Issue Ebook
cover story
Latest Issue
Volume 39 ， Issue 2 ， 2021
-
- Abstract：Jellyfish blooms have become a hot research topic in recent decades because they pose a serious threat to fisheries, coastal industries, tourism, and the marine ecosystem. The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage, where asexual reproduction and strobilation of the polyps directly affect the abundance of ephyra and subsequently medusa abundance. The dynamics of polyps are affected by both environmental and biological factors, and predation by natural predators is one of the most important biological factors. Nemopilema nomurai, Aurelia coerulea, and Rhopilema esculentum are three scyphozoan species that are commonly found in Chinese coastal waters, and previous studies reported that the survivorship of polyps differs among the three species when they are exposed to the same benthic community. To identify potential natural predators of polyps of these three species in Chinese coastal waters and to determine whether the predation rates on polyps of the three species differ, we collected 39 species of macrozoobenthos from the Bohai Sea, Yellow Sea, and East China Sea from May 2014 to June 2016 and conducted predation tests and predation rate measurements. We found that the nudibranchs Pleurobranchaea novaezealandiae, Okenia plana, and Chromodoris tinctoria and the sea anemones Paracalliactis sinica, Calliactis japonica, Anthopleura incerta, and Anthopleura midori could prey on the polyps of all three scyphozoan species. The predation rates increased with the body length of the predators. The predations rates were also related to the polyp species, although the different predators showed no consistent preference for a particular species of polyp. Our results indicate that introducing predators to locations inhabited by polyps might be a way to control the benthic polyp populations and prevent subsequent jellyfish blooms.Keywords：jellyfish bloom;polyps;predation rate;predators4|3|0Updated：2023-06-06
- Abstract：Planktonic Oikopleura dioica respond almost instantly to opportunistic algal blooms, but it is unknown whether the population increase can change from an exponential to a logistic model to avoid a final sudden collapse. To test the hypothesis that intraspecific competition regulates the intrinsic rate of natural increase (r), density-dependent effects on growth and reproduction performance were investigated in O. dioica via laboratory incubations. Over a large food concentration range, batch maturation was observed above the per capita food supply (PFS) of 8.1 μg C/ind. in 4.5 d. Somatic growth was saturated beyond this PFS value, whereas gonad length increased continuously. Below this threshold, individuals reached small body and gonad lengths, and maturation was rarely observed during the incubation period. The gonad/body volume and maturation ratios also increased with the PFS. Instead of the food concentration, the r values were regulated by competition pressure via variability in maturation duration and the proportion of mature individuals in the cohorts. When the minimum food demand was satisfied in the designated generation time, the r value tended to be regulated by the spawning proportion in the population. Otherwise, prolonged development duration and decreased r values were expected.Keywords：Oikopleura dioica;population size;intraspecific competition;growth;fecundity;rmax4|0|0Updated：2023-06-06
- Abstract：Nansi Lake and Hongze Lake are both water storage lakes along the East Route of the South-to-North Water Transfer project (ESNT). Frequent changes in hydrologic properties are responsible factors for controlling the zooplankton community assemblages in both lakes, so we studied the possible influence of water transfer and environmental factors on zooplankton community structure and abundance. Zooplankton assemblages were investigated seasonally for one year in both lakes; a total of 133 and 122 zooplankton taxa were identified in Nansi Lake and Hongze Lake, respectively. The most dominant rotifer species were littoral, e.g., Keratella tecta, Keratella valga and Lecane lunaris in Nansi Lake and Brachionus angularis, Brachionus forficula and Polyarthra vulgaris in Hongze Lake. Comparatively, Nansi Lake had a higher Shannon-Wiener diversity index value (5.13), while Hongze Lake had a higher species richness index (4.21). The average number of zooplankton across seasons in Nansi Lake (protozoa: 774±63 ind./L, rotifers: 4 817±212 ind./L, cladocerans: 896±14 ind./L, copepod: 435±42 ind./L) was comparatively lower than Hongze Lake (protozoa: 1 238±63 ind./L, rotifers: 6 576±112 ind./L, cladocerans: 1 013±20 ind./L, copepod: 534±25 ind./L). Canonical correspondence analysis identified differing environmental gradients that were most responsible for influencing zooplankton communities in the two lakes (Hongze Lake: NH4-N, total nitrogen, transparency and pH; Nansi: pH, temperature and total phosphorus). Frequent changes related to water transfer in lakes favoured the diversity of rotifers and protozoa communities. Zooplankton habitat preference, changes in community structure and opportunistic peaks and extinction of certain taxa were also observed in the study lakes.Keywords：zooplankton assemblage;water transfer;Hongze Lake;Nansi Lake4|2|0Updated：2023-06-06
