[Objective] This study aimed to observe and explore the behavior of Procambarus clarkii and Eriocheir sinensis in polyculture system. [Method] P. clarkii and E. sinensis with the same weight were used for the experime...[Objective] This study aimed to observe and explore the behavior of Procambarus clarkii and Eriocheir sinensis in polyculture system. [Method] P. clarkii and E. sinensis with the same weight were used for the experiment in a relatively small polyculture system. The agonistic behavior of P. clarkii and E. sinensis in the first 30 min of the initial encounter and the fighting results were observed and recorded; the approach-avoidance behavior of P. clarkii to bigger E. sinensis in a relatively large space （the ＂Y＂ maze） was observed and recorded. [Result] The re- sults showed that the times of first aggressions and approaches and the total times of active aggressions and approaches of P. clarkii in the initial period of polyculture experiment were all significantly more than E. sinensis （/：＇〈0.05）; after 30 d of poly- culture, P. clarkfi died in 30% of the groups while E. sinensis died in only 10% of the groups, and they coexisted in 60% of the groups. In the experiment of ap- proach-avoidance behavior of P. clarkii to bigger E. sinensis, with the increase of experiment times, the tendency of approach and avoidance of P. clarkii to the con- trol and E. sinensis became control-prefer （P〈0.05） from insignificantly different （P〉 0.05）, which indicated that the recognition ability of P. clarkii for E. sinensis was sig- nificantly improved, and the selection behavior of E. sinensis was obviously inhibited. [Conclusion] Presumably, polyculture of crayfishes and crabs can achieve better effi- ciency when under appropriate habitat conditions.展开更多
Several polyculture models of scallop Chlamys farreri and kelp Laminaria japonica currently employedin Sungo Bay and other parts of northern China are described in this paper. Economic benefits of differ-ent polycultu...Several polyculture models of scallop Chlamys farreri and kelp Laminaria japonica currently employedin Sungo Bay and other parts of northern China are described in this paper. Economic benefits of differ-ent polyculture models are analysed based on the growth rate, culture density and market price. In addi-tion, site selection, critical environmental conditions and polyculture problems are discussed in detail.展开更多
The nitrogen(N) and phosphorus(P) budget and the ecological efficiency of a polyculture system of sea cucumber(Apostichopus japonicus), jellyfish(Rhopilema esculenta) and shrimp(Fenneropenaeus chinensis) were studied ...The nitrogen(N) and phosphorus(P) budget and the ecological efficiency of a polyculture system of sea cucumber(Apostichopus japonicus), jellyfish(Rhopilema esculenta) and shrimp(Fenneropenaeus chinensis) were studied in a cofferdam, 120.2 ha in size. The nutrients were supplied by spring tide inflow. In total, 139600 kg N yr-1 and 9730 kg P yr-1 input to the system; while 118900 kg N yr-1 and 2840 kg P yr-1 outflowed from the system concurrently, thus the outflow was 85.7%(N) and 29.2%(P) of inflow. The production of N and P was 889.5 kg yr-1 and 49.28 kg yr-1(sea cucumber) and 204 kg yr-1 and 18.03 kg yr-1(jellyfish and shrimp), respectively. The utilization rate of N and P by polycultured animals was 7.8‰ and 6.9‰, respectively, 21.9% and 38% higher than that of monocultured sea cucumber. Our results indicated that the polyculture system was an efficient culture system of animals and a remediation system of coastal environment as well; it scavenged 14.3% and 70.8% of N and P, respectively. Such an ecological efficiency may be improved further by increasing either the stocking density or the size of sea cucumber or both.展开更多
Closed polyculture of Chinese penaeid shrimp,Taiwan red tilapia ,and molluscans(constricted tagelus and bay scallop) was studied from 1995 to 1997 with the enclosure experiment method, on a shrimp farm in Haiyang Coun...Closed polyculture of Chinese penaeid shrimp,Taiwan red tilapia ,and molluscans(constricted tagelus and bay scallop) was studied from 1995 to 1997 with the enclosure experiment method, on a shrimp farm in Haiyang County,Shandong Province. Four structure optimized closed polyculture systems, i.e., the “shrimp tagelus" system, the “shrimp scallop" system,the “shrimp tilapia" system and the “shrimp tilapia tagelus" system,were worked out. All these polyculture systems were superior to shrimp monoculture system in economic and ecological efficiencies. The order of these polyculture systems in efficiencies was “shrimp tilapia tagelus">“shrimp tagelus">“shrimp tilapia">“shrimp scallop". The “shrimp tilapia tagelus" system raised the production by 28% and the utilization efficiency of input nitrogen by 85%.These closed polyculture systems reduced the nitrogen discharge ratio to 6%-8%, instead of 40%-90% in the usual open culture systems. The ecological features of the systems were also investigated and many meaningful results have been obtained. The mechanism enhancing the efficiencies of these systems, the ways to enhance the efficiencies further and those to reuse the sedimented materials are disscussed.展开更多
Trophic interaction among various biomass groups in a swimming crab Portunus trituberculatus polyculture pond was investigated using carbon and nitrogen stable isotope analysis. The polycultured animal species also in...Trophic interaction among various biomass groups in a swimming crab Portunus trituberculatus polyculture pond was investigated using carbon and nitrogen stable isotope analysis. The polycultured animal species also included white shrimp Litopenaeus vannamei, short-necked clam Ruditapes philippinarum, and redlip mullet Liza haematochila. The mean δ^(13)C value for all the biomass groups in polyculture ecosystem ranged from -25.61‰ to -16.60‰, and the mean δ^(15)N value ranged from 6.80‰ to 13.09‰. Significant difference in the δ^(13)C value was found between particulate organic matter(POM) and sediment organic matter(SOM)(P < 0.05), indicating that these two organic matter pools have different material sources. Assuming that a ^(13)C-enrichment factor of 1.00‰ and a ^(15)N-enrichment factor of 2.70‰ existed between consumer and prey, diets of the four cultured animals were estimated using a stable isotope mixing model. The estimated model results indicated that P. trituberculatus mainly feed on Aloidis laevis; L. vannamei mainly feed on shrimp feed; while A. laevis, R. philippinarum and L. haematochelia mainly feed on POM. Shrimp feed was also an important food source of R. philippinarum and L. haematochelia. The diets of P. trituberculatus, L. vannamei, R. philippinarum, and L. haematochila showed complementary effects in this polyculture ecosystem. Our finding indicated that the polyculture of these four organisms with suitable farming density could make an effective use of most of the food sources, which can make a highly efficient polyculture ecosystem.展开更多
