Study of multifunctional anti-AD ligands: design, synthesis, X-ray crystal structure and biological evaluation of diosmetin derivatives.

The development of anti-AD drugs has attracted much attention as the number of AD patients is increasing year by year. Five diosmetin derivatives (1-5) were designed and synthesized by introducing carbamate groups. The crystal structure of 1 was analyzed by X-ray diffraction, which showed a large conjugated coplanar structure and might be favorable for the insertion into the Aß folding. Meanwhile, in vitro experiments were carried out to investigate the anticholinesterase activity, metal chelating property, antioxidant activity, and anti-Aß aggregation ability of 1-5. The results showed that 1-5 had good cholinesterase inhibitory activities. Compound 4 showed the highest inhibitory activities against butyrylcholinesterase (IC50 = 0.0760 µM). Further kinetic experiments and molecular docking studies showed that 4 could bind well to butyrylcholinesterase. The molecular dynamics simulations also signified that compared with diosmetin, 4 could reduce the flexibility of the butyrylcholinesterase protein skeleton to a greater extent, and thus had a better inhibitory effect. In addition, 1-5 could selectively chelate copper ions and all of them had good antioxidant activity as well as anti-Aß aggregation ability. Among them, 4 had the strongest activity to inhibit Cu2+-induced Aß aggregation (51.09%) and had low cytotoxicity. In addition, in vivo ROS activity assay (Caenorhabditis elegans) showed that 4 had the ability to scavenge ROS. Besides, the in vivo Aß aggregation assay showed that 4 could reduce Aß aggregation. In conclusion, 4 has the potential to be developed into a multifunctional anti-AD drug.

Elemental geochemical evidence for the river-derived sources of trace metals in surface sediments from Hangzhou Bay, East China Sea.

Coastal estuaries are often heavily subject to riverine influences by the inputs of sediment from terrestrial sources. Hangzhou Bay (HZB) is threatened by the riverine derived trace metals from two large rivers of Qiantang River (QTR) and Yangtze River (YZR). However, previous studies mainly focused on the incidental transport from the largest river in China (YZR) and failed to simultaneously evaluate the contributions of these two rivers, especially the directly flowing river of QTR, by their trace elemental geochemical composition and distribution. Herein, a comprehensive study identified the river-derived sources of multiple trace metals in surface sediments which transported from both of the rivers. The sampling stations were separated into three regions of YZR, HZB, and QTR based on their spatial distributions of sediment grain size and components. The significant variations for most of the trace metals concentrations, except for Cd, Th, and U, were found among three regions (χ2 ≥ 8.22, p ≤ 0.016). The highest concentrations in HZB were mainly resulted from the grain size effect (68.82% of the total variance), while the highest concentrations of Sr, Cd, and Ba in YZR and Zr and Hf in QTR were attributed to the anthropogenic source (11.90%) and mineral composition (6.21%) of river basins. After normalized the diversity of multiple trace metals concentrations and the influence of grain size by ratios of Igeo and EFLi, three regions were effectively distinguished. It was indicated that As, Cd, and Sb were enriched in the sediments of rivers by anthropogenic source (EFLi > 1.5 and/or Igeo > 1). The results evidenced that, after removing the influence of grain size, elemental geochemical composition of the surface sediments confidently identified the river-derived anthropogenic sources of the enriched trace metals from two major rivers, and largely from YZR.

The role of RNA epigenetic modification-related genes in the immune response of cattle to mastitis induced by Staphylococcus aureus.

