract：Illumina sequencing and quantitative PCR (qPCR) based on the 16S ribosomal RNA (rRNA) gene were conducted to characterize the vertical distribution of bacterial and archaeal communities in the sediments of two sites from the South Yellow Sea. Both bacterial and archaeal communities showed a clear stratified distribution with sediment depth. The microbial communities in the upper layers were distinct from those in the deeper layers; the relative abundances of sequences of Thaumarchaeota, Gammaproteobacteria, and Actinobacteria were higher in the upper than in the deeper sediments, whereas the sequences of Bathyarchaeia, Lokiarchaeota, Euryarchaeota, Chloroflexi, and Deltaproteobacteria were relatively more abundant in the deeper sediments. Sediment depth and total organic carbon (TOC) can significantly influence both the bacterial and archaeal communities. Furthermore, bacterial and archaeal groups potentially involved in nitrogen, sulfur, and methane metabolism were detected in both sites. In our study, both ammonia-oxidizing bacteria (Nitrospira) and ammonia-oxidizing archaea (Candidatus Nitrosopumilus) were responsible for ammonia oxidization. Additionally, sulfur-reducing bacteria SEEP-SRB1 forming consortia with anaerobic methane-oxidizing archaea ANME-2a-2b were capable of anaerobic methane oxidation (AOM) in the 3400-02 sediment samples.Keywords：microbial community;16S rRNA gene;high-throughput sequencing;South Yellow Sea;sediment4|0|3Updated：2023-05-20
- Abstract：Spatial variations of sediment microbes pose a great challenge for the estimation of anthropogenic influence on biogeochemical processes, yet remain very unclear in coastal ecosystems. Surface sediments in 9 stations from the eutrophic Jiaozhou Bay, China, were sampled, DNA was extracted within the sediments, and the 16S rDNA was sequenced with the Illumina Hiseq sequencing. Results reveal considerable heterogeneity of sediment bacteria in the Jiaozhou Bay, of which Proteobacteria and Bacteroidetes accounted for over 75%. Bacterial alpha-diversity indices decreased generally from the outside to the inner part of the bay and from the offshore to the nearshore area. Bacterial community structures of S3, S4, S7, and S8 clustered, those of S5, S13, and S14 grouped together, while those of S6 and S10 were distinct from each other and from those of the other stations. Major class Gammaproteobacteria were more abundant at the stations with mesoeutrophic to eutrophic levels (S4, S5, S8, and S10) and less abundant at oligotrophic stations (S6, S13, and S14), while Deltaproteobacteria had an opposite distribution pattern. Overall, bacterial community composition transitioned from being Xanthomonadales-dominant at S4 and S8 to being unidentifed_Gammaproteobacteria-dominant at S5, S6, S13, and S14, while in other stations there were comparable orders. The biogeochemical processes correspondingly changed from being nitrogen cycling-dominant at S4 and S8 to being sulfur cycling-dominant at S5, S6, S13, and S14. The bacterial distribution patterns were especially affected by the factors (dissolved organic phosphorus, DOP) in the overlying seawater due to the habitat status of P-insufficiency in the bay. Both orders Xanthomonadales and Alteromonadales could serve as bioindicators of anthropogenic pollution to different pollution types. At last, divergent distribution patterns of individual bacterial populations in the bay were revealed, the influential environmental gradients were clarified, and the uncertainty of microbes was reduced, helping to predict environmental functions in coastal areas.Keywords：Jiaozhou Bay;bacterial community;spatial variation;sediments;overlying water4|0|0Updated：2023-05-20
- Abstract：Bacteria are important regulators of carbon cycling in lakes and are central to sediment ecosystem processes. However, the sediment microbial communities and their respiratory responses to the lake wetland succession are poorly understood. In this study, we collected sediment samples from four different succession points (the Potamogeton lucens zone, the Scirpus tabernaemontani zone, the Scirpus triqueter zone, and the Juncus effusus zone) in the Caohai Wetland of the Guizhou Plateau (China). The bacterial communities at these succession points were studied using a high-throughput sequencing approach. The sediment microbial respiration (SR) was measured using static chambers in the field and basal respiration (BR) was determined in the laboratory. The results show that the dominant bacterial taxa in the sediment was Proteobacteria (34.7%), Chloroflexi (17.8%), Bacteroidetes (7.3%), Acidobacteria (6.6%), and Cyanobacteria (6.1%). Principal coordinate analysis showed that the microbial community structure differs significantly at different sampling points along the successional gradient, indicating that the bacterial community structure is sensitive to the lake wetland succession. Different hydrological regimes and soil characteristics such as NH4+-N, Fe2+, Mn2+, and sediment organic carbon (SOC) content may be important factors responsible for the differences in the sediment microbial characteristics of the different successional stages in the Caohai wetland. Additionally, it was found that the SR increased significantly from the P. lucens zone to the J. effusus zone, but BR had the opposite response. The shifts in the bacterial community structure along the successional gradient may be the main reason for the observed differences in sediment respiration.Keywords：sediment bacteria;microbial respiration;lake wetland;Caohai Wetland4|0|1Updated：2023-05-20
