Rotation cropping and organic fertilizer jointly promote soil health and crop production.

Identifying field management practices to promote crop production, while conserving soil health is essential to maintain long-term food production in a changing world. Also, providing experimental evidence to support the use of traditional agricultural practices is necessary to secure sustainable agriculture. Here, we conducted a long-term 12-year experiment to investigate the impact of different combinations of fertilization type (control, inorganic fertilizer, organic fertilizer) and cropping regimes (continuous cropping and rotation cropping) on the crop (tobacco) production and multiple soil attributes associated with soil health, including proportions of soil-borne pathogens and decomposers, soil microbial diversity, microbial network stability and biomass, nutrient pools and microbial resource limitations. Our long-term experiment supports that the combination of organic fertilizer with rotation cropping increased crop production by at least 40% compared to the other management combinations and improved soil nutrient pools (e.g. the content of soil organic matter), improved the relative proportion of soil decomposers, and promoted bacterial and fungal network stability and biodiversity. Furthermore, this combination treatment relieved microbial resource limitation and reduced the abundance of potential fungal plant pathogens by at least 20% compared to other management combinations. In summary, we provide experimental evidence to support that the combined use of organic fertilization and rotation cropping management can help maintain long-term soil health, crop production, and economic outputs.

[The Study of the Spectral Model for Estimating Pigment Contents of Tobacco Leaves in Field].

Fast and non-destructive measurements of tobacco leaf pigment contents by spectroscopy in situ in the field has great significance in production guidance for nutrient diagnosis and growth monitoring of tobacco in vegetative growth stage, and it is also very important for the quality evaluation of tobacco leaves in mature stage. The purpose of this study is to estimate the chlorophyll and carotenoid contents of tobacco leaves using tobacco leaf spectrum collected in the field. Reflectance spectrum of tobacco leaves in vegetative growth stage and mature stage were collected in situ in the field and the pigment contents of tobacco leaf samples were measured in this study, taking the tobacco leaf samples collected in each and both stages as modeling sets respectively, and using the methods of support vector machine (SVM) and spectral indice to establish the pigment content estimation models, and then compare the prediction performance of the models built by different methods. The study results indicated that the difference of estimation performance by each stage or mixed stages is not significant. For chlorophyll content, SVM and spectral indice modeling methods can both have a well estimation performance, while for carotenoid content, SVM modeling method has a better estimation performance than spectral indice. The coefficient of determination and the root mean square error of SVM model for estimating tobacco leaf chlorophyll content by each stage were 0.867 6 and 0.014 7, while the coefficient of determination and the root mean square error of SVM model for estimating tobacco leaf chlorophyll content by mixed stages were 0.898 6 and 0.012 3; The coefficient of determination and the root mean square error for estimating tobacco leaf carotenoid content by each stage were 0.861 4 and 0.002 5, while the coefficient of determination and the root mean square error of SVM model for estimating tobacco leaf carotenoid content by mixed stages were 0.839 9 and 0.002 5. The innovation point of this study is that on the basis of support vector machine and spectral indice, models established by each stage and mixed stages for estimating the pigment contents of tobacco leaf samples can provide scientific basis and technical support for quality control of tobacco leaf production in field and the ensurance of tobacco leaf recovery quality.

Dramatic declines in Euphausia pacifica abundance in the East China Sea: response to recent regional climate change.

As with other marine ecosystems around the world, water temperature has been anomalously warm in recent years in the East China Sea. We analyzed historical data to explore the effects of climatic change on the abundance and distribution variation of Euphausia pacifica in the East China Sea (the Changjiang River estuary and adjacent areas). In 1959, the highest abundance occurred in the spring and autumn, and this krill species was still abundant in May 1974; however, its abundance was significantly reduced in 2002, markedly in spring. Euphausia pacifica was the numerically dominant euphausiid in the East China Sea in 1959. Its mean abundance was up to 1.91 ind m(-3) and 1.64 ind/m(3) in 1959 and 1974, respectively; however, this figure decreased to 0.36 ind m(-3) in 2002. Since 2003, the abundances have been near zero in the most years. Both inter-annual (between November 1959 and 2002) and inter-monthly (between May and June 1959) comparisons suggest that E. pacifica has had a temperature-driven northward movement in response to rising sea surface temperature, especially the positive anomalies since 1997. However, E. pacifica did not come back to the previous habitat when temperature became relative cold. Hence additional factors affecting the E. pacifica distribution and abundance need to be investigated in the future study.

