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Volume 38 ， Issue 5 ， 2020
- Abstract：The dimensional and temporal distribution of Antarctic Intermediate Water (AAIW) and North Pacific Intermediate Water (NPIW) in the Philippine Sea were explored using Argo profiles and gridded Argo data. As the salinity minimum of intermediate water from mid-high latitude of the southern and northern hemisphere of the Pacific Ocean, the properties of AAIW and NPIW merge at about 10°N with different properties in the Philippine Sea. The core of AAIW is located below 600 dbar with potential density of 27 ≤ σθ ≤ 27.3 kg/m3 and salinity of 34.5 ≤ S ≤ 34.55. The core of NPIW is located between 300-700 dbar with potential density of 26.2 ≤ σθ ≤ 27 kg/m3 and salinity of 34 ≤ S ≤ 34.4. The volume of AAIW and NPIW during January 2004 to December 2017 is negatively correlated. The time series of AAIW and NPIW is dominated by significant periods of 6 and 8 months, respectively. The variations of AAIW and NPIW are mainly affected by volume transport through a 130°E section by the North Equatorial Current (NEC) and North Equatorial Undercurrent (NEUC).Keywords：the intermediate water;the Antarctic Intermediate Water;the North Pacific Intermediate Water;seasonal variation4|0|2Updated：2023-04-27
- Abstract：Based on nearly 4 year-long moored velocity measurements at 8°N/127°E and a high-resolution ocean model output, a significant 30-50-day variation in the subthermocline current east of Mindanao was identified for the first time in addition to the 60-80-day variation reported in previous studies. The 30-50-day variation is an important component and it explains considerable variance same as that of the 60-80-day variation. The 30-50-day variation is vertically coherent in the subthermocline current. The standard deviations of the 30-50-day variation in zonal and meridional directions are of comparable, and is about 4.5-5 cm/s. Eddy-tracking analysis indicated that ocean eddies originating from the North Equatorial Current (10°N-11°N) contribute to the 30-50-day and the 60-80-day variations. The 30-50-day eddies propagate faster than the 60-80-day eddies.Keywords：intraseasonal variability;subthermocline current;Mindanao4|0|0Updated：2023-04-27
- Abstract：Instability/stability in the North Equatorial Current (NEC) basin is studied based on data obtained from nine moorings deployed at 8.5°N, 10.5°N, 11.0°N, 12.5°N, 13.0°N, 15.0°N, 15.5°N, 17.5°N, and 18.0°N along 130.0°E during cruises in 2015-2017. In low latitudes, the Coriolis parameter and stratification ratio play important roles in NEC stability, whereas velocity shear and the layer depth ratio are important for NEC stability in high latitudes. Beneath the westward NEC, eastward zonal jets occur intermittently centered around 8.5°N, 12.5°N, and 17.5°N along 130.0°E. Similar to the NEC, the main body of these zonal jets also deepens with latitude. In the boundary layer comprising the bottom NEC and upper zonal jets, the growth rate of the NEC is attributed not only to velocity shear but also to zonal jet velocity based on the longwave assumption. Based on the shortwave assumption, the growth rate is proportional to zonal jet velocity but has no relationship with velocity shear. Climatologically, the growth rate in the boundary layer is not zero at 8.5°N, 12.5°N, and 13.0°N, where the velocity shear and zonal jets are larger than at other stations. The instability also occurs at the time node when the zonal jets are strong enough, although the mean zonal jets may disappear at this station.Keywords：instability;North Equatorial Current (NEC);zonal jets5|0|1Updated：2023-04-27
- Abstract：Parameter uncertainty is a primary source of uncertainty in ocean ecosystem simulations. The deep chlorophyll maximum (DCM) is a ubiquitous ecological phenomenon in the ocean. Using a theoretical nutrients-phytoplankton model and the conditional nonlinear optimal perturbation approach related to parameters, we investigated the effects of parameter uncertainties on DCM simulations. First, the sensitivity of single parameter was analyzed. The sensitivity ranking of 10 parameters was obtained by analyzing the top four specifically. The most sensitive parameter (background turbidity) affects the light supply for DCM formation, whereas the other three parameters (nutrient