p s d i r aquaculture crsp 22nd annual...

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AQUACULTURE CRSP 22ND ANNUAL TECHNICAL REPORT

PRODUCTION SYSTEM DESIGN AND INTEGRATION RESEARCH 63

NEW PARADIGM IN FARMING OF FRESHWATER PRAWN (MACROBRACHIUM ROSENBERGII) WITH CLOSED AND RECYCLE SYSTEMS

Eleventh Work Plan, Production System Design and Integration Research 2 (11PSDR2)

Final Report

Yuan Derun and Yang YiAquaculture and Aquatic Resources Management

School of Environment, Resources and DevelopmentAsian Institute of Technology

Pathumthani, Thailand

James S. Diana and C. Kwei LinSchool of Natural Resources and Environment

University of MichiganAnn Arbor, Michigan

Printed as Submitted

ABSTRACT

An experiment was conducted in 15 cement tanks (2 x 2.5 x 1m) at the Asian Institute of Technology, Thailand, during 5 January–12 May 2004, to develop closed and recycle systems for culture of giant freshwater prawn (Macrobrachium rosenbergii). Juvenile prawns were cultured in three systems as three treatments, each in triplicate: (A) open system with water exchange, (B) closed system with aeration, and (C) recycle system, in which water from a prawn tank was circulated through a Nile tilapia (Oreochromis niloticus) tank to a water mimosa (Neptunia oleracea) tank and back to the prawn tank. Prawn juveniles of 2.8 g were stocked in all prawn tanks at an average density of 19 prawns m-2, sex-re-versed Nile tilapia of 10.6 g were stocked in tilapia tanks at 2 fish m-2, and water mimosa seedlings at 0.4 kg m-2 were planted in mimosa tanks. Prawns were fed ad libitum two times daily.

Survival of prawns, ranging from 40.64% to 88.72%, was highest in the closed system, intermediate in the recycle system, and lowest in the open system (P < 0.05). There were also mass mortalities in one open and one recycle tank. Growth of prawns was not significantly different among all three systems (P > 0.05), while gross and net yields of prawn were significantly lower in the open system than in closed and recycle systems (P < 0.05). Feed conversion ratio (FCR) in the open system was 2.81, which was significantly higher than in the closed (1.67) and recycle (1.78) systems (P < 0.05). Prawn recovered 12.02% N and 7.01% P from feed and fertilizer in the open system, and 25.26% N and 13.67% P in the closed system. Prawn, tilapia, and water mimosa together recovered 39.55% N and 25.53% P in the recycle system. Economic analyses showed that there were no significant differences in net returns among the three systems.

The present study demonstrated that the closed and recycle systems are more environmentally friendly and have good profit potential compared to the open system. Further study is needed to determine appropriate ratio of culture area for prawn, tilapia, and mimosa to minimize environmental pollution, optimize production and maximize profits in the recycle system.

INTRODUCTION

The giant freshwater prawn (Macrobrachium rosenbergii) is indigenous to most Southeast Asian and South Pacific countries as well as Northern Oceania and Western Pa-cific islands (New, 1982; New, 2002). Since its successful domestication in the late 1960s (Ling, 1969), giant fresh-water prawn has attracted attention of aquaculturists

throughout the world and become a commonly cultured crustacean species because of its high market demand, wide scope of culture in freshwater ecosystem, success-ful hatchery production of post larvae and juveniles, and its suitability for culture in both large- and small-scale commercial farming (New, 1990; ADB/NACA, 1998; Shaha et al., 1999; New, 2000).

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AQUACULTURE CRSP 22ND ANNUAL TECHNICAL REPORT

PRODUCTION SYSTEM DESIGN AND INTEGRATION RESEARCH 63

Culture of giant freshwater prawn has gained great popularity, mostly in tropical and sub-tropical coun-tries, with limited production in temperate regions such as North America (D’Abramo et al., 1991). In recent years, the global production of freshwater prawns has increased steadily (FAO, 2004) with the major produc-tion in East, South, and Southeast Asian countries such as China, Bangladesh, India, Indonesia, Thailand, and Philippines. In 1998, Asian countries produced 127,627 metric tons, accounting for 98% of the global production (New, 2000).

