论文部分内容阅读
Abstract A twomonth 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， chickencattle 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， ChickenA， CattleA and CCA， respectively， following the order of Algae>ChickenA>CCA>Control>CattleA， 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.
Key words Algae; Chicken manure; Cattle manure; Tilapia production; Water quality
It is reported that more than 1 billion people in the world rely on fish as an important source of animal proteins （i.e.， fish provides at least 30% of their animal protein intakes）[1]. Aquaculture is an important way to increase fish production， which was achieved through higher fish stocking density and the application of artificial feeding. Unfortunately， the cost of feed is enormous; and therefore， interest has been diverted to other sources of enrichment of the water， such as using of animal manure. Using animal manure to culture fish had been widely used in many countries in the world in order to increase plankton production， decrease feed coefficient and enhance fish production[2]. The manure is directly consumed by fish， and the released nutrients support the growth of mainly photosynthetic organisms[3-4]. Additionally the manures were applied to produce some necessary plant nutrients which serve as a fertilizer by adding the organic matter. Therefore， compared with the feeding， manuring has been considered as a cheaper way to increase fish production.
Tilapia， which originated in Africa and Middle East， has become one of the most produced and internationally traded food fish in the world[5-6]with China taking the lead producing. In some areas of China， especially in Guangdong Province located in southern China produces almost half of the countrys total tilapia production[7]， tilapia aquaculture has the trend of changing from intensive aquaculture systems to integrated aquaculture systems for the economic reason. For tilapia has excellent tolerance even in bad environmental water condition， integrated tilapia culture system with pig， duck and other animals are very common for growout tilapia production. This kind of integrated tilapia culture system can decrease economy input， and what is more， tilapia manuring farming could be of interest in recycling animal manure in order to reduce the adverse environmental effect of intensive chicken， duck， pig and cattle farming. Different kinds of manure can be utilized; cattle， poultry dung and semiliquid pig manure are of the highest interest[8-9]. Among manures used， chicken is preferred because of its ready solubility and high level of phosphorus concentrations[10]. However， the use of manure， classified as hazardous organic matter originating from animal feces， poses a risk to the water environment[11]， and the information about the effect of manuring on water quality and fecal contamination is scarce. So the goal of this research was to assess the possibility of using algae and organic fertilizers in tilapia farming system.
Materials and Methods
Experimental design
The tests were carried out in round plastic tanks （the diameter is 1.3 m， the height is 1 m， the actual water depth is 0.77 m， and the actual quantity of water was 1 ton） in the Experimental Station of Freshwater Fisheries Research Center of Chinese Academy of Fishery Sciences.
The tanks were supplied with dechlorinated tap water that had been aerated for 20 d before the experiment. In order to make the aquatic microorganism， especially phytoplankton and zooplankton， in the test tanks with more species， high diversity and similar to the natural pond water environment， the aquatic microorganism in Taihu lake （which is the water resource for pond aquaculture in Taihu Lake Basin） were gained by phytoplankton net， and then were poured into every tank. Before the experiment， water pumpers （2 000 L/h， SOBO WPR 4000， China） were used to cascade all the tanks， and recirculate water between tanks sufficiently for 24 h to make the aquatic environment of every tank be the same.
The test water was not changed during the experiment. If the test water was lower than the water level that we have set because of water evaporation and water sampling， new water would be poured into the tank; and a levelcontrol hole was set in the tank at the water level we have set， so if the test water was higher than the levelcontrol hole in the rainy season， the excessive water would flow out through the hole. That is to say， the volume of test water will not change during the experiment.
Fertilizer and algae adding method
There were five treatments in the test， including control group （not use manure or algae）; algae treatment group （adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as Algae）; chicken manure and algae treatment group （adding amount of chicken manure was 0.5 g/L every time， adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as ChickenA）; cattle manure and algae treatment group （adding amount of cattle manure was 0.5 g/L every time， adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as CattleA）; chicken manure， cattle manure and algae treatment group （adding amount of chicken and cattle manure were all 0.25 g/L every time， adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as CCA）. Every treatment had three replicates. Chicken manure and cattle manure were all fermented manures， obtained from Jiangsu Shuyang Blue Sky Organic Fertilizer Factory. Chlorella vulgaris and Scenedesmus quadricauda were obtained from the Institute of Hydrobiology， Chinese Academy of Sciences （Wuhan city， China）. All algae were cultured with BG11 medium in natural environment. The density of Chlorella vulgaris and Scenedesmus quadricauda adding to tanks were 30×106 and 8×106 cell/ml respectively. Manures and alage were added into tank one time every 10 d during the first 20 d， and then once every 20 d after 20 d according to the water transparency and for the convenience of the analysis. Culture and sampling methods
The test lasted for 2 months from June 14 to August 13. The stocking density was 50 individual/tank， and the initial weight and length of tilapia were （2.49±0.58） g and （3.85±0.34） cm（n=30）respectively.
The total daily feed input was 5% of the tilapia biomass， with a commercial fish feed （Ningbo Techbank co.， LTD， China）， and the feed were divided into 3 equal amount and fed fish 3 times every day， that was 9：00， 12：30 and 16：00， respectively. And the total daily feed input was adjusted every week with estimated weight gains by the way of weighing five tilapia individuals caught from the control group randomly. And the feed was soon and completely consumed by the tilapia every time after feeding.
Sampling of the water was done at 0， 20， 40 and 60 d after starting the experiment at 10 AM of the sampling day. The sampling depth was 0.5 m under the surface.
Parameters and measurements
Temperature （T）， pH value （pH）， transparency （SD）， dissolved oxygen （DO）， total phosphorus （TP）， orthophosphate （PO3-4P）， total nitrogen （TN）， nitrate nitrogen （NO-3N）， nitrite nitrogen （NO-2N）， total ammonium nitrogen （TAN）， permanganate index （CODMn）， chlorophyll a （Chl. a）， and total organic carbon （TOC） of the test water were monitored once every 20 d. T， pH， SD， DO， TN， NO-2N， NO-3N， TAN， TP， PO3-4P， CODMnand Chl. a of the test water were analyzed according to methods for the examination of water and wastewater published by the State Environmental Protection Administration of China （2002）. TOC of test water was analyzed using TOC analyzer （HACH IL500， America）.