content of phytoplankton, nutrient recycling coefficient, and vertical turbulent diffusivity) control nutrient supply. To explore the interactions among different parameters, the sensitivity of multiple parameters was further studied by examining combinations of four parameters. The results show that background turbidity is replaced by the phytoplankton loss rate in the optimal parameter combination. In addition, we found that interactions among these parameters are responsible for such differences. Finally, we found that reducing the uncertainties of sensitive parameters could improve DCM simulations remarkably. Compared with the sensitive parameters identified in the single parameter analysis, reducing parameter uncertainties in the optimal combination produced better model performance. This study shows the importance of nonlinear interactions among various parameters in identifying sensitive parameters. In the future, the conditional nonlinear optimal perturbation approach related to parameters, especially optimal parameter combinations, is expected to greatly improve DCM simulations in complex ecosystem models.Keywords：deep chlorophyll maximum (DCM) simulation;parameter uncertainty;conditional nonlinear optimal perturbation related to parameters (CNOP-P);sensitivity6|0|3Updated：2023-04-27
- Abstract：Why did the predicted "super El Niño" fade out in the summer 2014 and the following year develop into one of the three strongest El Niño on record? Although some hypotheses have been proposed in previous studies, the quantitative contribution of oceanic processes to these events remains unclear. We investigated the role of various oceanic feedbacks, especially in response to intra-seasonal westerly wind busts, in the evolution of the 2014-2016 El Niño events, through a detailed heat budget analysis using high temporal resolution Estimating the Circulation and Climate of the Ocean-Phase Ⅱ (ECCO2) simulation outputs and satellite-based observations. Results show that the Ekman feedback and zonal advective feedback were the two dominant oceanic processes in the developing phase of the warm event in the spring of 2014 and its decay in June. In the 2015-2016 super El Niño event, the zonal advective feedback and thermocline feedback played a significant role in the eastern Pacific warming. Moreover, the thermocline feedback tended to weaken in the central Pacific where the zonal advection feedback became the dominant positive feedback.Keywords：El Niño-Southern Oscillation (ENSO);extreme El Niño;zonal advective feedback;thermocline feedback;Ekman feedback;inter-seasonal variability4|0|0Updated：2023-04-27
- Abstract：The mean velocity structure and variability of the Kuroshio east of Taiwan, China, were investigated using mooring observations acquired at 23°N/122°E between January 2016 and May 2017. Power spectrum analysis reveals marked intraseasonal variability in 70-95 days in the meridional Kuroshio velocity in the upper 800 m. Hybrid Coordinate Ocean Model assimilation data adequately reproduce variations of the Kuroshio. Westward propagating mesoscale eddies that originated from the Subtropical Countercurrent play an important role in intraseasonal variability in the Kuroshio velocity. Cyclonic (anticyclonic) eddies are often associated with negative (positive) sea surface height anomaly, resulting in positive (negative) potential vorticity in the subsurface layer of the eddy center, which decreases (increases) isopycnal slope and then weakens (strengthens) the Kuroshio. When anticyclonic (cyclonic) eddies are active, the Kuroshio axis moves offshore (inshore). Corresponding to the Kuroshio intraseasonal variability (ISV), the variation of the intermediate water salinity also had a significant ISV induced by the mesoscale eddies.Keywords：intraseasonal variability;Kuroshio;mesoscale eddy;intermediate water4|0|0Updated：2023-04-27