OBJECTIVE: RNA epigenetic modifications play an important role in regulating immune response of mammals. Bovine mastitis induced by Staphylococcus aureus (S. aureus) is a threat to the health of dairy cattle. There are numerous RNA modifications, and how these modification-associated enzymes systematically coordinate their immunomodulatory effects during bovine mastitis is not well reported. Therefore, the role of common RNA modificationrelated genes (RMRGs) in bovine S. aureus mastitis was investigated in this study. METHODS: In total, 80 RMRGs were selected for this study. Four public RNA-seq data sets about bovine S. aureus mastitis were collected and one additional RNA-seq data set was generated by this study. Firstly, quantitative trait locus (QTL) database, transcriptome-wide association studies (TWAS) database and differential expression analyses were employed to characterize the potential functions of selected enzyme genes in bovine S. aureus mastitis. Correlation analysis and weighted gene co-expression network analysis (WGCNA) were used to further investigate the relationships of RMRGs from different types at the mRNA expression level. Interference experiments targeting the m6A demethylase FTO and utilizing public MeRIP-seq dataset from bovine Mac-T cells were used to investigate the potential interaction mechanisms among various RNA modifications. RESULTS: Bovine QTL and TWAS database in cattle revealed associations between RMRGs and immune-related complex traits. S. aureus challenged and control groups were effectively distinguished by principal component analysis based on the expression of selected RMRGs. WGCNA and correlation analysis identified modules grouping different RMRGs, with highly correlated mRNA expression. The m6A modification gene FTO showed significant effects on the expression of m6A and other RMRGs (such as NSUN2, CPSF2, and METTLE), indicating complex co-expression relationships among different RNA modifications in the regulation of bovine S. aureus mastitis. CONCLUSION: RNA epigenetic modification genes play important immunoregulatory roles in bovine S. aureus mastitis, and there are extensive interactions of mRNA expression among different RMRGs. It is necessary to investigate the interactions between RNA modification genes regulating complex traits in the future.

Size-fractionated N2 fixation off the Changjiang Estuary during summer.

Recent evidence has shown active N2 fixation in coastal eutrophic waters, yet the rate and controlling factors remain poorly understood, particularly in large estuaries. The Changjiang Estuary (CE) and adjacent shelf are characterized by fresh, nitrogen-replete Changjiang Diluted Water (CDW) and saline, nitrogen-depletion intruded Kuroshio water (Taiwan Warm Current and nearshore Kuroshio Branch Current), where N2 fixation may be contributed by different groups (i.e., Trichodesmium and heterotrophic diazotrophs). Here, for the first time, we provide direct measurement of size-fractionated N2 fixation rates (NFRs) off the CE during summer 2014 using the 15N2 bubble tracer method. The results demonstrated considerable spatial variations (southern > northern; offshore > inshore) in surface and depth-integrated NFRs, averaging 0.83 nmol N L-1 d-1 and 24.3 µmol N m-2 d-1, respectively. The highest bulk NFR (99.9 µmol N m-2 d-1; mostly contributed by >10 µm fraction) occurred in the southeastern East China Sea, where suffered from strong intrusion of the Kuroshio water characterized by low N/P ratio (<10) and abundant Trichodesmium (up to 10.23 × 106 trichomes m-2). However, low NFR (mostly contributed by <10 µm fraction) was detected in the CE controlled by the CDW, where NOx concentration (up to 80 µmol L-1) and N/P ratio (>100) were high and Trichodesmium abundance was low. The >10 µm fraction accounted for 60% of depth-integrated bulk NFR over the CE and adjacent shelf. We speculated that the present NFR of >10 µm fraction was mostly supported by Trichodesmium. Spearman rank correlation indicated that the NFR was significantly positively correlated with Trichodesmium abundance, salinity, temperature and Secchi depth, but was negatively with turbidity, N/P ratio, NOx, and chlorophyll a concentration. Our study suggests that distribution and size structure of N2 fixation off the CE are largely regulated by water mass (intruded Kuroshio water and CDW) movement and associated diazotrophs (particularly Trichodesmium) and nutrient conditions.

Ecological risk assessment of trace metals in sediments and their effect on benthic organisms from the south coast of Zhejiang province, China.

To explore the ecological risks of trace metals in sediments and their relationship with benthic organisms, 12 trace metals were analyzed and the macrobenthos were identified in the sediments collected from the south coast of Zhejiang province which belongs to the East China Sea. Spatially, the concentrations of most trace metals were high in the estuary, except for Ba and Sr. There was no obvious enrichment for trace metals, except that the concentration of Cd slightly exceeded the coastal background. The ecological risks calculated by the concentrations of Cr, Cd, Cu, Zn, Pb, and Ni in sediments showed that the methods based on sediment quality guidelines could judge the ecological risk more intuitively than the methods based on background value (PN, PLI, RI). The significant correlations between ecological risks and benthos density and biomass revealed the negative impact of trace metals at high concentrations on macrobenthic survival in sediments.