TP， TN and TOC of feed， manure and tilapia were measured. TP and TN of feed were analyzed according to Method for the Determination of Crude Protein in Feedstuffs GB/T 643294 （China） and Method for the Determination of Phosphorus in Feedstuffs Photometric Method GB/T 64372002 （China）， respectively. TP and TN of feed were all analyzed according to the standard of Organic Fertilizer NY 5252002 （China）. TP and TN of tilapia were analyzed according to National Food Safety Standard Determination of Protein in Foods GB 5009.52010 （China） and Determination of Phosphorus in Foods GB/T 5009.872003 （China）， respectively. TOC of feed， manure and tilapia were all analyzed usingTOC analyzer （HACH IL500， America）.
Tilapia were counted and weighed at the end of the test.
Water quality assessment methods Parameters will be compared to Water Quality Standard for Fishery GB 1160789 （China）. And the comprehensive Trophic Level Index [TLI（∑）] which uses TN， TP， Chl.a， SD and CODMnas assessment factors together was used to assess the water quality according to Meng et al.[12].
Statistical analysis
Statistical analyses were performed using SPSS 15.0. Significant differences were analyzed with oneway analysis of variance （ANOVA）. Tukeys multiple comparison was used for statistical comparison with P<0.05 being considered significant.
Results
Input of C， N and P
The total amount of manure added to every treatment tank was shown in Table 1. The total amount of feed put into every test and control groups were all 2.61 kg. The C， N and P concentrations in manure， feed and tilapia were shown in Table 2. The total amount of C， N and P putting into the aquaculture water during the aquaculture process were shown in Table 3.
Weight and yield of tilapia
Survivals were all 100% in the test groups. The final mean weight and yield of tilapia were shown in Fig. 1. From Fig. 1， it could be seen that the final mean weight of tilapia was 69.20， 86.50， 76.16， 58.34 and 75.23 g in the Control， Algae， ChickenA， CattleA and CCA groups， respectively， following the order of Algae>ChickenA>CCA>Control>CattleA. The final mean weight of tilapia in Algae group was significantly （P<0.05） higher than that in the Control. The yield of tilapia was 3.46， 4.33， 3.81， 2.92 and 3.76 kg in the Control， Algae， ChickenA， CattleA and CCA groups， respectively， following the order of Algae>ChickenA>CCA>Control>CattleA. The tilapia yield in Algae group increased by 25.0% compared with the control.
Main physicochemical parameters of test water
The physical and chemical conditions of the test water are shown in Fig. 2 Fig. 6. The pH in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 6.56 to 8.27， from 6.29to 8.27， from 6.86 to 8.27， from 7.01 to 8.27 and from 7.04to 8.27， respectively. The pH in all the groups conformed to Water Quality Standard for Fishery GB 1160789 （China）. However， the pH had a decrease trend in all groups. The DO in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 3.13 to 6.77 mg/L， from 1.90 to 7.56 mg/L， from 0.75 to 6.77 mg/L， from 1.16 to 6.77 mg/L and from 0.60 to 6.77mg/L， respectively. The DO in control group was higher than that in the manure treatment groups. However， the DO in the control group was lower than that in the Algae group firstly and then higher than that in the Algae group from 40 to 60 d. The SD in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 7 to 62 cm， from 18 to 62 cm， from 14 to 62 cm， from 11 to 62， and from 12 to 62 cm， respectively. The SD in the algae and manure treatment groups were higher than that in the control. And SD in all groups decreased with the prolongation of the test time. TAN in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 0.33 to 9.13 mg/L， 0.31 to 1.70 mg/L， 0.33 to 2.84 mg/L， 0.33 to 2.58 mg/L and 0.33 to 2.89 mg/L， respectively. TAN in the control was higher than that in the Algae and manure treatment groups. NO-2N in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 0.010 to 6.109mg/L， 0.010 to 0.264 mg/L， 0.010 to 1.236 mg/L， 0.010to 5.467 and 0.010 to 3.884 mg/L， respectively. NO-2N in the control was higher than that in the algae and manure treatment groups， and following the order of Control>CattleA>CCA>ChickenA>Algae at the time between 40 and 60 d. NO-3-N in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 1.548 to 12.133 mg/L， 1.548 to 2.644 mg/L， 1.548 to 3.990 mg/L， 1.548 to 4.469 mg/L and 1.548 to 4.948 mg/L， respectively. NO-3-N in the control was higher than that in the algae and manure treatment groups at the end of the test. TN in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 2.08 to 28.48 mg/L， 2.08 to 15.12 mg/L， 2.08 to 15.36 mg/L， 2.08 to 19.14 mg/L and 2.08 to 16.95 mg/L， respectively. At the time between 40 and 60 d， TN in the control was higher than that in the algae and manure treatment groups， and following the order of Control>CattleA>CCA>ChickenA>Algae. NO-2N， NO-3N and TN in all groups increased with the test time delaying; and TAN in all groups increased over the test time the first 40 d， but decreased at 60 d.
PO3-4P in the Control， Algae， ChickenA， CattleA and CCAgroups ranged from 0.017 to 0.730 mg/L， 0.017 to 0.830 mg/L， 0.017 to 2.520 mg/L， 0.017 to 9.330 mg/L and 0.017 to 12.890 mg/L， respectively. TP in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 2.075 to 11.007 mg/L， 2.075 to 6.171 mg/L， 2.075 to 8.606 mg/L， 2.075 to 14.524 mg/L and 2.075 to 14.163 mg/L， respectively. PO3-4P and TP in the control and algae treatment groups were all lower than that in the manure treatment groups. PO3-4P and TP in all groups increased over the test time.