- Abstract：Subsurface eddies (SSEs) are common features of the ocean interior. They are particularly abundant in oceanic basins and the vicinity of major intermediate water outflows. They are responsible for subsurface transport of mass, heat, and salt. Analysis of high-resolution general circulation model data has revealed the existence of subsurface anticyclonic eddies (SSAEs) and subsurface cyclonic eddies (SSCEs) in the northwestern tropical Pacific Ocean. SSEs are abundant east of the Philippines (0°-22°N, 120°E-140°E) and in latitude bands between 9°N-17°N east of 140°E. The composite structure of SSEs was investigated. SSEs had a core at about 400-m water depth and their maximum meridional velocity exceeded 10 cm/s. They exhibited two cores with different salinity polarities in the surface and subsurface. Additionally, spatial distributions of heat transport induced by SSEs in the northwestern tropical Pacific were presented for the first time. A net equatorward heat flux toward a temperature up-gradient was observed. The analysis of eddy-mean flow interactions revealed that the circulation is baroclinically and barotropically unstable at different depths and to differing degrees. The energy conversions suggest that both barotropic and baroclinic instabilities are responsible for SSE generation east of the Philippines, whereas baroclinic instability caused by a horizontal density gradient and vertical eddy heat flux are important between 9°N and 17°N east of 140°E. Meridional movement of the north equatorial current and the north equatorial undercurrent can contribute to SSE generation in our study region.Keywords：the northwestern tropical Pacific Ocean;subsurface eddies;composite structures;heat transport;energy source4|0|3Updated：2023-04-27
- Abstract：Characteristics and generation of internal waves (IWs) in the Sulu Sea are studied using Moderate-Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) images taken from October 2016 to September 2019. Satellite observations show that IWs in the Sulu Sea mainly located in the shallower western areas with occasional observations in the deeper eastern regions. The dominant length of wave crest (LWC) of IWs is between 50 and 150 km with the largest LWC reaching over 300 km. The analysis of temporal distributions of IWs shows that March has the most IWs and July has the least. Further analysis shows that the seasonal variation is mainly due to the cloud contamination of optical satellite images. New generation sites of IWs are analyzed using satellite images. Six possible generation sites for IWs in the western Sulu Sea and one generation site for IWs in the eastern Sulu Sea are found using the ray-tracing method. Multi IW sources in the same strait are found, which may be due to the seawater flow over the strait in different directions. The analysis shows that IWs with long wave crest in the Sulu Sea is a combined effort of all straits between small islands in the Sulu Archipelago. Remote generated IWs with long wave crest in the eastern Sulu Sea are studied, which are generated at the straits around (121.5°E, 6°N) by the nonlinear evolution of internal tide originated from the Sulu Archipelago.Keywords：internal waves (IWs);Sulu Sea;Moderate-Resolution Imaging Spectroradiometer (MODIS);Suomi National Polar-Orbiting Partnership (NPP)4|0|0Updated：2023-04-27
- Abstract：Eleven climate system models that participate in the Coupled Model Intercomparison Project phase 5 (CMIP5) were evaluated based on an assessment of their simulated meridional transports in comparison with the Sverdrup transports. The analyses show that the simulated North Pacific Ocean circulation is essentially in Sverdrup balance in most of the 11 models while the Argo geostrophic meridional transports indicate significant non-Sverdrup gyre circulation in the tropical North Pacific Ocean. The climate models overestimated the observed tropical and subtropical volume transports significantly. The non-Sverdrup gyre circulation leads to non-Sverdrup heat and salt transports, the absence of which in the CMIP5 simulations suggests deficiencies of the CMIP5 model dynamics in simulating the realistic meridional volume, heat, and salt transports of the ocean.Keywords：Coupled Model Intercomparison Project phase 5 (CMIP5) models;Sverdrup balance;meridional transport;Argo geostrophic currents4|0|0Updated：2023-04-27