- Abstract：Deep-sea sediments are now recognized as a home for rich and largely microbial community. Recently, it has been believed in an increasing number of studies that bacteria could be abundant in deepsea sediments of many types; however, fungi in deep-sea sediments remain relatively unknown. The phylogenetic diversity and bioactivity of culturable deep-sea-derived fungi from Okinawa Trough sediments were investigated in traditional method combined with fungal identification of molecular biology in this study. A total of 76 isolates belonged to 15 fungal taxa were recovered in a harsh condition of low nutrient and low temperature, indicating that the fungal communities in deep-sea sediments from Okinawa Trough were relatively abundant and diversified. Aspergillus, Cladosporium, and Penicillium were the dominant fungal genera, while Mycosphaerella, Purpureocillium, and Schizophyllum were relatively rare in the deep-sea sediments from Okinawa Trough. Among the six genera recovered, Mycosphaerella was firstly recovered from deep-sea sediments in this study. Moreover, about 75% of the extracts from the 15 fungal representative isolates displayed distinct bioactivity against at least one indicator bacterium or marine macrofouler, emphasizing the potentials of these deep-sea-derived fungi from Okinawa Trough as producers of bioactive metabolites. Notably, isolates Cladosporium oxysporum SCSIO z001 and Penicillium citrinum SCSIO z049 displayed a wide spectrum of bioactivities, isolates Cladosporium cladosporioides SCSIO z015, Cladosporium sphaerospermum SCSIO z030, and Penicillium verruculosum SCSIO z007 exhibited a strong anti-bacterial-growth activity, and isolate Penicillium chrysogenum SCSIO z062 displayed a strong anti-larval-settlement activity. These results suggest that these isolates deserved further study as potential sources of novel bioactive metabolites.Keywords：deep-sea-derived fungi;phylogenetic diversity;bioactivity;Okinawa Trough;hydrothermal vents4|0|0Updated：2023-05-20
- Abstract：Blooms of Akashiwo sanguinea frequently break out around the world, causing huge economic losses to the aquaculture industry and seriously damaging coastal ecosystems. However, the formation mechanisms of A. sanguinea blooms remain unclear. We investigated the allelopathic effects of A. sanguinea on multiple phytoplankton species, explored the mode of allelochemicals action and the way of nutrient factors regulation of the allelopathic activity. Results show that strains of A. sanguinea could inhibit the growth of co-occurring phytoplankton including Scrippsiella trochoidea, Phaeocystis globosa, and Rhodomonas salina, but inhibition of Prorocentrum micans was not obvious. The inhibition rates on phytoplankton were positively correlated with the cell densities of A. sanguinea. The highest inhibition rate of 94% on R. salina was for A. sanguinea CCMA256 culture of 2 000 cells/mL at 72 h. We observed that cells of S. trochoidea, Ph. globosa, and R. salina were lysed when co-cultured with A. sanguinea, with the shortest time for S. trochoidea. Additionally, the growth rates of A. sanguinea were promoted by coculturing with S. trochoidea, Ph. globosa, and R. salina. Four components of A. sanguinea culture were all able to inhibit growth of R. salina: the strongest inhibitory effect was found in the sonicated culture, followed by whole-cell culture, filtrates of sonicated culture, and filtrate culture. The crude extract of A. sanguinea culture also lysed cells of R. salina, and the inhibition rates on R. salina increased with the increasing dose of crude extract. It was shown that both nutrient enrichment and nitrogen: phosphorus ratio imbalance enhanced remarkably the allelopathic activity of A. sanguinea. The highest inhibition rate on R. salina of 70% occurred in A. sanguinea JX13 treatment at 2 000 cells/mL under high nutrient condition in 48 h. In JX14 treatment at 2 000 cells/mL for N: P of 10:1, the inhibition rate increased by 1.7 times of that for N: P of 20:1. In addition, the allelopathy of A. sanguinea could not only be a competitive strategy but also a nutrition strategy, playing an important role in formation and/or maintenance of blooms of the mixotrophic dinoflagellate A. sanguinea.Keywords：Akashiwo sanguinea;harmful algal blooms;mixotrophy;allelopathy;nutrients4|0|1Updated：2023-05-20