A number of production systems for giant freshwater prawn have been developed, including primarily pond, pen, and rice field culture. Despite the expansion of prawn culture for several decades, few changes have taken place in culture technologies. The prawn is most commonly cultured in semi-intensive culture system in ponds (Lee and Wickins, 1992; D’Abramo and New, 2000). On average, annual prawn production may reach 2,000 kg ha-1 year-1, but varies greatly from less than 500 to 5,000 kg ha-1 year-1 based on intensity of culture (Lee and Wickins, 1992; Valenti and New, 2000). Intensive sys-tems are also popular in some countries, such as Thai-land. In intensive culture prawns are fed a formulated, protein-rich diet, and, as a result, pond water quality deteriorates rapidly. Mechanical aeration is rarely used in prawn ponds. Frequent exchange of pond water with external water is required to maintain acceptable wa-ter quality for prawn culture. Currently, prawn farms discharge effluents rich in nutrient and organic matter to public waterways, resulting in eutrophication of receiv-ing waters and profuse growth of aquatic weeds. This constrains use of receiving waters for other purposes, even prawn culture. In Thailand, for instance, most prawn farms are located along irrigation canals that sup-ply water to and receive discharge from ponds. Canals serve multiple users, and are often contaminated with domestic and agricultural wastes. Prawn culture tech-nologies need to be improved to mitigate these adverse environmental impacts.

Closed systems with little or zero water exchange using monoculture or integrated culture with other aquatic species such as tilapia (Oreochromis spp.) and seaweeds have proven to be better alternatives to open systems and have been successfully practiced at a commercial scale in marine shrimp culture (Lin, 1995; McIntosh et al., 1999; Burford et al., 2003). The advantage of a closed system is its isolation from the surrounding environ-ment, causing less pollution and less chance of intro-ducing external pathogens and pollutants into culture ponds. Wastewater from intensive fish culture can pro-duce phytoplankton to support Nile tilapia (Oreochro-mis niloticus) culture (Lin, 1990; Lin and Diana, 1995; Yi and Lin, 2001). Water mimosa (Neptunia oleracea) is widely cultivated in fertilized tanks and ponds, and har-vested for human consumption in the region. Its prolific

regeneration, rapid growth, and relatively high market price give it good economic potential as a polyculture species to reduce nutrients in closed systems for prawn culture.

The purpose of this study was to investigate a closed prawn monoculture system with aeration and a recycle system with integrated culture of prawn, Nile tilapia and water mimosa. Such diversification and integration is regarded as important practice to enhance sustain-able aquaculture (Adler et al., 1996; Pillay, 1996). Specific objectives were:

1) To develop closed and recycle systems for prawn culture; and

2) To assess economic and environmental impacts of those new systems

METHODS AND MATERIALS

This experiment was conducted in 15 cement tanks (2.5 x 2.0 x 1.0 m) at the Asian Institute of Technology (AIT), Thailand, for 128 days from 5 January–12 May 2004. Juvenile prawns were cultured under three treatments with three replicates each: (A) an open system with wa-ter exchange, (B) a closed system with aeration, and (C) a recycle system in which water from a prawn tank was circulated through a Nile tilapia tank to a water mimosa tank then back to the prawn tank.

Prior to the experiment, all tanks were completely drained and dried for two weeks. The bottoms of tanks were covered with 5.0 cm of soil collected from an earthen pond. The tanks were filled with the water to 1 m depth. Prior to stocking prawns, all tanks were fertil-ized weekly with urea and triple super phosphate (TSP) at rates of 28 kg N and 7 kg P ha-1 week-1 for two weeks.

Juvenile prawns were procured from a local prawn farm. Three batches of prawns were randomly sampled, bulk weighed, and counted to determine mean indi-vidual weight. Prawn juveniles, mean weight 2.8 g, were stocked at a total weight of 264.2 ± 1.3 g in each tank, giving an average stocking density of 19 ± 0.1 prawns m-2. In the recycle system, sex-reversed Nile tilapia, mean weight 10.6 g, were stocked in tilapia tanks at a density of 2 fish m-2, while water mimosa purchased from a local market was placed into water mimosa tanks at 2 kg tank-1 after trimming. During the experiment, no sampling of prawns or tilapia was done, while mimosa was partially harvested periodically to thin plant biomass for better growth.