- Abstract：Seasonal and spatial variations in the macrobenthic community in an intertidal gulfweed field off Naozhou Island were investigated from April 2011 to January 2012. We identified 407 macrobenthic organism species: 64 macroalgae (15.72% of total species); 123 Arthropoda (30.22%); 107 Mollusca (26.29%); 67 Annelida (16.46%); 15 Cnidaria (3.69%); 14 Echinodermata (3.44%); 8 Porifera (1.97%); 4 Chordata (0.98%); 2 Urochorda (0.49%); and 1 each of Echiura, Sipunculida and Angiospermae (0.25%). Arthropods, mollusks, annelids, and macroalgae were four main groups in the benthic organism community and accounted for 88.70% of the total species. In terms of abundance of biomass, there were 15 dominant species, including 8 macroalgal, 5 mollusk and 2 arthropod species. The species diversity indices ranged from 1.21 to 4.42 with an average of 2.80; the annual average of evenness was 0.47. Species richness indices varied from 2.97 to 7.24 (average 4.97); and Simpson dominance indices varied from 0.20 to 0.92 in annual average of 0.75. Macroalgal distribution showed clear vertical zonation and seasonal changes. The number of macroalgal species found in the high tide zone, upper middle tide zone, middle tide zone, lower middle tide zone, low tide zone, and below low tide zone were 1, 8, 10, 16, 22, and 32, respectively. Biomass among the benthic organisms, macroalgae and crustaceans had significant positive correlation (P < 0.05) with the coefficients of 0.802, 0.894, and 0.592, respectively. Macroalgal biomass showed a clearly negative correlation with the concentration of dissolved inorganic nitrogen (DIN) (R=0.486, P < 0.05). During the winter and spring, when macroalgae were growing vigorously, DIN reached the lowest level in seawater and displayed a clear weak correlation between macroalgal growth and the nutrient concentration.Keywords：macrobenthic marine algae;species diversity;seasonal distribution;spatial distribution;Naozhou Island4|3|0Updated：2023-06-06
- Abstract：We investigated the interaction between mesoscale eddies and the Kuroshio Current east of Taiwan, China, using a fine-resolution regional general circulation model. Mesoscale eddies are injected into a region east of Taiwan, China, according to the quasi-geostrophic theory of stratified fluids. Modeled eddies propagated westward at the velocity of the first baroclinic mode Rossby wave. When eddies collide with the Kuroshio Current east of Taiwan, China, the spatial structure and volume transport of the Kuroshio Current shows a significant variation. The upper 600 m of the anticyclonic eddy cannot cross the Kuroshio Current to reach the region west of the Kuroshio Current; rather, these waters flow northward along the eastern side of the Kuroshio Current. The upper water carried by the anticyclonic eddies cannot reach the shelf of the East China Sea (ECS). In contrast, the waters in the upper layer of the cyclonic eddy reach the western side of the Kuroshio Current and then flow northward. The dynamic mechanism analysis shows that the interaction between the Kuroshio Current and the cyclonic (anticyclonic) eddy decrease (increase) the horizontal potential vorticity (PV) gradient, or PV barrier, whereby the cyclonic (anticyclonic) eddy can (cannot) cross the Kuroshio Current. This study implies that the continental shelf could potentially be influenced by cyclonic eddies in the open ocean, which can transport heat and material from the upper open ocean across the Kuroshio Current to the shelf waters.Keywords：mesoscale eddies;Kuroshio;eddy-Kuroshio interaction;east of Taiwan, China6|2|0Updated：2023-06-06
- Abstract：Typhoon is one of the frequent natural disasters in coastal regions of China. As shown in many studies, the impact of typhoons on the South China Sea (SCS) should not be overlooked. Super typhoon Rammasun (2014) was studied that formed in the northwestern Pacific, passed through the SCS, then landed in the Leizhou Peninsula. Remote sensing data and model products were used to analyze the spatiotemporal variations of the cold eddies, upwelling, sea surface temperature, mixed layer depth, rainfall, sea surface salinity, suspended sediment concentration, and surface-level anomaly. Results confirm the constant presence of upwelling and cold eddies in the southeast of Hainan (north of the Zhongsha Islands) and the southeast of Vietnam in July. In addition, we found the strengthening effect of super typhoon Rammasun on the upwelling and cold eddies in the SCS. The major reasons for the continuous decrease in sea surface temperature and the slow regaining of seawater temperature were the enhanced upwelling and vertical mixing caused by the typhoon. The increasing of the surface runoff in the Indochina Peninsula was mainly affected by the typhoon, with some contribution for the southeast of Vietnam's cold eddy and upwelling.Keywords：sea surface temperature (SST);South China Sea (SCS);upwelling4|0|1Updated：2023-06-06
- Abstract：Typhoons are one of the most serious natural disasters that occur annually on China's southeast coast. A technique for analyzing the typhoon wind hazard was developed based on the empirical track model, and used to generate 1 000-year virtual typhoons for Northwest Pacific basin. The influences of typhoon decay model, track model, and the extreme value distribution on the predicted extreme wind speed were investigated. We found that different typhoon decay models have least influence on the predicted extreme wind speed. Over most of the southeast coast of China, the predicted wind speed by the non-simplified empirical track model is larger than that from the simplified tracking model. The extreme wind speed predicted by different extreme value distribution is quite different. Four super typhoons Meranti (2016), Hato (2017), Mangkhut (2018), and Lekima (2019) were selected and the return periods of typhoon wind speeds along the China southeast coast were estimated in order to assess the typhoon wind hazard.Keywords：typhoon;empirical track model;decay model;extreme wind speed;return period4|1|0Updated：2023-06-06
