Showing papers on "Polyculture published in 2013"

Elevated CO2 enrichment induces a differential biomass response in a mixed species temperate forest plantation

Abstract: Summary In a free-air carbon dioxide (CO2) enrichment study (BangorFACE), Alnus glutinosa, Betula pendula and Fagus sylvatica were planted in areas of one-, two- and three-species mixtures (n = 4). The trees were exposed to ambient or elevated CO2 (580 μmol mol−1) for 4 yr, and aboveground growth characteristics were measured. In monoculture, the mean effect of CO2 enrichment on aboveground woody biomass was + 29, + 22 and + 16% for A. glutinosa, F. sylvatica and B. pendula, respectively. When the same species were grown in polyculture, the response to CO2 switched to + 10, + 7 and 0% for A. glutinosa, B. pendula and F. sylvatica, respectively. In ambient atmosphere, our species grown in polyculture increased aboveground woody biomass from 12.9 ± 1.4 to 18.9 ± 1.0 kg m−2, whereas, in an elevated CO2 atmosphere, aboveground woody biomass increased from 15.2 ± 0.6 to 20.2 ± 0.6 kg m−2. The overyielding effect of polyculture was smaller (+ 7%) in elevated CO2 than in an ambient atmosphere (+ 18%). Our results show that the aboveground response to elevated CO2 is affected significantly by intra- and interspecific competition, and that the elevated CO2 response may be reduced in forest communities comprising tree species with contrasting functional traits.

Tree species diversity interacts with elevated CO2 to induce a greater root system response.

Abstract: As a consequence of land use change and the burning of fossil fuels, atmospheric concentrations of CO2 are increasing and altering the dynamics of the carbon cycle in forest ecosystems. In a number of studies using single tree species, fine root biomass has been shown to be strongly increased by elevated CO2. However, natural forests are often intimate mixtures of a number of co-occurring species. To investigate the interaction between tree mixture and elevated CO2, Alnus glutinosa, Betula pendula and Fagus sylvatica were planted in areas of single species and a three species polyculture in a free-air CO2 enrichment study (BangorFACE). The trees were exposed to ambient or elevated CO2 (580 µmol mol-1) for four years. Fine and coarse root biomass, together with fine root turnover and fine root morphological characteristics were measured. Fine root biomass, and morphology responded differentially to elevated CO2 at different soil depths in the three species when grown in monocultures. In polyculture, a greater response to elevated CO2 was observed in coarse roots to a depth of 20 cm, and fine root area index to a depth of 30 cm. Total fine root biomass was positively affected by elevated CO2 at the end of the experiment, but not by species diversity. Our data suggest that existing biogeochemical cycling models parameterised with data from species grown in monoculture may be underestimating the belowground response to global change.

SUITABILITY OF DUCKWEED (Lemna minor) AS FEED FOR FISH IN POLYCULTURE SYSTEM

Abstract: In the present study, we conducted an experiment to evaluate the effects of duckweed ( Lemna minor ) as feed on fish production in polyculture. The experiment had 2 treatments where in treatment 1 (T 1 ) ponds were supplied with duckweed as feed and in treatment 2 (T 2 ) ponds were kept as control (without supply of duckweed). Average survival rates in T 1 and T 2 were 90 and 89%, respectively. The specific growth rates (SGR) were higher in T 1 . Calculated net production in T 1 was 6.25 tons ha. -1 yr. -1 and in T 2 was 2.84 tons ha. -1 yr. -1 . The ranges of physico-chemical parameters analyzed were within the productive limit and more or less similar in all the ponds under both treatments during the experimental period. There were 24 genera of phytoplankton under 5 major groups and 10 genera of zooplankton under 3 major groups found in the experimental ponds. The net production in T 1 was significantly higher than that of T 2 indicated the use of duckweed as feed for fishes is economically sustainable in polyculture. DOI: http://dx.doi.org/10.3329/ijarit.v2i1.13994 Int. J. Agril. Res. Innov. & Tech. 2 (1): 42-46, June, 2012

The role of the agricultural matrix: coffee management and euglossine bee (Hymenoptera: Apidae: Euglossini) communities in southern Mexico.

Abstract: With growing concern surrounding global pollinator declines, it is important to understand how habitat destruction and agricultural intensification impact pollinator communities. Euglossine bees are tropical forest-dependent pollinators responsible for pollination of both economically important crops and wild plant species. A growing body of work has focused on the effect of habitat fragmentation on euglossine bees, yet little is known about how these bees are impacted by agricultural intensification. Coffee cultivation is widespread in the tropics, and its management is conducted along a gradient of intensity, which ranges from monoculture (i.e., no shade, high inputs) to polyculture (shade overstory retained, fewer inputs). We used a landscape in Soconusco, Chiapas, Mexico, that allowed for comparison between monoculture and polyculture coffee farms, while holding distance to native habitat, as well as native habitat quality, constant. We found that habitat management influenced abundance, estimated richness, and community composition of euglossine bees. The polyculture coffee farm boasts a more similar community composition to the forest than to the monoculture coffee farm. In addition, the polyculture farm had almost double the euglossine abundance compared with the monoculture farm. Our results suggest that coffee management regimes may strongly impact euglossine communities and that less intensive polyculture approaches may mitigate species losses of this important group of pollinators.

