Seasonal Changes in Food Uptake by the Sea Cucumber Apostichopus japonicus in a Farm Pond: Evidence from C and N Stable Isotopes

This study investigated the seasonal changes in carbon (C) and nitrogen (N) stable isotope values of several typical food sources of Apostichopus japonicus in a farm pond, including particulate organic matter (POM), macroalgae, benthic microalgae and animals such as nematode and copepod. The stable isotope technique was used to quantify relative contributions of various sources to the food uptake by A. japonicus. The results showed that significant changes occurred in the C and N stable isotope values of sea cucumber food sources due to the seasonality of micro-or macroalgae prosperity and the fluctuation of environmental conditions. The sea cucumber A. japonicus exhibited corresponding alterations in feeding strategy in response to the changes in food conditions. Calculation with a stable isotope mixing model showed that macroalgae was the principal food source for A. japonicus throughout the 1-yr investigation, with the relative contribution averaging 28.1% - 63.2%. The relative contributions of other food sources such as copepod and nematode, POM, benthic microalgae to the total food uptake by sea cucumber averaged 22.6% - 39.1%, 6.3% - 22.2%, 2.8% - 6.5%, and 2.8% - 4.2%, respectively. Together these results indicated that the seasonal changes in food sources led to the obvious temporal differences in the relative contribution of various food sources utilized by A. japonicus. Such findings provide the basic scientific information for improving the aquaculture techniques of A. japonicus, particularly for optimizing the food environment of A. japonicus culture in farm ponds.

Response of meiofaunal and nematode communities to sewage pollution abatement:a field transplantation experiment

To assess the recovery rate of meiofaunal and nematode communities upon abatement of sewage pollution, a field transplantation experiment was conducted in Tat Tam, which is a non-polluted, shallow subtidal habitat on the southern portion of Hong Kong Island. The sediments used were from one site located in Victoria Harbour that was heavily influenced by sewage pollution, and one site in the outside-harbor area, which was relatively clean. In addition, sediments from Tat Tam were used as a control. Fresh sediments with meiofauna were collected from the aforementioned sites, placed in plastic trays and transplanted to Tat Tam. Sediments were retrieved at the beginning of the experiment and at 1-, 3-, and 8-weeks after transplantation for analysis of the meiofaunal and nematode communities as well as the sediment characteristics. The results showed that the meiofaunal and nematode communities in the control sediments were consistent at the four sampling periods, while it took three and eight weeks, respectively, for the nematode communities from the outside-harbor and inside-harbor sites to become similar to the control. These findings indicated that the relatively poor habitat quality and the nematode community composition in the sewage polluted inside-harbor sediments required a longer time for recovery than samples from the better habitat quality and the nematode community composition in the outside-harbor sediments.

Flexible feeding patterns of copepod Centropages tenuiremis in fluctuating conditions: a possible survival strategy to cope with disturbance

Centropages tenuiremis is a species with a wide distribution range in disturbed coastal waters.However,due to a lack of dietary information,it remains unclear as to how they maintain such dominance in fluctuating conditions.In this study,C.tenuiremis was collected from the Daya Bay Nuclear Power Plant both in inlet and outfall regions at 06:00,12:00 and 18:00 on April 27,2011 and their in situ diet was analyzed using a PCR protocol targeting 18S ribosomal genes.Thirty-four species of prey organisms were identified totally,including Dinophyta,Baciliariophyta,Viridiplantae,Rhizaria,Apicomplexa,Chordata,Mollusca,Arthropoda and Fungi,indicating an obvious omnivorous feeding habit of C.tenuiremis.Centropages tenuiremis obviously exhibited spatial and temporal variations in diet composition.More plant prey(land plants and phytoplankton)were consumed in the morning(~50%),while more animal prey(metazoans and protozoans)were ingested at midday and night(60%–70%).Furthermore,a more diverse diet was detected in the outfall region(10–11 taxa),where the temperatures were relatively higher and more fluctuating,than in the control region(5–10 taxa).This finding indicated that C.tenuiremis could potentially expand its food spectrum under stressful condition.Specifically,C.tenuiremis exhibited phytoplankton preference(58.62%–67.64%)in the outfall region with a lower omnivory index(0.27–0.35)than in the control region(0.51–0.95).However,phytoplankton density was lower than that in the control region,suggesting a possible herbivorous tendency of C.tenuiremis under elevated temperatures to balance the energy acquirement and feeding effort.The flexible food choices of C.tenuiremis observed here could effectively buffer environmental fluctuations and might be an important survival strategy in coastal ecosystems.