- Abstract：Sri Lanka seasonal warm pools (SSWPs) with high sea surface temperature (SST) (greater than 29.6℃ in summer and greater than 28℃ in winter) around the Sri Lanka Island are discovered using 37-year (1982-2018) satellite remote sensing SST data. It is identified that during the onset of the summer (winter) monsoon, the maximum SST in the SSWPs can be 1.8℃ (0.8℃) higher than the surrounding ocean. Due to orographic influences, the wind intensity on the leeward side of Sri Lanka is weakened, reducing evaporation and oceanic mixing, and resulting in higher SST. The analysis of the long-term data shows that SSWPs are related to El Niño-Southern Oscillation (ENSO) events. Background currents are also found to play important roles in governing the SSWPs intensities through the heat advection.Keywords：Sri Lanka;monsoon;warm pool4|1|0Updated：2023-06-06
- Abstract：Many previous studies of the impact of oceanic environmental factors on chlorophyll (CHL) in a specific region focused on sea surface temperature (SST), mixed-layer depth (MLD), or wind stress (WS) alone. In this study, relationship between CHL and all those environmental factors (SST, MLD, and WS) in the open ocean was quantified for five regions within the subtropical gyres and the variation trend of 13-year (2003-2015) was analyzed using satellite observations and Argo measurements. The correlation analysis results show that MLD was correlated positively with CHL, SST was correlated negatively with CHL, and the correlation between CHL and WS was either positive or negative. Based on the significance of the correlations, models representing the relationships were established using the multiple linear regression and analyzed, showing that the environmental factors were the major determinants of CHL change. The regression coefficients show that both SST and MLD have remarkable effect on CHL. Our derived models could be used to diagnose the past changes, understand present variability, and predict the future state of CHL changes based on environmental factors, and help us understand the dynamics of CHL variation in the open ocean.Keywords：chlorophyll (CHL);mixed layer depth (MLD);multiple linear regression;sea surface temperature (SST)4|2|0Updated：2023-06-06
- Abstract：We present preliminary calibration results for Jason-3 and Sentinel-3A altimeters that we set up in the Wanshan Islands in Guandong Province, China. Two campaigns were carried out in 2018, from March 8 to April 16 and from November 3 to December 11, 2018. Three GPS reference stations and tide gauges were established on the islands of Zhiwan, Dangan, and Wailingding during the campaigns. The in-situ sea surface height (SSH) of the altimeter footprint was determined using the tide gauge. The tidal and geoid connection between the tide gauge locations and the altimeter footprints were computed with the NAO.99Jb tidal prediction system and the EGM 2008 geoid, respectively. The data of the tide gauges were defined using the GPS buoy and GPS reference stations during the campaigns. The results show that the waveform of the altimeters was slightly contaminated by the small islands. The bias associated with Jason-3 and Sentinel-3A amounted to approximately +20.7±49.7 mm and +30.1±39.4 mm, respectively, which agreed well with the results from other in-situ calibration fields. This indicates that the Wanshan area was very suitable as an in-situ calibration/validation field. The wet zenith delay (WZD) determined from the Microwave Radiometer (MWR) and the GPS measurements differed from each other for the Jason-3 and Sentinel-3A by -6.6±7.4 mm and 0±6.8 mm, respectively.Keywords：altimeter calibration;tide gauge;GPS buoy;wet zenith delay5|3|3Updated：2023-06-06
Physics
- Abstract：Continental shelf islands are contributors of terrestrial sediment supply to shelf regions, and the sediment flux from these islands shall be quantified. We calculated the sediment flux of continental shelf islands in the southeastern China using two empirical equations under two preconditions. The first, the sediment load/yield of the islands has the same pattern as the adjacent small, mountainous rivers along the coastline; and the second, each of the islands was treated as a single catchment. The results show that the sediment supply from these islands reached an order of magnitude of 1 Mt/a, which is comparable to the supply from the local smaller rivers. A sensitivity analysis indicates that this value represents the lower limit of estimate; if the accurate amount of sub-catchments of any island is considered, then this value will be enhanced slightly. This study demonstrates that the sediment supply from continental shelf islands to oceans is an important factor affecting the regional sedimentation and, therefore, should be paid with attention.Keywords：continental shelf islands;sediment flux;local rivers;shelf mud deposits;East and South China Seas4|2|0Updated：2023-06-06
- Abstract：The waters offshore the Shandong Peninsula separate the North Yellow Sea from the South Yellow Sea, and receive a large amount of terrestrial material from Chinese and Korean rivers, making it an ideal area for studying land-sea interactions. However, little attention has been given to measuring sediment transportation in most previous studies. Based on an analysis in composition of major and trace elements and particle size characteristics from 62 surface sediment samples from the northeastern region off Shandong Peninsula, the type, element composition, and controlling factors of the surface sediments were investigated. In addition, the transportation of sediments from source to sink was described from measured thermohaline data. The results show two types of surface sediments: sandy silt and silt. The sediments were mainly terrestrial; and marine carbonate had little effect on sediment composition. Shown on a binary diagram of Rb/Sc to Co/Sc, the Huanghe (Yellow) and Changjiang (Yangtze) rivers are the main sources of surface sediments in the study area. The component mixing model showed that the relative contribution of sediment from the Huanghe River was up to 92%, followed by the Changjiang River (8%). The Yellow Sea Warm Current and the North Shandong Peninsula Coastal Current met at ~37.7°N in the study area, and were the main forces carrying sediment from the two main river sources. However, there was a deficit of transported material into the study area in summer. The secondary distribution of sediment from the two river sources was controlled by tidal currents and waves.Keywords：sediment provenance;Shandong Peninsula;major and trace elements;quantitative analysis;seasonal circulation4|3|0Updated：2023-06-06