- Abstract：The inverse cascade flux of kinetic energy (KE) and its length scale in the South Indian Countercurrent (SICC) region were investigated using 24-year satellite altimeter daily data from 1993-2016. The evolution of the eddy life cycle in the SICC was presented systemically. It was found that the arrest and inject scales of inverse cascade were within the baroclinic most unstable scale and observed energy-containing eddy scale. The seasonal cycle of the arrest scale, inject scale, and amplitude of the inverse cascade were compared with the eddy kinetic energy seasonal cycle, which revealed a 1.5-month lag of the eddy kinetic energy to the vertical shear of zonal velocity, implying the existence of nonlinear processes during the eddy growth phase. Meanwhile, the anisotropy of the inverse cascade indicated that kinetic energy might be transferred from meridional motions to zonal motions, which is probably caused by β effect. These results would be beneficial for a better understanding of the KE transfer processes in the SICC region.Keywords：mesoscale eddies;spectral kinetic energy flux;inverse cascade;South Indian Countercurrent (SICC)4|0|0Updated：2023-04-27
Physics
- Abstract：A number of high-temperature processes (e.g., melt-rock reactions, metasomatism, partial melting) can produce significant Ca isotopic fractionation and heterogeneity in the mantle, but the mechanism for such fractionation remains obscure. To investigate the effect of mantle partial melting on Ca isotopic fractionation, we reported high-precision Ca isotopic compositions of depleted mid-ocean ridge basalts (MORBs) from the East Pacific Rise and Ecuador Rift in the northeastern Pacific. The δ44/40Ca of these MORB samples exhibit a narrow variation from 0.84‰ to 0.88‰ with an average of 0.85‰0.03‰, which are similar to those of reported MORBs (0.83‰0.11‰) and back-arc basin basalts (BABBs, 0.80‰0.08‰) in literature, but are lower than the estimate value for the bulk silicate Earth (BSE, 0.94‰0.05‰). The low δ44/40Ca signatures of MORB samples in this study cannot be caused by fractional crystallization, since intermediate-mafic differentiation has been demonstrated having only limited effects on Ca isotopic fractionation. Instead, the offset of δ44/40Ca between MORBs and the BSE is most likely produced by mantle partial melting. During this process, the light Ca isotopes are preferentially transferred to the melt, while the heavy ones tend to stay in the residue, which is consistent with the fact that δ44/40Ca of melt-depleted peridotites increases with partial melting in literature. The behavior of Ca isotopes during mantle partial melting is closely related to the inter-mineral (Cpx and Opx) Ca isotopic fractionation and melting mineral modes. Mantle partial melting is one of the common processes that can induce lower δ44/40Ca values in basalts and Ca isotopic heterogeneity in Earth's mantle.Keywords：Ca isotopes;mid-ocean ridge basalts (MORBs);mantle partial melting;magma differentiation4|0|3Updated：2023-04-27
- Abstract：Distribution of total organic carbon (TOC), total nitrogen (TN), stable isotope ratio of organic carbon and nitrogen (δ13C and δ15N) in 31 surface sediments were examined to quantitatively discriminate the source and burial of sedimentary organic matter (SOM) in the East China Sea (ECS). Results show that high content of TOC and TN occurred in the southern inner shelf and the northeast area due to the transport of organic matter (OM) from the Changjiang (Yangtze) River southwards by the Zhejiang Fujian Coastal Current (ZFCC) and the delivery from the old Huanghe (Yellow) River estuary by the Subei Coastal Current (SbCC), respectively. The significant relationship of TOC to clay provided evidence that the fine-grained sediment was the primary carrier for SOM from the inner shelf to open sea. The TN varied proportionally to the TOC with the neglected intercept, suggesting that most of nitrogen measured was related to the SOM and the influence of the sorption of inorganic nitrogen was insignificant. The seaward enrichment of δ13C and seaward depletion of C/N and δ15N illustrated the decrease of terrestrial OM (TOM) and the increase of marine OM (MOM). The close of average C/N ratio to the Redfield ratio indicated the minor role of terrestrial plant debris in the SOM. Distribution of bulk OM properties was ascribed to the terrestrial and marine input by the shelf circulation and phytoplankton with the contributions of 76.1% MOM and 23.9% TOM to SOM, respectively. The burial flux of OC ranged within 0.34-7.56 mg/(cm2·a) (averaged 2.80 mg/(cm2·a)) and enriched along the shore and in the fine-grained area, manifesting the significant input of the land-based sources and the effect of shelf mud depositional process on the fate of SOM. The sharp seaward decrease of burial fluxes of terrestrial and marine OC gave evidences that the majority of organic carbon were settled in the inner shelf with the small fraction of them further transported eastwards.Keywords：distribution;sedimentary organic matter;sources;burial;East China Sea (ECS)4|0|7Updated：2023-04-27