[Applying local neural network and visible/near-infrared spectroscopy to estimating available nitrogen, phosphorus and potassium in soil].

To establish the quantitative relationship between soil spectrum and the concentration of available nitrogen, phosphorus and potassium in soil, the critical procedures of a new analysis method were examined, involving spectral preprocessing, wavebands selection and adoption of regression methods. As a result, a soil spectral analysis model was built using VIS/NIRS bands, with multiplicative scatter correction and first-derivative for spectral preprocessing, and local nonlinear regression method (Local regression method of BP neural network). The coefficients of correlation between the chemically determined and the modeled available nitrogen, phosphorus and potassium for predicted samples were 0.90, 0.82 and 0.94, respectively. It is proved that the prediction of local regression method of BP neural network has better accuracy and stability than that of global regression methods. In addition, the estimation accuracy of soil available nitrogen, phosphorus and potassium was increased by 40.63%, 28.64% and 28.64%, respectively. Thus, the quantitative analysis model established by the local regression method of BP neural network could be used to estimate the concentration of available nitrogen, phosphorus and potassium rapidly. It is innovative for using local nonlinear method to improve the stability and reliability of the soil spectrum model for nutrient diagnosis, which provides technical support for dynamic monitoring and process control for the soil nutrient under different growth stages of field-growing crops.

The first record of Egglestonichthys bombylios (Gobiiformes: Gobiidae) from China with its first fresh colouration information.

During bottom trawl surveys carried out between 20132021, 52 specimens (33.854.0 mm SL) of Egglestones bumblebee goby Egglestonichthys bombylios were collected at a depth of 1.515 m from Dongshan Bay, Sanmen Bay, and Niushan Island, China. They represent the first records of this species from China. A full description, including fresh colouration of the species is provided as it is poorly known. The individuals collected in China agree with most morphological features of the holotype, except for the pelvic fin fraenum that was not observed or appears to be absent in most specimens. A strong relationship between E. bombylios, Larsonella pumilus, and the genus Priolepis is herein demonstrated by the mitochondrial genome sequences of E. bombylios and twenty closely related species. This study enriches the existing genetic data of the so-called Priolepis lineage and provides useful insights into the phylogenetic relationships across species of the genera Egglestonichthys, Priolepis, and Larsonella.

Microbiome-mediated alleviation of tobacco replant problem via autotoxin degradation after long-term continuous cropping.

Continuous cropping often results in severe "replant problem," across various crops due to the autotoxins accumulation, soil acidification, pathogens proliferation, and microbial dysfunction. We unveiled a groundbreaking phenomenon that long-term continuous cropping (LTCC) can alleviate the tobacco replant problem. This mitigation occurs through the enrichment of autotoxin-degrading microbes, and the transformative impact is evident with even a modest application (10%) of LTCC soil to short-term continuous cropping (STCC) soil. Our investigation has pinpointed specific autotoxin-degrading bacteria, particularly the Pseudomonas and Burkholderia species, which exhibit the capacity to alleviate the tobacco replant problem in STCC soil. Their autotoxin-degrading mechanism using axenic culture and soil samples was also conducted via comprehensive analyses of microbiome and transcriptome approach. This research sheds light on the potential of LTCC as a strategic approach for sustainable agriculture, addressing replant problems and promoting the health of cropping systems. UV, ultraviolet; OD, optical density.

Determination of tobacco-specific nitrosamines in tobacco and mainstream cigarette smoke using one-step clean-up coupled with liquid chromatography- tandem mass spectrometry.