All tanks in the closed system were provided with con-tinuous aeration using four air stones, 2” in diameter, hung at the middle depth of water. An air compressor (1 HP, 380 Volt, 3-phase) was connected to the air stones through PVC pipes.

TWENTY-SECOND ANNUAL TECHNICAL REPORT64 PRODUCTION SYSTEM DESIGN AND INTEGRATION RESEARCH 65

Water level in all tanks was maintained at 1 m through-out the experimental period. In the closed and recycle systems, water loss by evaporation was replaced weekly. In the open system, tank water was exchanged at rates of 10%, 20%, 30%, and 40% per week in the first two months, third, fourth, and fifth month, respectively. Water was exchanged once a week in the first four months and twice a week during the last month of the experiment. Water recirculation in the recycle system was achieved using siphoning pipes from prawn tanks through tilapia tanks to mimosa tanks and using a 2” submersible pump from mimosa tanks back to prawn tanks. Pelleted prawn feed (Charoen Pokaphand Foods Public Co. Ltd, Thailand) was used in this experiment. Small-size feed (40% crude protein) was used during the first month, with medium-size feed (30% crude protein) used during the rest of the experimental period. Prawns were fed ad libitum two times daily at 0730–0830 h and 1600–1700 h. One feeding tray (60 x 60 x 7 cm) was set in each tank. Feed was placed on the feeding trays, and the food remaining on the trays was determined two hours later. The ration was subsequently adjusted for the next feeding period.

Dissolved oxygen (DO), pH, and temperature were measured weekly at 0900 h from three water depths (10 cm and 40 cm below the surface and 10 cm above the bottom) with a DO meter (Model HI 9142, HANNA Instruments, Thailand) and a pH meter (Model HI 8424, HANNA Instruments, Thailand), respectively. DO and temperature were also measured biweekly at 1800, 0600, and 1800 h on consecutive days. Water samples were collected biweekly at 0900 h using a column sampler for analyses of total alkalinity, total ammonia nitrogen (TAN), nitrate nitrogen (NO3-N), nitrite nitrogen (NO2-N), total Kjeldahl nitrogen (TKN), total phosphorous (TP), soluble reactive phosphorous (SRP), total suspend-ed solids (TSS), total volatile solids (TVS), and chloro-phyll a (APHA et al., 1998).

Nutrient budgets for nitrogen and phosphorus were calculated based on inputs from fertilizers, feed, water, stocked prawns, tilapia and mimosa, and outputs from discharged or exchanged water, harvested prawns, tilapia, and mimosa. Three soil samples were collected at the beginning of the experiment after soil mass was thor-oughly mixed before dispersal into each tank. At the end of the experiment, soil samples were collected by remov-ing five cores of soil from each tank and mixing them into one composite sample. Bulk density, moisture, TN, and TP contents were determined. Moisture, TN, and TP contents in feed, prawns, tilapia, and mimosa were also analyzed at the beginning and end of the experiment fol-lowing the methods described by Yoshida et al. (1976).

An analysis was conducted to determine economic returns of the three prawn culture systems (Shang, 1990). The anal-ysis was based on farm-gate prices for harvested prawns, tilapia, and water mimosa and current local market prices for all other items in Thailand expressed in US dollars (US$1 = 40 baht). Farm-gate price for harvested prawns (30 g size) was fixed at US$3.75 kg-1, for tilapia at US$0.5 kg-1, and for water mimosa at US$0.125 kg-1. Market prices for prawn juveniles (US$7.5 kg-1), tilapia fingerlings (US$0.025 piece-1), prawn feed (US$0.75 kg-1), urea (US$0.187 kg-1), TSP (US$0.312 kg-1), and electricity (US$0.06 kwh-1) were applied to the analysis. The calculation for cost of work-ing capital was based on an annual interest rate of 8%. The profitability for different treatments was compared in terms of total variable cost (including cost of prawn juveniles, tilapia fingerlings, mimosa seedlings, feed, urea, TSP, electricity and cost of working capital), gross revenue (from selling prawns, tilapia and water mimosa), and net return (gross revenue-total variable cost).