April to October, 1997 comparative studies on the nitrogen budgets of closed shrimp polyculture systems showed that, in all the studied polyculture systems, nitrogen from feeds and fertilizers were the main input item...April to October, 1997 comparative studies on the nitrogen budgets of closed shrimp polyculture systems showed that, in all the studied polyculture systems, nitrogen from feeds and fertilizers were the main input items, which comprised 70.7%-83.9% of the total input nitrogen, 3.2%-7.4% of which was provided by nitrogen fixation. It was in monoculture enclosures (Y 4, Y 11 and Y 12) that the percentage reached the maximum value. The output nitrogen in harvested products comprised 10.8%-24.6% of total input nitrogen, and the highest percentage, 24.6%, was found in shrimp fish tagelus polyculture systems. In shrimp monoculture and shrimp fish polyculture systems, they were 19.1% and 21.9%, respectively. The nitrogen utilization efficiency was different and varied from 12.2% to 20.1%. The highest, 20.1%, was found in shrimp fish tagelus polyculture systems, and the average of 20.0% was found in shrimp tagelus polyculture systems. The lowest, 12.2%, was found in shrimp monoculture systems. All the nitrogen utilization efficiencies in shrimp fish systems or shrimp scallop systems seemed to be higher than that of the monoculture system, but they showed little statistical difference. The main outputs of nitrogen were found in sediment mud, and comprised 48.2%-60.8% of the total input, the lowest percentage was found in shrimp fish tagelus polyculture systems, and the highest percentage in shrimp scallop systems. During the experiment, nitrogen lost through denitrification and ammonia volatilization comprised 1.9%-6.2%, averaged 2.8%, of the total input, and the loss through seepage comprised 5.9%-8.9% of the total. The estimated nitrogen attached to the enclosure wall comprised 3.7%-13.3% of the total, and was highest in shrimp monoculture systems. Compared with the classic shrimp farming industry, the closed shrimp polyculture systems may improve the nitrogen utilization efficiency, and hence reduce the environmental impacts on coastal waters. The nitrogen discharging rates for all the studied polyculture systems ranged from 3.0% to 6.0% of total input nitrogen.展开更多
This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(i...This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(initial weight,0.012 g)were cultured at a density of 45 shrimp m^(-2),and juvenile crabs(initial weight,0.024 g)were cultured at five densities of 0,3,6,9,and 12 crabs m^(-2).The treatments were grouped as C0S45,C3S45,C6S45,C9S45,and C12S45,respectively.Water quality parameters,growth of shrimp and crabs,and nitrogen and phosphorus budget were measured.The results indicated that the shrimp performances in polyculture treatments C3S45 and C6S45 were superior to those in the crab-free treatment(C0S45).The crab in treatments C3S45 and C6S45 exhibited a significantly higher final mean weight and carapace width/length than those in treatments C9S45 and C12S45.The final size and survival of crabs had a negative correlation with the increasing crab stocking density.The contents of total phos-phorus and total nitrogen and the comprehensive contamination index values were higher in the C9S45 and C12S45 treatments than in the other treatments.The conversion ratios of nitrogen for crab and shrimp growth in treatment C3S45 were significantly higher than those in the crab-free treatment.These findings indicate that polyculturing shrimp with crabs at suitable densities can improve productivity,profitability,nutrient utilization,and the environmental quality.From the 60-day treatments,the optimal culture densi-ties were 3-6 crabs m^(-2) and 45 shrimps m^(-2).展开更多
This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservo...This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservoir. During the production cycle, water circulated between the shrimp and mollusk ponds, and the reservoir compensated for water loss from seepage and evaporation. Constricted tagelus, Sinonovacula con- stricta, was selected as the cultured mollusk, and Pacific white shrimp, Litopenaeus vannamei, as the cultured shrimp. The main managing measures during the production cycle were: setting and using the aerators; introduc- ing the probiotic products timely into the shrimp ponds; adopting a "pen-closing" method for controlling shrimp viral epidemics; setting the flow diversion barriers in the mollusk pond to keep the circulating water flowing through the pond along a sine-like curve and serve as substrate for biofilm; no direct feeding was necessary for the cultured mollusk until the co-cultured shrimp was harvested; natural foods in the water from the shrimp ponds was used for their foods. Two sets of the system were used in the experiment in 2002 and satisfactory re- sults were achieved. The average yield of the shrimp was 11 943.5 kg/hm2, and that of the mollusk was 16 965 kg/hm2. After converting the mollusk yield into shrimp yield at their market price ratio, the food coefficient of the entire system averaged at as low as 0.81. The water quality in the ponds was maintained at a desirable level and no viral epidemics were discovered during the production cycle.展开更多
The carbon cycle in shrimp polyculture mesocosm ecosystems was studied in the shrimp farm of the Huanghai Fisheries Group Corporation in Shandong Province from May to August, 1997. The results showed that the plankton...The carbon cycle in shrimp polyculture mesocosm ecosystems was studied in the shrimp farm of the Huanghai Fisheries Group Corporation in Shandong Province from May to August, 1997. The results showed that the plankton community respiration rate fluctuated between 0.07 and 2.28 mgC/(L·d), average of 0.82±0.42 mgC/(L·d), which was 49 percent of the rate of phytoplankton gross production;that the average respiration rates (mgC/(L·d)) of micro , nano and pico plankton were 0.07, 0.38 and 0.31, which were 175, 30 and 207 percent of the corresponding sized phytoplankton production rates; that the sediment respiration rate (mgC/(m 2·d)) varied from 178.64 to 373.23, average of 262.60±48.68, and increased gradually with the lapse of culture time; and that the organic carbon accumulation and the respiration in the sediment of the shrimp monoculture mesocosm was higher than that in the polyculture mesocosms. The total sediment respiration per 25 m 2 mesocosm in the culture period averaged 571.16 gC, which was 10 percent of the total organic carbon input of the mesocosm.展开更多
The organic carbon budget in shrimp polyculture ecosystems was studied with five experimental enclosures. The results showed that: (l ) the total Organic carbon income of the ecosystems varied from 4 847. 46 to 6 15...The organic carbon budget in shrimp polyculture ecosystems was studied with five experimental enclosures. The results showed that: (l ) the total Organic carbon income of the ecosystems varied from 4 847. 46 to 6 154. 67 g, averaged (5 646. 94 t 551.09) g, the average ratio among its components, i. e., (phytoplankton production ): (periphyte production ): (feed casted) was 0. 73: 0. 11: 0. 16; (2) the total output of organic carbon varied from 3 310. 28 to 3 974. 79 g, averaged (3 644. 21 281. 44) g, the average ratio among its components, i. e., (plankton community respiration): (periphyton respiration): (benthic community): (culture animal production): (culture animal respiration) was 0. 53: 0. 19: 0. 15: 0. 04:0. 09; (3) the organic carbon accumulation varied from 1 383. 45 to 2 707. 31 g, averaged (2 002. 73 546. 76) g, which was 26% --44 % of the total organic carbon income; the sequence of organic carbon accumulation in the ecosystems of different polyculture types was Y5 (Penaeus chinensis -- Argopecten irradians) > Y7 (P. chinensis -- Taiwan red tilapia) > Y4 (P. chinensis ) > T5 (P. chinensis -- Taiwan red tilapia -- Sinonovacula constricta ) > Y6 (P. chinensis S. constricta ); (4) the average conversion rate of organic carbon income to P. chinensis was (l. 77 0. 62) % (Y6>T5 > Y4 >YS > Y7), and that to total culture animals was (2. 18 0. 79) % (T5 >Y6 > Y5 > Y4 > Y7).展开更多