A method for determining tobacco-specific nitrosamines (TSNAs) in tobacco and cigarette smoke using liquid chromatography-tandem mass spectrometry was established. The established method amended the deficiencies that exist in current mainstream methods. In this method, TSNAs in tobacco and cigarette smoke were extracted by water. The aqueous extract was then extracted by dichloromethane, and the extract could be analyzed by liquid chromatography-tandem mass spectrometry after a solvent replacement. This method was used to analyze flue-cured tobacco samples, and the response of the target compounds was about 10 times higher than that of the ammonium acetate extraction method. When analyzing cigarette smoke samples, the response strength and chromatographic peak purity of the target compounds were also significantly improved. The proposed method exhibited good linearities for both tobacco and cigarette smoke samples (r2 > 0.99). The limits of detection (LODs) for tobacco and cigarette smoke samples were 0.2-1.0 ng/g and 0.1-0.3 ng/cigarette, respectively. Additionally, this method exhibited desirable accuracy and precision. The TSNAs recovery values from tobacco and cigarette smoke samples ranged from 95.7 % to 107.7 % with inter- and intra-day relative standard deviations (RSDs) of less than 7.4 %. This method is simple, effective, and has wide adaptability. It is a useful upgrade to the existing methods for analyzing TSNAs in tobacco and cigarette smoke.

Bacterial Community Structure and Function Shift in Rhizosphere Soil of Tobacco Plants Infected by Meloidogyne incognita.

Root-knot nematode disease is a widespread and catastrophic disease of tobacco. However, little is known about the relationship between rhizosphere bacterial community and root-knot nematode disease. This study used 16S rRNA gene sequencing and PICRUSt to assess bacterial community structure and function changes in rhizosphere soil from Meloidogyne incognita-infected tobacco plants. We studied the rhizosphere bacterial community structure of M. incognita-infected and uninfected tobacco plants through a paired comparison design in two regions of tobacco planting area, Yuxi and Jiuxiang of Yunnan Province, southwest China. According to the findings, M. incognita infection can alter the bacterial population in the soil. Uninfested soil has more operational taxonomic unit numbers and richness than infested soil. Principal Coordinate Analysis revealed clear separations between bacterial communities from infested and uninfested soil, indicating that different infection conditions resulted in significantly different bacterial community structures in soils. Firmicutes was prevalent in infested soil, but Chloroflexi and Acidobacteria were prevalent in uninfested soil. Sphingomonas, Streptomyces, and Bradyrhizobium were the dominant bacteria genera, and their abundance were higher in infested soil. By PICRUSt analysis, some metabolism-related functions and signal transduction functions of the rhizosphere bacterial community in the M. incognita infection-tobacco plants had a higher relative abundance than those uninfected. As a result, rhizosphere soils from tobacco plants infected with M. incognita showed considerable bacterial community structure and function alterations.

Cloning, structural features, and expression analysis of resistance gene analogs in tobacco.

Using degenerate primers based on the conserved nucleotide binding site (NBS) and protein kinase domain (PKD), 100 resistance gene analogs (RGAs) were isolated from tobacco variety Nicotiana repanda. BLASTx search against the GenBank database revealed that 27 belong to the NBS class and 73 belong to the protein kinase (PK) class. Cluster analysis and multiple sequence alignment of the deduced protein sequences indicate that RGAs of the NBS class can be divided into two groups: toll/interleukin receptor (TIR) and non-TIR types. Both types possess 6 conserved motifs (P-loop, RNBS-A, Kinase-2, RNBS-B, RNBS-C, GLPL). Based on their sequence similarity, the tobacco RGAs of the PK class were assigned to 8 subclasses. We examined their expression after infection with either Tobacco mosaic virus (TMV) or the tobacco black shank pathogen (Phytophthora parasitica var. nicotianae). The expression levels of 4 RGAs of the PK class were significantly elevated by TMV and 1 RGA of the PK class and 3 RGAs of the NBS class were up-regulated by P. parasitica var. nicotianae. The expression of two RGAs of the PK class was induced by P. parasitica var. nicotianae. Infection by either TMV or P. parasitica var. nicotianae enhanced the expression of NtRGA2, a RGA of the PK class. The present study shows that RGAs are abundant in the tobacco genome and the identification of tobacco RGAs induced by pathogens should provide valuable information for cloning related resistance genes in tobacco.