Data were analyzed statistically by analysis of variance (Steele and Torrie, 1980) using SPSS (version 11.0) statistic software package (SPSS Inc., Chicago, USA). Differences were considered significant at an alpha level of 0.05. Means were given with ± standard error (S.E.).

RESULTS

Survival of prawns, ranging from 40.64% to 88.72%, differed significantly among treatments and was highest in the closed system, intermediate in the recycle system, and lowest in the open system (P < 0.05; Table 1). Mass mortality occurred in one tank of the open system, while low survival occurred in the other two tanks. Mass mortality also occurred in one tank of the recycle system. Growth of prawns was not significantly different among treatments (P > 0.05), while production performance of prawn (final harvested biomass, extrapolated gross and net yields) was significantly lower in the open system than in closed and recycle systems (P < 0.05), which were not significantly different (Table 1). Feed conver-sion ratio (FCR) in the open system was 2.81, which was significantly higher than in the closed or recycle system (P < 0.05), while there was no significant difference be-tween the latter two (Table 1).

In the recycle system, mean weight of Nile tilapia was 97.3 g at harvest, giving daily weight gain of 0.68 g fish-1. Extrapolated annual gross and net yields of tilapia were 4,410 and 3,773 kg ha-1 year-1, respectively (Table 1). Ex-trapolated annual gross and net yields of water mimosa reached 33,630 and 21,630 kg ha-1 year-1, respectively (Table 1).

Final values for all measured water quality parameters except for DO at dusk were not significantly different among treatments (P > 0.05; Table 2). Final DO concen-tration at dusk in the open system (12.93 mg L-1) was


significantly higher than in closed and recycle systems (P < 0.05), which were not significantly different (Table 2). Aeration in the closed system made overall mean DO concentration at dawn significantly higher than that in the open and recycle systems (P < 0.05). DO concentra-tions fluctuated over wider ranges in the open system than in the closed and recycle systems (Figure 1). The values of pH were quite stable throughout the experi-mental period, while temperature fluctuated between 25° and 31°C and showed an increasing trend over time (Figure 2). During the most of the experimental period, total alkalinity concentrations were higher in the open system than in the closed and recycle systems (Figure 2), however, there were no significant differences in overall mean or final values (P > 0.05; Table 2). TAN concentra-tions fluctuated throughout the experimental period, without significant differences among the three systems (Figure 3; Table 2). The overall mean concentrations of nitrate-N, nitrite-N, TKN, TP, SRP, TSS, and TVS were significantly lower in the open and recycle systems than in the closed system (P < 0.05; Table 2; Figures 3, 4, and 5) due to water exchange or recirculation.

Final and overall mean values for most water quality parameters were not significantly different among the prawn, tilapia, and water mimosa tanks in the recycle system (P > 0.05; Table 2). Final concentration of DO at dusk was significantly lower in the prawn tanks than in tilapia and mimosa tanks (P < 0.05), which were not significantly different (Table 2). Final concentration of TP was significantly higher in the tilapia tanks than in prawn and mimosa tanks (P < 0.05), while overall mean concentration of TP was significantly higher in prawn tanks than in tilapia and mimosa tanks (P < 0.05; Table 2).

Moisture, TN, and TP contents in feed, fertilizer, prawns, tilapia, mimosa, and sediment samples at the begin-ning and end of the experiment are presented in Table 3. Nitrogen budgeting for prawn tanks showed that feed was the dominant input of both nitrogen and phospho-rus in all treatments (Table 4). In the closed and recycle systems, fertilizer was the second largest contributor for nitrogen input, while water contributed more nitrogen than fertilizer in the open system. For phosphorus, fertilizer was the second largest contributor in all three systems. Prawns incorporated 54.0 g N in the closed system and 54.6 g N in the recycle system, which were significantly higher than the 27.0 g incorporated in prawns in the open system (P < 0.05). Prawns incorpo-rated 3.3–6.2 g P in the three systems, which were not significantly different. Phosphorus accumulated in soils from prawn tanks in the open and closed systems, while soils in the recycle system released phosphorus to water (Table 4). We were unable to account for large amounts of nutrients in the systems, including 41.4–105.6 g N and 3.4–66.9 g P.