Stocking densities and feeding strategies in shrimp and tilapia polyculture in tanks

Abstract: The objective of this work was to evaluate the performance of Pacific marine shrimp (Litopenaeus vannamei) and tilapia (Oreochromis niloticus), in a polyculture in tanks subjected to different stocking densities and feeding strategies, in comparison with monoculture. Two experiments were performed, at the same time, in a completely randomized design with three treatments and four replicates each. Treatments for experiment I were: monoculture with 10 shrimp per m2 (10S:0T); polyculture with 10 shrimp and 0.5 tilapia per m2 (10S:0.5T); and polyculture with 10 shrimp and 1 tilapia per m2 (10S:1T). Shrimp was the main crop, and feed was provided based on shrimp biomass. Treatments for experiment II were: monoculture with 2 tilapia per m2 (2T:0S); polyculture with 2 tilapia and 2.5 shrimp per m2 (2T:2.5S); and polyculture with 2 tilapia and 5 shrimp per m2 (2T:5S). Tilapia was the main crop, and feed was provided based on fish requirements. In the experiment I, tilapia introduction to shrimp culture resulted in lower shrimp growth and poor feed conversion rate. In experiment II, shrimp introduction to tilapia culture did not interfere with fish performance. Polyculture is more efficient with the combination of 2 tilapia and 2.5 or 5 shrimp per m2 and feed based on fish requirements.

Polyculture of Litopenaeus vannamei shrimp and Mugil platanus mullet in earthen ponds

Abstract: The objective of the present study was to evaluate the growth performance of the shrimp Litopenaeus vannamei and the mullet Mugil platanus in earthen ponds (200 m²) located in the Laboratory of Continental Aquaculture of Universidade Federal do Rio Grande (FURG), in both polyculture and monoculture systems. The study consisted of three replicates, as follows: shrimp monoculture (SM), shrimp and mullet polyculture (PO) and mullet monoculture (MM). The stocking density was 10 post-larvae shrimp (PL) m−2 and 0.67 mullet m−2. Fish and shrimp were fed commercial shrimp meal (38% crude protein) once a day. Initially, the amount of feed to shrimp was 20% of their total biomass which was later reduced to 5%. Mullets were fed at 5% of their stocked biomass. The experiment lasted 79 days during the summer of 2007/2008. At harvest, shrimp in monoculture had weight gain (15.59 g), specific growth rate (8.40% day−1), apparent feed conversion (0.88), survival (91%) and production (1.454 kg ha−1) significantly higher than in polyculture (1.039 kg ha−1). Mullets in polyculture had significantly better weight gain (42.72 g) and specific growth rate (3.99 % day−1) than those in monoculture (31.04 g and 3.69% day−1, respectively), while the mullet condition factor was significantly smaller in polyculture (1.06) than in monoculture (1.13). The apparent feed conversion of the mullets did not present significant differences between monoculture (2.50) and polyculture (2.40). The physical and chemical water parameters were not significantly different in any of the experiments, except for the transparency, which was higher in earthen ponds with mullet monoculture. Polyculture of shrimp and mullet reared together in earthen ponds negatively affects the shrimp production and favors the production of mullets.

Feasibility Study of Aquaponics in Polyculture Pond

Abstract: The study was conducted to see the feasibility of raft aquaponics in polyculture pond. Three experimental ponds (with an area of 5.2, 3.12 and 3.12 decimal) were selected where the third one was considered as control pond. Locally available cheap materials were used in preparing rafts, e.g., bamboo splits, iron wire, plastic thread and disposable plastic water bottle. Okra (Abelmoschus esculentus), water spinach (Ipomoea aquatica), pudina (Mentha arvensis), brinjal (Solanum melongena), tomato (Lycopersicon esculentum), giant taro (Alocasia macrorrhiza) and Indian spinach-red (Basella rubra) saplings were planted in the raft. Pond 1 and 2 were found to be covered with 4.12% and 2.56% with raft vegetable respectively. The percentage of specific growth rate (SGR) per day for Pangas (Pangasius hypophthalmus) was 2.57, 1.27 and 2.36 but it was found to be 0.822, 0.795 and 0.438 for Tilapia (Oreochromis mossambicus) in ponds 1, 2 and 3 respectively. For both fishes, the highest growth was found in pond 1. The production from each raft for pudina, water spinach and okra was about 266.7, 333.3 and 66.7 g respectively. Only pudina production was well enough to get benefit from raft vegetable culture and benefit-cost ratio of pudina production was about 7.82. In the study period giant taro showed good growth. Fruits and flowers were observed in Indian spinach-red and brinjal respectively at the end of the study period. Brinjal plants was affected by disease and tomato plants did not survive in the pond condition due to algae and other fouling clog on the roots which prevented nutrients up take from the pond water.

