The Effects of Environmental Factors on the Growth and Competition of Algae

In order to study the effect of environmental factors on the algae growth and competition,the author summarized overseas and domestic related researches in recent years.Most of the researches are about the influence of single factor on growth of algae.However,there is insufficient investment on the interaction of different factors and the competition between algae growth.This paper briefly introduced the classification of algae and the role they played in ecological system and focused on the influence which included temperature,illumination,nitrogen,phosphorus and pH on the growth and competition of algal.In the end,the author proposed key questions which were still needed to be studied in order to know more about the relationship between environment effects and growth and competition of algae.Therefore,people could better improve the community structure of algae and water ecological environment,and improve water primary productivity.

Effect of Atrazine on Antioxidant Enzyme and Its Bioaccumulation in Kidney of Crucian Carp,Carassius auratus

Etrazine is one of the most widely used herbicides in China and the world.Acute and chronic toxicity tests were carried out to assess the possible toxicity effect of atrazine on crucian carp(Carassius auratus).Results showed that 96 h LC50 of atrazine to Carassius auratus was 105.94 mg L-1.The enzyme activities of superoxide dismutase(SOD),catalase(CAT) and glutathione-S-transferases(GST) in kidney of Carassius auratus were all influenced by atraizine,and CAT was more sensitive to atrazine compared with SOD and GST.Atrazine residues in kidney of Carassius auratus reached the stable state at day 19,and the bioaccumulation factors(BAF) of atrazine in kidney of Carassius auratus treated with 1.0 mg L-1 and 10.0 mg L-1 atrazine were 8.3 and 4.4,respectively.The research demonstrated that atrazine could cause oxidative stress to fish kidney,but atrazine was not easy to accumulate in Carassius auratus kidney,and the antioxidant enzymes could be used as biomarker to the early detection of pollution.

Combining otolith elemental signatures with multivariate analytical models to verify the migratory pattern of Japanese Spanish mackerel(Scomberomorus niphonius) in the southern Yellow Sea

Japanese Spanish mackerel,Scomberomorus niphonius,is a commercially important,highly migratory species that is widely distributed throughout the northwestern Pacific region.However,its life history and migratory patterns are only partially understood.This study used otolith chemistry to investigate the migratory pattern of S.niphonius in the southern Yellow Sea,an important fishing ground.Transverse sections of otoliths from 15 age-1 spawning or spent individuals,comprising up to one complete migration cycle,were analyzed from the core to the margin by using laser ablation inductively coupled plasma mass spectrometry.The ratios of the element to Ca were integrated with microstructural analysis to produce age-related elemental profiles.Combining multielemental analysis of otolith composition with multivariate analytical models,we quantified structural changes in otolith chemistry profiles.Results revealed there were diverse changing patterns of otolith chemistry profiles for detected elements and the elements of Na,Mg,Sr and Ba were important for the chronological signal.Five clusters were identified through chronological clustering,representing the five life stages from the early stage to the spawning stage.Variation of Ba:Ca ratio was most informative,showing a step-decreasing pattern in the first four stages and a rebound in the spawning stage.These results support the hypothesized migratory pattern of S.niphonius:hatching and spending their early life in the coastal sandy ridges system of the southern Yellow Sea,migrating northeastward and offshore for feeding during juvenile stage,aggregating in early October and migrating outward to the Jeju Island for wintering,and returning to the coastal waters for spawning.This study demonstrated the value of life-history related otolith chemistry profiles combined with multivariate analytical models was a means to verify the migration patterns of S.niphonius at regional scales with potential application in fisheries assessment and management.

Research Progress of Rice-Fish Integrated Farming

Rice-fish integrated farming( RFIF) can change the agricultural production pattern from mono-farming model to the co-farming model,and the stereoscopic and integrated farming system established by RFIF can change the flat production to the stereoscopic production. Therefore,RFIF is the important development direction for agriculture to change pattern and adjust structure. In order to further promote development of the research and application of RFIF,the general development situation of RFIF in China was reviewed; the effects of RFIF on increasing farmer' income and enhancing agricultural efficiency were clarified. The technologies matched with RFIF,such as rice paddy engineering technology,safe plant protection technology,security fertilization technology,fish disease prevention and control technology and water quality management technology,were summarized,and the supporting role of RFIF for agriculture was pointed out. In addition,the development prospect of RFIF was proposed,as well as the key research direction of RFIF.