Soil acidification in continuously cropped tobacco alters bacterial community structure and diversity via the accumulation of phenolic acids.

Studying the obstacles associated with continuous cropping is necessary for sustainable agricultural production. Phenolic acids play an important role in continuous cropping systems, although their mechanism of action in these systems remains unclear. Using High-performance Liquid Chromatography, we characterized the changes in phenolic acid contents in soils that had been continuously cropped with tobacco for different time periods and evaluated the interactions between soil physicochemical properties, bacterial community structure and diversity, and phenolic acids. Prolonged continuous cropping was associated with a significant increase in the content of phenolic acids and a significant decrease in soil pH and bacterial diversity. A significant negative correlation between pH and phenolic acids content was observed, suggesting that soil acidification potentially leads to the accumulation of phenolic acids. The Mantel test indicated that phenolic acids were positively associated with relative bacterial abundance (R = 0.480, P < 0.01), signifying that the accumulation of phenolic acids is a potential factor leading to changes in bacterial community structure. Continuous cropping lowered the soil pH, which stimulated phenolic acid accumulation and consequently altered the bacterial community structure and diversity, ultimately impacting tobacco plant growth.

[Zooplankton community structure in relation to influencing factors in different parts of Hangzhou Bay in autumn].

Based on the data collected from three oceanographic surveys in the east area of north (30.68°-30.83° N,121.67°-121.87° E), the east area of south (29.95°-30.24° N,121.60°- 121.85° E), and the west area of north (30.58°--30.77° N,121.31°--121.56° E) Hangzhou Bay during the autumn of 2009, 2011 and 2012, we analyzed the species composition, ecological groups and the similarity of zooplankton community, as well as influencing factors. The results indicated that a total of 14 species belonging to 6 groups were identified in the west area of north Hangzhou Bay. Tortanus vermiculus was the predominant species. The zooplankton assembles were mainly influenced by the runoff strength of the Qiantang River. The zooplankton fauna was mainly composed of the subtropical estuarine brackish-water species, accounting for 79.8% in the total abundance. A total of 19 species belonging to 6 groups were identified in the east area of north Hangzhou Bay. The composition of zooplankton community was mainly influenced by the Changjiang diluted water and offshore water of the East China Sea. It was mainly composed of warm-temperature and subtropical nearshore low-salinity species, accounting for 43.5% and 31.1% in the total abundance, respectively. In the east area of south Hangzhou Bay, a total of 25 species belonging to 7 groups were identified. The composition of zooplankton community was mainly influenced by the offshore water of the East China Sea. The dominate eco-group types were subtropical nearshore low-salinity and subtropical nearshore species, accounting for 72.3% and 18.3% in the total abundance, respectively. And the ecological groups of species with the highest abundance was Labidocera sinilobata, accounting for 65.3% in the total abundance. By hierarchical cluster analysis and non-metric multidimensional scaling (NMDS) method, it was found that the zooplankton communities in the three parts of Hangzhou Bay were significantly different, which were closely associated with the impacts of different water masses from these parts.

[Fish assembles in the coastal water of Lüsi fishing ground during spring and summer].

Based on data from bottom trawl surveys during spring and summer of 2010, the species composition and community structure of fish community in Lüsi fishing ground were investigated and compared with those at different latitudes. A total of 21 were identified in spring and 28 identified in summer. In spring, it was mainly composed of warm-temperate fish (9 species), accounting for 45.2% and 72.9% in the individual density and biomass density, respectively. Warm-temperate species Larimichthys polyactis, Cynoglossus joyneri and Cynoglossus semilaevis were dominant in spring. In summer, warm water species appeared in large numbers by 21, accounting for 75.2% and 71.7% in the individual density and biomass density, respectively. Collichthys lucidus and Coilia mystus were the predominant species in summer. One way-ANOVA indicated that the temperature and salinity between spring and summer in Lüsi fishing ground were significantly different, which resulted in the succession of fish community, i. e. the gradual decrease of the warm-temperate, neritic and nearshore species and the concomitant gradual increase of warm-water and estuarine species.