Method for freshwater fish polyculture through Chinese herbal medicine

Abstract: The invention discloses a method for freshwater fish polyculture through Chinese herbal medicine The method includes the steps of cleaning a pool, breeding fries outside freely, throwing bait for feeding fishes periodically, conducting water quality management and the like Through the method, the method for fish polyculture is green and environmentally friendly Due to the fact that Chinese herbal medicine composition contained in feed is mutually synergetic and complementary, the method has the effects of being resistant to microorganism, virus, parasite, and fungus, and improving immunity, and can effectively accelerate growth and development of fishes Meanwhile, the toxic and side effects of the Chinese herbal medicine are little, pollution to the environment is little, taste of fish flesh is not affected, and the method is suitable for feeding of chub, grass carp and crucian carp

Novel high-efficiency environment-friendly fish and shrimp polyculture feed

Abstract: The invention discloses a novel high-efficiency environment-friendly fish and shrimp polyculture feed, and aims to provide a fish and shrimp polyculture feed which is easy to prepare and is balanced in nutrition According to the technical scheme, the novel high-efficiency environment-friendly fish and shrimp polyculture feed comprises the following components: 7-24 percent of bean pulp, 3-8 percent of peanut pulp, 9-15 percent of cotton seed mill, 5-20 percent of rapeseed meal, 1-35 percent of cuttlefish paste, 12-17 percent of dried white vinasse, 6-8 percent of rice bran, 15-25 percent of flour, 05-15 percent of lecithin powder, 2-3 percent of monocalcium phosphate, 15-3 percent of bentonite, 003 percent of a mildew preventive, 003-005 percent of allicin, 02-03 percent of composite vitamin, 01 percent of choline chloride, 008 percent of potassium chloride, 002-005 percent of vitamin C, 01-03 percent of crystal lysine, 1-2 percent of beer yeast, 005-01 percent of shell element and 1-2 percent of composite mineral The novel high-efficiency environment-friendly fish and shrimp polyculture feed belongs to the technical field of fish feeds

Reed-fish-shrimp-crab ecological polyculture method for inland soda saline-alkaline reed swamps

Abstract: The invention provides a reed-fish-shrimp-crab ecological polyculture method for inland soda saline-alkaline reed swamps, which includes crab acclimation, stocking densities of fries, juvenile shrimps and juvenile crabs, culture management and catch and reed culture. After the method is adopted, the survival rate of acclimated crabs is 81.3 percent; the average stocking densities of river crabs, fishes and shrimps are 2138 river crabs/hm , 510 fishes/hm and 11750 shrimps/hm , the average catch weights of the river crabs, fishes and shrimps are 87.15kg/hm , 233.30kg/hm and 52.88kg/hm , the average catch specifications of the river crabs, fishes and shrimps are 145.2g per crab, 670.6g per fish and 5.3g per shrimp, the average recapture rates of the river crabs, fishes and shrimps are 26.83 percent, 69.45 percent and 83.63 percent, the average density of reed is increased by 9.69 percent, the average yield is increased by 12.47 percent, and the input-output ratio of the experimental area is 1:3.174.

The Effect of Stocking Different Ratios of Nile Tilapia Oreochromis niloticus, Striped Mullet Mugil cephalus, and Thinlip Grey Mullet Liza ramada in Polyculture Ponds on Biomass Yield, Feed Efficiency, and Production Economics

Abstract: A 180-d trial was done to evaluate the effect of stocking different ratios of Nile Tilapia Oreochromis niloticus, Striped Mullet Mugil cephalus, and Thinlip Grey Mullet Liza ramada on production and economic return in brackish-water ponds. The trial was conducted in twelve 3,000-m2 earthen ponds with four treatments (3 ponds/treatment): Nile Tilapia alone (100% Nile Tilapia, monoculture group [MG]); 75% Nile Tilapia and 25% Thinlip Grey Mullet (polyculture group 1 [PG1]); 75% Nile Tilapia, 12.5% Thinlip Grey Mullet, and 12.5% Striped Mullet (PG2); and 75% Nile Tilapia and 25% Striped Mullet (PG3). Fish were fed a commercial diet containing 25% crude protein twice per day. The efficiency of feed utilization was determined in terms of feed conversion ratio (FCR; feed intake/weight gain). Polyculture group 3 had the best FCR, whereas the FCR results did not differ significantly among the MG, PG1, and PG2 treatments. In addition, PG3 had the highest total yield (3,350.3 kg/pond), followed in descendi...