Geology
- Abstract：To evaluate how the decay of bloom-forming algae affect the coastal dissolved oxygen, a laboratory simulation was conducted in terms of three typical harmful algae, Alexandrium catenella, Prorocentrum donghaiense, and Skeletonema costatum. Algae of same biomass (55 μg/mL) were conducted in lightproof columns, and the cell density, dissolved oxygen (DO), and ammonia nitrogen of different layers were monitored at certain time series. Results show that the decomposition of algae significantly decreased the DO, and increased the ammonia nitrogen in all layers; and significant deference between different species was observed. The A. catenella treatment showed the lowest DO (average concentration of 3.4 mg/L) and the highest ammonia nitrogen (average concentration of 0.98 mg/L) at the end of test, followed by P. donghaiense; and the S. costatum showed relatively high DO and low ammonia nitrogen due to slow decay rate. Results indicate that decomposition of harmful bloom algae, especially dinoflagellate, would cause significantly DO depletion and toxic ammonia nitrogen increase, which will detrimentally affect both pelagic and benthic ecosystem.Keywords：harmful algal bloom;hypoxia;Alexandrium catenella;Prorocentrum donghaiense;Skeletonema costatum4|0|0Updated：2023-06-06
- Abstract：Phaeocystis globosa is an important harmful algal bloom causative species distributing widely in temperate and tropical coastal waters in the world. The morphological, physiological, and biochemical characteristics are different among geographic strains, which can not be distinguished with nuclear ribosomal DNA markers at present. Therefore, the genetic distance and phylogeographic relationships of nuclear 28S rDNA D1-D2 and ITS regions, and three chloroplast intergenic spacers (petN-trnS1, trnM1-psbA, and rbcS-rpl27) were analyzed and compared among 13 strains of P. globosa isolated from the Pacific Ocean and Atlantic Ocean in this study. In addition, the nucleotide polymorphisms of 28S rDNA D1-D2, ITS, and rbcS-rpl27 regions were evaluated in two P. globosa strains. The various levels of nucleotide polymorphism were in the nuclear 28S rDNA D1-D2 region and ITS region, but no polymorphism was in the chloroplast rbcS-rpl27 intergenic spacer. A reasonable intraspecific phylogeographic relationship was presented by rbcS-rpl27 intergenic spacer, which had the strongest distinction to geographic strains compared to those of 28S rDNA D1-D2 and ITS regions. In the phylogenetic tree of rbcS-rpl27 intergenic spacer, the two strains from the North Sea of the Atlantic Ocean were divided firstly from the species of P. globosa, and then formed an independent clade, while the other Atlantic strains and all of Pacific strains joined up to build the other clade. It was implied that at least two genetically distant populations of P. globosa existed in the Atlantic coastal regions. This study provided a high-resolution chloroplast marker to analyze intraspecific phylogeographic populations of P. globosa, and preliminarily clarified the genetic relationships of the Pacific and Atlantic strains of P. globosa.Keywords：Phaeocystis globosa;chloroplast;DNA marker;phylogeny4|0|1Updated：2023-06-06
- Abstract：Iron is a vital micronutrient for growth of bloom-forming Microcystis aeruginosa and competition with other algae, and its availability is affected by humic acid. The effect of iron and humic acid on growth and competition between M. aeruginosa and Scenedesmus obliquus was assessed. The results showed the growth of M. aeruginosa and S. obliquus in mono-cultures was inhibited by humic acid at low iron concentrations (0.01 mg/L); the maximum inhibition ratios were 67.84% and 38.31%, respectively. The inhibition of humic acid on the two species was significantly alleviated when iron concentrations were 1.00 mg/L, with the maximum inhibition rate reduced to 5.82% for M. aeruginosa and to 23.06% for S. obliquus. S. obliquus was the dominant species in mixed cultures, and the mutual inhibition between M. aeruginosa and S. obliquus at low iron concentration was greater than that at high iron concentration. The inhibition of S. obliquus on M. aeruginosa was reduced at low iron concentrations; it increased at high iron concentrations, as concentrations of humic acid rose.Keywords：Microcystis;Scenedesmus;iron;humic acid;competition;pigment4|0|1Updated：2023-06-06
- Abstract：To understand the influence of Kuroshio intrusion on the phytoplankton community, a field investigation was conducted in spring 2017 in the East China Sea (ECS), and 130 seawater samples were collected and analyzed. Trichodesmium comprised the highest cell abundance contributing about 66% of the total phytoplankton followed by diatoms (17%) and dinoflagellates (16%). The dominance of the Kuroshio Waters (KW) and the Taiwan Warm Currents (TWC) were higher than the Coastal Waters (CW). The vertical distribution of physicochemical parameters depicted the intrusion of KW at the bottom layer, but it failed to reach the surface as strong upwelling was not initiated. Therefore, the dissolved inorganic phosphate (DIP) concentrations and P/N ratios were the lowest in the CW and the upper water layers, which limited the diatom growth in this area. Besides, the dinoflagellates cell abundance was also lower except in the surface and CW, though they comprised the maximum richness of species among the phytoplankton community. However, the unique characteristics such as diazotrophy and gas vacuoles of Trichodesmium made the situation advantageous, and they comprised the maximum cell abundance in this area especially in KW and the TWC. Temperature, DIP and P/N ratios appeared to be the major environmental drivers for Trichodesmium proliferation in the ECS during the study period.Keywords：Kuroshio waters;phytoplankton;Trichodesmium;community shift4|0|1Updated：2023-06-06