A study was made on the polyculture of the red algae Gracilaria tenuistipitata Chang et Xia f. Liui Zhang et Xia, f. nov. , the shrimp Penaeus penicillatus Alcock and the mud crab Scylla serrata (Forskal) . The photos...A study was made on the polyculture of the red algae Gracilaria tenuistipitata Chang et Xia f. Liui Zhang et Xia, f. nov. , the shrimp Penaeus penicillatus Alcock and the mud crab Scylla serrata (Forskal) . The photosynthesis of the algae produces the oxygen on which the shrimp and the crab breathe. The algae are the reproductive place of the organism for the food of the shrimp and the carb, also is the shelter of the shrimp and the crab. The shrimp and the crab regard the algae as the vegetable展开更多
A study comparative of rearing of the Pacific white shrimp （Litopenaeus vannamei） with the Nile tilapia （Oreochromis niloticus） in three earthen ponds （5,600 m^2） with the salinity ranged from 0.5-1.2 ppt and th...A study comparative of rearing of the Pacific white shrimp （Litopenaeus vannamei） with the Nile tilapia （Oreochromis niloticus） in three earthen ponds （5,600 m^2） with the salinity ranged from 0.5-1.2 ppt and three treatment ponds with salinity of 2-4 ppt by adding brine water into the ponds. Postlarvae 12 （PL12） of L. vannamei were stocked at density of 9 PL/m^2 and after one week the Nile tilapia fingerlings were stocked at density of I fish/m^2. Only pelleted feed were given to the fish during the 196-day rearing period. Shrimps were partially harvested by sieve net at day 80 and 120, and five days later PLI2 were stocked at the rate of 3 PL/m^2. After final harvesting at day 196, the production, body weight and survival from the treatment group were significantly higher （P 〈 0.05） than those of the control group. While the fish production body weight and survival rate from both groups were not significant differences （P 〉 0.051）. The ionic concentration of six major ions （CI, SO42, Ca^2＋, Na^＋, Mg^2＋ and K^＋）, salinity and hardness in the treatment ponds were significantly higher than those of the control ponds （P 〈 0.05）. Moreover, the ionic profiles of the treatment ponds were similar to seawater at the salinity of 2 ppt while only 1 ppt in the control ponds. Results from the study indicated that in order to achieve good growth and survival rate of L. vannamei, brine water should be added into grow-out ponds prior to stocking and during the rearing： period to obtain and maintain the salinity not less than 2 ppt.展开更多
Knowledge on stocking density enables the farmer decide on the density limits that will enhance fish yield when intuition and experience are used as guide. Twelve weeks experiment conducted in concrete tanks assessed ...Knowledge on stocking density enables the farmer decide on the density limits that will enhance fish yield when intuition and experience are used as guide. Twelve weeks experiment conducted in concrete tanks assessed the growth performance and survival rate at different stocking densities of test specimens. Data analysis revealed that the highest stocking density produced the highest （157.85 ±36.54a） mean weight gain for C. gariepinus. Mean weight gain for O. niloticus in the same tank as just mentioned, took the reverse order. Specific growth data recorded for C. gariepinus revealed an intermediate value at the highest （4.25 ±1.3ab） and lowest （4.23 ±1.2ab） stocking densities, while the highest value was recorded at the intermediate stocking density （4.41 ± 1.34a）. Data on performance index revealed significant differences between the lowest （339.24 ± 86.95b） and intermediate （397.07±103.81a） and also between the lowest （339.24 ± 86.95b） and the highest （397.81±113.14a） stocking densities. The lowest stocking density recorded the highest food conversion efficiency, while the least was recorded at the highest stocking density. Clarias gariepinus recorded 98.3% survival at the highest stocking density, whereas O. niloticus in the same tank recorded 70.83%. The authors therefore conclude that since the highest stocking density gave the best yield in most of the output parameters, it should be recommended to farmers.展开更多
A fishers’women-led Participatory Action Research(PAR)was conducted in 30 homestead ponds to assess the potential for polyculture of Tilapia(Oreochromis niloticus)and major carps Rohu(Labeo rohita)and Catla(Catla cat...A fishers’women-led Participatory Action Research(PAR)was conducted in 30 homestead ponds to assess the potential for polyculture of Tilapia(Oreochromis niloticus)and major carps Rohu(Labeo rohita)and Catla(Catla catla)in two coastal fishing villages of Bangladesh.Three treatments,namely T1(Tilapia 200 fish per decimal;1 decimal=40 m^2),T2(Tilapia 200+Rohu 32+Catla 8 fish per decimal)and T3(Tilapia 200+Rohu 8+Catla 32 fish per decimal),each with 5 replicates,were tried in Hossainpur and Anipara villages.Formulated commercial Mega-feed was applied to the ponds twice daily at an initial rate of 10%body weight(bw)/day of Tilapia down to 4%bw/day throughout the culture period.The water quality parameters of ponds including transparency,salinity and dissolved oxygen significantly varied among treatments except temperature and pH and remained within optimum range for carp polyculture except salinity.The survival rate,harvesting weight and yield of Tilapia were significantly highest in T1(85.63±05%,258.59±18.76 g&11073±805 kg/ha,respectively)in Anipara and lowest in T3(75.63±0.37%,136.97±10.63 g&5180±406 kg/ha,respectively)in Hossainpur.The gross fish production was the significantly highest in T1(11354±806 kg/ha)of Anipara and lowest in T1(6325±227 kg/ha)of Hossainpur.Statistically,the highest net return(866,627±84874 BDT/ha)was found in T1 of Anipara and lowest in T3(279,389±46104 BDT/ha)of Hossainpur with a significantly higher benefit-cost ratio(BCR)obtained in T1(3.26±0.20)for Tilapia and lower in T3(1.58±0.10)for polyculture Tilapia and carp of Hossainpur.Therefore,it may be concluded that Tilapia production in small homestead coastal ponds has a higher potential than its mix with carps in polyculture for generating food and supplemental income opportunity for coastal fishers’women in Bangladesh.展开更多