- Abstract：Marine sediment is the primary sink of microplastics and is an indicator of pollution levels. However, although there are well-developed detection methods, detection is rarely focused on lowmicrometer-sized particles, mainly due to technique limitations. In this study, a simplified process omitting digestion procedures was developed to pretreat microplastics obtained from marine sediment and was coupled with micro-Raman spectroscopy to identify microplastics. Based on the overall analysis of the characteristic peak assignments, a Raman spectral reference library was constructed for 18 types of plastic. In addition, the effects of the measurement parameters were systematically described. Field research was then conducted to validate the developed process and investigate microplastic contamination in Huiquan Bay, Qingdao, China. This simplified process could retain the original appearance of microparticles and accomplish the detection of < 500 μm-sized microplastics in environmental samples. Microplastics in the size range of 10-150 μm accounted for 76% of all microplastics, and 56% of the total particles was particles smaller than 50 μm. Polypropylene (42%) and polyethylene (20%) were predominant components of the particles. In particular, polypropylene particles smaller than 10 μm were identified in marine sediment. This work demonstrates that Raman spectroscopy is not only an effective tool for detecting environmental particles but also highly applicable for identifying particles extracted from marine sediment.Keywords：microplastics;confocal;Raman spectroscopy;marine sediment4|0|5Updated：2023-04-27
Geology
- Abstract：The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu2O nanoparticles on the surface of TiO2 nanotubes via anodic oxidation and constant current deposition. Field emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses showed that Cu2O nanoparticles not only deposited on the surface of TiO2 nanotube array, but also on the wall of TiO2 nanotubes. The Cu2O deposition amount could be adjusted by changing the deposition time. The photoelectrochemical cathodic protection (PECCP) performance of the prepared photoelectrodes for 316L stainless steel (SS) was tested under visible light. The constant current deposition time had a significant effect on the PECCP performance of Cu2O/TiO2-X photoelectrodes and Cu2O/TiO2-20 had the best PECCP performance for the coupled 316L SS. This was attributed to the appropriate amount and thickness of Cu2O to form p-n heterojunctions with TiO2, in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.Keywords：Cu2O/TiO2;p-n heterojunction;316L SS;photoelectrochemical cathodic protection4|0|2Updated：2023-04-27
- Abstract：A new aromatic bisabolene-type sesquiterpenoid (7S, 8S)-8-hydroxysydowic acid (1), together with a pair of new bisabolene derivative (±)-(7R*, 10R*)-10-hydroxysydowic acid (2), as well as two known analogues hydroxysydonic acid (3) and sydowic acid (4) were isolated and identified from the endophytic fungal strain Aspergillus sydowii EN-434 that was obtained from the marine red alga Symphyocladia latiuscula. Their structures were elucidated by nuclear magnetic resonance (NMR), high resolution electrospray ionization mass spectroscopy (HRESIMS), and quantum chemical electronic circular dichroism (ECD) calculations as well as comparison of the data with literature reports. Compound 1 exhibited potent DPPH free radical scavenging activity with IC50 value of 113.5 μmol/L.Keywords：Aspergillus sydowii;algal-derived fungus;bisabolene-type sesquiterpenoid;antioxidant activity4|0|0Updated：2023-04-27