- Abstract：It has been a scientific consensus that Ulva prolifera green tide that break out annually between May and August in the recent decade off eastern coast of Yellow Sea. To investigate the ecological mechanism of the decline of U. prolifera green tide, we compared the physiological characteristics of U. prolifera samples collected in three stages of the green tide in Subei Shoal north Jiangsu, the initiation point, on May 10 (early, the initiation), July 10 (middle, the outbreak), and in Taipingjiao, Qingdao on August 10 (late, the decline). Compared to the early samples, the middle, and late samples showed a lower chlorophyll content and photosynthetic efficiency at a higher lipid peroxidation level. The middle and later samples had fewer chloroplasts in the cells of U. prolifera than those in the early samples. In addition, the cells of U. prolifera sampled in the late stage showed ruptured and deformed cell walls. Differences in physiological function were reflected in the growth rate. Both the middle and late U. prolifera samples presented negative growth rates. Correlation analysis results show that the rising temperature was mainly responsible for the local decline of U. prolifera green tide. The high light-intensity that could induce the photoinhibition was also an important factor for the decline. Therefore, U. prolifera population that remained in the Subei Shoal and those that northward drifted to Qingdao experienced the same decline processes: rising temperature and continuous high light conditions in the late phase of green tide reduced the photosynthetic capacity and destroyed the antioxidant system of the thallus, which lead to decrease of biomass. The only difference is that the temperature in the Subei Shoal rose earlier than that in Qingdao; thus, U. prolifera remaining in the Subei Shoal went disappeared first.Keywords：Ulva prolifera;green tide;decline process;photoinhibition;lipid peroxidation4|0|0Updated：2023-05-20
- Abstract：Phosphorus overenrichment of shallow ponds prevailing in wetlands leads to their eutrophication causing the collapse of those vulnerable habitats. The potential of phosphorus accumulation by periphyton developed on artificial substrata has been investigated in two shallow ponds (Baračka and Široki Rit) in northwest Serbia and compared to the same ability of plankton and metaphyton. The periphyton substrate carrier has been submerged from May to October. Both continuously (CS) and monthly developed (MS) periphyton were sampled. Autotrophic component of all investigated communities has been qualitatively assessed. Maximum accumulation of only 14.7 mg TP/m2 was recorded in three-month exposed periphyton CS. MS exposed from July to August reached maximal 12.7 mg TP/m2. Plankton community that was characterized by more diverse and abundantly developed algal component was more effective in phosphorus accumulation (0.7 mg/g dry weight) in comparison with dominantly inorganic and diatom-dominated periphyton in Baračka. Unstable conditions caused by recent revitalization (dredging organic matter and mud from pond basin—redigging) as well as rapid desiccation of Široki Rit disabled making an unambiguous conclusion about the efficiency of phosphorus accumulation among different communities, but suggested slight potential of phosphorus harvesting by metaphyton in this pond. Due to the shorter exposure time that brings the reduced risk of unpredictable changes in the ecosystem, as well as the considerable amount of accumulated phosphorus, large-scale application of one-month exposed periphyton developed on artificial substrates would be more advisable for phosphorus harvesting in nutrient affected shallow ponds.Keywords：periphyton;phosphorus accumulation;shallow ponds;(phyto)plankton;metaphyton;eutrophication4|0|0Updated：2023-05-20
- Abstract：Antibiotic resistance genes (ARGs) have been considered as emerging contaminants in nature owing to their wide distribution and human health risk. Anthropogenic activities can increase the diversity and abundance of ARGs and promote their spread in environment. Offshore environment is affected by multiple types of anthropogenic activities, of which excessive accumulation of petroleum substances poses a serious threat. Our previous experimental study has demonstrated that petroleum can increase the abundance of sulfonamide resistance genes (SRGs) in the seawater through horizontal gene transfer. However, the influence of petroleum substances on SRGs in offshore environment, especially adjacent the petroleum exploitation platform, is still unclear. Therefore, the effect of offshore oil exploitation on SRGs was investigated in the surface sediments collected from the Liaodong Bay, north China. The genes of sul1 and sul2 were present in all of the collected samples, while the sul3 gene was not detected in any sediments. The absolute abundance of sul2 gene in each sample was higher than sul1 gene. Class 1 integrons enhanced the maintenance and propagation of sul1 gene but not sul2 gene. More importantly, the results indicate that the absolute abundance of sul2 gene present in the offshore sediments that affected by petroleum exploitation was significantly higher than those in control. These findings provided direct evidence that offshore oil exploitation can influence the propagation of SRGs and implied that a more comprehensive risk assessment of petroleum substances to public health risks should be conducted.Keywords：petroleum exploitation;sulfonamide resistance gene;quantitative real-time PCR;offshore sediment;Class 1 integrase5|0|1Updated：2023-05-20