Influence of biodeposition by suspended cultured oyster on the distributions of trace elements in multiple media in a semi-enclosed bay of China.

It remains unclear how the suspended non-fed bivalve mariculture will alter the coastal transfer and cleaning process of trace elements, the non-degradable contaminants, which have been reported to accumulate in sediment from bivalve mariculture areas. Herein, we set up a field in situ comparative test in the suspended oyster (Crassostrea plicatula) farming area (OF) and reference area (RA) of Xiangshan Bay to verify our hypothesis that the biodepositon of suspended oysters would consolidate trace elements from the water column and transport them to the sediment. Distribution of trace elements in multiple media of biodeposits (BDs), settling particles (SPs), sediments (SEs), and seawater demonstrate that the accelerated deposition of BDs which enriched trace elements from the water column by oysters filtering suspended particles led to trace elements accumulation in SEs from OF. Additionally, As, Cd, Co, Cr, Cu, Ni, V, and Zn were strongly regulated by this process with significant (p < 0.05) higher concentrations in SEs from OF (10.96, 0.20, 13.98, 82.40, 38.47, 38.22, 108.57, and 111.20 µg/g, repectively) than those from RA (9.43, 0.13, 11.76, 63.30, 30.34, 29.55, 86.59, and 100.24 µg/g, repectively), but the extent was different for Mn, Mo, Pb, and W with concentrations in SEs from OF (737.37, 0.81, 30.98, and 3.96 µg/g, repectively) and RA (765.25, 0.69, 31.27, and 3.34 µg/g, repectively), especially for Rb and Sr with concentrations in SEs from OF (131.13 and 96.24 µg/g, repectively) and RA (142.21 and 161.10 µg/g, repectively), due to their geochemical and geophysical properties. Moreover, the harvest of hyper-accumulated oysters as a sink for removing trace elements from water column cannot hide the impact of this process.

Heavy metal concentrations in tissues of marine fish and crab collected from the middle coast of Zhejiang Province, China.

Concentrations of the heavy metals As, Cd, Cu, Hg, Pb, and Zn in various tissues of five marine fish species and one crab species collected from the middle coast of Zhejiang Province of China were investigated in this study. The results indicated considerable variation in heavy metal concentrations in different tissues and species. Elevated concentrations of most heavy metals were identified in fish gills and crab gills and hepatopancreas, with some differences by heavy metal type. In addition, carnivorous and benthivorous fish species generally contained relatively high concentrations of heavy metals due to feeding habits and habitats. Geographical variations of heavy metal concentrations in muscle may be attributable to species-dependent differences and terrigenous contamination. The potential health risk assessment suggested that exposure doses of most heavy metals were safe for human consumption, with the exception of As.

Kelp cultivation effectively improves water quality and regulates phytoplankton community in a turbid, highly eutrophic bay.

Coastal eutrophication and its associated harmful algal blooms have emerged as one of the most severe environmental problems worldwide. Seaweed cultivation has been widely encouraged to control eutrophication and algal blooms. Among them, cultivated kelp (Saccharina japonica) dominates primarily by production and area. However, the responses of water quality and phytoplankton community to kelp farming remain unclear. Here, thirteen cruises were conducted in the kelp farms and control areas in the turbid, highly eutrophic Xiangshan Bay of the East China Sea from 2008 to 2015. Results indicated that kelp cultivation slightly increased dissolved oxygen and pH, but reduced dissolved inorganic nitrogen and phosphorus. We estimated that kelp harvesting would remove 297 t of nitrogen and 42 t of phosphorus from this bay annually. Because of decreased flow velocity, turbulence, and sediment resuspension, kelp farming greatly reduced suspended solids and increased transparency, resulting in increases in phytoplankton chlorophyll a and abundance. Additionally, kelp farming appreciably increased phytoplankton species number, Marglef richness, and Shannon-Wiener diversity indices by 51.6%, 40.1%, and 13.1%, respectively. Analysis of similarity and similarity percentages demonstrated that phytoplankton community composition differed significantly between the farm and control area, which was mostly attributed to long-chained diatoms and single-celled dinoflagellates. However, after the kelp harvesting, all measurements of water quality and phytoplankton biomass, diversity, and community composition exhibited no significant difference. Our study highlights that kelp cultivation alleviates eutrophication and acidification and enhances phytoplankton diversity, thus providing guidance for macroalgal aquaculture and remediation in eutrophic waters.