CODMnin the Control， Algae， ChickenA， CattleA and CCAgroups ranged from 3.80 to 77.93 mg/L， 3.80 to 38.21 mg/L， 3.80 to 45.29 mg/L， 3.80 to 59.49 mg/L and 3.80 to 52.01mg/L， respectively. TOC in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 2.6 to 86.3 mg/L， 2.6to 33.8 mg/L， 2.6 to 53.3 mg/L， 2.6 to 57.5 mg/L and 2.6 to 54.4 mg/L， respectively. CODMnand TOC in the control were all higher than that in the algae and manure treatment groups at 40 and 60 d. However， as to the CODMnand TOC before 40 d， they were all lower in the control than that in the manure treatment groups， but higher than that in the algae treatment groups. CODMnand TOC in all groups increased with the prolongation of the test time. Chl. a in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 1.21 to 26.95 μg/L， 1.21 to 10.90 μg/L， 1.21 to 6.08 μg/L， 1.21 to 10.01 μg/L and 1.21 to 8.48 μg/L， respectively. Chl. a in the algae and manure treatment groups were more stable than that in the control. TLI（∑） in the ChickenA， CattleA and CCA groups were higher than that in the control at 20 d， but lower than that in the control at 40 and 60 d. And TLI（∑） in the algae treatment group was lower than that in all the groups during the experiment time.
Discussion
In this study， the final mean weight of tilapia in the groups followed the order of Algae>ChickenA>CCA>Control>CattleA. So it could be concluded that algae was better than manures; and as to the different manures， chicken manure was better than cattle manure， and could be used in tilapia farming. Lu et al.[13]found a similar phenomenon when they used chicken manure as fertilizer in tilapia pond， and concluded that chicken manure not only increase plankton production in water， but also could be eaten directly by tilapia. However， Zoccarato et al.[2]found an inversing phenomenon that the fish productions followed the order of feed only group>manure and feed group>manure only group， when they used pig manure as fertilizer in carp culture pond in Northern Italy. Maybe different fish species have different environment adaptation， and tilapia is more eutrophication resistant compared with carp， so they resulted in different results. Therefore， it is important to choose a suitable fish species when using animal manure to culture fish.
DO stands for O2 dissolved in water. DO is necessary to aquaticorganisms. If there were no oxygen in water， all the aquatic organisms except anaerobic microorganisms will die. DO can oxidize the organic materials in water and ample DO is necessary to maintain good water quality. In our test， DO in control and algae treatment groups were higher than that in the manure treatment groups， Zoccarato et al.[2]and Chen et al.[14]also found the similar result when they used pig manure as fertilizer in carp culture pond in Northern Italy and used chicken manure as fertilizer in aquaculture pond， respectively. Simultaneously， we found that DO had a decrease trend in all the manure treatment groups， Dai et al.[15]also found the similar result when they used duck manure as fertilizer in aquaculture pond. For there are a lot of organic materials in animal manure， and oxidization process will consume DO， so the DO decreased in manure treatment group. The phenomenon suggested that aeration is needed in aquaculture pond usingmanure as fertilizer， especially in high temperature season， for the temperature would influence the saturated concentration of DO in water， the higher of the temperature the lower of the saturated DO in water[16]. SD means the clarification of water. The more of suspended solid is in water， the lower of transparency. Our results showed that SD in all groups decreased with the prolongation of the test time， which revealed the suspended solid increased with the test time delaying. Chen et al.[14]also found the similar result when they used chicken manure as fertilizer in aquaculture pond， and what is more， they found SD in manure treatment groups was lower than that in the control. However， different from Chen et al.[14]， we found SD in manure treatment groups was higher than that in the control， revealing manure could decrease suspended solid in tilapia pond.
Nitrogen and phosphorus are essential for all living things. However， excessive nitrogen and phosphorus， especially higher TAN and NO-2N， is hazardous to aquatic organism directly or indirectly. The nitrogen and phosphorus in pond water mainly come from feed residual， fish feces， fertilizer; and for nitrogen， the microorganisms are also an important source， such as blue algae， could fix nitrogen from the air. In this study， TAN， NO-2N， NO-3N and TN in the control was higher than that in the algae and manure treatment groups， revealing algae and manure could decrease nitrogen concentration in aquaculture water to some extent. However， Lu et al.[13]found an inversing phenomenon in TN when they used chicken manure as fertilizer in tilapia pond. As to PO3-4P and TP， in this study， PO3-4P and TP in the control were lower than that in the manure treatment groups， Lu et al. [13]also found the similar result in TP when they used chicken manure as fertilizer in tilapia pond. And our result showed that PO3-4P and TP in the algae treatment group were lower than that in the control， revealing algae that would be used by fish was good in decrease phosphorus in aquaculture pond. Furthermore， our results showed TAN， NO-2N， NO-3N， TN， PO3-4P and TP in all test groups increased with the test time delaying， Dai et al.[15]also found the similar result in TP when they used duck manure as fertilizer in aquaculture pond. For the water in all the test groups were not changed during the experiment， so this phenomenon is normal， which revealed the accumulation of TAN， NO-2N， NO-3N， TN， PO3-4P and TP in aquaculture water.