Impacts of Inclusion of Column Feeder Rohu (Labeo Rohita) at Different Stocking Densities on Growth and Production in Freshwater Prawn-Finfish Polyculture System

Abstract: Normal 0 false false false EN-US X-NONE BN-BD MicrosoftInternetExplorer4 An experiment was conducted to assess the impacts of inclusion of column feeder rohu ( Labeo rohita ) on growth and production in freshwater prawn-carp-mola polyculture system at the Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh for a period of 172 days (June - December, 2008). Four stocking densities of Rohu were maintained as 500, 1,000, 1,500 and 2,000 ha -1 in treatment R 500 , R 1000 , R 1500 and R 2000 , respectively in triplicates. All ponds each 120 m 2 were stocked with juvenile freshwater prawn ( Macrobrachium rosenbergii ), silver carp ( Hypophthalmichthys molitrix ), catla ( Catla catla ) and small fish mola ( Amblypharyngodon mola ) at the fixed stocking densities of 20,000, 1,500 , 1,000 and 20,000 ha -1 , respectively. Prawns were fed with pelleted feed twice daily started initially with 10% and gradually reduced to 3% of body weight and continued throughout the study period. All fish were fed with mixture of soaked rice bran and mustard oilcake (2:1) at the rate of 3% of the body weight daily. All the water quality parameters such as temperature, transparency, pH, dissolved oxygen, total alkalinity, NH 3 -N, NO 2 -N, NO 3 -N, PO 4 -P and chlorophyll- a did not differed significantly (>0.05) among the treatments. The survival rate, mean individual weight and production of prawn were decreased with increasing density of rohu. Therefore, the density of rohu significantly (P<0.05) influenced the growth and production of freshwater prawn. Catla and Mola production were affected adversely with increasing rohu density. The production of rohu increased with increasing density although the individual weight decreased. The combined production of all finfish was significantly lower in R 0 whereas, the combined production of all species including prawn did not differ significantly (P<0.05) among the treatments. The treatments R 0 and R 500 fetched higher net profit without significant difference between them. Therefore, inclusion of rohu at a density of 500 ha -1 may be recommended for prawn-carp-mola polyculture.

Polyculture of seabass with tilapia for the utilization of brown fields in the coastal areas of Cox's Bazar, Bangladesh

Abstract: Disease outbreak in shrimp culture sector has abandoned the vast coastal areas of Bangladesh. These abandoned areas treated as ‘brown fields’ could be utilized for finfish culture using low cost inputs. This type of culture practice has the potential to be successful in the coastal waters due to having seasonally fluctuating salinity of 0 to 15 ppt. The present study was conducted to determine the growth and survival of seabass (Lates calcarifer) and tilapia (Oreochromis niloticus) using different stocking ratios without giving any supplementary feed to seabass. Tilapia was stocked at 1 individual/m2. Tilapia fry was expected to provide food for seabass in the selected culture ponds. The stocking ratio of tilapia and seabass were 4:1, 5:1 and 6:1 in ponds with three replicates for each treatment. During 3 months culture period, the highest harvest weight of seabass and tilapia was recorded as 74.3 and 49.1 g/m2, respectively and the highest survival rate of seabass and tilapia was recorded as 78.3 and 61.9%, respectively. The highest growth rate of seabass was recorded as 14.67 g/day and the highest biomass of seabass and tilapia (collectively) was found as 116.9 g/m2. The present study reveals that seabass-tilapia polyculture may be a good solution to utilize the coastal brown fields of Cox’s Bazar, Bangladesh. Key words: Polyculture, seabass (Lates calcarifer), tilapia (Oreochromis niloticus), brown fields.

Productivity of polycultured nile tilapia (Oreochromis niloticus) and pacific white shrimp (Litopenaeus vannamei) in a recirculating system