Effects of 1-Naphthol on Physiological Parameters of Chlorella vulgaris

[Objective]This study aimed to investigate the effects of 1-naphthol on primary productivity in aquatic ecosystems.[Method]The effects of 1-naphthol on biomass,chlorophyll a content,malondialdehyde( MDA) content and soluble protein content of Chlorella vulgaris were investigated.[Result]1-Naphthol could significantly inhibit the growth of Chlorella vulgaris. On the 7thd,the biomass of Chlorella vulgaris exposed to 1. 0,3. 0,6. 0,12. 0 and 18. 0 mg /L 1-naphthol was 60. 26%,48. 15%,41. 32%,28. 59% and 27. 10% of that in control respectively,exhibiting a significant dose-response relationship. Chlorella vulgaris was exposed to different concentrations of 1-naphthol( 0,1,5 and 10 mg /L) for 7 d; with the increase of 1-naphthol concentration,chlorophyll a content of Chlorella vulgaris was reduced,MDA content increased gradually,soluble protein content increased first and then declined.[Conclusion]According to the experimental results,1-naphthol can significantly inhibit the growth of Chlorella vulgaris,thus reducing primary productivity in aquatic ecosystems.

Community Structure of Phytoplankton in Pond Industrial Eco-aquaculture System for Megalobrama amblycephala

In order to find out the change pattern of phytoplankton community structure in pond industrial eco-aquaculture system and explain its ecological mechanism,tests were carried out using Megalobrama amblycephala as aquaculture species with two stocking densities.Shannon-Wiener diversity index and Pielou uniformity index were used to study the phytoplankton community structure in aquaculture area( including low stocking density aquaculture area and high stocking density aquaculture area),inlet area,outlet area,purification area,recirculation area,back area of the pond industrial eco-aquaculture system.The results showed that a total of 92 species of 5 phyla were identified,including 46 species of Chlorophyta,15 species of Cyanophyta,15 species of Euglenophyta,10 species of Bacillariophyta,5 species of Cryptophyta,and 1 species of Pyrrophyta.The numbers of phytoplankton species,biodiversity indexes,uniformity indexes,Chlorophyta biomass and its proportion in total phytoplankton followed the order of inlet area,purification area,recirculation area,back area > low stocking area > high stocking area > outlet area.The total biomass of phytoplankton,Cyanophyta biomass and its proportion in total phytoplankton followed the order of inlet area,purification area,recirculation area,back area < low stocking area < high stocking area < outlet area.However,all these parameters showed no significant differences or change rules among inlet area,purification area,recirculation area,back area.It could be concluded according to the biodiversity that the water quality in outlet area was at middle pollution level,the water quality in high stocking area was in light pollution level,and the water quality in other 5 areas were at clean level,which suggested that the water quality was in good states except that in outlet area,and the pond industrial eco-aquaculture system functioned well.

Acute Toxicity Effects of 2,2',4,4',5,5'-Hexabromodiphenyl Ether on Chlorella vulgaris

[Objectives] This study was conducted to investigate the toxic effects of 2,2',4,4',5,5'-hexabromobiphenyl ether on Chlorella vulgaris and provide basic data for protecting aquatic ecosystems. [Methods] The acute toxicity effects of 2,2',4,4',5,5'-hexabromodiphenyl ether on C. vulgaris was investigated by the semi-static water contacting acute toxicity method. [Results] The 48,72 and 96 h-EC(50) of 2,2',4,4',5,5'-hexabromodiphenyl ether to C. vulgaris were23. 58,18. 71 and 14. 75 μg/L,respectively,and the safe concentration of 2,2',4,4',5,5'-hexabromodiphenyl ether to C. vulgaris was 1. 475μg/L. For the water solubility of 2,2',4,4',5,5'-hexabromodiphenyl ether is extremely low( 1 μg/L),it could not cause the acute poisoning death of C. vulgaris. According to the grading standards for the assessment of the toxicity on algae,2,2',4,4',5,5'-hexabromodiphenyl ether was extremely highly toxic to C. vulgaris. [Conclusions]The extremely high toxicity of 2,2',4,4',5,5'-hexabromodiphenyl ether to C. vulgaris shows that it has heavy potential harm to aquatic ecosystems and the maximum residue limit standards of 2,2',4,4',5,5'-hexabromodiphenyl ether in water should be formulated to better protect aquatic ecosystems.

Response of Vitellogenin in Tilapia Liver to 2,2′,4,4′-Tetrabromodiphenyl Ether Stress

[Objectives]This study was conducted to understand the potential harm of BDE-47 to fish and aquatic ecosystems and obtain relevant toxicological data from the perspective of vitellogenin.[Methods]Adopting the semi-static water exposure method,three exposure concentrations of 5,50,and 500μg/L and five sampling time of 1,3,7,15,and 30 d were set to investigate the effect of BDE-47 on vitellogenin in tilapia liver.[Results]The low concentration of BDE-47(5μg/L)had no effect on the level of vitellogenin in the liver of tilapia.When exposed to high concentrations of BDE-47(50 and 500μg/L),the VTG content of tilapia liver showed a trend of first decreasing,then returning to normal,and then increasing.An abnormal VTG content indicates that the endocrine system of tilapia is disturbed to a certain extent.[Conclusions]This study plays a role in promoting the formulation of relevant water quality standards and the protection of aquatic living resources.