- Abstract：The modern landscape patterns of islands usually show obvious spatial heterogeneity and complex ecological effects due to the vulnerability of ecosystems with natural characteristics under increasing human activities. In this work, we studied the variation in landscape pattern of the Miaodao Archipelago in Bohai Sea, North China, from 1990 to 2019, and an evaluation index system was established to explore the impacts of natural conditions and human disturbances on the ecological effects in the pressure-state-response (PSR) framework. Empirical analysis was conducted on the natural conditions, human disturbances, and ecological effects. The results show that forest was the main component of the landscape pattern in the archipelago. Both of the areas of forest and construction land were increasing, and the areas of cropland and grassland were declining. Other landscape types changed slightly, and the landscape fragmentation was increasing. The natural condition exhibited positive effects while human disturbance showed negative effects on the local ecology. Human disturbances come mainly from shoreline use while the natural conditions were mainly from the elevation change. The ecological effects were resulted mainly from the net primary productivity and water yield.Keywords：Miaodao Archipelago;landscape pattern;ecological effect;structural equation modeling4|0|2Updated：2023-05-20
Ecology
- Abstract：Microplastics pollution and seawater temperature rise have been the major environmental issues, threatening the survival and biodiversity of marine organisms. This study evaluated the combined effect of temperature and polystyrene microplastics (MP) on Artemia, a filter-feeding crustacean that is widely used for environmental toxicology studies. Brine shrimp Artemia franciscana were exposed to three MP concentrations (0, 0.2, and 2.0 mg/L) and three temperatures (22, 26, and 30 ℃) for 14 d. In general, higher MP concentration and temperature led to a decreased survival rate and growth. Two-way ANOVA analysis indicated that the survival rate of Artemia was significantly impacted by both MP concentration and temperature (P < 0.05), but there was no significant interaction between two factors (P > 0.05). Growth of Artemia was significantly impacted by temperature (P < 0.05), and with a significant interaction between two factors (P < 0.05). Furthermore, the enzymatic activity, intestinal histological analyses, and immune gene expression were determined for Artemia reared at 30 ℃ with three MP concentrations (0, 0.2, and 2.0 mg/L). The results showed that 2.0-mg/L MP resulted in reduced Artemia intestinal microvilli and exfoliated epithelia cells, significantly increased acid phosphatase (ACP) activity (P < 0.05) and immunerelated gene ADRA1B and CREB3 expression, revealing that higher MP concentration could induce oxidative and immunological stress on Artemia at 30 ℃. Overall, our study suggests that MP and temperature have combined adverse effect on Artemia, especially at relatively high temperature and polystyrene MP concentration. These findings are important to understand the potential ecological risks posed by these two factors on the organisms in marine environment.Keywords：Artemia franciscana;combined effect;microplastics;temperature4|0|2Updated：2023-05-20
- Abstract：Aurelia spp. ephyrae have been reported to form blooms in sea cucumber aquaculture ponds in the Bohai and Yellow Seas. To identify the species, we carried out a genetic analysis of Aurelia spp. ephyrae and medusae based on mitochondrial 16S rRNA gene. Samples of four Aurelia sp. ephyrae populations were collected in sea cucumber aquaculture ponds and samples of four Aurelia sp. medusae populations were collected in coastal waters. Using a BLASTn search, we found that both the ephyrae collected in the aquaculture ponds and medusae collected in coastal waters belong to Aurelia coerulea. Seventeen haplotypes were recovered from the 16S rRNA gene. The overall haplotype diversity and nucleotide diversity of the 166 A. coerulea individuals were 0.686% and 0.329%, respectively, indicating high haplotype diversity and low nucleotide diversity. Moreover, the haplotype diversity of ephyrae populations were generally lower than that of medusae populations with close sampling points. The genetic differentiation between ephyrae populations collected in the sea cucumber aquaculture ponds and A. coerulea medusae collected in coastal waters was not significant, suggesting the ephyrae populations in the sea cucumber culture ponds were part of the same genetic group as the medusae populations in the coastal waters. Phylogeographic analysis of the 16S rRNA region revealed that there was no significant correlation between the haplotypes and the geographic distribution of populations. Pairwise fixation index values showed significant genetic differentiation and limited gene flow between A. coerulea population of Weifang and other locations.Keywords：Aurelia coerulea;medusae;ephyrae;16S rRNA gene analyzes;genetic differentiation;genetic variability4|0|0Updated：2023-05-20