Abstract: Two experiments were conducted in the Environmental Research Laboratory of the University of Arizona in Tucson, AZ, USA, to evaluate the production of Pacific white shrimp (Litopenaeus vannamei) and Nile tilapia (Oreochromis niloticus) in recirculating polyculture and monoculture systems. The experiments were conducted for six weeks in twenty and sixteen 200-l fiberglass tanks, respectively, at a salinity of 10 ppt. In the first experiment, tilapia were fed pelleted feed at 3%, 2.25%, or 1.5% of their body weight. In the second experiment, tilapia were stocked at 12, 8, or 4 fish/cage, submerged in the shrimp tanks. In general, total production of fish and shrimp was higher in polyculture than in monoculture. The better growth of shrimp in polyculture appears to be because shrimp were able to utilize waste from the tilapia. In experiment 1, shrimp growth did not significantly differ between treatments (p>0.05) but tilapia growth was rapid, with significant differences between treatments; higher feeding rates produced higher biomasses. In experiment 2, growth significantly differed between shrimp grown in polyculture with 12 fish/cage and shrimp grown in monoculture. Final mean shrimp weights averaged 10.83±0.97, 10.37±0.96, and 10.20±0.94 g in polyculture, but only 9.85±0.73 in monoculture while tilapia growth did not significantly differ between treatments. This study shows that adding Nile tilapia to shrimp tanks at suitable stocking densities and appropriate feeding rates produces positive interactions. The IJA appears exclusively as a peer-reviewed on-line open-access journal at http://www.siamb.org.il. To read papers free of charge, please register online at registration form. Sale of IJA papers is strictly forbidden. Sale of IJA papers is strictly forbidden. 2 Hernández-Barraza et al. Introduction Polyculture of tilapia together with shrimp increases shrimp production (Mires, 1987; Akiyama and Anggawati, 1999). In most extensive, semi-intensive, and intensive shrimp/tilapia polyculture systems, shrimp is the major species and tilapia is the secondary species (Gonzales-Corre, 1988; Akiyama and Anggawati, 1999; Saelee, 2002) but, in some cases, tilapia is the major cultured species and prawns are secondary (Mires, 1987; Thien et al., 2004). In either case, polyculture systems produce better results than shrimp monoculture in terms of water quality, yield, and profitability. The addition of Nile tilapia to shrimp ponds can improve water quality, feed utilization efficiency, economic returns, and environmental pollution (Yuan et al., 2010) and also creates a sustainable aquaculture system (Fitzsimmons, 2001). Tilapia are among the most widely cultured fishes due to their general hardiness, ease of breeding, rapid growth, tolerance to a wide range of environmental conditions, adaptation to fresh and brackish water environments, resistance to disease, ability to efficiently convert organic and domestic wastes into high quality protein, amenability to handling and captivity, and tasty flavor (Stickney et al., 1979; Balarin and Haller, 1982; Suresh and Lin, 1992). Tilapias are ideal species for polyculture (Hepher and Pruginin, 1981; Yakupitigage et al., 1991). Recirculating aquaculture systems are the most sustainable type of aquaculture production system, particularly because of their ability to reduce water and land use and allow environmentally safe waste management treatment (Mozes et al., 2003; Timmons and Ebeling, 2007). However, fish cultured in recirculating aquaculture systems grow less compared to fish cultured in flow-through systems, e.g., sea bass Dicentrarchus labrax (Deviller et al., 2005). The accumulation of substances from the biofilter (e.g., bacteria metabolites) and/or the fish (e.g., alarm pheromones, cortisol) and/or the feed (e.g., heavy metals) may be responsible for such growth retardation (Martins et al., 2007, 2009ab). This study evaluates recirculating systems designed around principles that have proven beneficial in extensive polyculture. To this end, we compared the performance of recirculation systems in the co-production of shrimp (Litopenaeus vannamei) and Nile tilapia (Oreochromis niloticus). Materials and Methods Tanks and animals. The experiments were conducted in round 200-l fiberglass tanks under plastic greenhouse roofing. Each tank was equipped with air stone diffusion. One air blower (2 hp) supplied air for all tanks. PVC pipes (5 cm diameter) with twenty 1.5 mm (diameter) holes every 40 cm were connected to the outlet of the air blower and extended along the tanks. Ten days before the beginning of the experiments, the tanks were filled with saline water at 10 ppt and the system was monitored. Juvenile Pacific white shrimp (L. vannamei) were supplied by Shrimp Improvement Systems, Inc. (Biotechnology industry), Miami, FL; tilapia (O. niloticus) were taken from existing stocks of the Environmental Research Lab, University of Arizona, Tucson. Fish and shrimp were fed commercial pellets for one week of acclimation. Then, fish and shrimp appearing in good health were selected for the experiment. Experimental design. In the first experiment, shrimp and fish were randomly distributed into 20 tanks (four replicates of five treatments) and cultured for six weeks. The first twelve tanks had tilapia and shrimp, together, while the other eight tanks had only shrimp or fish (four monoculture tanks for each species). Shrimp (5.24±1 g) were stocked at 50 individuals/m and fish (50.4±1 g) at 33.4 individuals/m. Shrimp were fed food pellets at 6% of their body weight. Fish were fed 3%, 2.25%, or 1.5% of their body weight in the polyculture tanks and 3% in the monoculture tanks. In the second experiment, shrimp and fish were randomly distributed into 16 tanks (four replicates of four treatments); three treatments for polyculture and one for shrimp monoculture. Shrimp (2.45±0.53 g) were stocked at 10 individuals/tank and fish (22.31±3 g) at 12, 8, or 4 fish/tank. The fish were placed in cages and the cages were submerged in the shrimp tanks. Productivity of Nile tilapia and Pacific white shrimp polyculture 3 In both experiments, shrimp and fish were fed sinking and floating feeds once a day. The tilapia were fed a commercial extruded feed with 35% crude protein (Ace Hi Feeds Starling, CA) at 3% of their body weight. The shrimp were fed a commercial pellet with 35% crude protein (Rangen Company, ID) at 6% of their body weight. Water parameters were within ranges considered optimal for shrimp and tilapia growth. Salinity was maintained at 10.0 ppt, mean dissolved oxygen was 7.7 mg/l, and pH was 7.6 ppt. Average weekly water temperatures ranged 28.1-28.9°C, NH3-N ranged 0.001-0.007 mg/l, NO2-N ranged 0.02-0.04 mg/l, NO3-N ranged 0.147-0.186 mg/l, and TAN rose from 0.12 mg/l in week 1 to 0.33-0.44 mg/l in the following weeks. The water flow rate was 38 ml/s in both experiments. Growth and yield. Fish and shrimp were collected every two weeks with a small fish net for measurement and feed adjustment. In the first experiment, shrimp were not fed prior to weighing to reduce stress. Fish and shrimp were individually weighed and immediately returned to the water. The total fish and shrimp weight of each pond was determined by multiplying the individual weight by the total number of fish or shrimp. At the end of the experiment, all fish and shrimp were harvested, the total number and weight of both species were determined, and the survival rate and yield were calculated. The feed conversion ratio (FCR) was calculated as feed fed/wt gain (Tidwell et al., 1999). Differences in growth were evaluated using one-way ANOVA and Bonferroni test for post hoc analysis. Results There were no significant differences between treatments in weights of shrimp at the end of experiment 1 (Table 1). FCR of shrimp was lower in the polyculture treatments with tilapia feeding rates of 3% or 2.25% than in the 1.5% treatment or in monoculture (F3, 12 = 93.9, p<0.0001). The final weight of the monocultured fish was significantly less than in the polyculture treatment where fish were also fed 3% (F3, 95 = 459.9, p<0.0001). Average production of shrimp and fish in polyculture with a tilapia feeding rate of 3% was 116.9 g and 614.7 g/tank, respectively, while in monoculture average production was 109.2 and 589.1 g/tank, respectively. In experiment 2, the mean weight of shrimp at the end of the experiment was highest in the polyculture treatment with the highest tilapia density (12 fish/tank) and lowest in the monoculture treatment (Table 2). Shrimp grew significantly faster in polyculture than in monoculture (F3, 156 = 8.06, p<0.0001) and shrimp FCR was lower in polyculture than in the monoculture (F3, 12 =14, p<0.0003). Survival of both species in both experiments was 100%. Table 1. Growth performance of monocultured and polycultured shrimp and tilapia fed at different rates in closed recirculation systems (means±SD). Polyculture (tilapia feeding rate; % body weight) Monoculture