CODMnand TOC are always used as the index standing for organic pollution， and CODMnis also used as the index standing for reductive inorganic pollution， such as nitrite and sulfide. In this study， CODMnand TOC had the similar change trend， CODMnand TOC in all test groups increased with the test time delaying， Dai et al.[15]also found the similar result in CODMnwhen they used duck manure as fertilizer in aquaculture pond. Furthermore， our result showed that CODMnand TOC in the control were all lower than that in the manure treatment groups for the first 20 d， Lu et al.[13]found a similar phenomenon in CODMnwhen they used chicken manure as fertilizer in tilapia pond. It is known that CODMnis the index standing for organic pollution and reductive inorganic pollution， because a lot of organic manure were put into manure treatment groups， so that is why the CODMnin the control was lower than that in the manure treatment groups for the first 20 d. And the result of our experiment that TOC in the control was lower than that in the manure treatment groups also demonstrated our conclusion. What is more， for TOC was lower and NO-2N was higher in the control than that in the manure treatment groups for the first 20 d， so it might be concluded that the organic material was the main source of CODMnfor the first 20 d. However， after 20 d， the CODMnand TOC in the control were significant higher than that in the manure treatment groups. And the reason of the phenomenon might be that the reductive inorganic materials and organic materials in the control were higher than that in the manure treatment groups. And the results of our experiment that NO-2N and TOC in the control were all significant higher than that in the manure treatment groups demonstrates our conclusion. Chl. a can represent the quantity of phytoplankton to some extent， and the higher Chl. a means the higher quantity of phytoplankton. In this study， Chl. a in the algae and manure treatment groups were more stable than that in the control and there was a violent increase in Chl. a in the control at 60 d. The phenomenon showed that phytoplankton biomass in the algae and manure treatment groups were more stable than that in the control and there was a violent increase in phytoplankton biomass in control at the end of the test.
TLI（∑） is usually used as an index reflecting the trophic level of water body. And the TLI（∑） is calculated according to five parameters， that is total nitrogen （TN）， total phosphorus（TP）， transparency （SD）， chlorophyll a （Chl. a） and permanganate index （CODMn）. The higher the TN， TP， Chl. a， CODMnand the lower the SD， the larger the TLI（∑）， revealing the severer of the trophic level; and the reverse is the same. And according to the value of TLI（∑）， the trophic level of water quality can be classified as oligotrophic level （TLI（∑） value （between 0 and 30）， mesotrophic level （TLI（∑） value （between 30 and 50） and eutrophic level （TLI（∑） value （higher than 50）[15]. In this study， TLI（∑） in the control was lower for the first 20 d and was higher after 20 d， than that in the manure treatment groups， revealing the water quality in the control was better for the first 20 d and was worse after 20 d， than that in the manure treatment groups. Furthermore， TLI（∑） in the algae treatment group was lower than that in all the group during the test， revealing the water quality in the algae treatment group was better than the other groups and Chlorella vulgaris and Scenedesmus quadricauda were the good algae to used in aquaculture.
Conclusion
Algae and chicken manure could increase the tilapia production， but cattle manure has no the effect. And the tilapia yields following the order of Algae>ChickenA>CCA>Control>CattleA， tilapia yield in the Algae and chicken manure treatment groups increased by 25.0% and 10.1% respectively compared with the control.
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. References
[1] OMOJOWO FS， OMOJASOLA PF. Microbiological quality of fresh catfish raised in ponds fertilized with raw and sterilized poultry manures[J]. Am. J. Res. Commun， 2013， 1： 1-2.
[2] ZOCCARATO I， BENATTI G， CALVI SL， et al. Use of pig manure as fertilizer with and without supplement feed in pond carp production in northern italy[J]. Aquaculture， 1995， 129： 387-390.
[3] MOAV R， WOHLFARTH G， SHROEDER GL， et al. Intensive polyculture of fish in freshwater ponds. 1. Substitution of expensive feeds by liquid cow manure[J]. Aquaculture， 1977， 10： 25-43.
[4] LITTLE DC， EDWARDS P. Alternative strategies for livestockfish integration with emphasis on Asia[J]. AMBIO A J. Hum. Environ， 1999， 28 （2）： 118–124.
[5] DEY MM， BIMBAO GB， LOU L， et al. Current status of production and consumption of tilapia in selected Asian countries[J]. Aquaculture Econ. Manag.， 2000， 4： 13-31.
[6] GUPTA MV， ACOSTA BO. A review of global tilapia farming practices[J]. Aquacult. Asia， 2004， IX： 7-16.
[7] KANG L， CLAUSEN JH， MURRELL KD， et al. Risks for fishborne zoonotic trematodes in tilapia production systems in Guangdong Province， China[J]. Veterinary Parasitology， 2013， 198（1-2）： 223-229.
[8] GOVIND DV， RAJAGOPAL KV， SINGH GS. Study on the comparative efficiency of organic manures as fish food producers[J]. J. Inland Fish. Soc. India， 1978， 10： 101-106.
[9] WOHLFARTH GW， SCHROEDER G. Use of manure in fish farming—A review[J]. Agric. Wastes， 1979， 1： 279-299.
[10] KNUDHANSEN CF， BATTERSON TR， MC NABB CD， et al. Nitrogen input， primary productivity and fish yield in fertilized freshwater ponds in Indonesia[J]. Aquaculture， 1991， 94： 49-63.
[11] MLEJNKOVA H， SOVOVA K. Impact of fish pond manuring on microbial water quality[J]. Acta Univ. Agric. Silvic. Mendel. Brun.， 2012， LX （3）： 117-124.
[12] MENG SL， CHEN JZ， HU GD， et al. Preliminary study on ecorestoration effect of releasing suspensionfeeding animal on west Wuli Lake[J]. Chiness Agricultural Science Bulletin， 2009， 25（16）： 225-230.
[13] LU J， LI D， XU N， et al. Effects of different fertilizers on phytoplankton community in a shrimp pond[J]. Chinese Journal of Applied & Environmental Biology， 1997， 3（2）：172-176.
[14] CHEN ZB， PENG X， ZHANG XL， et al. Effects of organic manure and chemical fertilizer application on the bacterial community in ponds[J]. Freshwater Fisheries， 2012， 42（2）： 15-21.
[15] DAI Y， TANG J， WANG Y， et al. I. Effect of three fertilization programs on the chemical water quality for integrated culture of freshwater pearl mussel and fish[J]. Journal of Fisheries of China， 2013， 37（3）： 407-416.
[16] IBRAHIM N， NAGGAR GE. Water quality， fish production and economics of Nile tilapia， Oreochromis niloticus， and african catfish， Clarias gariepinus， monoculture and polycultures[J]. Journal of the World Aquaculture Society， 2010， 41（4）： 574-582.