[Shrimp community structure and its influential factors in the Jiaojiang River estuary during spring and autumn].

Based on the data from two oceanographic surveys during April and October 2010, the spatial and seasonal variations in composition, dominance, and diversity of shrimp communities, as well as the influential factors in the Jiaojiang River estuary were analyzed. A total of 16 species of shrimp were found, which belonged to 12 families under 8 genera. 14 species of shrimp were found in spring (April) and 12 species in autumn (October). With the employment of index of relative importance (IRI), in spring 6 dominant species were identified, as Acetes chinensis, Alpheus distinguendus, Parapenaeopsis hardwickii, Leptochela gracilis, Alpheus juponicus and Palaemon gravieri, and in autumn 3 dominant species were found as Solenocera crassicornis, Parapenaeopsis hardwickii and Metapenaeus joyneri. Eurythermal and eurysaline shrimp community prevailed in the Jiaojiang River estuary, followed by eurythermal and hyposaline shrimp community. Margalef index (D), Shannon index (H) and Pielou's evenness index were used to evaluate the diversity of shrimp community in the studied area. The stations with higher value of D and H were mainly located in the west of the Dachen Island, whereas the Pielou's evenness index was stable all across the Jiaojiang River estuary. By hierarchical cluster analysis and non-metric multidimensional scaling (NMDS) method, the results indicated that shrimp communities had significant seasonal and spatial variations. Depth was the most important factor that affected variations in the shrimp community structure in the Jiaojiang River estuary.

[Population division of Larimichthys polyactis in China Sea].

Previous approaches prevalently believed that there were three populations of Larimichthy spolyactis existed in China Sea. To clarify the number of the populations, an improved approach was adopted in this paper, based on the suite of methodologies including geographical isolation, population dynamics, morphology, anatomy, and molecular genetics. In our finding, there were two instead of three L. polyactis populations in the China Sea, one in Northern Yellow Sea and Bohai Sea, and the other in Southern Yellow Sea and East China Sea. Three evidences were against traditional approaches. Firstly, the traditional division was not supported by morphology, anatomy, and molecular genetics evidences. Secondly, in accordance with our study by referring the 1971-1982 fishing yield statistics from 14 major fishery companies in China, the geographical isolation for L. polvactis between Southern Yellow Sea group and East China Sea group was insignificant. In fact, the two L. polyactis groups inhabited at the same overwintering ground in offshore during winter, and the spawning fishes migrated towards to the nearshore of Zhoushan, Yushan, and Liisi fishing grounds in the following spring. At the same time, another L. polyactis group originally inhabited at the southern nearshore of mid East China Sea during winter migrated northwards and amalgamated with the fishes in the waters of Zhoushan. After spawning, these fishes aggregated into a large feeding group outside the prohibited fishing zone line from May to August. In contrast, the population from the northern Yellrw Sea and Bohai Sea had significant geographic isolation with the population from the southern Yellow Sea and East China Sea. Last but not least, no evidences could support that there were two populations existed at Southern Yellow Sea and the East China Sea, because the productivity of these two areas increased synchronously in recent years while the resource density at northern Yellow Sea and Bohai Sea was still much lower.

[Water environment adaptability and ecological groups of hydroidomedusae in East China Sea].