Pond efficient ecological polyculture method suitable for grass carps, chubs, bighead carps, paddlefish and crucian carps

Abstract: The invention belongs to the field of pond culture, and relates to a pond efficient ecological polyculture method suitable for grass carps, chubs, bighead carps, paddlefish and crucian carps. The method comprises the steps of: 1) filling fresh water after 1 week after preparation and disinfection of a pond and carrying out probationary culture of chub till the chub survives; 2) stocking 150g of grass carp, 100g of chub, 100g of bighead carp, 150g of paddlefish and 60g of crucian carp at one time, wherein the polyculture proportion is that grass carps account for 75%, chubs account for 8%, bighead carps account for 6%, paddlefish account for 6% and crucian carps account for 5%, and the average culture density is 3/sq.cm; 3) feeding twice a day, wherein the total feeding weight per day accounts for 5% of total weight of grass carps in the pond, the feed is polyculture fish seed particle matched feed, and the time of manual feeding begins from the time when the fish seeds are cast to 210 days; 4) adding 20cm of fresh water into the pond every week; maintaining the water quality at pH 7.5-8.5, temperature at 20.0-31.0 DEG C, nonionic ammonia smaller than or equal to 0.02mg/L, total alkalinity 1.00-2.00mmol/L, dissolved oxygen greater than or equal to 5.0mg/L, transparency 28-32cm, chemical oxygen consumption smaller than or equal to 15mg/L, biochemical oxygen demand smaller than or equal to 5mg/L and total escherichia coli smaller than 5000/L for 210 days. The average fish yield in the middle and lower reaches of the Yangtze River can reach 1000kg/667 sq.cm.

Carbon footprint of aquaculture in eastern India

Abstract: The present study was conducted to determine the carbon (C) footprint of different aquaculture production systems in India. The total input (kg CE/ha) in different cultures, respectively, was 1,811 to 4,144 for scampi, 4,417 to 5,913 for polyculture, 4,090 to 8,873 for shrimp and 2,417 to 2,786 for carp. Of the total inputs, feed accounts for around 90% of carbon equivalent (CE), in all cultures. The output in different cultures, expressed on live weight basis (kg/ha) and on input basis (kg/kg), respectively, was 1,280 to 3,288 and 0.71 to 0.79 for scampi culture, 4,639 to 5,998 and 1.00 to 1.05 for polyculture, 2,130 to 5,436 and 0.52 to 0.61 for shrimp culture, 4,100 to 4,160 and 1.49 to 1.70 for carp culture. On the basis of output:input ratio, the carp (three species of Indian major carp) culture is more sustainable followed by polyculture (carp with scampi), scampi and shrimp culture, respectively.