Non-traditional aquaculture practices are crucially needed to overcome the climate change consequences,especially in countries suffering from water shortages.Polyculture strategy depends on the diversification and com...Non-traditional aquaculture practices are crucially needed to overcome the climate change consequences,especially in countries suffering from water shortages.Polyculture strategy depends on the diversification and compilation between different aquatic animal species to fasten farmed species’growth and improve available resources’utilization.In this study,European seabass and Nile tilapia were poly-cultured in brackish water(salinity 12)in a recirculating aquaculture system(RAS).For this reason,fish were distributed into five groups with triplicates in each.The first group(G1)of aquaria(120 L)was stocked with 40 specimens of European seabass,the second group(G2)was stocked with 30 specimens of European seabass+10 specimens of Nile tilapia,the third group(G3)was stocked with 20 specimens of European seabass+20 specimens of Nile tilapia,the fourth group(G4)stocked with 10 specimens of European seabass+30 specimens of Nile tilapia,and the fifth group(G5)stocked with 40 specimens of Nile tilapia.The dissolved oxygen(DO),total ammonia nitrogen(TAN),and NH_(3)–N showed higher levels in G2,G3,G4,and G5 than in G1(P<0.05).Except for G5,European seabass showed higher growth performance indices(FW,WG,and SGR)and lower FCR in G4 than in G1,G2,and G3(P<0.05).On the other hand,Nile tilapia growing in G2 resulted in higher FW,WG,and SGR and lower FCR than in G3,G4,and G5(P<0.05).The total biomass of poly-cultured European seabass and Nile tilapia is higher in G3 than in G1 and G5(P<0.05).All groups had no significant differences in the somatic indices(P˃0.05).In European seabass,the crude protein and total lipids were significantly increased in fish compared to the initial carcass composition(P<0.05).Besides,in Nile tilapia,the total lipids were significantly increased in fish compared to the initial carcass composition(P<0.05).Furthermore,no significant differences were seen be-tween all groups(P>0.05)on the blood total protein,albumin,globulin,ALT,and AST.In conclusion,the polyculture strategy is appropriate for farming European seabass and Nile tilapia in RAS with brackish water without compromising growth performance,health status,and survivability.展开更多
Objective:To study the distribution of marine luminous bacteria in shrimp culture systems of West Bengal and the effect of polyculture of shrimp with fish to reduce luminous bacteria.Methods:Luminous bacterial counts ...Objective:To study the distribution of marine luminous bacteria in shrimp culture systems of West Bengal and the effect of polyculture of shrimp with fish to reduce luminous bacteria.Methods:Luminous bacterial counts were enumerated by spread plating on seawater complex agar from shrimp grow-out pond water and pond sediment samples of West Bengal,India.Results:About 31.16%and 51.44%of pond sediment and pond water samples respectively had detectable levels of luminous bacteria.It was noticed that in normal ponds a shift happened in bacterial profile of water from the day of flooding up to 60 d,with the dominance of luminous bacteria among vibrios,reaching counts 10^(4) cells/mL or more.While in diseased ponds,luminous bacterial abundance within the ponds was noticed in the first 6 weeks of culture.Marked reduction in luminous bacterial counts of water and sediment was observed through out the culture period in polyculture ponds compared to monoculture ponds.There was no incidence of white spot syndrome viral disease and luminous vibriosis in both controlled and experimental ponds.Conclusions:The results suggest vigilant monitoring of ponds for luminous bacteria abundance and polyculture of shrimp with fish in ecofriendly sustainable aquaculture can reduce the impact of shrimp disease outbreak.展开更多
Monthly changes in sedimentation and sediment properties were studied for three different culture treatments： sea cucumber monoculture （Mc）, sea cucumber and scallop polyculture （Ps-c） and scallop monoculture （M...Monthly changes in sedimentation and sediment properties were studied for three different culture treatments： sea cucumber monoculture （Mc）, sea cucumber and scallop polyculture （Ps-c） and scallop monoculture （Ms）. Results indicated that the survival rate of sea cucumber was significantly higher in Ps-c cultures than in Mc cultures. Sea cucumber yield was 69.6% higher in Ps-c culture than in Mc culture. No significant differences in body weight and scallop shell length were found between Ps-c and Ms cultures. The mean sedimentation rate of total particulate matter （TPM） was 72.2 g/（m^2.d） in Ps-c cultures, with a maximum of 119.7 g/（mE.d）, which was markedly higher than that of Mc （mean value）. Sedimentation rates of organic matter （OM）, total organic carbon （TOC）, total nitrogen （TN） and total phosphorus （TP） in Ps-c cultures were also significantly higher than those in Mc cultures. TOC and TN contents of sediment increased rapidly in the first 5 months in Ms cultures and remained at a high level. TOC and TN contents in Mc and Ps-c cultures decreased during sea cucumber feeding seasons and increased during sea cucumber dormancy periods （summer and winter）. The study demonstrates that co-culture of sea cucumber and scallop in earthen ponds is an alternative way to alleviate nutrient loads and improve water quality in coastal aquaculture systems. Moreover, it provides the additional benefit of an increased sea cucumber yield.展开更多
We used a distance-sampling survey method and multivariate statistics to obtain a unique estimate of bird species density and seasonal variation in shade-coffee plantations. Our aim was to determine which cultivation ...We used a distance-sampling survey method and multivariate statistics to obtain a unique estimate of bird species density and seasonal variation in shade-coffee plantations. Our aim was to determine which cultivation practices among plantations contribute most to bird abundance. We conducted avian species counts at 200 points distributed across 10 shade-coffee plantations bordering the lower slopes of the Mombacho Volcano Natural Reserve, in western Nicaragua. We measured vegetation structure (coffee plants and overstory). We used principal components analysis (PCA) among 14 habitat variables to derive a single phyto-geoclimate summary measure (PGSM). We also used PCA to derive an avian abundance summary measure (AASM) from three bird survey variables, which proved to be a good predictor of bird density. We found higher bird species densities (AASM) in organic and traditional polyculture shade coffee plantations whose structurally complex and diverse overstory could be verified by PGSM. However, this finding was true only for birds that were habitat specialists. Our results provide further evidence for promoting organic coffee cultivation practices that maintain a structurally diverse overstory and help retain avian species richness and abundance in coffee plantations.展开更多
