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.

Review on Pond Aquaculture Tail Water Treatment Technologies

Carrying out the treatment of aquaculture tail water and realizing the discharge and recycling of the aquaculture tail water are the inevitable trend in the development of the fishery industry at present and in the future.For this reason,this paper reviewed the characteristics of pond aquaculture tail water,the sources of pollutants in intensive aquaculture tail water,the important parameters in the water body that affect the growth of cultured organisms,and the water treatment methods in the process of aquaculture,and prospected from the technical level and industrial policy level,hoping to accumulate data for promoting the green development of aquaculture and cleaner production.

Effect of Organic Fertilizer on Aquaculture Water Quality and Tilapia Production

A two-month trial was carried out in China to evaluate the possibility of recycling animal manure through pond tilapia production.And the effects of chicken manure,cattle manure and chicken-cattle mixture together on the water quality and tilapia production were investigated.The results showed that the yield of tilapia was 3.46,3.89,2.49 and 3.20 kg in the control,chicken M,cattle M,and chicken-cattle M,respectively,and the tilapia yields following the order of chicken M>control>chicken-cattle M>cattle M.The tilapia yield in chicken M group increased by 12.43% compared with the control.Chicken manure could increase the tilapia production,but cattle manure has no the effect.And the effect of animal manure on water quality showed that adding chicken manure into tilapia pond could make water quality decreased at the beginning 20 d,but could increase water quality after 20 d and stabilize the phytoplankton structure.

Construction of Suppression Subtractive Hybridization Library for Testis of Male Tilapia Under the Stress of Methomyl

[Objectives]This study was conducted to construct forward and reserve libraries of suppression subtractive hybridization (SSH) in the testis of male tilapia under the stress of methomyl by using SSH technology.[Methods]Using male tilapia as the test animal,the forward and reserve libraries of SSH in the testis of tilapia under the stress of methomyl were constructed by using the SSH technology.[Results]45 expressed sequence tags (ESTs) were obtained,and 25 expressed sequence tags were successfully noted,including 13 forward libraries and 12 reverse libraries.The genes with confirmed functions were classified into five types.Genes related to catalytic activity and cell characteristics were up-regulated,while genes related to structural molecule's activity and biological process were down-regulated.The expression amount of integrin β1 was up-regulated,while serine/threonine protein kinase pim-3,Ca^2+-ATPase,Na^+-K^+-ATPase and ribosomal protein L22 were down-regulated.[Conclusions]The research results could lay a foundation for revealing the molecular mechanism of methomyl's reproductive toxicity to tilapia.

Production and Water Quality Responses in Tilapia Aquaculture Tanks Receiving Organic Fertilizers and Algae

A two-month trial was carried out to evaluate the possibility of using algae and animal manure in tilapia culture.And the effect of algae,chicken manure and algae mixture together,cattle manure and algae mixture together,chicken-cattle manure and algae mixture together on the water quality and tilapia production was researched.The results showed that the yield of tilapia were 3.46,4.33,3.81,2.92 and 3.76 kg in Control,Algae,Chicken-A,Cattle-A and C-C-A,respectively,following the order of Algae>Chicken-A>C-C-A>Control>Cattle-A,and tilapia yield in Algae and chicken manure treatment groups increased by 25.0%and 10.1%respectively compared with the control.Algae and chicken manure could increase the tilapia production,but cattle manure has no the effect.And the effect of algae and animal manure on water quality showed that adding chicken manure into tilapia pond could make water quality decreased at the beginning 20 d,but could increase water quality after 20 d and it can stabilize the phytoplankton structure in aquaculture water.Adding Chlorella vulgaris and Scenedesmus quadricauda into tilapia pond could make water quality in a good state during the aquaculture process and it can stabilize the phytoplankton structure in aquaculture water.

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.

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.

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 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.

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.

Testis of Male Tilapia Under Methomyl Stress: Transcriptome Changes and Signal Pathway Analysis

This study was conducted to find the differentially expressed genes and understand the transcriptome change characteristics in the testis of tilapia(Oreochromis niloticus) stressed by methomyl.The tilapia were exposed to 200 μg/L methomyl for 30 d,and then the testis samples were collected and used for the highthroughput sequencing.The results showed that 369 significant differentially expressed genes were obtained,including 160 significantly down-regulated genes,and209 significantly up-regulated genes.The enrichment of the differentially expressed genes in ECM-receptor interaction signaling pathway and MAPK signaling pathway was obvious.The adhesion of testis tissue cells was influenced by methomyl stress,which induced the expression of related gene in ECM-receptor interaction up-regulating,such as laminins,integrin α6 and integrin β1,in order to stabilize testis tissue structure.JNK,MAP3 K and MKK4 in the JNK pathway were significantly up-regulated,which enhanced transcription factor AP-1 to promote the expression of P53,Bax and other pro-apoptotic proteins.The expression of growth-related factors in the ERK pathway of MAPK signal pathway was influenced by methomyl stress.The apoptosis-related genes and pregnancy-related genes have significant differential expression under methomyl stress,and thereby,the proliferation of reproduction cells in the testis tissue may be affected.

Serum Antioxidant Enzymes SOD and CAT of Nile Tilapia(Oreochromis niloticus)in Response to Pesticide Methomyl and Recovery Pattern

Tilapia were exposed to sub-lethal concentrations of 0, 0.2, 2, 20 or 200 μg/L for 30 d, and then transferred to methomyl-free water for 18 d. CAT and SOD in tilapia serum were examined at 0, 6, 12, 18, 24 and 30 d after methomyl exposure and at 18 d after transferring to methomyl-free water. There were no significant changes in antioxidants activities in tilapia exposed to 0.2 μg/L. Significant increases in SOD, CAT were observed following methomyl exposure to 2, 20 or 200 μg/L, suggesting the presence of oxidative stress. Thus, the 0.2 μg/L methomyl might be considered the no observed adverse effect level. Recovery data showed that the effects produced by lower concentration of 20 μg/L were reversible but not at the higher concentration of 200 μg/L.

Significant decline of water pollution associated with inland fishery across China

Water pollution seriously threatens the sustainable development of fisheries in China.To inform effective pollution control policies,a comprehensive understanding of the fishery environment status is needed.However,nationwide data on the temporal changes of major pollutants in the fishery waters of China are scarce.This study collected data on the major water pollutants,including total nitrogen,total phosphorus,heavy metals,and total petroleum hydrocarbons(TPHs),from 2003 to 2017 to evaluate dynamic changes in the inland fishery water environment across China.We discovered that the levels of four heavy metals(Cu,Zn,Pb,and Cd)and TPH decreased during the 15-year period,corresponding to the reduced national discharge of pollution sources from 2003 to 2015.However,nitrogen and phosphorus levels in the inland fishery waters showed no significant changes during this period.A comparative analysis of water quality in different periods indicated that these improvements were highly associated with effective measures for water pollution control in China.In addition,the decline in pollution was consistent among the three regions of China(north,west,and southeast)from 2003 to 2017,while southeast China exhibited the weakest pollution mitigation among the three regions.These findings suggest that the inland fishery water quality improved during 2003–2017,but still faced eutrophication risk.