Effects of fish cage culture and suspended oyster culture on macrobenthic communities in Xiangshan Bay, a semi-enclosed subtropical bay in eastern China.

The impacts of fish cage culture and suspended oyster culture on macrobenthic communities were investigated in Xiangshan Bay, China, on a seasonal basis from January to October of 2015. Samples were collected from a fish cage farm, a suspended oyster farm, and two corresponding reference sites. Two-way ANOVA results showed that species richness, abundance, biomass, and Shannon-Wiener diversity differed significantly between the four different investigated areas, and different seasons as well. Cluster analysis showed that macrobenthic community composition in the fish and oyster culture areas significantly differed from that in the reference sites, respectively. Trophic structure of macrobenthos in the fish and oyster culture areas mostly clustered together owing to higher abundance and biomass of surface-deposit feeders and carnivores. The macrobenthic communities and feeding guilds correlated highly with environmental factors, such as bottom water chlorophyll a and nutrients, as well as sediment total organic carbon. Although integrated multi-trophic aquaculture is regarded as a suitable approach to coordinate desirable economic, social, and environmentally sustainable outcomes, coastal ecosystems may suffer from large-scale nutrient enrichment due to aquaculture and other human activities, which should not be considered in isolation.

Oyster farming control on phytoplankton bloom promoted by thermal discharge from a power plant in a eutrophic, semi-enclosed bay.

Temperature increase caused by thermal discharge from power plants promotes phytoplankton growth and frequent bloom in eutrophic subtropical waters, particularly in cold seasons. Suspension filter-feeding bivalves show size-selective grazing on phytoplankton. Thus, we hypothesized that algal bloom under thermal stimulation could be controlled and that phytoplankton community was structured by oyster farming. Here, ten cruises were conducted in two oyster farms (OFs) and control areas (CAs) adjacent to the Ninghai Power Plant in the upper section of Xiangshan Bay during 2009-2015. We found that thermal discharge induced severe winter algal blooms. Phytoplankton abundance and chlorophyll a (chla) were significantly lower (46.3% and 28.3%, respectively) in OF than in CA, indicating a high filtration efficiency by oysters and the associated biofouling assemblages. In addition, oyster farming significantly increased species richness (by 26.3%), Shannon-Wiener diversity (by 38.3%), and Pielou's evenness indices (by 28.8%) and reduced suspended solids (by 12.2%), total organic carbon (by 18.4%), dissolved inorganic nitrogen (by 1.5%), and phosphorus (by 3.7%). Furthermore, oyster farming considerably reduced (increased) micro-chla contribution (pheophytin/chla) by 34.8% (71.1%), suggesting a strong size-selective grazing on phytoplankton. Analysis of similarity revealed a significant difference in phytoplankton community composition between OF and CA. However, after the removal of culture rafts, all the abundance, chla, species diversity, dominant species, size structure, and community composition of phytoplankton showed no significant difference. Our study demonstrated that oyster farming effectively alleviated eutrophication and algal bloom and enhanced phytoplankton diversity, which provides guidance for aquaculture and ecological restoration in subtropical coastal eutrophic waters.

Heavy metal concentrations in commercial marine organisms from Xiangshan Bay, China, and the potential health risks.

Commercial marine organisms were collected from the coast of Xiangshan Bay to investigate the concentrations of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and evaluate the potential health risks. The results indicated considerable variations in the heavy metal concentrations among six species groups, of them mollusks (seasnail, benthic bivalve, and oyster) generally contained relative high levels of most metals, followed by crustaceans (crab and shrimp), by contrast, fish had low concentrations of all metals, except Hg. Three heavy metal groups were identified to interpret the accumulative characteristics in the marine organisms. Spatial distributions illustrated the geographical variations of heavy metal concentrations in the sampling areas. Moreover, maricultured organisms demonstrated lower heavy metal concentrations than did the wild. Health risks of most heavy metals exposed from marine organism consumption were safe, except for As which is associated with the high target cancer risk values.