Red jumbo tilapia and M. americanum prawns were placed in 1000 L units in polyculture at three different densities of tilapia (4/5, 9/5 and 14/5 m2;tilapia/prawn) during 112 days with initial weight of? 6.5 ± 2.8...Red jumbo tilapia and M. americanum prawns were placed in 1000 L units in polyculture at three different densities of tilapia (4/5, 9/5 and 14/5 m2;tilapia/prawn) during 112 days with initial weight of? 6.5 ± 2.8 g for tilapia and 25.9 ± 8.5 g for prawn. Prawn (0/5 m2) and tilapia (4/0, 9/0 and 14/0 m2) controls were included. Tanks were maintained outdoors and under shade. Total weight gain (WG), daily individual weight gain (DWG), specific growth rate (SGR), survival, production of gross mass and food conversion ratios (FCR), ammonia, nitrite and nitrate, and chlorophyll a were measured in all units. Only prawn weight gain was significantly higher in polyculture. For tilapia, the highest survival at the end of the trial was 94% and the lowest was 75%, while prawns had final survival rates from 43% to 86%. No statistical differences were observed in weight increase among treatments at p ≤ 0.05.展开更多
基金Supported by National R&D Special Fund for Public Welfare Industry of China(201003070)National Natural Science Foundation of China (NSFC J0730641)~~
文摘[Objective] This study aimed to observe and explore the behavior of Procambarus clarkii and Eriocheir sinensis in polyculture system. [Method] P. clarkii and E. sinensis with the same weight were used for the experiment in a relatively small polyculture system. The agonistic behavior of P. clarkii and E. sinensis in the first 30 min of the initial encounter and the fighting results were observed and recorded; the approach-avoidance behavior of P. clarkii to bigger E. sinensis in a relatively large space （the ＂Y＂ maze） was observed and recorded. [Result] The re- sults showed that the times of first aggressions and approaches and the total times of active aggressions and approaches of P. clarkii in the initial period of polyculture experiment were all significantly more than E. sinensis （/：＇〈0.05）; after 30 d of poly- culture, P. clarkfi died in 30% of the groups while E. sinensis died in only 10% of the groups, and they coexisted in 60% of the groups. In the experiment of ap- proach-avoidance behavior of P. clarkii to bigger E. sinensis, with the increase of experiment times, the tendency of approach and avoidance of P. clarkii to the con- trol and E. sinensis became control-prefer （P〈0.05） from insignificantly different （P〉 0.05）, which indicated that the recognition ability of P. clarkii for E. sinensis was sig- nificantly improved, and the selection behavior of E. sinensis was obviously inhibited. [Conclusion] Presumably, polyculture of crayfishes and crabs can achieve better effi- ciency when under appropriate habitat conditions.
文摘Several polyculture models of scallop Chlamys farreri and kelp Laminaria japonica currently employedin Sungo Bay and other parts of northern China are described in this paper. Economic benefits of differ-ent polyculture models are analysed based on the growth rate, culture density and market price. In addi-tion, site selection, critical environmental conditions and polyculture problems are discussed in detail.
基金supported by the National Key R & D Program (2011BAD13B03)National Marine Public Welfare Project of China (200905020)
文摘The nitrogen(N) and phosphorus(P) budget and the ecological efficiency of a polyculture system of sea cucumber(Apostichopus japonicus), jellyfish(Rhopilema esculenta) and shrimp(Fenneropenaeus chinensis) were studied in a cofferdam, 120.2 ha in size. The nutrients were supplied by spring tide inflow. In total, 139600 kg N yr-1 and 9730 kg P yr-1 input to the system; while 118900 kg N yr-1 and 2840 kg P yr-1 outflowed from the system concurrently, thus the outflow was 85.7%(N) and 29.2%(P) of inflow. The production of N and P was 889.5 kg yr-1 and 49.28 kg yr-1(sea cucumber) and 204 kg yr-1 and 18.03 kg yr-1(jellyfish and shrimp), respectively. The utilization rate of N and P by polycultured animals was 7.8‰ and 6.9‰, respectively, 21.9% and 38% higher than that of monocultured sea cucumber. Our results indicated that the polyculture system was an efficient culture system of animals and a remediation system of coastal environment as well; it scavenged 14.3% and 70.8% of N and P, respectively. Such an ecological efficiency may be improved further by increasing either the stocking density or the size of sea cucumber or both.
基金Project3 94 3 0 1 50supportedbyNSFC .WorkalsosupportedbytheNationalKeyProgramfortheNinth Five Year PlanunderGrantNo.96 92 2
文摘Closed polyculture of Chinese penaeid shrimp,Taiwan red tilapia ,and molluscans(constricted tagelus and bay scallop) was studied from 1995 to 1997 with the enclosure experiment method, on a shrimp farm in Haiyang County,Shandong Province. Four structure optimized closed polyculture systems, i.e., the “shrimp tagelus" system, the “shrimp scallop" system,the “shrimp tilapia" system and the “shrimp tilapia tagelus" system,were worked out. All these polyculture systems were superior to shrimp monoculture system in economic and ecological efficiencies. The order of these polyculture systems in efficiencies was “shrimp tilapia tagelus">“shrimp tagelus">“shrimp tilapia">“shrimp scallop". The “shrimp tilapia tagelus" system raised the production by 28% and the utilization efficiency of input nitrogen by 85%.These closed polyculture systems reduced the nitrogen discharge ratio to 6%-8%, instead of 40%-90% in the usual open culture systems. The ecological features of the systems were also investigated and many meaningful results have been obtained. The mechanism enhancing the efficiencies of these systems, the ways to enhance the efficiencies further and those to reuse the sedimented materials are disscussed.
基金supported by the National Great Project of Scientific and Technical Supporting Programs(No.2011BAD13B03)the Programs for Excellent Youth Foundation of Shandong Province(No.JQ201009)
文摘Trophic interaction among various biomass groups in a swimming crab Portunus trituberculatus polyculture pond was investigated using carbon and nitrogen stable isotope analysis. The polycultured animal species also included white shrimp Litopenaeus vannamei, short-necked clam Ruditapes philippinarum, and redlip mullet Liza haematochila. The mean δ^(13)C value for all the biomass groups in polyculture ecosystem ranged from -25.61‰ to -16.60‰, and the mean δ^(15)N value ranged from 6.80‰ to 13.09‰. Significant difference in the δ^(13)C value was found between particulate organic matter(POM) and sediment organic matter(SOM)(P < 0.05), indicating that these two organic matter pools have different material sources. Assuming that a ^(13)C-enrichment factor of 1.00‰ and a ^(15)N-enrichment factor of 2.70‰ existed between consumer and prey, diets of the four cultured animals were estimated using a stable isotope mixing model. The estimated model results indicated that P. trituberculatus mainly feed on Aloidis laevis; L. vannamei mainly feed on shrimp feed; while A. laevis, R. philippinarum and L. haematochelia mainly feed on POM. Shrimp feed was also an important food source of R. philippinarum and L. haematochelia. The diets of P. trituberculatus, L. vannamei, R. philippinarum, and L. haematochila showed complementary effects in this polyculture ecosystem. Our finding indicated that the polyculture of these four organisms with suitable farming density could make an effective use of most of the food sources, which can make a highly efficient polyculture ecosystem.