- Abstract：Seawater pumped storage systems have bright prospect for energy storage in the coming years. The operational conditions of seawater pumped storage system are complex and harsh, where metal materials suffer from severe general and local corrosion. The corrosion behavior of Q235B carbon steel in simulated seawater pumped storage system under operational conditions was studied by potentiodynamic polarization, cyclic potentiodynamic polarization, and scanning electron microscope (SEM). The results confirm that the working pressure affected the corrosion resistance of Q235B carbon steel during the whole immersion period. The pressure promoted the electrochemical reaction of corrosion process and the corrosion rate increased with pressure at the initial immersion period. However, the stable rust layer formed after longtime immersion at different pressures increased the corrosion resistance of carbon steel, and decreased the corrosion degree of carbon steel. Meanwhile, the working pressure affected the pitting corrosion behavior of Q235B carbon steel during the whole immersion period. The pitting corrosion potential was more negative and the tendency of pitting corrosion was higher at 4 MPa during the whole immersion period. However, pressure also accelerated the formation rate of protective rust layer on the steel surface. Q235B carbon steel has higher susceptibility to pitting corrosion at 4 MPa in the static seawater.Keywords：seawater pumped storage system;seawater pipeline;pressure;corrosion resistance;pitting corrosion4|0|2Updated：2023-04-27
Chemistry
- Abstract：The moon jellyfish Aurelia spp. is a worldwide distributed scyphozoan species that seasonally blooms in coastal waters. Although the strobilation is directly responsible for the scale of jellyfish bloom, the underlying mechanisms remain largely unknown. We exposed Aurelia coerulea polyps to 18 bioactive substances to test their ability to induce strobilation at the natural typically non-strobilation temperature of 21℃. Results revealed that A. coerulea polyps responded in four types. Type Ⅰ-no change for estradiol, folic acid, iodine, retinoic acid, serotonin hydrochloride, and vitamin A. We suggested that 5-aza-2-deoxycytidine and N-acetyl-L-glutamic acid could not induce strobilation, since the percent of strobilated polyps in these two substances treatments was 3.3% and 1%, respectively. Type Ⅱ-polyp body elongation for 3, 5-diiodo-Ltyrosine, indole-3-acetic acid, L-dopamine, and noradrenaline treatments. Type Ⅲ-transverse constrictions for L-thyroxine, progesterone, and melatonin treatments. Finally, Type Ⅳ-complete strobilation for 5-methoxy-2-methylindole, acetylcholine chloride, and indomethacin treatments, where the pre-strobilation periods were 2, 4, and 2 days, and the mean numbers of ephyrae released per strobila were 4.7, 5.7, and 5.7, respectively. The results reveal that indole derivatives, which contained methoxy or methyl pharmacophore, were the common strobilation inducer in the genus Aurelia. Iodinated organic compounds, catecholamine, acetylcholine chloride, and retinoic acid are species-specific strobilation inducer. Therefore, A. coerulea strobilation is regulated by neuronal and endocrine processes. Our findings provide clues in understanding the mechanism of strobilation and contribute to developing specific strobilation antagonists in controlling moon jellyfish blooms.Keywords：Aurelia coerulea;jellyfish;strobilation;bioactive substances;metamorphosis4|0|0Updated：2023-04-27
- Abstract：This study analyzed and compared variations of the sulcus and otolith outlines of three geographic stocks (Huanghe (Yellow) River estuary (HHE), Jiaozhou Bay (JZB), and Changjiang (Yangtze) River estuary (CJE)) of white croaker Pennahia argentata in northern Chinese coastal waters. The sulcus and otolith outline analyses via elliptical Fourier transform (EFT, i.e., outline analysis) achieved an overall classification rate of 80.4% and 87.2%, respectively. Based on a combination of sulcus and otolith shape indices (SIs) and two derivative ratios, a moderate discriminatory efficiency of 64.7% was obtained. The results indicate that sulcus outline analysis could be used alone to discriminate white croaker stocks, and that both sulcus and otolith outline analyses discriminated the fish stocks at a higher classification rate than the shape indices. The sulcus outline analysis provided complementary information to the whole otolith outline analysis for stock discrimination. Both the sulcus and otolith outline analyses efficiently discriminated between the most geographically separated CJE and HHE stocks, indicating that they could be considered discrete stocks for fishery management.Keywords：sulcus;otolith;elliptic Fourier coefficients;shape indices;stock discrimination4|0|0Updated：2023-04-27