Development of marine water quality criteria for inorganic mercury in China based on the retrievable toxicity data and a comparison with relevant criteria or guidelines.

The development of marine water quality criteria (WQC) in China has been insufficient because data on the toxicity of pollutants for marine organisms based on the species sensitivity distribution (SSD) method are lacking. The Chinese aquatic environmental quality standards, including those for seawater, were derived from the developed countries. Therefore, establishing Chinese marine WQC is crucial for identifying the sensitivity of marine species in China and will improve their protection from threats. Mercury (Hg) is one of the primary pollutants commonly exceeding Chinese seawater quality standards. Several countries have developed their marine WQC for inorganic Hg in the past decades, but no study has been conducted in China. In this study, 45 acute toxicity and 14 chronic toxicity data of inorganic Hg on the marine species which inhabit in China were obtained mainly from the ECOTOX database, the CNKI, and the Google Scholar. The acute and chronic hazardous concentrations for 5% of the species (HC5) were calculated based on the best-fit distribution model Sweibull. The criteria for maximum and continuous concentrations of 1.30 and 0.66 µg/L, respectively, for inorganic Hg to protect marine organisms in China were derived by halving the HC5 values. The criteria were comparable to those of the United States, Australia, and the European Union countries, indicating the general applicability of WQCs developed based on the classical SSD method using different species groups. This study may provide valuable information for assessing marine ecological risk in China.

Overexpression of GmFDL19 enhances tolerance to drought and salt stresses in soybean.

The basic leucine zipper (bZIP) family of transcription factors plays an important role in the growth and developmental process as well as responds to various abiotic stresses, such as drought and high salinity. Our previous work identified GmFDL19, a bZIP transcription factor, as a flowering promoter in soybean, and the overexpression of GmFDL19 caused early flowering in transgenic soybean plants. Here, we report that GmFDL19 also enhances tolerance to drought and salt stress in soybean. GmFDL19 was determined to be a group A member, and its transcription expression was highly induced by abscisic acid (ABA), polyethylene glycol (PEG 6000) and high salt stresses. Overexpression of GmFDL19 in soybean enhanced drought and salt tolerance at the seedling stage. The relative plant height (RPH) and relative shoot dry weight (RSDW) of transgenic plants were significantly higher than those of the WT after PEG and salt treatments. In addition, the germination rate and plant height of the transgenic soybean were also significantly higher than that of WT plants after various salt treatments. Furthermore, we also found that GmFDL19 could reduce the accumulation of Na+ ion content and up-regulate the expression of several ABA/stress-responsive genes in transgenic soybean. We also found that GmFDL19 overexpression increased the activities of several antioxidative enzyme and chlorophyll content but reduced malondialdehyde content. These results suggested that GmFDL19 is involved in soybean abiotic stress responses and has potential utilization to improve multiple stress tolerance in transgenic soybean.

Responses of summer phytoplankton community to drastic environmental changes in the Changjiang (Yangtze River) estuary during the past 50 years.

The phytoplankton community in the Changjiang Estuary is subject to intensive physical and chemical stresses because of human- and climate-driven changes. We obtained historical data on summer phytoplankton communities from 1959 to 2009 to explore responses to long-term environmental changes. The nitrogen (N) and phosphorus (P) concentrations and ratios (N/P and N/Si) increased because of persistent riverine loading, but silicon (Si) levels remained constant. Climatic changes and extensive water diversions and withdrawals (sediment retention) resulted in a series of physical alterations, including increased temperature, turbidity reduction, and river plume shrinkage. These changes induced a dramatic increase in microalgal biomass (cell density and chlorophyll a) with a decreasing diatom-dinoflagellate ratio, and exacerbated harmful algal blooms. In the past dominant net-collected species were usually chain-forming diatoms; however, more recently, large dinoflagellates and filamentous cyanobacteria dominate. This was not consistent with information from water samples (co-dominated by small dinoflagellates), because of the loss of solitary species collected using a 76-µm net. The dominant species shifted from temperate-subtropical/eurythermal to subtropical-tropical/eurythermal taxa in the warmer water caused by global warming and hydrographic changes. There was also an increased dominance of euryhaline/high-salinity species due to increase in Kuroshio transport and the northward Taiwan Warm Current and reduction in Changjiang Diluted Water. All these changes in phytoplankton communities appear to be closely related to an increase in anthropogenic activities and climatic changes.