Based on the data of four seasonal oceanographic censuses in East China Sea (23 degrees 30' - 33 degrees 00' N, 118 degrees 30' - 128 degrees 00' E) in 1997-2000, the optimal water temperature and salinity and the ecological groups of Hydroidomedusae were studied by curve fitting, mathematical model forming, and geographic distribution analyzing. The results showed that Hydroidomedusae could live in the waters with different temperature and salinity. 15 species of Hydroidomedusae had an optimal water temperature of <20 degrees C, 8 species at 20 degrees C - 25 degrees C, 12 species at 22.5 degrees C - 25 degrees C, and 17 species at > or =25 degrees C. 32 species of Hydroidomedusae had an optimal salinity of 32-34, 13 species at 34, 6 species at 30-32, and only 2 species at <30. The weak adaptability of most Hydroidomedusae species to the variation of water salinity made them have low density and limited distribution in East China Sea. Sugiura chengshanense and Clytia hemisphaerica were of nearshore warm temperate water species, Cunina octonaria and other 12 species were of offshore warm temperate water species, 8 species represented by Ectopleura latitaeniata were of nearshore subtropical water species, 5 species represented by Aglaura hemistoma showed some oceanic tropical features, while 25 species represented by Liriope tetraphylla were of offshore subtropical species. Some Hydroidomedusae species could be used as an important bio-indicator of water mass in East China Sea.

[Labidocera euchaeta: its distribution in Yangtze River Estuary and responses to global warming].

Based on the investigation data from eight oceanographic censuses in Yangtze River Estuary (28 degrees 00'-32 degrees 00' N, 122 degrees 00'-123 degrees 30' E) in four seasons of 1959 and 2002, the seasonal distribution pattern of Labidocera euchaeta in the Estuary and the responses of this zooplankton to global warming were analyzed. In the study area, L. euchaeta had a higher average abundance in winter and spring than in summer and autumn, with the highest occurrence frequency in winter and an obvious aggregation in spring and summer. Water salinity was the key factor determining the horizontal distribution of L. euchaeta. The optimal water temperature and salinity for L. euchaeta were 16 degrees C and 12-20, respectively, indicating that this zooplankton belonged to a warm temperate brackish water species. Comparing with that in 1959, the abundance of L. euchaeta in 2002 decreased obviously, which could be related to global warming and suggested that L. euchaeta could be used as an important indictor species of ocean warming in Yangtze River Estuary. The high abundance of L. euchaeta in spring appeared in the most turbid zone of Yangtze River Estuary, being of significance in maintaining the functions of fishing grounds in the waters.

[Ecological character of pelagic mysids in Yangtze Estuary of China].

Based on the four seasonal oceanographic cruises investigation data in the Yangtze Estuary (122 degrees 00'-123 degrees 30' E, 29 degrees 00'-32 degrees 00' N) in 2002-2003, the diversity and abundance dynamics of pelagic mysids as well as their relationships with fishing ground were studied. A total of 14 species were identified, among which, 10 species occurred in autumn, 8 species in spring and summer, and 2 species in winter. Clear seasonal alterations were observed, among which the highest alteration ratio (90.9%) occurred from autumn to winter. Shannon diversity index (H') in spring, summer and autumn was above 2, and that in winter was 1. Mean abundance was the highest in summer [234.70 ind x (100 m3)(-1)], followed by in autumn [103.34 ind x (100 m3)(-1)], spring [80.36 ind x (100 m3)(-1)], and winter [12.40 ind x (100 m3)(-1)]. The changes in mean abundance were in accordance with the fluctuation of seasonal temperature. Due to the adaptation to a wide range of temperature and salinity, Gastrosaccus pelagicus was dominant in spring, autumn and winter. Acanthomysis brevirostris was dominant in summer and autumn, and A. longirostrisas in winter. The dominant species in each season all made a significant contribution to total abundance. A. brevirostris was observed in large agglomerates in summer. As a kind of fish diet, mysids were of importance in the formation of fishing grounds in the Yangtze Estuary and Zhoushan Islands.

[Comparison of mesozooplankton communities in North Channel and North Branch of Yangtze River Estuary].