- Abstract：To examine the phytoplankton assemblages and the effect of diluted waters on them, a research cruise was conducted from July 19 to August 7, 2015 in the Zhujiang (Pearl) River estuary in the northern South China Sea (21°N-23.5°N, 111°E-117°E). Samples were collected from 65 stations including one for time-series sampling. A total of 212 phytoplankton taxa were identified from 61 genera belonging to 4 phyla. Among them, 122 species identified from 42 genera of Bacillariophyta and 83 species from 15 genera of Pyrrophyta. Chain-forming diatoms dominated the phytoplankton community where Pseudo-nitzschia delicatissima, Guinardia striata, Thalassionema nitzschioides, and P. pungens comprised about 52% of the total abundance. However, higher cell abundances concentrated on both sides of the estuary, because of low salinity and high nutrients brought by diluted water. In addition, Canonical Correspondence Analysis revealed that salinity and dissolved inorganic nitrogen shaped the species composition in the study area. Furthermore, the Jaccard similarity index showed prevailing high similarity in the distribution of species in low-salinity diluted waters, and the Bray-Curtis similarity depicted distinguished grouping for phytoplankton assemblages along the salinity gradient. However, phytoplankton diel vertical cycles showed maximum abundance occurred at 2:00 am, which was mainly contributed by benthic phytoplankton species Pseudo-nitzschia spp. and T. nitzschioides.Keywords：phytoplankton;canonical correspondence analysis;Diel Cycle;Zhujiang (Pearl) River estuary4|2|3Updated：2023-06-06
- Abstract：To examine the eukaryotic biodiversity of aquatic ecosystems in the Qiantang River, China, eukaryotic microbes in the river were investigated using 18S rRNA gene sequencing during the breeding season (July to August 2018). Four distinct distribution patterns (1. Jiande; 2. Tonglu and Fuyang; 3. Jiubao; 4. Yanguan) of the microbial community and their potential effects on fishery activities were observed. Results show lower abundances of Dinophyta and Fungi and higher abundances of Cryptophyta and Chlorophyta in Tonglu and Fuyang than those in the other three sections. In addition, the reserves (Tonglu and Fuyang) destabilized the original eukaryotic microbial co-occurrence network. Among all the environmental factors measured, nitrogen (nitrite, nitrate, ammonium), water temperature and total chlorophyll a acted as major driving factors that controlled the eukaryotic microbial distribution. Furthermore, the existence of some algae (e.g., Chrysophyceae, Cryptophytes, and Chlorophyceae) and fungi (e.g., Rhizophydium) in Tonglu and Fuyang was beneficial to juvenile fish growth and water quality, although some detrimental species (e.g., Aphanomyces) needed attention. This study provides further insights into the sustainable protection and utilization of rivers.Keywords：Qiantang River;fish reserves;18S rRNA;asymmetric eigenvector maps;molecular ecological network analyses;biological indicators6|2|0Updated：2023-06-06
- Abstract：Depth-dependent distribution patterns of bacterial and archaeal communities in deep sea water column around the Ninetyeast Ridge in the Indian Ocean were investigated using 16S rRNA gene profiling. Sampling was conducted at the northern Ninetyeast Ridge (1°59.89'N-9°59.70'S, 87°58.90'E-88°00.03'E) from September to November 2016 where samples were collected from the bathyal (1 000 m) to bathypelagic depths (>4 000 m) in four different stations. A total of 1 565 405 clean data falling into 6 712 bacterial OTUs and 1 452 727 clean data falling into 806 archaeal OTUs based on 97% similarity level were analyzed. Most of the bacterial 16S rRNA gene sequences were affiliated with Gammaproteobacteria, followed by Alphaproteobacteria and Bacteroidia. The archaeal 16S rRNA gene sequences mostly affiliated to Nitrososphaeria (Thaumarchaeota) dominated with relative abundances ranging from 52.68% to 97.2%, followed by Thermoplasmata (Euryarchaeota). Vertical partitioning of bacterial and archaeal communities among different water layers was observed. Canonical correspondence analysis (CCA) and Spearman's correlations revealed that depth (P=0.003), dissolved oxygen (P=0.019), and nitrite (P=0.033) were the main environmental factors affecting bacterial community structure at genus level in the Ninetyeast Ridge. On the other hand, the first two CCA axes accounted for 74.4% of the explained total variance, it seems that the archaeal communities at genus level were heavily influenced by the environmental variables including depth, dissolved oxygen (DO), nitrite, salinity, phosphate, ammonia, nitrate, and silicate, but none of them exhibited any significant correlation on the structuring (P>0.1).Keywords：deep sea water;the Ninetyeast Ridge;16S rRNA gene;bacteria;archaea4|3|1Updated：2023-06-06
Ecology