Effects of fish farming on phytoplankton community under the thermal stress caused by a power plant in a eutrophic, semi-enclosed bay: induce toxic dinoflagellate (Prorocentrum minimum) blooms in cold seasons.

Six cruises were conducted in a fish farm adjacent to the Ninghai Power Plant in Xiangshan Bay, East China Sea. Fish farming significantly increased NH4(+), DIP, and TOC concentrations, while it significantly decreased the DO level. These increase/decrease trends were more pronounced in warmer seasons. Although culture practices did not significantly increase phytoplankton density, it drastically enhanced dinoflagellate abundance and domination. Significant differences in species diversity and community composition between the cages and the control area were also observed. Temperature elevation caused by thermal discharge associated with eutrophication resulted in a dominant species shift from diatoms alone to dinoflagellates and diatoms. This is the first report of stress-induced toxic dinoflagellate (Prorocentrum minimum) blooms in winter and the winter-spring transition in this bay. Therefore, the effects of aquaculture activity and power plant construction in such a eutrophic, semi-enclosed bay require further attention.

[Spatial niches of dominant zooplankton species in Sanmen Bay, Zhejiang Province of East China].

Ecological niche has close relations with inter-species competition and resources utilization, and thus, can be used as an indicator to symbolize the resources utilization capability of certain groups of related species. In this paper, the niche breadth and overlap of the dominant zooplankton species in the Sanmen Bay of Zhejiang were determined by Shannon's formula and Petraitis index, respectively, and the differentiation of the niche was studied by canonical correspondence analysis (CCA), aiming to approach the distribution features of coastal zooplankton and related affecting factors in the Bay. In the study area, some coastal species such as Zonosagitta bedoti, Centropages dorsispinatus, and brachyuran larvae had wider niche breadth than the pelagic species such as Flaccisagitta enflata and Pseudeuphausia sinica, and the species of different groups with prey-predator relation had a greater niche overlap than those of the same groups without this relation. The CCA analysis showed that the spatial distribution of the zooplankton was more affected by water temperature, salinity, and chlorophyll a content rather than nutrients. The spatial niche of the zooplankton species was correlated with their living habit, inter-species competition, and prey- predator relationship.

[Microcosm experiments on the influence of different N/P ratios on phytoplankton community growth in the East China Sea].

In the present study, a microcosm experiment was conducted in situ for 30 days, in order to investigate the effects of different N/P ratios (1N: 1P, 4N: 1P, 8N: 1P, 16N: 1P, 32N: 1P, 64N: 1P, 128N: 1P, and 256N: 1P) on phytoplankton community growth in the East China Sea. The results indicated that the species number, cell abundance, Chl-a content, specific growth rate as well as species composition of the phytoplankton community significantly varied with the N/P ratios. After 6 days of culture, the species number, cell abundance, Chl-a content and specific growth rate in the high N/P ratio groups were significantly higher than those in the low N/P ratio groups. After 30 days of culture, the cell abundance in the groups close to the Redfield ratio (8N: 1P, 16N: 1P, and 32N: 1P) was significantly higher than those in the other treatments. On the other hand, the phytoplankton community in all the treatments was observed a definite succession from diatoms to dinoflagellates during the present study. Nonetheless, the N/P ratios strongly affected the duration of dinoflagellate bloom as well as the dominated species: at the beginning of culture (0th day-12th day), the diatoms dominated the phytoplankton community; then the relative contribution of dinoflagellates to the total cell abundance exceeded diatoms in the 4N: 1P, 16N: 1P, and 32N: 1P groups on the 18th day. After that, the relative contribution of dinoflagellates exceeded diatoms ordinally in the other groups from the 24th day to 30th day. At the end of culture, the phytoplankton community was dominated by the dinoflagellates in all the groups except for the 8N: 1P, 16N: 1P, and 32N: 1P treatments.