Ecology
- Abstract：The Japanese eel (Anguilla japonica) is a commercially important fish species in East Asia and its recruitment has been rapidly declining since 1990s. Clarifying the genetic population structure of A. japonica is the basis of multinational cooperation on its management and protection, due to its large distribution range. Gene-associated markers have been proved powerful in delineating fine-scale population genetic structure and spatially varying selection. In the present study, we developed 24 polymorphic gene-associated microsatellite markers including 18 loci associated with the genes under selection in the two North Atlantic eel species (Anguilla anguilla and Anguilla rostrata) and 6 loci based on transcript sequences. A total of 13 geographic populations were sampled across its distribution range, including 11 samples from China (9 from China's mainland and 2 from Taiwan region), and 2 samples from Japan. A total of 416 individuals (mostly glass eels) were collected and genotyped at the 24 microsatellites. All measures of differentiation were accordant with a panmictic scenario (FST=-0.001) in A. japonica. No footprints of spatially varying selection were found, indicating that the selection pattern in A. japonica might be different from that in the two North Atlantic eel species. We suggest that A. japonica should be managed as a single unit and management and conservation efforts must be coordinated at the international level, as overexploitation in any region will decrease its recruitment across the whole distributional range.Keywords：Japanese eel;Anguilla japonica;panmixia;gene-associated microsatellite;spatially varying selection4|0|0Updated：2023-04-27
- Abstract：In this paper, the material of the genus Ampharete Malmgren, 1866 from China Seas (Annelida:Ampharetidae) deposited in the collections of the Marine Biological Museum of the Chinese Academy of Sciences (MBMCAS) is reviewed and previous identifications reassessed. In total, four species were found among all specimens examined. Material previously attributed to A. acutifrons (Grube, 1860) and A. arctica Malmgren, 1866 had been misidentified and is now confirmed as belonging to A. lindstroemi Hessle, 1917 and A. finmarchica (Sars, 1865), respectively; the presence of A. falcata Eliason, 1955 is also confirmed; A. orientalis (Annenkova, 1929) is recorded for the first time from China.Keywords：Ampharete;Polychaeta;taxonomy;China4|0|0Updated：2023-04-27
Biology
- Abstract：Neptunea cumingii is an important nutrition-rich economic species in China. Juveniles of N. cumingii suffer from high mortality at low temperatures, which has proved a limiting factor in raising seedlings in artificial habitats. Previous research has shown that N. cumingii displays aggregation behavior in response to adverse environmental changes. Therefore, we determined the effects of temperature, food, size of juvenile snails, substratum type, and density of juvenile snails on the aggregation behavior of N. cumingii. Results show that, at a low (4℃) or a high (22℃) temperature, juvenile snails adjusted to the inhospitable environment by exhibiting increased aggregation behavior. However, their aggregation behaviors differed at these two temperatures. There was no significant difference in the aggregation rate, but the typical aggregation size was larger at 4℃ than at 22℃. At 10℃ or 16℃, aggregation behavior of juvenile snails reduced. Aggregation increased in the satiation treatment at 10℃ and 16℃. Small-sized juveniles tended to have higher aggregation rates (92.22%) and a larger typical aggregation size. More juveniles were distributed in the bottom of shaded substrata. A larger typical aggregation size or higher density significantly reduced the mortality of juvenile snails at a low temperature (4℃). These results broaden our understanding of gastropod aggregation behavior and can be used to develop and improve commercial breeding strategies and resource recovery for N. cumingii.Keywords：aggregation behavior;Neptunea cumingii;environmental temperature;survival rate;seed production4|0|5Updated：2023-04-27
Aquaculture and Fisheries
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