Editor： Yingzhi GUANG Proofreader： Xinxiu ZHU
Key words Algae; Chicken manure; Cattle manure; Tilapia production; Water quality
It is reported that more than 1 billion people in the world rely on fish as an important source of animal proteins （i.e.， fish provides at least 30% of their animal protein intakes）[1]. Aquaculture is an important way to increase fish production， which was achieved through higher fish stocking density and the application of artificial feeding. Unfortunately， the cost of feed is enormous; and therefore， interest has been diverted to other sources of enrichment of the water， such as using of animal manure. Using animal manure to culture fish had been widely used in many countries in the world in order to increase plankton production， decrease feed coefficient and enhance fish production[2]. The manure is directly consumed by fish， and the released nutrients support the growth of mainly photosynthetic organisms[3-4]. Additionally the manures were applied to produce some necessary plant nutrients which serve as a fertilizer by adding the organic matter. Therefore， compared with the feeding， manuring has been considered as a cheaper way to increase fish production.
Tilapia， which originated in Africa and Middle East， has become one of the most produced and internationally traded food fish in the world[5-6]with China taking the lead producing. In some areas of China， especially in Guangdong Province located in southern China produces almost half of the countrys total tilapia production[7]， tilapia aquaculture has the trend of changing from intensive aquaculture systems to integrated aquaculture systems for the economic reason. For tilapia has excellent tolerance even in bad environmental water condition， integrated tilapia culture system with pig， duck and other animals are very common for growout tilapia production. This kind of integrated tilapia culture system can decrease economy input， and what is more， tilapia manuring farming could be of interest in recycling animal manure in order to reduce the adverse environmental effect of intensive chicken， duck， pig and cattle farming. Different kinds of manure can be utilized; cattle， poultry dung and semiliquid pig manure are of the highest interest[8-9]. Among manures used， chicken is preferred because of its ready solubility and high level of phosphorus concentrations[10]. However， the use of manure， classified as hazardous organic matter originating from animal feces， poses a risk to the water environment[11]， and the information about the effect of manuring on water quality and fecal contamination is scarce. So the goal of this research was to assess the possibility of using algae and organic fertilizers in tilapia farming system.
Materials and Methods
Experimental design
The tests were carried out in round plastic tanks （the diameter is 1.3 m， the height is 1 m， the actual water depth is 0.77 m， and the actual quantity of water was 1 ton） in the Experimental Station of Freshwater Fisheries Research Center of Chinese Academy of Fishery Sciences.
The tanks were supplied with dechlorinated tap water that had been aerated for 20 d before the experiment. In order to make the aquatic microorganism， especially phytoplankton and zooplankton， in the test tanks with more species， high diversity and similar to the natural pond water environment， the aquatic microorganism in Taihu lake （which is the water resource for pond aquaculture in Taihu Lake Basin） were gained by phytoplankton net， and then were poured into every tank. Before the experiment， water pumpers （2 000 L/h， SOBO WPR 4000， China） were used to cascade all the tanks， and recirculate water between tanks sufficiently for 24 h to make the aquatic environment of every tank be the same.
The test water was not changed during the experiment. If the test water was lower than the water level that we have set because of water evaporation and water sampling， new water would be poured into the tank; and a levelcontrol hole was set in the tank at the water level we have set， so if the test water was higher than the levelcontrol hole in the rainy season， the excessive water would flow out through the hole. That is to say， the volume of test water will not change during the experiment.
Fertilizer and algae adding method
There were five treatments in the test， including control group （not use manure or algae）; algae treatment group （adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as Algae）; chicken manure and algae treatment group （adding amount of chicken manure was 0.5 g/L every time， adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as ChickenA）; cattle manure and algae treatment group （adding amount of cattle manure was 0.5 g/L every time， adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as CattleA）; chicken manure， cattle manure and algae treatment group （adding amount of chicken and cattle manure were all 0.25 g/L every time， adding amount of Chlorella vulgaris and Scenedesmus quadricauda were all 5 ml every time， abbreviate as CCA）. Every treatment had three replicates. Chicken manure and cattle manure were all fermented manures， obtained from Jiangsu Shuyang Blue Sky Organic Fertilizer Factory. Chlorella vulgaris and Scenedesmus quadricauda were obtained from the Institute of Hydrobiology， Chinese Academy of Sciences （Wuhan city， China）. All algae were cultured with BG11 medium in natural environment. The density of Chlorella vulgaris and Scenedesmus quadricauda adding to tanks were 30×106 and 8×106 cell/ml respectively. Manures and alage were added into tank one time every 10 d during the first 20 d， and then once every 20 d after 20 d according to the water transparency and for the convenience of the analysis. Culture and sampling methods
The test lasted for 2 months from June 14 to August 13. The stocking density was 50 individual/tank， and the initial weight and length of tilapia were （2.49±0.58） g and （3.85±0.34） cm（n=30）respectively.
The total daily feed input was 5% of the tilapia biomass， with a commercial fish feed （Ningbo Techbank co.， LTD， China）， and the feed were divided into 3 equal amount and fed fish 3 times every day， that was 9：00， 12：30 and 16：00， respectively. And the total daily feed input was adjusted every week with estimated weight gains by the way of weighing five tilapia individuals caught from the control group randomly. And the feed was soon and completely consumed by the tilapia every time after feeding.
Sampling of the water was done at 0， 20， 40 and 60 d after starting the experiment at 10 AM of the sampling day. The sampling depth was 0.5 m under the surface.
Parameters and measurements
Temperature （T）， pH value （pH）， transparency （SD）， dissolved oxygen （DO）， total phosphorus （TP）， orthophosphate （PO3-4P）， total nitrogen （TN）， nitrate nitrogen （NO-3N）， nitrite nitrogen （NO-2N）， total ammonium nitrogen （TAN）， permanganate index （CODMn）， chlorophyll a （Chl. a）， and total organic carbon （TOC） of the test water were monitored once every 20 d. T， pH， SD， DO， TN， NO-2N， NO-3N， TAN， TP， PO3-4P， CODMnand Chl. a of the test water were analyzed according to methods for the examination of water and wastewater published by the State Environmental Protection Administration of China （2002）. TOC of test water was analyzed using TOC analyzer （HACH IL500， America）.