- Abstract：Songkhla Lagoon in southern Thailand is a large lagoon with brackish water where the mysid Nanomysis siamensis inhabit. N. siamensis has long been the dominant mysid species in this lagoon. However, nothing is known about the biology and ecology of N. siamensis. Here for the first time, we provide information about its demographic structure and reproductive biology in the Songkhla Lagoon system. We conducted monthly sampling from June 2017 to June 2018 at five stations in Thale Sap and seven stations in Thale Sap Songkhla. Individuals were classified into six categories. The monthly mean density ranged 8.44-807.33 inds./100 m2 in Thale Sap and 8.81-434.44 inds./100 m2 in Thale Sap Songkhla. The peak occurrence of this species was in May 2018 in Thale Sap. The population composition was as follows: juvenile 10.13%, immature males 13.45%, immature females 10.54%, mature males 26.19%, mature females 21.63% and ovigerous females 18.05%. The proportion of ovigerous females was statistically significant and brooding females in the nauplioid stage were more dominant than embryonic phase and post-nauplioid stages. Brood size varied from 1 to 17, the embryo diameter ranging from 0.2 to 0.4 mm and the lengths of the larvae ranged from 0.5 to 1.0 mm. There was a positive correlation between brood size and brood length with ovigerous female body length. Overall, mature males were predominant over the five population composition types, and reproduction in N. siamensis was observed every month.Keywords：brackish water;reproductive trait;Thale Sap;Thale Sap Songkhla4|2|0Updated：2023-05-20
- Abstract：Marine symbiotic fungi represent an intriguing source of discovery of novel secondary metabolites with various biological activities. Sea anemones are benthic marine invertebrates, however, the cultivable symbiotic fungi residing in the sea anemones are paid few attentions compared to those derived from their cnidarian counterparts. Here we show the identification of antimicrobial secondary metabolites from the sea anemone-derived symbiotic fungi. Out of five isolated fungal strains, only the strain SMA01 showed strong antimicrobial activities, which was assigned into the genus Emericella based on the morphological characteristics and the ITS sequencing. Media swift from liquid fermentation to solid rice medium presented little influence on its antibacterial activity. A chemical investigation of the ethyl acetate extract of the Emericella sp. SMA01 led to discovery of the primary antibiotic metabolite phenazine-1-carboxylic acid. The IC50 values of the phenazine-1-carboxylic acid against Phytophthora capsici, Gibberella zeae, and Verticillium dahliae were determined to be 23.26-53.89 μg/mL. To the best of our knowledge, this was the first report of Emericella sp. in sea anemones. The current study may benefit understanding of the defensive chemical interactions between the symbiotic fungi and their host sea anemones.Keywords：sea anemone;symbiotic fungi;phenazine-1-carboxylic acid;antimicrobial activity4|0|1Updated：2023-05-20
- Abstract：Marine benthic dinoflagellates in the genus Coolia were reported in both tropical and temperate regions. We conducted a morphological and phylogenetic characterization of Coolia species from Hainan Island, South China Sea. The morphologies of three Coolia species were similar to those of the original descriptions of Coolia canariensis, C. tropicalis, and C. malayensis. In phylogenetic analyses based on the LSU rDNA and ITS regions (ITS1-5.8S-ITS2), the Hainan strains of C. canariensis, C. tropicalis, and C. malayensis clustered within the clades of these species with other isolates from different areas. No differences (p-distance) in LSU rDNA sequences were found between the Hainan C. malayensis strains and the strains from New Zealand, Florida of USA, Malaysia, Japan, Dominican Republic and Guangxi and Hong Kong of China. For C. canariensis and C. tropicalis, no differences (p-distance) in the LSU rDNA sequences were found between the Hainan strains (D1C2 and DS5F4, respectively) and the Australian strains (NQAIF252 and NQAIF90, respectively). Our study reveals the morphological and genetic diversity of Coolia species from Hainan Island, South China Sea, which provides a detailed understanding of Coolia species of this area.Keywords：Coolia;Hainan Island;morphology;phylogeny;rDNA4|0|1Updated：2023-05-20
- Abstract：The diversity and distribution of Hippodonta species on the coast of China are largely unknown due to limited investigations. In this paper, we report the detailed morphology and ultrastructure of two new species: H. nanjiensis sp. nov., collected from intertidal sandy sediments of Nanji Islands, the East China Sea and H. qingdaoensis sp. nov., collected from intertidal sandy sediments of the No. 1 Bathing Beach in Qingdao City, the Yellow Sea. Both species occur mainly in the middle part of the intertidal zone. H. nanjiensis possesses a unique large round central area. H. qingdaoensis differs from congeners in having a unique stria pattern, wherein the areolae in the middle transapical striae are less developed or absent on the primary side of the valve, and two areolae per stria are apparent under light microscopy (LM). This study expands our knowledge of Hippodonta diversity and distribution on the coast of China.Keywords：Hippodonta;intertidal sediment;new species;Yellow Sea;East China Sea4|0|0Updated：2023-05-20