文摘April to October, 1997 comparative studies on the nitrogen budgets of closed shrimp polyculture systems showed that, in all the studied polyculture systems, nitrogen from feeds and fertilizers were the main input items, which comprised 70.7%-83.9% of the total input nitrogen, 3.2%-7.4% of which was provided by nitrogen fixation. It was in monoculture enclosures (Y 4, Y 11 and Y 12) that the percentage reached the maximum value. The output nitrogen in harvested products comprised 10.8%-24.6% of total input nitrogen, and the highest percentage, 24.6%, was found in shrimp fish tagelus polyculture systems. In shrimp monoculture and shrimp fish polyculture systems, they were 19.1% and 21.9%, respectively. The nitrogen utilization efficiency was different and varied from 12.2% to 20.1%. The highest, 20.1%, was found in shrimp fish tagelus polyculture systems, and the average of 20.0% was found in shrimp tagelus polyculture systems. The lowest, 12.2%, was found in shrimp monoculture systems. All the nitrogen utilization efficiencies in shrimp fish systems or shrimp scallop systems seemed to be higher than that of the monoculture system, but they showed little statistical difference. The main outputs of nitrogen were found in sediment mud, and comprised 48.2%-60.8% of the total input, the lowest percentage was found in shrimp fish tagelus polyculture systems, and the highest percentage in shrimp scallop systems. During the experiment, nitrogen lost through denitrification and ammonia volatilization comprised 1.9%-6.2%, averaged 2.8%, of the total input, and the loss through seepage comprised 5.9%-8.9% of the total. The estimated nitrogen attached to the enclosure wall comprised 3.7%-13.3% of the total, and was highest in shrimp monoculture systems. Compared with the classic shrimp farming industry, the closed shrimp polyculture systems may improve the nitrogen utilization efficiency, and hence reduce the environmental impacts on coastal waters. The nitrogen discharging rates for all the studied polyculture systems ranged from 3.0% to 6.0% of total input nitrogen.
基金supported by the National Key Technology Research and Development Program of Chi-na for the Eleventh Five-Year Plan(No.2006BAD09A01).
文摘This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(initial weight,0.012 g)were cultured at a density of 45 shrimp m^(-2),and juvenile crabs(initial weight,0.024 g)were cultured at five densities of 0,3,6,9,and 12 crabs m^(-2).The treatments were grouped as C0S45,C3S45,C6S45,C9S45,and C12S45,respectively.Water quality parameters,growth of shrimp and crabs,and nitrogen and phosphorus budget were measured.The results indicated that the shrimp performances in polyculture treatments C3S45 and C6S45 were superior to those in the crab-free treatment(C0S45).The crab in treatments C3S45 and C6S45 exhibited a significantly higher final mean weight and carapace width/length than those in treatments C9S45 and C12S45.The final size and survival of crabs had a negative correlation with the increasing crab stocking density.The contents of total phos-phorus and total nitrogen and the comprehensive contamination index values were higher in the C9S45 and C12S45 treatments than in the other treatments.The conversion ratios of nitrogen for crab and shrimp growth in treatment C3S45 were significantly higher than those in the crab-free treatment.These findings indicate that polyculturing shrimp with crabs at suitable densities can improve productivity,profitability,nutrient utilization,and the environmental quality.From the 60-day treatments,the optimal culture densi-ties were 3-6 crabs m^(-2) and 45 shrimps m^(-2).
基金This work was supported by the Science and Technology Commissionof Ningbo under the grant No. Yong-ke-ji: [2001]235
文摘This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservoir. During the production cycle, water circulated between the shrimp and mollusk ponds, and the reservoir compensated for water loss from seepage and evaporation. Constricted tagelus, Sinonovacula con- stricta, was selected as the cultured mollusk, and Pacific white shrimp, Litopenaeus vannamei, as the cultured shrimp. The main managing measures during the production cycle were: setting and using the aerators; introduc- ing the probiotic products timely into the shrimp ponds; adopting a "pen-closing" method for controlling shrimp viral epidemics; setting the flow diversion barriers in the mollusk pond to keep the circulating water flowing through the pond along a sine-like curve and serve as substrate for biofilm; no direct feeding was necessary for the cultured mollusk until the co-cultured shrimp was harvested; natural foods in the water from the shrimp ponds was used for their foods. Two sets of the system were used in the experiment in 2002 and satisfactory re- sults were achieved. The average yield of the shrimp was 11 943.5 kg/hm2, and that of the mollusk was 16 965 kg/hm2. After converting the mollusk yield into shrimp yield at their market price ratio, the food coefficient of the entire system averaged at as low as 0.81. The water quality in the ponds was maintained at a desirable level and no viral epidemics were discovered during the production cycle.
文摘The carbon cycle in shrimp polyculture mesocosm ecosystems was studied in the shrimp farm of the Huanghai Fisheries Group Corporation in Shandong Province from May to August, 1997. The results showed that the plankton community respiration rate fluctuated between 0.07 and 2.28 mgC/(L·d), average of 0.82±0.42 mgC/(L·d), which was 49 percent of the rate of phytoplankton gross production;that the average respiration rates (mgC/(L·d)) of micro , nano and pico plankton were 0.07, 0.38 and 0.31, which were 175, 30 and 207 percent of the corresponding sized phytoplankton production rates; that the sediment respiration rate (mgC/(m 2·d)) varied from 178.64 to 373.23, average of 262.60±48.68, and increased gradually with the lapse of culture time; and that the organic carbon accumulation and the respiration in the sediment of the shrimp monoculture mesocosm was higher than that in the polyculture mesocosms. The total sediment respiration per 25 m 2 mesocosm in the culture period averaged 571.16 gC, which was 10 percent of the total organic carbon input of the mesocosm.