TP， TN and TOC of feed， manure and tilapia were measured. TP and TN of feed were analyzed according to Method for the Determination of Crude Protein in Feedstuffs GB/T 643294 （China） and Method for the Determination of Phosphorus in Feedstuffs Photometric Method GB/T 64372002 （China）， respectively. TP and TN of feed were all analyzed according to the standard of Organic Fertilizer NY 5252002 （China）. TP and TN of tilapia were analyzed according to National Food Safety Standard Determination of Protein in Foods GB 5009.52010 （China） and Determination of Phosphorus in Foods GB/T 5009.872003 （China）， respectively. TOC of feed， manure and tilapia were all analyzed usingTOC analyzer （HACH IL500， America）.
Tilapia were counted and weighed at the end of the test.
Water quality assessment methods Parameters will be compared to Water Quality Standard for Fishery GB 1160789 （China）. And the comprehensive Trophic Level Index [TLI（∑）] which uses TN， TP， Chl.a， SD and CODMnas assessment factors together was used to assess the water quality according to Meng et al.[12].
Statistical analysis
Statistical analyses were performed using SPSS 15.0. Significant differences were analyzed with oneway analysis of variance （ANOVA）. Tukeys multiple comparison was used for statistical comparison with P<0.05 being considered significant.
Results
Input of C， N and P
The total amount of manure added to every treatment tank was shown in Table 1. The total amount of feed put into every test and control groups were all 2.61 kg. The C， N and P concentrations in manure， feed and tilapia were shown in Table 2. The total amount of C， N and P putting into the aquaculture water during the aquaculture process were shown in Table 3.
Weight and yield of tilapia
Survivals were all 100% in the test groups. The final mean weight and yield of tilapia were shown in Fig. 1. From Fig. 1， it could be seen that the final mean weight of tilapia was 69.20， 86.50， 76.16， 58.34 and 75.23 g in the Control， Algae， ChickenA， CattleA and CCA groups， respectively， following the order of Algae>ChickenA>CCA>Control>CattleA. The final mean weight of tilapia in Algae group was significantly （P<0.05） higher than that in the Control. The yield of tilapia was 3.46， 4.33， 3.81， 2.92 and 3.76 kg in the Control， Algae， ChickenA， CattleA and CCA groups， respectively， following the order of Algae>ChickenA>CCA>Control>CattleA. The tilapia yield in Algae group increased by 25.0% compared with the control.
Main physicochemical parameters of test water
The physical and chemical conditions of the test water are shown in Fig. 2 Fig. 6. The pH in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 6.56 to 8.27， from 6.29to 8.27， from 6.86 to 8.27， from 7.01 to 8.27 and from 7.04to 8.27， respectively. The pH in all the groups conformed to Water Quality Standard for Fishery GB 1160789 （China）. However， the pH had a decrease trend in all groups. The DO in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 3.13 to 6.77 mg/L， from 1.90 to 7.56 mg/L， from 0.75 to 6.77 mg/L， from 1.16 to 6.77 mg/L and from 0.60 to 6.77mg/L， respectively. The DO in control group was higher than that in the manure treatment groups. However， the DO in the control group was lower than that in the Algae group firstly and then higher than that in the Algae group from 40 to 60 d. The SD in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 7 to 62 cm， from 18 to 62 cm， from 14 to 62 cm， from 11 to 62， and from 12 to 62 cm， respectively. The SD in the algae and manure treatment groups were higher than that in the control. And SD in all groups decreased with the prolongation of the test time. TAN in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 0.33 to 9.13 mg/L， 0.31 to 1.70 mg/L， 0.33 to 2.84 mg/L， 0.33 to 2.58 mg/L and 0.33 to 2.89 mg/L， respectively. TAN in the control was higher than that in the Algae and manure treatment groups. NO-2N in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 0.010 to 6.109mg/L， 0.010 to 0.264 mg/L， 0.010 to 1.236 mg/L， 0.010to 5.467 and 0.010 to 3.884 mg/L， respectively. NO-2N in the control was higher than that in the algae and manure treatment groups， and following the order of Control>CattleA>CCA>ChickenA>Algae at the time between 40 and 60 d. NO-3-N in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 1.548 to 12.133 mg/L， 1.548 to 2.644 mg/L， 1.548 to 3.990 mg/L， 1.548 to 4.469 mg/L and 1.548 to 4.948 mg/L， respectively. NO-3-N in the control was higher than that in the algae and manure treatment groups at the end of the test. TN in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 2.08 to 28.48 mg/L， 2.08 to 15.12 mg/L， 2.08 to 15.36 mg/L， 2.08 to 19.14 mg/L and 2.08 to 16.95 mg/L， respectively. At the time between 40 and 60 d， TN in the control was higher than that in the algae and manure treatment groups， and following the order of Control>CattleA>CCA>ChickenA>Algae. NO-2N， NO-3N and TN in all groups increased with the test time delaying; and TAN in all groups increased over the test time the first 40 d， but decreased at 60 d.
PO3-4P in the Control， Algae， ChickenA， CattleA and CCAgroups ranged from 0.017 to 0.730 mg/L， 0.017 to 0.830 mg/L， 0.017 to 2.520 mg/L， 0.017 to 9.330 mg/L and 0.017 to 12.890 mg/L， respectively. TP in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 2.075 to 11.007 mg/L， 2.075 to 6.171 mg/L， 2.075 to 8.606 mg/L， 2.075 to 14.524 mg/L and 2.075 to 14.163 mg/L， respectively. PO3-4P and TP in the control and algae treatment groups were all lower than that in the manure treatment groups. PO3-4P and TP in all groups increased over the test time.