- Abstract：Circadian clock genes are crucial for generating and sustaining most rhythmic daily functions in the animal kingdom, which entrain the rhythms of biochemical, physiological, and behavioural processes. To better understand the molecular oscillations of the circadian rhythms in darkbarbel catfish (Pelteobagrus vachellii), we isolated and characterized two circadian clock genes in P. vachellii, period 1 (per1), and period 3 (per3). The circadian clock gene per1 was found to encode a 1 428-amino acid polypeptide, including PER-ARNT-SIM (PAS) dimerisation domains, a PAS-associated C-terminal motif (PAC), a short mutable domain (S/M), and a nuclear export signal (NES). The 4 902-bp per3 cDNA includes an open reading frame encoding a 1 292-amino acid residue polypeptide with a PER-ARNT-SIM (PAS) domain, cytoplasmic localisation domain (CLD), interaction site (TIS), and a nuclear localisation signal (NLS). The per1 and per3 gene was constitutively expressed in all examined tissues. Moreover, per1 expression within a light/dark cycles showed rhythmic expression in the diencephalon, brain, liver and intestine, with the acrophase at 15:15, 12:52, 7:51, and 12:55, respectively. Daily expression of per3 was rhythmic in the diencephalon, brain, liver and intestine, with the acrophase at 8:15, 9:54, 10:39, and 10:25 h, respectively. These findings expand our understanding of circadian mechanism at the molecular level in this species.Keywords：cDNA;circadian rhythm;diurnal expression;Pelteobagrus vachellii;period 1;period 34|0|1Updated：2023-06-06
- Abstract：The genotoxic effects of quinalphos (QP) were evaluated in the erythrocytes of Cyprinus carpio using the comet, micronucleus, and nuclear abnormality assays. The 96 h LC50 value of quinalphos, estimated by static renewal system, was 10.9 μL/L. On the basis of the LC50 value, two sublethal concentrations (1.09 and 2.18 μL/L) of the compound were used together with cyclophosphamide (5 mg/L) as the positive control. The fish were exposed for 35 d, and sampling was done at the end of 7, 14, 21, 28, and 35 d. Our results reveal a significant dose-dependent increase in the frequencies of DNA strand breaks, micronucleus, and nuclear abnormalities. Similar responses were also observed in fish exposed to the positive genotoxin cyclophosphamide. The collective findings demonstrated that quinalphos exerts a genotoxic effect on C. carpio. The results further confirmed that the comet, micronucleus, and nuclear abnormality assays are useful tools in determining the potential genotoxicity of pesticides towards aquatic organisms.Keywords：quinalphos (QP);micronucleus;nuclear abnormalities;cyclophosphamide;Cyprinus carpio5|0|0Updated：2023-06-06
- Abstract：Comprehensive understanding of marine biodiversity is essential for conservation, especially for vulnerable ecosystems. In this paper, we implemented and illustrated a checklist of molluscs from the Abrolhos Parcel, Brazil, the most important coralline area in South Atlantic waters. The list features 100 species belonging to 4 classes and 85 genera, of which 15 are new records for Bahia State, northeast Brazil. The results highlight the potential for new records in the area. The species came from 54 unconsolidated sediment samples collected from the bottom of the reef with a 0.042-m2 van Veen grab. Among the listed species, Curveulima sp., Notarchus sp. and Guyanella clenchi are new records for the South Atlantic, while Caecum metamorphosicum, Eratoidea janeiroensis, Volvarina serrei, Solemya notialis, Solariorbis shimeri, and Amphithalamus glabrus are endemic to Brazilian waters. A comparison of our results with those obtained in other reef environments indicates that the Abrolhos Parcel has a rich malacofauna and suggests that many more species can still be found with more samplings.Keywords：bivalvia;Gastropoda;micromolluscs;Scaphopoda;Solenogastres;southwest Atlantic4|3|0Updated：2023-06-06
- Abstract：One new species and one new record species of Sphaerolaimus are described. Sphaerolaimus longispiculatus sp. nov. is characterized by body length 2 213-2 470 μm, amphideal fovea 12%-16% corresponding body diameters in males and 9%-10% corresponding body diameters in females, long slender spicules 2.8-3.8 cloacal body diameters, eight small papilliform precloacal supplements, gubernaculum without apophysis, and tail conico-cylindrical, 2.5-3.7 cloacal/anal body diameters long. Sphaerolaimus gracilis is recorded from the first time in the mangroves wetlands, it can be distinguished from the original desceiption by longer spicules (66-71 μm vs 56 μm) and wider body (a=20.1-21.4 vs 25).Keywords：free-living marine nematodes;taxonomy;Sphaerolaimus longispiculatus sp. nov.4|0|0Updated：2023-06-06
- Abstract：Emiliania huxleyi is the most prominent modern coccolithophore, a group of marine unicellular eukaryotes that play a critical role in ocean biogeochemistry. Coccolithoviruses are large double stranded DNA viruses, which is responsible for the demise of large oceanic blooms formed by E. huxleyi. E. huxleyi virus (EhVs) acquired a series of enzyme-coding genes predicted to be involved in the sphingolipid biosynthesis by horizontal gene transfer between virus-host. Currently, there is limited experimental validation identifying the functions of these genes in EhV. Genetic transformation of eukaryotic cells is a powerful tool to get an insight into gene functions of the studied organisms. Serine palmitoyltransferase (SPT) catalyzes the first committed step in de novo sphingolipid biosynthetic pathway. Here, a novel vector system for the transformation of E. huxleyi was designed. It contained fragments of promoter and terminator sequences of E. huxleyi endogenic fucoxanthin chlorophyll a/c-binding protein gene "fcp" and harbored EhV-99B1 spt gene. The resultant recombinant transformation vectors pEhux-I-spt and pEhux-II were co-transferred into E. huxleyi BOF92 by electroporation. Transformants were obtained upon glufosinate-ammonium selection, and confirmed by Southern hybridization, genome PCR, qRT-PCR and Western blot screening of spt gene, which indicated that spt gene was integrated into the nuclear genome and was expressed at the mRNA and protein levels. The expression of the viral spt gene led to differences in lipid compositions analyzed using thin-layer chromatography (TLC). The results present the genetic transformation system for E. huxleyi, providing additional genetic resource with potential for exploring basic biological questions such as the virus-host interactions.Keywords：Emiliania huxleyi;Coccolithovirus;genetic transformation;serine palmitoyltransferase (SPT);total lipid4|0|0Updated：2023-06-06