基金the National Natural Science Foundation of China under contract! No. 39430150 National Scaling He
文摘The organic carbon budget in shrimp polyculture ecosystems was studied with five experimental enclosures. The results showed that: (l ) the total Organic carbon income of the ecosystems varied from 4 847. 46 to 6 154. 67 g, averaged (5 646. 94 t 551.09) g, the average ratio among its components, i. e., (phytoplankton production ): (periphyte production ): (feed casted) was 0. 73: 0. 11: 0. 16; (2) the total output of organic carbon varied from 3 310. 28 to 3 974. 79 g, averaged (3 644. 21 281. 44) g, the average ratio among its components, i. e., (plankton community respiration): (periphyton respiration): (benthic community): (culture animal production): (culture animal respiration) was 0. 53: 0. 19: 0. 15: 0. 04:0. 09; (3) the organic carbon accumulation varied from 1 383. 45 to 2 707. 31 g, averaged (2 002. 73 546. 76) g, which was 26% --44 % of the total organic carbon income; the sequence of organic carbon accumulation in the ecosystems of different polyculture types was Y5 (Penaeus chinensis -- Argopecten irradians) > Y7 (P. chinensis -- Taiwan red tilapia) > Y4 (P. chinensis ) > T5 (P. chinensis -- Taiwan red tilapia -- Sinonovacula constricta ) > Y6 (P. chinensis S. constricta ); (4) the average conversion rate of organic carbon income to P. chinensis was (l. 77 0. 62) % (Y6>T5 > Y4 >YS > Y7), and that to total culture animals was (2. 18 0. 79) % (T5 >Y6 > Y5 > Y4 > Y7).
文摘A study was made on the polyculture of the red algae Gracilaria tenuistipitata Chang et Xia f. Liui Zhang et Xia, f. nov. , the shrimp Penaeus penicillatus Alcock and the mud crab Scylla serrata (Forskal) . The photosynthesis of the algae produces the oxygen on which the shrimp and the crab breathe. The algae are the reproductive place of the organism for the food of the shrimp and the carb, also is the shelter of the shrimp and the crab. The shrimp and the crab regard the algae as the vegetable
文摘A study comparative of rearing of the Pacific white shrimp （Litopenaeus vannamei） with the Nile tilapia （Oreochromis niloticus） in three earthen ponds （5,600 m^2） with the salinity ranged from 0.5-1.2 ppt and three treatment ponds with salinity of 2-4 ppt by adding brine water into the ponds. Postlarvae 12 （PL12） of L. vannamei were stocked at density of 9 PL/m^2 and after one week the Nile tilapia fingerlings were stocked at density of I fish/m^2. Only pelleted feed were given to the fish during the 196-day rearing period. Shrimps were partially harvested by sieve net at day 80 and 120, and five days later PLI2 were stocked at the rate of 3 PL/m^2. After final harvesting at day 196, the production, body weight and survival from the treatment group were significantly higher （P 〈 0.05） than those of the control group. While the fish production body weight and survival rate from both groups were not significant differences （P 〉 0.051）. The ionic concentration of six major ions （CI, SO42, Ca^2＋, Na^＋, Mg^2＋ and K^＋）, salinity and hardness in the treatment ponds were significantly higher than those of the control ponds （P 〈 0.05）. Moreover, the ionic profiles of the treatment ponds were similar to seawater at the salinity of 2 ppt while only 1 ppt in the control ponds. Results from the study indicated that in order to achieve good growth and survival rate of L. vannamei, brine water should be added into grow-out ponds prior to stocking and during the rearing： period to obtain and maintain the salinity not less than 2 ppt.
文摘Knowledge on stocking density enables the farmer decide on the density limits that will enhance fish yield when intuition and experience are used as guide. Twelve weeks experiment conducted in concrete tanks assessed the growth performance and survival rate at different stocking densities of test specimens. Data analysis revealed that the highest stocking density produced the highest （157.85 ±36.54a） mean weight gain for C. gariepinus. Mean weight gain for O. niloticus in the same tank as just mentioned, took the reverse order. Specific growth data recorded for C. gariepinus revealed an intermediate value at the highest （4.25 ±1.3ab） and lowest （4.23 ±1.2ab） stocking densities, while the highest value was recorded at the intermediate stocking density （4.41 ± 1.34a）. Data on performance index revealed significant differences between the lowest （339.24 ± 86.95b） and intermediate （397.07±103.81a） and also between the lowest （339.24 ± 86.95b） and the highest （397.81±113.14a） stocking densities. The lowest stocking density recorded the highest food conversion efficiency, while the least was recorded at the highest stocking density. Clarias gariepinus recorded 98.3% survival at the highest stocking density, whereas O. niloticus in the same tank recorded 70.83%. The authors therefore conclude that since the highest stocking density gave the best yield in most of the output parameters, it should be recommended to farmers.
文摘A fishers’women-led Participatory Action Research(PAR)was conducted in 30 homestead ponds to assess the potential for polyculture of Tilapia(Oreochromis niloticus)and major carps Rohu(Labeo rohita)and Catla(Catla catla)in two coastal fishing villages of Bangladesh.Three treatments,namely T1(Tilapia 200 fish per decimal;1 decimal=40 m^2),T2(Tilapia 200+Rohu 32+Catla 8 fish per decimal)and T3(Tilapia 200+Rohu 8+Catla 32 fish per decimal),each with 5 replicates,were tried in Hossainpur and Anipara villages.Formulated commercial Mega-feed was applied to the ponds twice daily at an initial rate of 10%body weight(bw)/day of Tilapia down to 4%bw/day throughout the culture period.The water quality parameters of ponds including transparency,salinity and dissolved oxygen significantly varied among treatments except temperature and pH and remained within optimum range for carp polyculture except salinity.The survival rate,harvesting weight and yield of Tilapia were significantly highest in T1(85.63±05%,258.59±18.76 g&11073±805 kg/ha,respectively)in Anipara and lowest in T3(75.63±0.37%,136.97±10.63 g&5180±406 kg/ha,respectively)in Hossainpur.The gross fish production was the significantly highest in T1(11354±806 kg/ha)of Anipara and lowest in T1(6325±227 kg/ha)of Hossainpur.Statistically,the highest net return(866,627±84874 BDT/ha)was found in T1 of Anipara and lowest in T3(279,389±46104 BDT/ha)of Hossainpur with a significantly higher benefit-cost ratio(BCR)obtained in T1(3.26±0.20)for Tilapia and lower in T3(1.58±0.10)for polyculture Tilapia and carp of Hossainpur.Therefore,it may be concluded that Tilapia production in small homestead coastal ponds has a higher potential than its mix with carps in polyculture for generating food and supplemental income opportunity for coastal fishers’women in Bangladesh.