CODMnin the Control， Algae， ChickenA， CattleA and CCAgroups ranged from 3.80 to 77.93 mg/L， 3.80 to 38.21 mg/L， 3.80 to 45.29 mg/L， 3.80 to 59.49 mg/L and 3.80 to 52.01mg/L， respectively. TOC in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 2.6 to 86.3 mg/L， 2.6to 33.8 mg/L， 2.6 to 53.3 mg/L， 2.6 to 57.5 mg/L and 2.6 to 54.4 mg/L， respectively. CODMnand TOC in the control were all higher than that in the algae and manure treatment groups at 40 and 60 d. However， as to the CODMnand TOC before 40 d， they were all lower in the control than that in the manure treatment groups， but higher than that in the algae treatment groups. CODMnand TOC in all groups increased with the prolongation of the test time. Chl. a in the Control， Algae， ChickenA， CattleA and CCA groups ranged from 1.21 to 26.95 μg/L， 1.21 to 10.90 μg/L， 1.21 to 6.08 μg/L， 1.21 to 10.01 μg/L and 1.21 to 8.48 μg/L， respectively. Chl. a in the algae and manure treatment groups were more stable than that in the control. TLI（∑） in the ChickenA， CattleA and CCA groups were higher than that in the control at 20 d， but lower than that in the control at 40 and 60 d. And TLI（∑） in the algae treatment group was lower than that in all the groups during the experiment time.
Discussion
In this study， the final mean weight of tilapia in the groups followed the order of Algae>ChickenA>CCA>Control>CattleA. So it could be concluded that algae was better than manures; and as to the different manures， chicken manure was better than cattle manure， and could be used in tilapia farming. Lu et al.[13]found a similar phenomenon when they used chicken manure as fertilizer in tilapia pond， and concluded that chicken manure not only increase plankton production in water， but also could be eaten directly by tilapia. However， Zoccarato et al.[2]found an inversing phenomenon that the fish productions followed the order of feed only group>manure and feed group>manure only group， when they used pig manure as fertilizer in carp culture pond in Northern Italy. Maybe different fish species have different environment adaptation， and tilapia is more eutrophication resistant compared with carp， so they resulted in different results. Therefore， it is important to choose a suitable fish species when using animal manure to culture fish.
DO stands for O2 dissolved in water. DO is necessary to aquaticorganisms. If there were no oxygen in water， all the aquatic organisms except anaerobic microorganisms will die. DO can oxidize the organic materials in water and ample DO is necessary to maintain good water quality. In our test， DO in control and algae treatment groups were higher than that in the manure treatment groups， Zoccarato et al.[2]and Chen et al.[14]also found the similar result when they used pig manure as fertilizer in carp culture pond in Northern Italy and used chicken manure as fertilizer in aquaculture pond， respectively. Simultaneously， we found that DO had a decrease trend in all the manure treatment groups， Dai et al.[15]also found the similar result when they used duck manure as fertilizer in aquaculture pond. For there are a lot of organic materials in animal manure， and oxidization process will consume DO， so the DO decreased in manure treatment group. The phenomenon suggested that aeration is needed in aquaculture pond usingmanure as fertilizer， especially in high temperature season， for the temperature would influence the saturated concentration of DO in water， the higher of the temperature the lower of the saturated DO in water[16]. SD means the clarification of water. The more of suspended solid is in water， the lower of transparency. Our results showed that SD in all groups decreased with the prolongation of the test time， which revealed the suspended solid increased with the test time delaying. Chen et al.[14]also found the similar result when they used chicken manure as fertilizer in aquaculture pond， and what is more， they found SD in manure treatment groups was lower than that in the control. However， different from Chen et al.[14]， we found SD in manure treatment groups was higher than that in the control， revealing manure could decrease suspended solid in tilapia pond.
Nitrogen and phosphorus are essential for all living things. However， excessive nitrogen and phosphorus， especially higher TAN and NO-2N， is hazardous to aquatic organism directly or indirectly. The nitrogen and phosphorus in pond water mainly come from feed residual， fish feces， fertilizer; and for nitrogen， the microorganisms are also an important source， such as blue algae， could fix nitrogen from the air. In this study， TAN， NO-2N， NO-3N and TN in the control was higher than that in the algae and manure treatment groups， revealing algae and manure could decrease nitrogen concentration in aquaculture water to some extent. However， Lu et al.[13]found an inversing phenomenon in TN when they used chicken manure as fertilizer in tilapia pond. As to PO3-4P and TP， in this study， PO3-4P and TP in the control were lower than that in the manure treatment groups， Lu et al. [13]also found the similar result in TP when they used chicken manure as fertilizer in tilapia pond. And our result showed that PO3-4P and TP in the algae treatment group were lower than that in the control， revealing algae that would be used by fish was good in decrease phosphorus in aquaculture pond. Furthermore， our results showed TAN， NO-2N， NO-3N， TN， PO3-4P and TP in all test groups increased with the test time delaying， Dai et al.[15]also found the similar result in TP when they used duck manure as fertilizer in aquaculture pond. For the water in all the test groups were not changed during the experiment， so this phenomenon is normal， which revealed the accumulation of TAN， NO-2N， NO-3N， TN， PO3-4P and TP in aquaculture water.