Atmospheric polychlorinated biphenyls measured during the 2008 Chinese National Arctic Research Expedition

From July to September 2008, air samples were collected aboard the R/V XUE LONG icebreaker （Snow Dragon） as part of the 2008 Chinese National Arctic Research Expedition program. ∑20PCBs in the atmosphere ranged from 6.20 to 365 pg.m^-3 with average concentration 117±107 pg.m^- 3. Congener profiles in all samples showed a prevalence of tri- and tetrachlorobiphenyls, dominated by PCB-18, PCB-28, PCB-44 and PCB-52. Along the cruise, the highest concentration was observed over the Sea of Japan and the lowest over the high-latitude Arctic Ocean. Air mass backward trajectories indicated that samples with relatively high levels of PCBs might have been influenced by atmospheric transport of these chemicals from primary and/ or secondary sources. PCB-18 displayed a significant correlation between vapor pressure and ambient temperature along the cruise, but there was no such correlation between gas-phase concentration and latitude. This suggests that atmospheric PCB-18 was related to volatilization from the earth surface during summer 2008, during which temperatures were relatively high. PCB-52 presented a significant correlation between gas-phase concentration and latitude, but no such correlation was found between vapor pressure and ambient temperature, indicating that atmospheric PCB-52 detected during the cruise might be attributed directly to atmospheric transport from source regions. In the Arctic, levels of PCB-52 in the floating sea ice region were higher than those measured in the open sea area and pack ice region. Intense ice retreat during summer 2008 might have enhanced the volatilization of previously accumulated PCBs from sea ice, especially those with heavier molecular weight and lower vapor pressure such as PCB-52.

Enhanced photocatalytic H2-production activity of WO3/TiO2 step-scheme heterojunction by graphene modification

Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated electron-hole recombination rates of TiO2-based photocatalysts.Here,a graphene-modified WO3/TiO2 step-scheme heterojunction(S-scheme heterojunction)composite photocatalyst was fabricated by a facile one-step hydrothermal method.In the ternary composite,TiO2 and WO3 nanoparticles adhered closely to reduced graphene oxide(rGO)and formed a novel S-scheme heterojunction.Moreover,rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO2 by forming a Schottky junction between TiO2 and rGO.The positive cooperative effect of the S-scheme heterojunction formed between WO3 and TiO2 and the Schottky heterojunction formed between TiO2 and graphene sheets suppressed the recombination of relatively useful electrons and holes.This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites.Thus,the novel ternary WO3/TiO2/rGO composite demonstrated a remarkably enhanced photocatalytic H2 evolution rate of 245.8μmol g^-1 h^-1,which was approximately 3.5-fold that of pure TiO2.This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H2 generation without using noble metals,but also provides new insights into the design of novel heterojunction photocatalysts.

Effects of root morphology and anatomy on cadmium uptake and translocation in rice(Oryza sativa L.)

A clear description of the certain mechanisms of cadmium(Cd) uptake and translocation in rice(Oryza sativa L.) may help to reduce Cd accumulation in rice grain. Hydroponic experiments were carried out to determine the effects of cultivation conditions(aerated and stagnant) on the uptake, translocation and subcellular distribution of Cd in relation to the morphology and anatomy of roots in two rice genotypes with different Cd accumulations in grains. Marked differences in morphology and anatomy were observed between these two genotypes under different cultivation conditions. Genotypes with low Cd accumulation in grains tended to develop fewer root tips per root surface area, larger root porosity and more mature apoplastic barriers. The stagnant cultivation condition decreased the number of root tips per root surface area but increased root porosity and accelerated apoplastic barrier formation in root tissues.Correlative Cd uptake studies revealed that rice plants with fewer number of root tips per root surface area reduced root Cd uptake ability, while mature apoplastic barriers increased root Cd retention in cell walls and the symplast. Thus, the fewer number of root tips per root surface area and the earlier formation of mature apoplastic barriers led to lower Cd uptake and translocation. The results indicated that the morphology and anatomy of roots could play important roles in Cd uptake and translocation in rice, and could be influenced by both genotype and cultivation conditions. The present results would be useful in screening and planting rice plants with low Cd accumulation.