- Abstract：We report on eight species of the freshwater diatom genus Gomphonema from aquatic habitats from the Yuntai Mountains of Henan Province, China. This work represents the first detailed descriptions of the freshwater diatoms from this centrally-located province in China. Of the eight taxa considered, five are new to science and another is given a "cf." designation. Four of the eight species are similar in morphological features to other, "classical" species, with external areolar occlusions forming C-shaped openings. Another species is astigmate, and has distinct siliceous papillae located marginally on the exterior of the valves; this morphology has not been recognized previously for the genus. Two of the species have internal areolar and stigma occlusions. The diversity of morphological types of species in Gomphonema may relate to the ecosystems, with more diverse ecosystems harboring greater diversity of these morphological groups of Gomphonema.Keywords：Gomphonema;new species;Bacillariophyceae;morphology;diatoms4|0|0Updated：2023-05-20
- Abstract：Twelve putative "Chantransia" isolates were collected from six locations across Hubei, Shanxi, Guizhou, and Henan Provinces in China. Their morphological characters were evaluated via the Ward's method of hierarchical cluster analysis in SPSS software to classify phylogenetic relationships among the isolates. The morphological data revealed that isolate HN31 (called group "MALL") was distinct from the other specimens being macroscopic with large vegetative cells and monosporangia (> 20 μm in diameter). The 11 other isolates were grouped into three clusters, corresponding to the species Audouinella tenella, A. hermannii, and A. pygmaea. The morphological "Chantransia" stage of the species, reportedly belonging to the orders Batrachospermales, Thoreales, and the phylogenetically distant genus Audouinella, are very similar, resulting in the difficulty to distinguish them based just on morphology. Therefore, molecular analysis of rbcL, UPA, and COI-5P was conducted to infer the phylogenetic position of all isolates in this study. All "A. tenella" and "A. hermannii" sequences belong to order Batrachospermales, while the isolate HN31 was the "Chantransia" of Thorea hispida. The six other specimens varied morphologically, but they were within the circumscription of "A. pygmaea". All three molecular markers show that all "pygmaea" isolates also represent the "Chantransia" of T. hispida. Furthermore, results from this investigation proposed a new species—Sheathia qinyuanensis, corresponding to the isolates QY1 and QY2.Keywords：Batrachospermales;COI-5P;rbcL;Thoreales;UPA4|0|1Updated：2023-05-20
- Abstract：Polysiphonia hainanensis was previously described from Hainan, China, but DNA sequence had never been provided and its phylogenetic position in Polysiphonieae has not been clear so far. The classification of Polysiphonieae has changed recently based on the molecular analyses and detail morphological anatomy, consequently, the generic assignment of some species must be reassessed. In this study, we analyzed phylogenetic relationships of P. hainanensis and the related taxa in Polysiphonieae and Streblocladieae based on rbcL sequences, with specimens collected from the type locality and the area around. Two genetic types were detected, and formed a clade with Bryocladia thyrsigera with strong bootstrap support, in which the divergence was less than 0.81%. Furthermore, based on morphological analyses, we found characteristics of Chinese specimens, number of pericentral cells, percurrent axis, determinate branchlets, branching pattern, spermatangial axes development, and arrangement of tetrasporangia, etc., were consistent with those of Bryocladia. Combined with morphological and molecular analyses, P. hainanensis was taken a synonymous of B. thyrsigera, and gametophytes of this species were found from China for the first time.Keywords：Bryocladia;phylogeny;Polysiphonieae;rbcL4|0|1Updated：2023-05-20
- Abstract：A new free-living marine nematode species of the family Xyalidae from Laizhou Bay of the Bohai Sea, China is described and illustrated herein. Paragnomoxyala papillifera sp. nov. is characterized by large funnel-shaped buccal cavity, circular amphidial fovea located posterior to buccal cavity, straight spicules with slightly curved distal end, gubernaculum absent, four papilliform precloacal supplements, tail conico-cylindrical with two ventral embossments in males and having longitudinal rows of cervical setae and subventral caudal setae in males. The new species is easily identified from other two recorded species in the genus by having papilliform precloacal supplements and ventral embossments along conical portion of tail of males. A pictorial key for three species of Paragnomoxyala and comparative table of three species with important characteristics are provided.Keywords：free-living marine nematodes;taxonomy;new species;Laizhou Bay4|0|0Updated：2023-05-20
Biology