According to the four cruises investigations in the Yangtze River Estuary from May, August and November 2004 and February 2005, and by using species diversity indices, K-dominance curves, and similarity analysis (ANOSIM), the features of mesozooplantkon communities and their dominant species in the North Channel (NC) and North Branch (NB) were analyzed, with the effects of ecological factors, especially water salinity and temperature, on the dominant species and communities in these two waters discussed. The results indicated that the NC was composed of tidal water and oligo-haline water, while the NB was featured by meso-haline or poly-haline water. Consequently, the zooplankton communities in these two waters were significantly different. In spring, the abundance and diversity of the communities were larger in NB than in NC. In NC, Sinocalanus sinicus was the only dominant species; while in NB, there were several dominate species, among which, Labidocera euchaeta was most important. In summer, the diversity of the communities in NC and NB was quite similar, but the species richness and total abundance of zooplankton were less in NC than in NB. The zooplankton in NC was made up of olio-haline communities, and that in NB was composed of brackish species, e.g., Schmackeria poplesia and Tortanus vermiculus. In autumn, similar to those in spring, the abundance and diversity of the communities were larger in NB than in NC. As usual, in NC, S. sinicus was the most important species; while in NB, the zooplankton was composed of neritic community (Paracalanus parvus, P. aculeatus, L. euchaeta, and Calanus sinicus, etc. ). In winter, the species richness and diversity were the lowest, and there were no obvious difference between the zooplankton communities in NC and NB. It was concluded that water salinity, water temperature, and their combination were the key factors determining the characters of the mesozooplanktonic communities. Water temperature mainly affected the seasonal alteration of the dominant species, while water salinity, which was influenced by the interaction between runoff and ocean mass, determined the local mesozooplantkon communities in NC and NB.

[Pelagic Mysidacea in East China Sea and its significance as the indicator of water mass].

Based on the investigation data of four seasonal oceanographic censuses in the area 23 degrees 30' - 33 degrees N and 118 degrees 30' - 128 degrees E of East China Sea in 1997-2000, this paper studied the ecotypes and geographic and seasonal distribution of pelagic Mysidacea in this sea area, with its significance as the indicator of water mass approached. The results showed that among the species of pelagic Mysidacea, Acanthomysis latiscauda, Gastrosaccus pelagicus, Siriella sinensis and Hemisiriella pulchra were the coastal subtropical species with some features of warm temperate species, while Pseudanchialina pusilla, Promysis orientalis, Erythrops minuta and Anisomysis bipartoculata were the offshore subtropical species with some features of tropical species. Different from other zooplanktons, most of the pelagic Mysidacea species had lower optimal temperature and salinity and distributed more at near-shore in spring and winter, showing the features of warm temperate near-shore species. The areas with high abundance of A. latiscauda, S. sinensis and H. pulchra were just the converging areas of the Changjiang dilute waters and warm current masses and of coastal waters and offshore high salinity waters. Erythrops minuta and Anisomysis bipartoculata could be used as the indicators of warm current, P. orientalis and Doxomysis quadrispinosa were the indicators of the Taiwan warm current, while the rest were not good enough to be the indicators of water masses.

[Species characteristics and diversity of pelagic Mysidacea in East China Sea].

Based on the investigation data of four oceanographic cruises in the East China Sea (23 degrees 30' - 33 degrees 00' N, 118 degrees 30' - 128 degrees 00') in 1997-2000, this paper studied the species characteristics and diversity of mysids, and the relationships between its species number and environmental factors. A total of 18 mysids species were observed, with 14 species occurred in autumn, 9 species occurred in summer, 7 species occurred in spring, and 4 species occurred in winter. The species composition showed a clear seasonal alternation, especially from autumn to winter. Seawater salinity was the main environmental factor affecting the distribution of the mysids. In summer and winter, mysids distribution was mainly affected by the runoff from continental rivers, and species number had a significant negative correlation with seawater salinity, while in autumn, the species number had a negative correlation with surface seawater temperature but a positive correlation with bottom seawater salinity. The spatial-temporal variation of mysids geographical distribution was linked with the ebb and flow of the Changjiang River, and the dominant species of mysids tended to agglomerate, which was the major reason of the low diversity of mysids in the East China Sea.