Total nitrogen and phosphorus inputs from fertiliz-

ers and feeds were significantly higher in the closed and recycle systems than in the open system (Table 5). Prawns in the open system recovered 12.02% of total N input, which was significantly lower than the amount recovered by prawns in the closed and recycle systems (25.26% and 25.74%, respectively). Nile tilapia and water mimosa recovered 7.19% and 6.62% of total N input, respectively, in the recycle system. Total N recovery was highest in the recycle system (39.55%), intermediate in the closed system (25.26%), and lowest in the open system (12.02%) (P < 0.05; Table 5). Phosphorus recovery by prawns was 11.00% + 2.03 and was not significantly different among the three systems (P > 0.05; Table 5). Nile tilapia recovered 8.01%, and water mimosa recov-ered 5.20% of total P input in the recycle system. Total P recovery was 25.53% in the recycle system, which was significantly higher than in the open (7.01%) and closed system (13.67%) (P < 0.05), which were not significantly different (Table 5).

Feed cost in the closed and recycle systems was signifi-cantly higher than that in the open system (P < 0.05; Table 6). Electricity cost was highest in the recycle sys-tem, intermediate in the closed system, and lowest in the open system (P < 0.05). The total cost was significantly lower in the open system than in the closed and recycle systems (P < 0.05), which were not significantly differ-ent. Gross return was significantly higher in the closed and recycle systems than in the open system (P < 0.05). However, the recycle system gave lowest cost and gross return, followed by the open system and closed system (P < 0.05). The open system gave negative net return (-0.57 US$ tank-1), while the closed system and recycle system gave positive net returns (1.23 and 0.48 US$ tank-1, respectively), however, there were no significant differences in net return among the three systems (P < 0.05; Table 6).

DISCUSSION

The growth of giant freshwater prawn was not sig-nificantly different among an open system with water exchange, closed system with aeration, or recycle sys-tem. However, mass mortality occurred in one replicate and low survival in the other two replicates in the open system with water exchange, while mass mortality also occurred in one replicate of the recycle system. Low DO at dawn observed in the open and recycle systems might have caused the mass mortality and low survival. Fre-quent water exchange might also have caused stress to prawns due to differences in some water quality param-eters such as temperature between the tank water and source water in the open system. High average survival in the closed system with aeration (88.7%) may indicate that sufficient and stable oxygen supply through aera-tion can effectively reduce prawn culture risk.

Survival in the closed and recycle systems in the pres-


ent study was similar to the survival range (50–80%) reported by New and Singholka (1985), Vasudevappa et al. (1998), and Lee and Wickins (1992) for prawn mono-culture. Similar growth rates of prawns were observed in all three systems, however, actual density of prawns in the open system with water exchange was lower due to higher mortality. This implies that aeration and water recirculation in the closed and recycle systems more ef-fectively maintained growth of prawns at relatively high densities than did water exchange. Daily weight gains attained in the present study ranged from 0.16 to 0.23 g prawn-1 during the 19-week culture period, and were greater than the 0.14 g prawn-1 day-1 reported by Ang et al. (1992) during a 24-week culture.

The significantly higher yields in the closed and re-cycle systems were due mainly to significantly higher survival. Yields from the three systems in this study reached 11,000 kg ha-1year-1, and were higher than the 1,000–5,000 kg ha-1 year-1 reported by Hsieh et al. (1989) and New (1995) or the 6,210 kg ha-1 year-1 obtained in intensive indoor tanks reported by Valenti and New (2000). Suitable temperature (25–31°C) throughout the experimental period, optimal levels of most water qual-ity parameters, the relatively small size of culture units, and intensive care probably contributed to the higher yields. Use of mechanical aeration in a closed system or water recirculation in an integrated system can signifi-cantly increase prawn production, compared to an open system with water exchange.

The observed FCR of 2.1 to 3.1 for commercial feed is typical (New, 2002). A similar FCR (2.85) was achieved in the open system with water exchange, while better FCRs were achieved in the closed and recycle systems (1.67 and 1.78, respectively). Aeration and water recirculation may significantly improve feed utilization efficiency, even more than water exchange, probably by improving water quality and providing a more stable environment for prawn growth.