- Abstract：Microorganisms plays an important role in the growth of Pyropia haitanensis. To understand the structural and functional diversity of the microorganism community of P. haitanensis (PH40), the associated metabolic pathway network in cluster of orthologous groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG), and carbohydrate-active enzymes (CAZymes) were explored in metagenomic analysis. DNA extraction from gametophytes of P. haitanensis was performed first, followed by library construction, sequencing, preprocessing of sequencing data, taxonomy assignment, gene prediction, and functional annotation. The results show that the predominant microorganisms of P. haitanensis were bacteria (98.98%), and the phylum with the highest abundance was Proteobacteria (54.64%), followed by Bacteroidetes (37.92%). Erythrobacter (3.98%) and Hyunsoonleella jejuensis (1.56%) were the genera and species with the highest abundance of bacteria, respectively. The COG annotation demonstrated that genes associated with microbial metabolism was the predominant category. The results of metabolic pathway annotation show that the ABC transport system and two-component system were the main pathways in the microbial community. Plant growth hormone biosynthesis pathway and multi-vitamin biosynthesis functional units (modules) were the other important pathways. The CAZyme annotation revealed that the starch might be an important carbon source for microorganisms. Glycosyl transferase family 2 (GT2) and glycosyl transferase family 3 (GT3) were the highly abundant families in glucoside transferase superfamily. Six metagenome-assembled genomes containing enzymes involved in the biosynthesis of cobalamin (vitamin B12) and indole-3-acetic acid were obtained by binning method. They were confirmed to belong to Rhodobacterales and Rhizobiales, respectively. Our findings provide comprehensive insights into the microorganism community of Pyropia.Keywords：P. haitanensis;metagenomic;microbial community;cluster of orthologous groups (COG);Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways;carbohydrate-active enzymes (CAZymes)5|0|0Updated：2023-05-20
- Abstract：Pyropia yezoensis is an important macroalga because of its extensive global distribution and economic importance. Color is an important trait in the thalli of P. yezoensis, it is also an effective marker to identify the hybridization in genetic breeding. In this study, a high-density genetic linkage map was constructed based on high-throughput single nucleotide polymorphism (SNP) markers, and used for analyzing the quantitative trait loci (QTLs) of red color trait in the thalli of P. yezoensis. The conchospore undergoes meiosis to develop into an ordered tetrad, and each cell has a haploid phenotype and can grow into a single individual. Based on this theory, F1 haploid population was used as the mapping population. The map included 531 SNP markers, 394.57 cM long on average distance of 0.74 cM. Collinear analysis of the genetic linkage map and the physical map indicated that the coverage between the two maps was 79.42%. Furthermore, QTL mapping identified six QTLs for the chromosomal regions associated with the red color trait of the thalli. The value of phenotypic variance explained (PVE) by an individual QTL ranged from 4.71%-63.11%. And QTL qRed-1-1, with a PVE of 63.11%, was considered the major QTL. Thus, these data may provide a platform for gene and QTL fine mapping, and marker-assisted breeding in P. yezoensis in the future.Keywords：Pyropia yezoensis;high-density genetic linkage map;quantitative trait loci (QTL) mapping;F1 haploid population;red pigment variant4|0|0Updated：2023-05-20
- Abstract：Ancherythroculter nigrocauda is a fish endemic to the upper areas of the Changjiang (Yangtze) River in China. Quantitative trait locus (QTL) mapping is a powerful tool to identify potential genes affecting traits of economic importance in domestic animals. In this study, a high-density genetic map was constructed with 5 901 single nucleotide polymorphism (SNP) makers by sequencing 92 individual fish from a F1 family using the specific-locus amplified fragment sequencing approach. Initially, 48 QTLs for total length, body length, body height, and body weight were identified according to the high density of the genetic map with 24 LGs, a total length of 3 839.4 cM, and marker spacing of about 0.82 cM. These QTLs explained 27.1%-49.9% of phenotypic variance. The results of this study suggest that major QTLs are responsible for the growth of A. nigrocauda, and these are potentially useful in comparative genomics research, genome assembly, and marker-assisted breeding programs for this species.Keywords：Ancherythroculter nigrocauda;specific-locus amplified fragment;high-density genetic map;quantitative trait locus4|0|0Updated：2023-05-20