CODMnand TOC are always used as the index standing for organic pollution， and CODMnis also used as the index standing for reductive inorganic pollution， such as nitrite and sulfide. In this study， CODMnand TOC had the similar change trend， CODMnand TOC in all test groups increased with the test time delaying， Dai et al.[15]also found the similar result in CODMnwhen they used duck manure as fertilizer in aquaculture pond. Furthermore， our result showed that CODMnand TOC in the control were all lower than that in the manure treatment groups for the first 20 d， Lu et al.[13]found a similar phenomenon in CODMnwhen they used chicken manure as fertilizer in tilapia pond. It is known that CODMnis the index standing for organic pollution and reductive inorganic pollution， because a lot of organic manure were put into manure treatment groups， so that is why the CODMnin the control was lower than that in the manure treatment groups for the first 20 d. And the result of our experiment that TOC in the control was lower than that in the manure treatment groups also demonstrated our conclusion. What is more， for TOC was lower and NO-2N was higher in the control than that in the manure treatment groups for the first 20 d， so it might be concluded that the organic material was the main source of CODMnfor the first 20 d. However， after 20 d， the CODMnand TOC in the control were significant higher than that in the manure treatment groups. And the reason of the phenomenon might be that the reductive inorganic materials and organic materials in the control were higher than that in the manure treatment groups. And the results of our experiment that NO-2N and TOC in the control were all significant higher than that in the manure treatment groups demonstrates our conclusion. Chl. a can represent the quantity of phytoplankton to some extent， and the higher Chl. a means the higher quantity of phytoplankton. In this study， Chl. a in the algae and manure treatment groups were more stable than that in the control and there was a violent increase in Chl. a in the control at 60 d. The phenomenon showed that phytoplankton biomass in the algae and manure treatment groups were more stable than that in the control and there was a violent increase in phytoplankton biomass in control at the end of the test.
TLI（∑） is usually used as an index reflecting the trophic level of water body. And the TLI（∑） is calculated according to five parameters， that is total nitrogen （TN）， total phosphorus（TP）， transparency （SD）， chlorophyll a （Chl. a） and permanganate index （CODMn）. The higher the TN， TP， Chl. a， CODMnand the lower the SD， the larger the TLI（∑）， revealing the severer of the trophic level; and the reverse is the same. And according to the value of TLI（∑）， the trophic level of water quality can be classified as oligotrophic level （TLI（∑） value （between 0 and 30）， mesotrophic level （TLI（∑） value （between 30 and 50） and eutrophic level （TLI（∑） value （higher than 50）[15]. In this study， TLI（∑） in the control was lower for the first 20 d and was higher after 20 d， than that in the manure treatment groups， revealing the water quality in the control was better for the first 20 d and was worse after 20 d， than that in the manure treatment groups. Furthermore， TLI（∑） in the algae treatment group was lower than that in all the group during the test， revealing the water quality in the algae treatment group was better than the other groups and Chlorella vulgaris and Scenedesmus quadricauda were the good algae to used in aquaculture.
Conclusion
Algae and chicken manure could increase the tilapia production， but cattle manure has no the effect. And the tilapia yields following the order of Algae>ChickenA>CCA>Control>CattleA， tilapia yield in the Algae and chicken manure treatment groups increased by 25.0% and 10.1% respectively compared with the control.
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. References
[1] OMOJOWO FS， OMOJASOLA PF. Microbiological quality of fresh catfish raised in ponds fertilized with raw and sterilized poultry manures[J]. Am. J. Res. Commun， 2013， 1： 1-2.
[2] ZOCCARATO I， BENATTI G， CALVI SL， et al. Use of pig manure as fertilizer with and without supplement feed in pond carp production in northern italy[J]. Aquaculture， 1995， 129： 387-390.
[3] MOAV R， WOHLFARTH G， SHROEDER GL， et al. Intensive polyculture of fish in freshwater ponds. 1. Substitution of expensive feeds by liquid cow manure[J]. Aquaculture， 1977， 10： 25-43.
[4] LITTLE DC， EDWARDS P. Alternative strategies for livestockfish integration with emphasis on Asia[J]. AMBIO A J. Hum. Environ， 1999， 28 （2）： 118–124.
[5] DEY MM， BIMBAO GB， LOU L， et al. Current status of production and consumption of tilapia in selected Asian countries[J]. Aquaculture Econ. Manag.， 2000， 4： 13-31.
[6] GUPTA MV， ACOSTA BO. A review of global tilapia farming practices[J]. Aquacult. Asia， 2004， IX： 7-16.
[7] KANG L， CLAUSEN JH， MURRELL KD， et al. Risks for fishborne zoonotic trematodes in tilapia production systems in Guangdong Province， China[J]. Veterinary Parasitology， 2013， 198（1-2）： 223-229.
[8] GOVIND DV， RAJAGOPAL KV， SINGH GS. Study on the comparative efficiency of organic manures as fish food producers[J]. J. Inland Fish. Soc. India， 1978， 10： 101-106.
[9] WOHLFARTH GW， SCHROEDER G. Use of manure in fish farming—A review[J]. Agric. Wastes， 1979， 1： 279-299.
[10] KNUDHANSEN CF， BATTERSON TR， MC NABB CD， et al. Nitrogen input， primary productivity and fish yield in fertilized freshwater ponds in Indonesia[J]. Aquaculture， 1991， 94： 49-63.
[11] MLEJNKOVA H， SOVOVA K. Impact of fish pond manuring on microbial water quality[J]. Acta Univ. Agric. Silvic. Mendel. Brun.， 2012， LX （3）： 117-124.
[12] MENG SL， CHEN JZ， HU GD， et al. Preliminary study on ecorestoration effect of releasing suspensionfeeding animal on west Wuli Lake[J]. Chiness Agricultural Science Bulletin， 2009， 25（16）： 225-230.
[13] LU J， LI D， XU N， et al. Effects of different fertilizers on phytoplankton community in a shrimp pond[J]. Chinese Journal of Applied & Environmental Biology， 1997， 3（2）：172-176.
[14] CHEN ZB， PENG X， ZHANG XL， et al. Effects of organic manure and chemical fertilizer application on the bacterial community in ponds[J]. Freshwater Fisheries， 2012， 42（2）： 15-21.
[15] DAI Y， TANG J， WANG Y， et al. I. Effect of three fertilization programs on the chemical water quality for integrated culture of freshwater pearl mussel and fish[J]. Journal of Fisheries of China， 2013， 37（3）： 407-416.
[16] IBRAHIM N， NAGGAR GE. Water quality， fish production and economics of Nile tilapia， Oreochromis niloticus， and african catfish， Clarias gariepinus， monoculture and polycultures[J]. Journal of the World Aquaculture Society， 2010， 41（4）： 574-582.
Editor： Yingzhi GUANG Proofreader： Xinxiu ZHU