Acute toxicity of crude oil water accommodated fraction on marine copepods: the relative importance of acclimatization temperature and body size.

Recent oil spillage accidents around the world greatly increase harmful risks to marine ecology. This study evaluated the influences of petroleum water accommodated fraction (WAF) on 15 typical species of marine copepods collected from a subtropical bay in East China Sea at different seasons. Copepods showed impaired swimming ability, restlessness, loss of balance, anoxic coma, and even death when they were acutely exposed to the crude oil WAF under laboratory conditions. The LC(50) values (expressed in total petroleum hydrocarbon concentration) indicated that the tolerances of copepods to WAF decreased significantly (P < 0.05) with increased exposure duration and natural water temperatures (acclimatization temperature). The sensitivity of the copepods was species-specific (P < 0.01), and there was a significant (P < 0.05) positive correlation between the 48-h LC(50) and body size. Therefore, the small copepod species confront more survival challenges under oil contamination stress, especially in the warm months or regions.

[Community structure of fish in Zhoushan Fishing Ground and its adjacent waters in spring and summer].

Based on the investigation data of the fishery resources and environment in Zhoushan Fishing Ground and its adjacent waters in August 2006 and April 2007, and by using multi-dimensional scaling (MDS) and canonical correspondence analysis (CCA), this paper studied the species composition and the characteristics of fish community in the area. In spring, a total of 62 fish species were captured, belonging to 56 genera, 36 families and 11 orders. The dominant species were Amblychaeturichthys hexanema and Larimichthys polyactis, and their abundance occupied 82. 9% of the total. In summer, 58 fish species were captured, belonging to 51 genera, 38 families and 11 orders. Amblychaeturichthys hexanema, Champsodon snyderi, Dysomma anguillaaris and Acropoma japonicum were the dominant species, with the abundance accounted for 60.8% of the total. In the two seasons, twenty stations were separated into three groups. Among the fishes captured, 26 and 30 fish species had an occurrence rate larger than 5.0% in spring and summer, respectively, and formed two and three assemblages correspondingly.

[Spatial distribution patterns of heterotrophic, nitrogen, and phosphate bacteria in hypoxic zone of Yangtze River Estuary].

In August 15-28, 2009, a preliminary study was conducted on the spatial distribution characteristics of heterotrophic bacteria (HB), inorganic phosphate bacteria (IPB), organic phosphate bacteria (OPB), denitrifying bacteria (DB), and ammonifying bacteria (AB) in the hypoxic zone of Yangtze River Estuary. In the water surface, water bottom, and sediment surface of the zone, the average quantity of AB was the largest, being 307.52 x 10(4) cells x L(-1), 184.50 x 10(4) cells x L(-1), 199.97 x 10(2) cells x g(-1), followed by that of HB (87.35 x 10(4) cfu x L(-1), 86.85 x 10(4) cfu x L(-1), and 19.56 x 10(2) cfu x g(-1)), and of OPB (19.26 x 10(4) cfu x L(-1), 18.82 x 10(4) cfu x L(-1), and 19.56 x10(2) cfu x g(-1), respectively). IPB was only observed within the Yangtze Estuary, south passage of the Estuary, and Zhoushan inshore, and its average quantity in the water surface, water bottom, and sediment surface was 18.50 x 10(4) cfu x L(-1), 31.00 x 10(4) cfu x L(-1), and 7.17 x 10(2) cfu x g(-1) respectively. DB had a wide distribution, but its average quantity was low, being 3.94 x 10(4) cells x L(-1), 23.08 x 10(4) cells x L(-1), and 6.22 x 10(2) cells x g(-1) in the water surface, water bottom, and sediment surface, respectively. Salinity, NO3(-)-N, PO4(3-)-P, SiO3(2)-Si, and pH were the main factors affecting the distribution of HB, IPB, OPB, and DB in water body and sediment surface. The HB, IPB, and OPB in water bottom and sediment surface had significant positive correlation with water temperature; the HB and OPB in water bottom and the IPB in sediment surface were significantly positively correlated with dissolved oxygen (DO); while the AB in sediment surface was significantly negatively correlated with DO. Cluster analysis showed that hypoxia affected the bacterial community structure in sediment surface.