Study on Nitrogen and Phosphorus Budget in Polyculture Systems of Litopenaeus vannamei and Portunus trituberculatus

Abstract: Nitrogen(N)and phosphorus(P)budget in different polyculture systems of Portunus trituberculatus with Litopenaeus vannamei were studied.The polyculture systems were established as enclosures in seawater ponds.The results showed that the feed was the main nitrogen and phosphorus input,accounting for 79.77%~91.53%and 94.31%~98.43%,respectively;while that contributed by seawater accounted for 7.06%~16.22%and 1.12%~4.53%input of nitrogen and phosphorus,respectively.The major nitrogen and phosphorus output came from sediments,which accounted for 40.29%~65.89% and76.11%~86.54% of total of total nitrogen and phosphorus output,respectively.The biomass harvested removed away 8.7%~24.44%and 14.11%~18.90%of total nitrogen and phosphorus input,respectively.The utilization efficiency of nitrogen in polyculture systems was higher than monoculture systems.The polyculture system yielding the best culturing benefit was consisted of at 6crabs/m2and 45shrimps/m2.

Impacts of inclusion of column feeder rohu (Labeo rohita) at different stocking densities on growth, production and environment in freshwater prawn-carp-mola polyculture system

Abstract: The research investigated the impacts of inclusion of column feeder rohu (Labeo rohita) on growth and production in freshwater prawn-carp-mola polyculture system for a period of 172 days. Four stocking densities of Rohu were maintained as 500, 1,000, 1,500 and 2,000 ha -1 in treatment R500, R1000, R1500 and R2000, respectively in triplicates. All ponds each 120 m 2 were stocked with juvenile freshwater prawn (Macrobrachium rosenbergii), silver carp (Hypophthalmichthys molitrix), catla (Catla catla) and small fish mola (Amblypharyngodon mola) at the fixed stocking densities of 20,000, 1,500, 1,000 and 20,000 ha -1 , respectively. Prawns were fed with pelleted feed twice daily started with 10% and gradually reduced to 3% of body weight and continued throughout the study period. All fish were fed with mixture of soaked rice bran and mustard oilcake (2:1) at the rate of 3% of the body weight daily. All the water quality parameters and chlorophyll-a were measured. The density of rohu significantly (P<0.05) influenced the survival rate, growth and production of freshwater prawn. Catla and Mola production were affected adversely with increasing rohu density. The production of rohu increased with increasing density although the individual weight decreased. The combined production of all finfish was significantly lower in R0 whereas, the combined production of all species including prawn did not differ significantly (P<0.05) among the treatments. The treatments R0 and R500 fetched higher net profit without significant difference between them. Therefore, inclusion of rohu at a density of 500 ha -1 may be recommended for prawn-carp-mola polyculture.

A preliminary assay on the mixed culture of red Florida tilapia and freshwater prawn Macrobrachium americanum stocked in outdoor tanks at different tilapia densities

Abstract: 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 m 2 ; 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 m 2 ) and tilapia (4/0, 9/0 and 14/0 m 2 ) 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.

Effect of varying stocking density of bottom feeder fish Cirrhinus mrigala and Cyprinus carpio on growth performance and fish yield in polyculture system

Abstract: The present project was planned to study gradual replacement of Cirrhinus mrigala with Cyprinus carpio and its impact on pond ecosystem. A total of 900 fishes belonging to six species viz. Catla catla, Labeo rohita, Cirrhinus mrigala, Ctenopharyngodon idella, Hypophythylmichthys molitrix and Cyprinus carpio were stocked in four earthen ponds. The dimensions of each pond were 220 × 198 × 7 feet length, breadth and depth. The stocking density in pond 1 (T1) was C. catla 150, L. rohita 200, C. mrigala 200, C. idella 150, H. molitrix 150 and C. carpio 50. The stocking density of C. mrigala and C. carpio in pond 2 (T2) was 150 and 100, in pond 3 (T3), 100 and 150 and in pond 4 (T4) it was 50 and 200, respectively while the stocking density of all the other four fish species remained constant in all the four ponds. All the fish were fed with a diet of 25.16% crude protein at 2% body weight. C. idella and C. mrigala showed maximum growth in T1, C. catla and H. molitrix in T2, L. rohita and C. carpio in T3. Maximum growth was observed in T3 followed by T4, T1 and T2. Among fish species C. idella and C. carpio showed higher growth rates than the rest of fish species. Our results reveal that in polyculture system stocking density of C. mrigala and C. carpio in a ratio of 1: 1.5 gives better results. Key words: Aquaculture, freshwater, phytoplankton, zooplankton, exotic fish.

