The distribution of diatoms in surface sediments in the Minjiang Estuary, southeast China, was investigated in 2009. Total 56 species and other species belonging to 25 genera were identified, among them 11 species were dominant over 5%. Dominant species included Actinocyclus ehrenbergii, Coscinodiscus curvatulus, C. divisus, C. jonesianus, C. radiatus, C. rothii, C. subtilis, Cyclotella stylorum, Epithemia hyndmanii, Hydrosera whampoensis, and Trachyneis aspera. Diatom abundance varied spatially, with the absolute abundance of diatoms ranging from 13 valves/g to 11×10⁴ valves/g, and averaging 2.5×10⁴ valves/g. A canonical correspondence analysis (CCA) was used to explain the relationships between diatom distribution and sediment properties in the Minjiang Estuary. CCA revealed that the major elements (Fe₂O₃, Na₂O, CaO, MgO, TiO₂, SiO₂, Al₂O₃, and K₂O) were closely related to diatom abundance. Four diatom assemblages were distinguished, representing different sediment properties, which may assist late Quaternary palaeoceanographic reconstructions of the Minjiang Estuary.

Four units and twenty-four zones of diatom have been discerned in the Borehole ZKS in the estuarine plain of the)iulong River,Fujian Province.Comprehensive analysis of these,together with microbiological assemblages and age determinations in some other boreholes,shows that during the Late Wiirm Glacial,sea level of the study area rose and fell frequently,but had principally been in the environments of estuary-bay.This mainly resulted from the tectonic subduction.In this period 3 low sea levels occurred,at 18,16 and 12 kaBP respectively.During Hokx"ene,sea water intruded massively and the sea level over the transgression maximum had been 5-10 m higher than that of the present.

The abundance and temporal patterns of viable diatom resting stage cells in sediments of the East China Sea in 2006 have been investigated. The abundance of viable resting stages was enumerated with the most probable number (MPN) technique. Overall, 25 diatom species (including varieties) belonging to 16 genera were detected. Viable resting stage cells were common, on the order of 10³ to 10⁶ cells/g dry mass. The abundant taxa included Skeletonema marina, S. dohrnii, Chaetoceros curvisetus and Thalassiosira spp., with Skeletonema accounting for 83.3% of the cell. The effects of temperature (10, 15, 20, 25℃), salinity (20, 25, 30, 35 psu) and light intensity (0, 300, 4 000, 8 000 lux) on the germination of resting stages in sediment samples were also determined. The results showed that light intensity had a significant positive effect on the germination of diatom resting stage cells (p <0.01) and that diatoms could not germinate in darkness. Temperature and salinity had no noticeable effects on the germination. The present study suggests that there are abundant diatom resting cells in sediments of the East China Sea, which could serve as a "seed bank" in the phytoplankton population succession and contribute to the initiation of algal blooms.

The uptake of zinc and cadmium by a species of marine diatom Thalassirosira weissflogii and the nutrient variation(phosphorus and silicon) in the culture medium were estimated when exposed to zinc and cadmium stress under controlled laboratory conditions.It was found that low cadmium addition could stimulate the culture to grow with a relatively high rate and exert its toxicity at the elevated concentration.The cellular uptake of zinc and cadmium by the diatom varied in the ranges of 1.21~3.75 and 0.060~0.629 fmol per cell respectively in the whole cultivation period.The mean cellular phosphorus and silicon drawdowns were constant with 0.26~0.42 and 0.30~0.46 pmol per cell respectively in those healthy cultures.It is illustrated that the algal cells can adjust some physiological mechanisms to decrease metal accumulation and keep metal homeostasis in the organism.The correlation analysis results further indicate that the cellular cadmium uptake might be closely related with the cellular phosphorus,silicon drawdown and the growth rate of diatom(P<0.05,0.001,0.01); and the cultures grow better in good conditions,the lower amount of phosphorus,silicon materials are consumed by a single cell to keep a high efficiency of utilization.

Six genera and thirteen species of diatoms are collected from the intertidal zone of Xisha Islands,Hainan Province,and observated under the transmitted light microscopy (LM),transmission electron microscopy (TEM) and scanning electron microscopy (SEM).of them,four new species,and one genus are newly recorded (marked).
They are: Synedra cyclophoroides sp.nov.,*Cyclophora tennis,Plagiogramma pava sp.nov.,Plagiogramma pandurata sp.nov.,P.atomus,P.reimeri,Opephora elliptica sp.nov.O.martyi,O. olsenii,O.sp.,*Fragilaria brevistriala v.elliptical,*F.construens and Pseudostaurosira brevistriata.