A large portion of both nitrogen and phosphorus was unaccounted for in the nutrient budget in this study. The unaccounted nitrogen in prawn tanks of the three systems may have been lost through denitrification and ammonia volatilization (Boyd, 1990). Since there was no nitrogen input to the tilapia and mimosa tanks, the unac-counted nitrogen may have been gained from air diffu-sion or nitrogen fixation. Soil on the tank bottom was collected from an aquaculture pond rich in phosphorous, as a result, phosphorus was released from the soil into the water in the three tanks of the recycle system, which had relatively low phosphorus concentrations in the water. Discharge of water for harvest prior to sampling sediment may have also caused the loss of nutrients.

Environmental impacts of intensive marine shrimp cul-ture are frequently associated with water exchange dur-

ing culture, water discharge at harvest and nutrient-rich sediment removal (Pruder, 1992; Phillips et al., 1993; Fast and Menasveta, 2000; Lin, 2000). The open system with water exchange had highest nitrogen and phosphorous losses to receiving water, followed by the closed system, and the prawn tanks in the recycle system, indicat-ing reduced nutrient loss to the environment. Nutrient recovery by harvestable organisms in a culture system is a key remediator of environmental impacts, as they can consume feed and fertilizers, which are major sources of nutrients in the culture system. Previous research showed that 22% TN and 8.3% TP from feed and fertiliz-ers added to intensive marine shrimp ponds in Thailand could be recovered by shrimp (Briggs and Funge-Smith, 1994). In the present study, prawns incorporated 12.02% TN and 7.01% TP from feed and fertilizers in the open system, and 25.26% TN and 13.67% TP in the closed system. Prawns, tilapia, and mimosa together recovered 39.55% TN and 25.53% TP in the recycle system. The recovery rates in the closed system with aeration and recycle systems were considerably higher than those reported by Briggs and Funge-Smith (1994) in intensive marine shrimp ponds. Prawn culture integrated with tilapia and mimosa in a recycle system has potential to increase nutrient utilization efficiency and reduce envi-ronmental pollution compared to other culture systems. Lin (1995) pointed out that recycling systems with fish for intensive shrimp culture had several advantages, in-cluding utilization of excessive biomass of phytoplank-ton and detritus, nutrient recycling, maintenance of stable phytoplankton blooms, and reduction of organic matter and nutrients from discharged water. Studies by Lin (1990), Lin and Diana (1995), and Yi and Lin (2001) also showed that wastewater from intensive fish culture could produce phytoplankton to support Nile tilapia culture. The present study demonstrated that tilapia could grow upon effluents from prawn ponds with comparable yield to manured or fertilized ponds, while mimosa further helped to increase nutrient recovery.

Net economic returns per unit area in the recycle system were not significantly different from the closed or open systems in the present study, although the recycle sys-tem occupied a culture area three times as large as other two systems. Through better management, the produc-tion of Nile tilapia and water mimosa in the recycle system could be further improved, making the recycle system more sustainable economically.

The closed system with aeration and prawn-tilapia-mi-mosa integrated recycle system are more environmental-ly friendly and have better profit potential than the open system with water exchange. Further study is needed to determine appropriate ratios of culture area for prawns, tilapia, and mimosa to minimize environmental pollu-tion, optimize production, and maximize profits.

ANTICIPATED BENEFITS


The closed and recycle culture systems for prawn farm-ing will make culture technologies more sustainable by reducing environmental contamination to public water-ways and reusing the waste for other crops. This ap-proach is important not only to increase farmers’ aware-ness of environmental problems but also to provide new means to improve the system. Successful demonstration of this research in Thailand will serve as a future model for prawn farming in the region.

ACKNOWLEDGMENTS

The authors wish to acknowledge the Asian Institute of Technology for providing the field and laboratory facilities. P. Clayden, A. A. Mon, M. A. Quaiyyum, and P. Yingcharoenphon are greatly appreciated for their field and lab assistance.