文摘Non-traditional aquaculture practices are crucially needed to overcome the climate change consequences,especially in countries suffering from water shortages.Polyculture strategy depends on the diversification and compilation between different aquatic animal species to fasten farmed species’growth and improve available resources’utilization.In this study,European seabass and Nile tilapia were poly-cultured in brackish water(salinity 12)in a recirculating aquaculture system(RAS).For this reason,fish were distributed into five groups with triplicates in each.The first group(G1)of aquaria(120 L)was stocked with 40 specimens of European seabass,the second group(G2)was stocked with 30 specimens of European seabass+10 specimens of Nile tilapia,the third group(G3)was stocked with 20 specimens of European seabass+20 specimens of Nile tilapia,the fourth group(G4)stocked with 10 specimens of European seabass+30 specimens of Nile tilapia,and the fifth group(G5)stocked with 40 specimens of Nile tilapia.The dissolved oxygen(DO),total ammonia nitrogen(TAN),and NH_(3)–N showed higher levels in G2,G3,G4,and G5 than in G1(P<0.05).Except for G5,European seabass showed higher growth performance indices(FW,WG,and SGR)and lower FCR in G4 than in G1,G2,and G3(P<0.05).On the other hand,Nile tilapia growing in G2 resulted in higher FW,WG,and SGR and lower FCR than in G3,G4,and G5(P<0.05).The total biomass of poly-cultured European seabass and Nile tilapia is higher in G3 than in G1 and G5(P<0.05).All groups had no significant differences in the somatic indices(P˃0.05).In European seabass,the crude protein and total lipids were significantly increased in fish compared to the initial carcass composition(P<0.05).Besides,in Nile tilapia,the total lipids were significantly increased in fish compared to the initial carcass composition(P<0.05).Furthermore,no significant differences were seen be-tween all groups(P>0.05)on the blood total protein,albumin,globulin,ALT,and AST.In conclusion,the polyculture strategy is appropriate for farming European seabass and Nile tilapia in RAS with brackish water without compromising growth performance,health status,and survivability.
基金Supported by the Indian Council of Agricultural Research,Government of India,New Delhi under the National Agricultural Technology Project.
文摘Objective:To study the distribution of marine luminous bacteria in shrimp culture systems of West Bengal and the effect of polyculture of shrimp with fish to reduce luminous bacteria.Methods:Luminous bacterial counts were enumerated by spread plating on seawater complex agar from shrimp grow-out pond water and pond sediment samples of West Bengal,India.Results:About 31.16%and 51.44%of pond sediment and pond water samples respectively had detectable levels of luminous bacteria.It was noticed that in normal ponds a shift happened in bacterial profile of water from the day of flooding up to 60 d,with the dominance of luminous bacteria among vibrios,reaching counts 10^(4) cells/mL or more.While in diseased ponds,luminous bacterial abundance within the ponds was noticed in the first 6 weeks of culture.Marked reduction in luminous bacterial counts of water and sediment was observed through out the culture period in polyculture ponds compared to monoculture ponds.There was no incidence of white spot syndrome viral disease and luminous vibriosis in both controlled and experimental ponds.Conclusions:The results suggest vigilant monitoring of ponds for luminous bacteria abundance and polyculture of shrimp with fish in ecofriendly sustainable aquaculture can reduce the impact of shrimp disease outbreak.
基金Supported by the National Key Technology Research and Development Program of China (Nos. 2006BAD09A01, 200905020)the National Natural Science Foundation of China (No. 30871931)the Program for New Century Excellent Talents in University (No. NCET-08-0503)
文摘Monthly changes in sedimentation and sediment properties were studied for three different culture treatments： sea cucumber monoculture （Mc）, sea cucumber and scallop polyculture （Ps-c） and scallop monoculture （Ms）. Results indicated that the survival rate of sea cucumber was significantly higher in Ps-c cultures than in Mc cultures. Sea cucumber yield was 69.6% higher in Ps-c culture than in Mc culture. No significant differences in body weight and scallop shell length were found between Ps-c and Ms cultures. The mean sedimentation rate of total particulate matter （TPM） was 72.2 g/（m^2.d） in Ps-c cultures, with a maximum of 119.7 g/（mE.d）, which was markedly higher than that of Mc （mean value）. Sedimentation rates of organic matter （OM）, total organic carbon （TOC）, total nitrogen （TN） and total phosphorus （TP） in Ps-c cultures were also significantly higher than those in Mc cultures. TOC and TN contents of sediment increased rapidly in the first 5 months in Ms cultures and remained at a high level. TOC and TN contents in Mc and Ps-c cultures decreased during sea cucumber feeding seasons and increased during sea cucumber dormancy periods （summer and winter）. The study demonstrates that co-culture of sea cucumber and scallop in earthen ponds is an alternative way to alleviate nutrient loads and improve water quality in coastal aquaculture systems. Moreover, it provides the additional benefit of an increased sea cucumber yield.
文摘We used a distance-sampling survey method and multivariate statistics to obtain a unique estimate of bird species density and seasonal variation in shade-coffee plantations. Our aim was to determine which cultivation practices among plantations contribute most to bird abundance. We conducted avian species counts at 200 points distributed across 10 shade-coffee plantations bordering the lower slopes of the Mombacho Volcano Natural Reserve, in western Nicaragua. We measured vegetation structure (coffee plants and overstory). We used principal components analysis (PCA) among 14 habitat variables to derive a single phyto-geoclimate summary measure (PGSM). We also used PCA to derive an avian abundance summary measure (AASM) from three bird survey variables, which proved to be a good predictor of bird density. We found higher bird species densities (AASM) in organic and traditional polyculture shade coffee plantations whose structurally complex and diverse overstory could be verified by PGSM. However, this finding was true only for birds that were habitat specialists. Our results provide further evidence for promoting organic coffee cultivation practices that maintain a structurally diverse overstory and help retain avian species richness and abundance in coffee plantations.
文摘Red jumbo tilapia and M. americanum prawns were placed in 1000 L units in polyculture at three different densities of tilapia (4/5, 9/5 and 14/5 m2;tilapia/prawn) during 112 days with initial weight of? 6.5 ± 2.8 g for tilapia and 25.9 ± 8.5 g for prawn. Prawn (0/5 m2) and tilapia (4/0, 9/0 and 14/0 m2) controls were included. Tanks were maintained outdoors and under shade. Total weight gain (WG), daily individual weight gain (DWG), specific growth rate (SGR), survival, production of gross mass and food conversion ratios (FCR), ammonia, nitrite and nitrate, and chlorophyll a were measured in all units. Only prawn weight gain was significantly higher in polyculture. For tilapia, the highest survival at the end of the trial was 94% and the lowest was 75%, while prawns had final survival rates from 43% to 86%. No statistical differences were observed in weight increase among treatments at p ≤ 0.05.