Owing to the significant differences in environmental characteristics and explanatory factors among estuarine and coastal regions, research on diatom transfer functions and database establishment remains incomplete. This study analysed diatoms in surface sediment samples and a sediment core from the Lianjiang coast of the East China Sea, together with environmental variables. Principal component analysis of the environmental variables showed that sea surface salinity (SSS) and sea surface temperature were the most important factors controlling hydrological conditions in the Lianjiang coastal area, whereas canonical correspondence analysis indicated that SSS and pH were the main environmental factors affecting diatom distribution. Based on the modern diatom species–environmental variable database, we developed a diatom-based SSS transfer function to quantitatively reconstruct the variability in SSS between 1984 and 2021 for sediment core HK3 from the Lianjiang coastal area. The agreement between the reconstructed SSS and instrument SSS data from 1984–2021 suggests that diatom-based SSS reconstruction is reliable for studying past SSS variability in the Lianjiang coastal area. Three low SSS events in AD 2019, 2013, and 1999, together with an increased relative concentration of freshwater diatom species and coarser sediment grain sizes, corresponded to two super-typhoon events and a catastrophic flooding event in Lianjiang County. Thus, a diatom-based SSS transfer function for reconstructing past SSS variability in the estuarine and coastal areas of the East China Sea can be further used to reflect the paleoenvironmental events in this region.

The biomass, species composition and diversity of benthic diatom assemblages in mud-flat soils in Kandelia candel (L.) Druce communities with and without vegetation were studied seasonally at the Houyu Bay in Fuding City, Fujian Province, China. A total of 103taxa were identified (including varieties). Eighty-four taxa were found in the mud-flat with vegetation and 74 taxa in the mud-fiat without vegetation, while the biomass was large in January and April and decreased from July to October. The most abundant species in the mud-flat with vegetation are Nitzschia cocconeiformis, Gyrosigma scalproides and N. Fasciculata, compared with G. Scalproides and N.obtusa var. Scalpelliformis in the mud-flat without vegetation. High H' values at 2 sites during all seasons suggest that diatom assemblages in the sediments of the Houyu Bay represent an original environment. Multi-dimensional scaling of diatom assemblages from mud-flats with and without vegetation shows that a slight seasonal change and only a single association occur in the angroves.

The concentration and composition of nutrients, such as N, P, and Si, respond to biogeochemical processes and in turn, impact the phytoplanktons’ community structure and primary production. In this study, historical data was systematically analyzed to identify long-term variations in nutrient trends, red tide frequency, phytoplankton community abundance, and dominant species succession in the southern Yellow Sea (SYS). Results showed that N/P concentration ratios dramatically increased as a function of increasing dissolved inorganic nitrogen concentrations, and Si/N concentration ratios were generally larger than 1, indicating that N limitation morphed to P limitation and potentially to Si limitation, which impacted the phytoplankton community. Furthermore, inter-annual trends over the past 50 years show that phytoplankton community abundance has been higher in spring and summer, relative to autumn and winter. Moreover, with respect to red tide frequency, diatom abundance gradually decreased, while that of dinoflagellates gradually increased. Dominant species succession showed that the phytoplankton community exhibited an evident tendency to transform from diatoms to dinoflagellates. These research results clearly depict the presence of an important correlation between the phytoplankton community and nutrient structure in the SYS.

Fossil diatom groups from 85 samples of drill holes and 13 samples of the known depositional environment are analysed. The boundary of the Zhujiang Delta is discussed from the distribution of fossil diatom. The horizonal variation of Holocene sedimentary facies can be divided into four kinds of depositional environment corresponding to the delta plain subfacies and the delta front subfacies. The vertical variation of Holocene depositional facies shows twice changes of transgression from weak to vigorous.

The variations in nutrients (molar ratios) and chlorophyll a in the Jiaozhou Bay were examined before and after a diatom bloom in a period that lasted from November 2003 to March 2004. Negative relationships between nutrient concentrations, Si/P, Si/N ratios and chlorophyll a content were found during the bloom, which reflected the relationship between nutrient concentrations, phytoplankton biomass and growth. Large increase in nutrient concentrations, particularly SiO₃-Si after the late autumn, is one of major reasons inducing the diatom bloom in winter, and the bloom was finally controlled due to SiO₃-Si depletion by phytoplankton. The bloom was mainly controlled by SiO₃-Si. Before 1998, relatively low level of SiO₃-Si kept ecological balance of eutrophication waters in the Jiaozhou Bay. In recent years, however, human activities have increased SiO₃-Si concentration, which is likely one of the primary cause for the increased diatom blooms in the Jiaozhou Bay. Therefore, it is necessary to control SiO₃-Si concentration in the Jiaozhou Bay.