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Parameter Open system Closed system Recycle system

Prawn tanks Tilapia tanks Mimosa tanks

STOCKING

Biomass (g tank-1) 267.8±2.1 263.6±1.5 261.5±1.5 106.1±0.9 2,000.0±0.0Number (No. tank-1) 94±0.7 93±0.5 92±0.5 10±0.0 -Density (prawn or fish m-2) 19±0.2 19±0.1 18±0.1 2±0.0 -Mean weight (g prawn-1

or fish-1) 2.8±0.0 2.8±0.0 2.8±0.0 10.6±0.1 -HARVESTING

Number (No. tank-1) 39±5.5a 83±3.9b 59±11.0ab 8±0.5 -Biomass (g tank-1) 1,035.0±225.0a 1,920.0±175.2b 1,885.0±445.0b 735.0±125.0 5,605.0±2,525.0Mean weight (g prawn-1) 26.6±2.0 23.5±3.4 31.6±1.6 97.3±10.2 -

WEIGHT GAIN

Total weight gain (g tank-1 crop-1) 767.2±222.9a 1,656.4±176.7b 1,623.5±443.5b 628.9±124.1 3,605.0±2,525.0

Daily weight gain (g prawn-1 or fish-1 day-1) 0.19±0.02 0.16±0.03 0.23±0.01 0.68±0.08 -

YIELD

Gross yield (g m-2 day-1) 1.6±0.4a 3.0±0.3b 3.0±0.7b 1.2±0.2 8.8±4.0Extrapolated gross yield (kg ha-1 crop-1) 2,070.0±450.0a 3,840.0±350.4b 3,770.0±890.0b 1,470.0±250.0 11,210.0±5,050.0

Extrapolated annual gross yield (kg ha-1

year-1)6,210.0±1,350.0a 11,520.0±1,051.3b 11,310.0±2,670.0b 4,410.0±750.0 33,630.0±15,150.0

Net yield (g m-2 day-1) 1.2±0.4a 2.6±0.3b 2.5±0.7b 1.0±0.2 5.6±4.0Extrapolated net yield (kg ha-1 crop-1) 1,534.4±445.8a 3,312.9±353.3b 3,247.0±887.0b 1,257.8±248.2 7,210.0±5,050.0

Extrapolated annual net yield (kg ha-1year-1) 4,603.2±1,337.4a 9,938.6±1,060.0b 9,740.9±2,660.9b 3,773.4±744.6 21,630.0±15,150.0

SURVIVAL (%) 40.64±5.49a 88.72±3.74b 63.78±11.53ab 75.00±5.00 -FCR 2.81±0.62a 1.67±0.16b 1.78±0.48b - -

Mean values with different superscript letters in the same row for prawn tanks were significantly different (P < 0.05).

Table 1. Growth and production performance of giant freshwater prawn, tilapia and mimosa in tanks in each treatment.


Parameter Open system

Closed system

Recycle systemPrawn tanks Tilapia tanks Mimosa tanks

OVERALL MEAN VALUES

DO (mg L-1) at dawn 4.23±0.70a 5.81±0.17b 3.75±0.25a 5.47±0.35 4.11±0.84DO (mg L-1) at 0900 h 5.59±0.47ab 6.56±0.15b 5.28±0.43a 5.95±0.21 5.29±0.06DO (mg L-1) at dusk 12.12±0.19a 7.54±0.34b 7.73±0.23b 7.85±0.21 8.20±0.81pH 7.67±0.01 7.65±0.05 7.49±0.05 7.47±0.01 7.46±0.05Temperature (C) 28.7±0.03 28.7±0.05 28.7±0.2 28.7±0.1 28.5±0.1Total alkalinity (mg L-1) 74±3.9 60±4.9 57±2.5 57±0.5 60±2.5

TAN (mg L-1) 0.33±0.03 0.35±0.05 0.25±0.05 0.17±0.00 0.16±0.01NO3-N (mg L-1) 0.20±0.00a 0.44±0.04b 0.24±0.10ab 0.12±0.00 0.12±0.01NO2-N (mg L-1) 0.03±0.01a 0.09±0.01b 0.02±0.01a 0.02±0.00 0.01±0.00TKN (mg L-1) 2.42±0.29a 3.91±0.31b 2.02±0.25a 1.31±0.23 1.48±0.28TP (mg L-1) 0.71±0.01a 0.97±0.06b 0.70±0.02a

d 0.61±0.02e 0.58±0.00eSRP (mg L-1) 0.03±0.01a 0.09±0.01b 0.03±0.01a 0.02±0.01 0.02±0.01Chlorophyll a (µg L-1) 45±4.9 79±23.3 27±2.3 25±0.8 23±2.5TSS (mg L-1) 28±0.5a 152±14.4b 43±4.8a 31±4.2 36±6.0TVS (mg L-1) 15±0.4a 35±2.0b 13±0.8a 11±1 14±0.1