Methane formation in soil–plant systems treating wastewater as influenced by microbial populations

Abstract: The present study evaluated the effect of plant species on methane (CH4) emission and microbial populations in three types of soil–plant systems. Results showed large variation of CH4 flux rate ranging from 1.35 to 212.61 mg CH4 m−2 h−1. Emission peak of CH4 occurred in July. No significant difference was found in the non-vegetation system spanning 2 years. Compared with non-vegetation, vegetation systems had much higher flux of CH4, and obvious seasonal variation was observed. The polyculture system planted with Zizania latifolia (Z. latifolia) and Phragmites australis (P. australis) released higher CH4 fluxes than the mono system (P. australis), reflecting that Z. latifolia growth could simulate CH4 emission. The fluorescence in situ hybridization (FISH) results support the characteristics of CH4 fluxes. Much higher methanotrophs amount and lower methanogens amount from the mono system than those from the polyculture system was observed indicating that Z. latifolia growth may limit the oxygen transportation resulting in higher CH4 emission. The polyculture system has the highest potential of CH4 emission.

Effect of paclobutrazol on three different aquatic macrophytes under in vitro monoculture or polyculture conditions

Abstract: Three aquatic plants, coontail (Ceratophyllum demersum L.), hydrilla [Hydrilla verticillata (L. f.) Royle] and giant duckweed [Spirodela polyrhiza (L.) Schleiden], were successfully surface sterilized and cultured on liquid basal MS (Murashige and Skoog, 1962) medium under aseptic conditions. Shoot explants obtained from these plants were transferred to basal MS medium supplemented with 0, 0.25 and 0.5 mg/l paclobutrazol (PBZ) under in vitro monoculture or polyculture conditions. There were some differences in the patterns of fresh weight increases of the three aquatic plants under monoculture and polyculture conditions. Among the three macrophytes studied, coontail was the most sensitive to 0.25 or 0.5 mg/l PBZ as its fresh weights did not increase at these PBZ concentrations during eight weeks under both monoculture and polyculture conditions. Giant duckweed were relatively more sensitive than hydrilla in response to addition of PBZ to the growth medium under both monoculture or polyculture conditions suggesting that PBZ might not be an effective aquatic pest control agent for hydrilla. The dominance of giant duckweed over hydrilla was effectively overturned with the addition of 0.5 mg/l PBZ to the polyculture medium.

Polyculture feed for eel fries and loach fries

Abstract: The invention discloses a polyculture feed for eel fries and loach fries. The polyculture feed comprises the following components in parts by weight: 7-9 parts of fish meal, 3-4 parts of soybean meal, 2-5 parts of corn meal, 1-2 parts of manure and 0-1 part of earthworm. The feed disclosed by the invention is designed against fry varieties, combined with a modern feed processing technology and matched with the decomposed manure and earthworms, and then the fries of eels and loaches can be simultaneously fed; and according to statistics, the feed disclosed by the invention is utilized for feeding under polyculture, the growth speed of the eels is increased by 15% in comparison with that by adopting the traditional feed, the body weight gain is 5.5%, and the growth speed of the loaches is increased by 12% in comparison with that by adopting the traditional feed.

IMPACT OF SOME TECHNOLOGICAL FACTORS ON THE GROWTH OF CARP FISH (CyPRINIdAE) REAREd IN AUTOCHTHONOUS POLyCULTURE

Abstract: NIKOLOVA, L., 2013. Impact of some technological factors on the growth of carp fish (Cyprinidae) reared in autochthonous polyculture. Bulg. J. Agric. Sci., 19: 1391-1395 The study was conducted in two consecutive years in the Fisheries and Aquaculture Institute – Plovdiv. For the needs of ecologo- and bio-friendly fish farming, the impact of some factors on the growth of carp fish reared in polyculture, based on a natural nutritive basis, have been investigated. Rearing in autochthonous polyculture led to satisfactorily fish growth. The polyculture structure is a significant source of common carp growth variation, as the impact decreases when taking into ac count intense vegetation in the pond, and increases when taking into account the size of the pond. Common carp had better growth in one-year polyculture. The polyculture structure had no impact on bighead carp growth. One-year old grass carp grew more intensively compared to two-year old grass carp. Fertilization is a significant source for growth variation, but the impact is specific for the different species. Positive effect of the factor is established only for bighead carp. Significant sources for growth variation in all studied species are pond size and macrophytes density level.

Evaluating Monoculture Versus Polyculture Planting Regimes in a Newly-Restored Southern California Salt Marsh

Abstract: Salt marsh plants are a key source of primary productivity, ameliorate harsh abiotic conditions, and provide habitat structure to many organisms. As a consequence, rapid re-establishment of plant cover following restoration can speed the recovery of degraded ecosystems. Despite demonstrated positive relationships between plant biodiversity and ecosystem functions, many salt marsh restoration plans still incorporate single-species plantings under the belief that this approach will lead to faster increases in plant cover (a typical management goal). In this study, we evaluated post-restoration recovery of a non-vegetated high marsh berm in Brookhurst Marsh, Huntington Beach, CA, with two active planting strategies: monoculture plots of the competitive dominant Sarcocornia pacifica (pickleweed) versus polyculture plots of pickleweed and eight other common salt marsh plant species. Although monocultures did increase in total percent plant cover faster than polycultures, both treatments had reached 80...