- Abstract：Pyropia haitanensis polysaccharide (LP) have been found for having many excellent functions such as anti-aging. Using Caenorhabditis elegans models, we evaluated the anti-aging activity of LP by observing the lifespan, reproduction, pharyngeal pumping, stress response, quantitative fluorescence of polyglutamic acid, and nuclear localization of DAF-16 of worms. The results reveal that LP could extend the adult lifespan of wild-type and polyQ nematodes, indicating a connection of its anti-aging benefit with the toxicity-suppressing effect. The number of polyglutamic acid aggregates in high concentration groups decreased by 24.39% (P < 0.05) to the control. The high-dose group strongly induced DAF-16 nuclear translocation over intermediate and cytosolic localizations compared with the control (P < 0.001). Therefore, we believe that LP could extend the lifespan and reduce the protein aggregation in C. elegans through nuclear DAF-16:: GFP expression.Keywords：Pyropia haitanensis;polysaccharide;protein aggregation;Caenorhabditis elegans4|0|0Updated：2023-06-06
- Abstract：It has been reported that there was a linkage of 5S rRNA gene to 18S-5.8S-25S rRNA gene in a few of species in Ochrophyta. In regard to the usual two positions of linked 5S rDNA to the 3' end of 25S rDNA, two pairs of primers were designed for amplification to verify this linkage of two genes in a kelp cultivar of Saccharina japonica, one of species in Ochrophyta. This result supplemented the previous report that 5S rDNA was unlinked to 25S rDNA in this kelp. In order to simultaneously visualize this unlinkage of two genes, dual-color fluorescence in situ hybridization (FISH) technique was applied to the cytogenetics of S. japonica. Dual-color FISH images showed that two and four hybridization signals were present in the kelp gametophyte and sporophyte, respectively, metaphase nuclei hybridized simultaneously with the labeled probes of 18S rDNA and 5S rDNA. Both haploid and diploid karyotypes in decreasing length of chromosomes showed that 18S-5.8S-25S rDNA was localized at the interstitial region of Chromosome 23, whereas 5S rDNA resided at the sub-telomeric region of Chromosome 27. These karyotypes suggested that the kelp nuclear genome had only one locus of each rRNA gene, and their loci on different chromosomes indicated the physical unlinkage of 5S rDNA to 18S-5.8S-25S rDNA in this kelp. Therefore, dual-color FISH seems to be a powerful technique for the discrimination and pairing of chromosomes featured in both small size and nearly identical shape in S. japonica.Keywords：5S rDNA;18S-5.8S-25S rDNA;chromosome;fluorescence in situ hybridization (FISH);kelp;linkage;locus4|2|0Updated：2023-06-06
Biology
- Abstract：Fish populations have declined in many estuarine and freshwater ecosystems in part due to the loss of habitat in recent decades. Reconstructing lost habitat for larvae fish is a potential method for recovering larvae fish populations. Three-dimensional artificial floating wetlands (AFWs) on which Phragmites australis was planted were experimentally deployed to recover the lost habitat in the Changjiang (Yangtze) River estuary from May to July 2018. The AFW area was characterized by slow velocity, high transparency, low dissolved oxygen, and relatively constant water temperature. The total individuals of larvae fish in the AFW area (12 122 in total) was higher than that in the non-AFW area (1 250 in total), and the densities of most larvae fish species were higher in the AFW habitat than in the non-AFW area. The distributions of larvae fish species were positively influenced by habitat type because they were strongly related to the negative part of the first axis of the redundancy analysis, and Cyprinus carpio and Cyprinus auratus were inclined to habitat in the slow velocity and high transparency AFW habitat area. These results indicate that larvae fish species are inclined to inhabit the AFW habitat. The use of three-dimensional P. australis AFWs would be a potential method for enhancing the habitat of larvae fish in the degraded habitats along the estuary.Keywords：habitat rehabilitation;larvae fish;biodiversity conservation;artificial floating wetland;Changjiang (Yangtze) River estuary4|2|1Updated：2023-06-06
- Abstract：With the decline in the most fisheries resources in the Yellow Sea, the yellow goosefish Lophius litulon has increased in commercial and ecological importance in recent years. We studied the length distribution, length-weight relationship, age composition, growth pattern, mortality, and exploitation rates of the yellow goosefish in the Yellow Sea. Total length (TL) of females and males ranged from 173 to 582 mm and 178 to 500 mm, respectively. The length-weight relationships were also estimated for females and males. Age classes from 2 to 4 years predominated in the samples. The von Bertalanffy growth function (VBGF), estimated based on non-linear least-squares methodology, showed significant differences between sexes. Females attained a greater estimated asymptotic total length (765 mm TL) compared to males (579 mm TL). The VBGF did not differ significantly between stocks of the northern Yellow Sea and the southern Yellow Sea. Estimated natural instantaneous mortality rate (M) ranged from 0.25/a to 0.33/a based on four age- and length-based methods. Total instantaneous mortality rate (Z) of total samples calculated by the age-based catch curve method was 0.591/a and the average fishing mortality (F) was 0.30/a. Estimated exploitation rate (E) was approximately 0.5, indicating that the population of L. litulon in the Yellow Sea may be sustainable. These results provide a reference for the present status of L. litulon and information for the management.Keywords：Lophius litulon;Yellow Sea;age;growth;mortality rate4|0|1Updated：2023-06-06