Occurrence and fate of endogenous steroid hormones,alkylphenol ethoxylates, bisphenol A and phthalates in municipal sewage treatment systems

Steroid hormones, alkylphenol ethoxylates（APEOs） and phthalic acid esters（PAEs） are emerging endocrine disrupting chemicals（EDCs） that can interfere with the endocrine function in organisms at low concentrations. The occurrence, distribution behavior, removal rate and the fate of 31 target EDCs in sewage treatment plants, which consist of various treatment facilities and receiving water in Hong Kong, were investigated. Estrone,nonylphenol-di-ethoxylate and diethyl phthalate were found to be dominant in each group of influent samples with concentrations ranging from 11–33, 747–3945 and 445–4635 ng/L,respectively. Conversely, progesterone, nonylphenol-mono-ethoxylate and bis（2-ethylhexyl）phthalate were the most abundant in dewatered sludge, with concentrations ranging from 0.9–237, 75–19,743 and 4310–37,016 ng/g（dry weight）. The removal rates of primary sedimentation and disinfection approaches were lower than 30% for most of the chemicals,while those of activated sludge and reverse osmosis were greater than 80% for more than two-thirds of the compounds, noticeably decreasing the estrogenic risk of sewage discharged into the environment. Steroid hormones were removed via biological degradation, while some APEOs and PAEs adsorbed to the sludge. Victoria Harbor poses a low to medium estrogenic risk mainly contributed by estrone and estradiol and deserves attention.

Sea Nine 211 as antifouling biocide: A coastal pollutant of emerging concern

Sea Nine 211, with 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one（DCOIT） being the biocidal ingredient, is a widely-used antifouling agent to deter the undesirable biofouling phenomenon. It is commercially promoted as an environmentally acceptable antifoulant mainly due to its claimed rapid degradation in marine environment. However, increasing researches document varying degradative kinetics in different environments, proving that Sea Nine 211 is actually not degraded equally fast around the world（half-life between〈 1 day and 13.1 days）. Large-scale application of Sea Nine 211 in antifouling coatings has also caused global contamination of marine environment in various compartments. For example, accumulation of Sea Nine 211 is detected as high as 3700 ng/L in Spanish seawater and 281 ng/g dry weight in Korean sediment. Considering that Sea Nine 211 is highly toxic against non-target marine organisms, environmental risk assessment finds that most marine organisms are endangered by Sea Nine 211 in worst-case scenario. Its endocrine disrupting and reproductive impairing effects at environmentally worst-case concentrations further constitute a long-term threat to the maintenance of population stability.Therefore, in the light of the varying degradability, environmental pollution and high toxicity, especially the endocrine disruption, Sea Nine 211 as an antifouling agent is likely to cause non-negligible damages to the marine ecosystem. There is an urgency to perform a systematic ecological risk assessment of Sea Nine 211 to prevent the potential impacts on the health of marine environment. A regular monitoring also becomes necessary to place the usage of antifouling biocides under control.

Profiles and removal efficiency of polycyclic aromatic hydrocarbons by two different types of sewage treatment plants in Hong Kong

Sewage discharge could be a major source of polycyclic aromatic hydrocarbons （PAHs） in the coastal waters. Stonecutters Island and Shatin Sewage Treatment Works （SCISTW and STSTW） in Hong Kong, adopted chemically enhanced primary treatment and biological treatment, respectively. This study aimed at （1） determining the removal efficiencies of PAHs, （2） comparing the capabilities in removing PAHs, and （3） characterizing the profile of each individual PAHs, in the two sewage treatment plants （STPs）. Quantification of 16 PAHs was conducted by a Gas Chromatography. The concentrations of total PAHs decreased gradually along the treatment processes （from 301 ± 255 and 307 ± 217 ns/L to 14.9 ± 12.1 and 63.3 ± 54.1 ng/L in STSTW and SCISTW, respectively）. It was noted that STSTW was more capable in removing total PAHs than SCISTW with average total removal effidency 94.4% ± 4.12% us. 79.2% ± 7.48% （p 〈 0.05）. The removal of PAHs was probably due to sorption in particular matter, confirmed by the higher distribution coefficient of individual and total PAHs in solid samples （dewatered sludge contained 92.5% and 74.7% of total PAHs in SCISTW and STSTW, respectively） than liquid samples （final efffluent-total contained 7.53% and 25.3% of total PAHs in STSTW and SCISTW, respectively）. Despite the impressive capability of STSTW and SCISTW in removing PAHs, there was still a considerable amount of total PAHs （1.85 and 39.3 ks/year, respectively for the two STPs） being discharged into Hone Kon coastal waters, which would be an environmental concern.