Response of 11-Ketotestosterone in Tilapia Liver to 2,2′,4,4′-Tetrabromodiphenyl Ether Stress

[Objectives]This study was conducted to investigate the effect of tetrabromodiphenyl ether(BDE-47)on the activity of 11-ketotestosterone(11-KT)in tilapia liver,with a view to understanding the potential hazard of BDE-47 on fish and aquatic ecosystems from the perspective of sex steroid hormones.[Methods]Adopting the semi-static water exposure method,3 exposure concentrations of 5,50,and 500μg/L and 5 sampling time of 1,3,7,15,and 30 d were set to investigate the effect of BDE-47 on 11-ketotestosterone in tilapia liver.[Results]The low concentration of BDE-47(5μg/L)had no effect on the 11-KT level of tilapia liver;and when exposed to high concentrations of BDE-47(50 and 500μg/L),11-KT in the liver of tilapia was first suppressed and then returned to the normal level.Because the fish reproductive process is completed under the coordinated regulation of sex steroid hormones,significant changes of 11-KT in the liver of tilapia may cause its reproductive dysfunction to a certain extent.[Conclusions]This study provides relevant toxicological data for promoting the formulation(revision)of relevant water quality standards and the formulation of limit standards,and facilitating the protection of aquatic living resources and aquatic ecosystems.

Acute Toxicity of Tetrabromodiphenyl Ether on Three Model Aquatic Organisms

The acute toxicity of 2,2′,4,4′-tetrabromodiphenyl ether on Chlorella vulgaris, Dqohnia magna and Barchydanio rerio was analyzed using semi-static water contacting acute toxicity method. The results showed that the 96 h-EC50 of 2,2′,4,4′-tetrabromodiphenyl ether(BDE-47) on C. vulgaris was 3.97 μg/L, the 48 h-LC50 and 96 h-LC50 of BDE-47 on D. magna were 1.09 and 0.84 mg/L respectively, and the 96 h-LC50 of BDE-47 on B. rerio was higher than 56.2 mg/L. According to the grading standard of toxicity evaluation, BDE-47 had extremely high toxicity to C. vulgaris, high toxicity to D. magna, and low to medium toxicity to B. rerio. The toxicity of BDE-47 to C. vulgaris, D. magna and B. rerio followed the order of C. vulgaris>D. magna>B. rerio. For the water solubility of BDE-47 is extremely low(15 μg/L), it could not cause the acute poisoning death of D. magna and B. rerio.

Effects of water-borne copper on the gills and hepatopancreas of Macrobrachium rosenbergii

We focused on elucidating the toxic effects of water-borne copper on the giant freshwater prawn Macrobrachium rosenbergii.After seven days of exposure to copper(Cu2+)at concentrations ranging from 0.01 mg L–1 to 0.5 mg L–1,three isozymes,malate dehydrogenase,alkaline phosphatase and esterase,were analyzed and compared using polyacrylamide electrophoresis(PAGE)and biochemical staining.The results indicated that the electrophoretic patterns of the isozymes showed a copper-concentration-related difference.Low doses of copper stimulated strong expression of the three isozymes.Electrophoretic patterns of malate dehydrogenase and alkaline phosphatase gradually became weaker or even lost as the level of copper increased.In contrast,esterase patterns exhibited an increased molecular heterogeneity at higher copper concentrations.A transmission electron microscope was used to study ultrastructure differences in the gills and hepatopancreas of M.rosenbergii,and the results showed significant structural damage at increased levels of copper compared with the control group.The basement mem-branes and mitochondira in the gills were seriously damaged,the cuticle electron density distribution was not homogeneous,and an infolded basement membrane,circularized nucleus,disintegrated nuclear membrane,and decreased mitochondria number and size were observed in the gills.Similarly,flowing out of karyoplasms,partly falling microvilli,decreased mitochondrion,partly disappeared mitochondrial cristae,and a thinned matrix were observed in the hepatopancreas.These findings indicate that exposure to elevated copper levels might damage the ultrastructure of the gills and hepatopancreas of M.rosenbergii and might further weaken their normal physical activities.Isozymes were quite sensitive to environmental stress and changes in isozyme elctrophoretic patterns might be effective biomarkers of environmental contamination.