- Abstract：The single and synergistic effects of dietary arabinoxylan-oligosaccharide (AXOS) and inulin at different doses (2, 4, and 8 mg/g diet) on survival, growth performance, gut microbiota, and immune response in Pacific white shrimp Litopenaeus vannamei were assessed. Singular application of either inulin or AXOS at doses of 4 mg/g diet showed the most stimulatory effects on the growth rate and gene expression levels of chitinase, cathepsin L, chymotrypsin, and extracellular signal-regulated kinase (ERK) in each single prebiotic feeding trial. Compared with single prebiotic treatments, simultaneous application of AXOS and inulin at 4 mg/g diet enhanced remarkably the growth parameters of shrimp and the expression of related genes (chitinase, cathepsin L, chymotrypsin, ERK, myeloid differentiation factor 88, and phenoloxidase) after 8-week feeding (P < 0.05). Additionally, gut microbiota analysis indicated the dietary supplementation with combined prebiotics increased significantly the bacterial community richness and relative abundance of Bacillus, Pseudomonas, Bacteriovorax, and Lactobacillus, and reduced the abundance of Vibrio, Rhodococcus, and Photobacterium in the digestive tract of L. vannamei. Compared with the single prebiotic treatment and the control, combined prebiotics supplementation boosted notably the survival rate and expression levels of immune-related genes in shrimp infected with Vibrio alginolyticus or white spot syndrome virus. Therefore, simultaneous application of AXOS and inulin shall have a great potential of dietary supplement in the culture of L. vannamei.Keywords：prebiotic;growth;intestinal microflora;immunity;Litopenaeus vannamei4|0|4Updated：2023-06-06
- Abstract：Anadara broughtonii is one of the main commercially important species of shellfish in northern China. A. broughtonii lives in relatively stable subtidal zone where the clam could respond to environmental changes with minimum energy. Therefore, slight fluctuations in water environment may have a great impact on physiological processes such as feeding and metabolism. Large-scale mortality often occurs during the intermediate rearing processes, and high temperatures in summer are considered the leading cause of mortality. To understand the physiological and molecular response patterns of A. broughtonii at high temperatures and to estimate the appropriate metabolism temperature for A. broughtonii, the effects of temperature on the respiratory metabolism and food intake at different growth stages were studied. The response patterns of heat shock protein genes to heat stress and post-stress recovery were also explored. Results show that the temperature and growth stage of A. broughtonii were two important factors affecting metabolism and feeding. The optimum temperature for feeding and physiological activities in each shell-length group was 24℃. The temperature at which the peak metabolic rate occurred in each shell-length group increased with the increase in shell length. With the increase in heat stress, the expression of three heat shock protein genes (Abhsp60, Abhsp70, and Abhsp90) in the tissues of two size groups of A. broughtonii increased significantly when temperature was above 24℃ and reached a peak at 30℃. After heat shock at 30℃ for 2 h, the expression of the three heat shock protein genes rapidly increased, peaked at 2 h after the heat shock, and then gradually decreased to the level of the control group at 48 h after the heat shock. The three heat shock protein genes respond rapidly to heat stress and can be used as indicators to the cellular stress response in A. broughtonii under an environmental stress.Keywords：Anadara broughtonii;temperature;oxygen consumption rate;clearance rate;heat shock protein gene4|0|1Updated：2023-06-06
- Abstract：Fishery-independent surveys can provide high-quality data and support fishery assessment and management. Optimization of sampling design is crucial to increase the quality of fishery surveys. Crab pots are important fishing gears used to catch crabs. We analyzed the impacts of sampling design of crab pots on the abundance of Portunus trituberculatus in the Changjiang (Yangtze) River estuary to the Hangzhou Bay and its adjacent waters in East China Sea. The crab pots were cylindrical, 240 mm in height and 600 mm in diameter of the iron ring. Our sampling designs (including fixed-station sampling, simple random sampling, stratified fixed-station sampling, and stratified random sampling), three number of stations (9, 16, and 24), and three numbers of crab pots (500, 1 000, and 3 000) were simulated and compared with the "true" abundance that obtained from bottom trawl surveys in the study area in 2007. The scenarios with 16 stations were set in stratification as a control group for comparison with unstratified designs. Results show that simple random sampling can obtain more stable results than fixed-station sampling in the abundance estimation of P. trituberculatus. In addition, stratified sampling resulted in more accurate abundance than unstratified sampling. The accuracy of the simulated results improved with the increase of the number of stations. No remarkable differences in the results were found among the scenarios of different number of crab pots at each station. However, resource-intensive areas exerted great impacts on simulation results. Thus, prior information or pre-survey results about resource abundance and density distribution are necessary. This study may serve as a reference for future sampling designs of crab pots of P. trituberculatus and other species.Keywords：sampling design;number of sampling station;sampling time;Portunus trituberculatus;abundance estimation;crab pot4|0|3Updated：2023-06-06
Aquaculture and Fisheries
- Address：Editorial Office of JOL, 88 Haijun Rd. Qingdao, 266000, China
- Tel：+86-532-82898754 Email：jol@qdio.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0