The impacts of suspended mariculture on coastal zones in China and the scope for Integrated Multi-Trophic Aquaculture

Introduction:China is responsible for more than 60%of global aquaculture production.As the frontiers of food production have expanded,the cultivation of marine organisms in coastal zones and the open ocean has grown rapidly.The dominant mariculture industry in China is suspended mariculture,which uses net cages,ropes,or other structures suspended in the water column to cultivate aquatic organisms.This systematic,quantitative review provides a clear and comprehensive account of research that has investigated the adverse impacts of suspended mariculture in China and reviews research that has applied Integrated Multi-Trophic Aquaculture(IMTA)systems for mitigating impacts.This work builds on 218 peer reviewed papers that have been published in English-language journals.Outcomes:Eighteen impacts were identified,including chemical,ecological,physical,and socioeconomic impacts.Eighteen measures for improving suspended mariculture were recommended consisting of government department,farm management,and ecological engineering measures.IMTA was the most frequently recommended measure.The capabil-ities of IMTA for bioremediation and increased farm production were the most frequently studied advantages.Seven other benefits have been explored but remain understudied.The current challenges facing the expansion of commercial IMTA include limited use of new technology,limited skills development,decreasing production of low trophic-level species,biogeographic and temporal barriers,and negative system feedbacks.Conclusion:Despite challenges,implementing commercial IMTA is a promising measure for reducing the impacts of sus pended mariculture because it presents a range of secondary benefits that can improve the overall sustainability of aquaculture in the coastal zone.

Protective effects of Amaranthus hybridus against aflatoxin B1 and fumonisin B1-induced genotoxicity in H4IIE-luc cells

Aim:Protective effects of aqueous extract of Amaranthus hybridus against afl atoxin B1(AFB_(1))and/or fumonisin B1(FB_(1))on the H4IIE-luc cell line were determined by use of the methyl thiazol tetrazolium viability assay and disruption of DNA integrity.Methods:H4IIE-luc cells were incubated with different concentrations of AFB_(1) and/or FB_(1) for 24 and 48 h with or without aqueous extract of A.hybridus.Results:AFB_(1) decreased the viability of cells after 24 and 48 h of exposure.EC_(50)values for AFB_(1) were 10.5 and 1.8μmol/L for the two periods,respectively.When the 48 h exposure to mycotoxin repeated with a pre-treatment of 20 and 40μg/mL extract of A.hybridus,the EC_(50)changed to 3.88 and 7.67μmol/L,respectively.H4IIE-luc cells exposed to FB_(1) for 24 h responded more than those incubated for 48 h.Cells treated with a combination of AFB_(1) and FB_(1) were less viable with a signifi cant decrease in the greater concentration.The mixture of AFB_(1) and FB_(1) resulted in a signifi cant threat to H4IIE-luc as indicated by the absence or appearance of new bands in random amplifi ed polymorphic DNA analysis,which demonstrated damage to DNA.The protective effects were probably due to greater content of total phenolics,carotenoids,β-carotene,folic-,linolenic-,linoleic and palmitic acids,as well as calcium,magnesium,iron,zinc,and selenium observed in the extract.Conclusion:Exposure to 40μg/mL of extract of A.hybridus protected cells from damage to DNA by stabilizing DNA.

Aqueous extract of Corchorus olitorius decreases cytotoxicityof aflatoxin B1 and fumonisin B1 in H4IIE-luc cells

Aim:Afl atoxin B1(AFB1)and fumonisin B1(FB1)are important food-borne mycotoxins.Co-contamination of foodstuffs with these two mycotoxins is well-known and has been implicated in a possible development of hepatocellular carcinoma in humans living in regions of the world where exposures to these mycotoxins in grain are greatest.The aim of the current study was to evaluate the potential protective effects of an aqueous extract of Cochorus olitorius(C.olitorius,moroheiya)against cytotoxicity of AFB1 and/or FB1 in H4IIE-luc rat hepatoma cells,using assays to measure cell viability and disruption of DNA integrity.Although this transactivation assay was originally developed to specifi cally respond to aryl hydrocarbon agonists,this cell line was used because of its hepatic origin.Methods:H4IIE-luc cells were incubated with different concentrations of AFB1 and/or FB1 for 24 and 48 h with or without aqueous extract of C.olitorius.Results:Both mycotoxins decreased cell viability and increased DNA damage.Cytotoxicity was more pronounced when cells were exposed simultaneously to AFB1 and FB1.Conclusion:Aqueous extract of C.olitorius protected cells against cytotoxicity of mycotoxins.C.olitorius contains a water-soluble,natural chemo-preventative agent for cancer that should be isolated and identifi ed.

Environmental threats to the Three Gorges Reservoir Region:Are mutagenic and genotoxic substances important?

The Three Gorges Dam project（TGDP）,with a total static investment of 95.46 billion RMB（US$10.97 billion）based on the 1993 price level,commenced in 1994 and was completed in 2012.The creation of the Three Gorges Reservoir following the completion of the TGDP had brought about significant changes to the Three Gorges Reservoir Region（TGRR）,stretching from the town of Sandouping in Hubei Province to the Jiangjin District of Chongqing Municipality.The TGDP has led to progressive urbanization and industrialization of the TGRR,accompanied by increased shipping activities,greater