- Abstract：The use of high alkaline medium is a feasible way to provide carbon source and prevent biological contamination for the outdoor cultivation of alkaliphilic microalgae and cyanobacteria. A novel cyanobacterial strain was isolated from the open pond of a marine green alga (Picochlorum sp. SCSIO-45015, Sanya, Hainan) and identified as Cyanobacterium sp. SCSIO-45682. The effects of initial sodium bicarbonate (NaHCO3) concentrations on the growth and biochemical composition of Cyanobacterium sp. SCSIO-45682 were investigated. The results demonstrated that Cyanobacterium sp. SCSIO-45682 had good adaptation to 16.8-g/L NaHCO3 (the same concentration of NaHCO3 used in Zarrouk medium for Spirulina). Moreover, the yields of biomass, polysaccharide, chlorophyll a (chl a), and phycocyanin increased under high NaHCO3 concentrations. The maximum final biomass concentration of 2.5 g/L was observed at 8.4-g/L NaHCO3, while the highest intracellular total saccharide content of 49.2% of dry weight (DW) and exopolysaccharide (EPS) concentration of 93 mg/L were achieved at the NaHCO3 concentration of 16.8 g/L. The crude protein content declined under high NaHCO3 concentrations, which provide a possible explanation for the accumulation of polysaccharide. This study shows a good potential of alkaliphilic Cyanobacterium sp. SCSIO-45682 as a polysaccharide feedstock.Keywords：alkaliphilic cyanobacterium;biochemical composition;Cyanobacterium sp. SCSIO-45682;high sodium bicarbonate (NaHCO3) concentrations;polysaccharide4|0|0Updated：2023-05-20
- Abstract：Bacteria play a major role in metabolizing ammonia and other metabolites in recirculating aquaculture systems (RASs). To characterize and compare the bacterial communities in the biofilters of two full-scale RASs for the culture of puffer fish, Takifugu rubripes, at different ages and densities were studied. In overall, 47 807 optimized reads of the 16S rRNA gene with V4-V5 region were obtained from four biofilm samples collected after biofilm maturation. At 97% cut-off level, these sequences were clustered into 500 operational taxonomic units, and were classified into 19 bacterial phyla and 138 genera. At the phylum level, Proteobacteria and Bacteroidetes were the most abundant, followed by Nitrospirae and Planctomycetes. At the genus level, Colwellia, Marinifilum, Oceanospirillum, Lutibacter, Winogradskyella, Pseudoalteromonas, Arcobacter, and Phaeobacter were the top members. Nitrosomonas and Nitrospira were main ammonia- and nitrite-oxidizing bacteria. Differences in bacterial communities at different sampling dates and similarities of both biofilters were revealed in the Venn diagram and cluster analysis. Maintaining a good water quality and health of farmed fish in RASs depended on the correct management of the bacterial communities. This study provides more accurate information on the bacterial communities associated with the bifilters of both RASs.Keywords：biofilters;bacterial community;recirculating aquaculture system;Illumina-MiSeq sequencing4|2|0Updated：2023-05-20
- Abstract：Integrated multi-tropic aquaculture (IMTA) systems have been used in China for many years and have achieved significant economic, social, and ecological benefits. However, there is still a lack of benthic bioremediation species that can effectively utilize the aquaculture particulate organic waste in the system. Polychaete Perinereis aibuhitensis Grube is used as an environmental remediation species for large-scale aquaculture to reduce particulate organic waste, which is of great significance to environmental protection. To improve bio-elements utilization efficiency, P. aibuhitensis was applied for IMTA indoor fish (Hexagrammos otakii) farming. Results showed that in the system, production of 1 kg of the fish discharged 2 141-2 338 mg of carbon and 529-532 mg of nitrogen, while in the monoculture of the fish, the figures were 3 033-3 390 mg and 764-794 mg, or 24.84%-35.26% and 30.35%-33.32% less, respectively. This approach promoted IMTA technology that could utilize the particulate organic waste from intensive aquaculture and reduce the adverse environmental effects.Keywords：Perinereis aibuhitensis Grube;Hexagrammos otakii;integrated multi-tropic aquaculture (IMTA);carbon and nitrogen budget;sediment remediation4|0|1Updated：2023-05-20
- Abstract：Identification of squids in the family Loliginidae is a time-consuming exercise because of the highly overlapping distributions of species and their overall similarity (fin shape and size, sucker ring dentition, and color). Identifying squid based on statolith morphology is considered more accurate than identifying species based on beaks or gladius morphology. We report and compare the statolith shape of five commercially Loliginidae squid (Uroteuthis (Photololigo) duvaucelii, U. edulis, U. chinensis, Loliolus beka, L. japonica) to determine how well these structures discriminate species. Based on statolith morphology, variation in the lateral and dorsal domes enables an 84.8% success rate at classifying species. Environmental factors correlate with statolith shape, and for vertically migrating squid, statolith relative size decreases with increased depth of habitation. Statolith morphology can be used to effectively and accurately identify species of Loliginidae squid occurring in Chinese waters, and may prove valuable for identifying and managing squid resources.Keywords：statolith shape analysis;Loliginidae squid;fishery management;Chinese waters4|3|0Updated：2023-05-20
Aquaculture and Fisheries
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