FINAL VALUES

DO (mg L-1) at dawn 4.48±1.22 5.16±0.35 3.87±0.27 4.85±0.08 3.87±0.27DO (mg/L) at 0900 h 6.10±0.60 5.98±0.23 5.97±0.02 5.67±0.43 5.80±0.38DO (mg/L) at dusk 12.93±0.24a 7.34±0.44b 7.26±0.02bd 7.43±0.03e 7.48±0.01epH 7.74±0.00 7.73±0.07 7.77±0.04 7.74±0.04 7.72±0.09Temperature (C) 30.6±0.13 30.5±0.08 30.3±0.11 30.3±0.09 30.4±0.07Total alkalinity (mg L-1) 82±12.0 82±6.1 78±6.0 79±4.0 82±2.5

TAN (mg L-1) 0.15±0.03 0.37±0.10 0.25±0.06 0.24±0.08 0.25±0.07NO3-N (mg L-1) 0.10±0.01 0.32±0.12 0.37±0.17 0.12±0.02 0.10±0.00NO2-N (mg L-1) 0.01±0.00 0.03±0.01 0.05±0.03 0.02±0.00 0.02±0.00TKN (mg L-1) 5.10±0.80 8.21±1.67 3.92±0.47 3.68±0.84 3.51±0.23TP (mg L-1) 1.30±0.02 1.76±0.30 1.34±0.01e 1.42±0.02d 1.05±0.04eSRP (mg L-1) 0.01±0.00 0.01±0.00 0.01±0.01 0.01±0.01 0.01±0.00Chlorophyll a (µg L-1) 88±42.9 141±94.5 43±2.3 43±0.0 25±15.8TSS (mg L-1) 28±15.5 128±54.6 75±33.2 22±0.0 30±8.9TVS (mg L-1) 8±2.5 24±4.2 24±13.0 16±0.0 14±5.6

Mean values with different superscript letters in the same row for prawn tanks among the three systems or in the same row for prawn, tilapia, and mimosa tanks in the recycle system were significantly different (P < 0.05).

Table 2. Values of water quality parameters measured during the experiment.


Parameter Open system Closed system

Recycle systemPrawn tanks Tilapia

tanksMimosa

tanks

BEGINNING

Prawns/tilapia /mimosa Moisture (%) 73.22±0.00 73.22±0.00 73.22±0.00 79.82±0.00 75.63±0.00 TN (%) 9.45±0.00 9.45±0.00 9.45±0.00 10.62±0.00 1.06±0.00 TP (%) 1.22±0.00 1.22±0.00 1.22±0.00 2.16±0.00 0.26±0.00Soil Moisture (%) 34.18±0.00 34.18±0.00 34.18±0.00 34.18±0.00 34.18±0.00 TN (%) 0.09±0.00 0.09±0.00 0.09±0.00 0.09±0.00 0.09±0.00 TP (%) 0.16±0.00 0.16±0.00 0.16±0.00 0.16±0.00 0.16±0.00END

Prawns/tilapia /mimosa Moisture (%) 71.28±0.58 71.85±1.67 68.81±0.10 78.27±1.65 76.59±0.86 TN (%) 9.08±0.25 10.23±1.28 9.71±1.81 9.94±0.63 1.29±0.22 TP (%) 1.12±0.03 1.14±0.07 0.98±0.07 2.28±0.12 0.26±0.00Soil Moisture (%) 48.79±0.77 52.92±1.50 48.53±4.98 48.42±1.15 51.32±1.64 TN (%) 0.10±0.01 0.12±0.01 0.12±0.01 0.10±0.02 0.13±0.04 TP (%) 0.19±0.01 0.18±0.01 0.15±0.01 0.13±0.01 0.14±0.00PRAWN FEED

Small size Moisture (%) 10.58 10.58 10.58 - - TN (%) 7.16 7.16 7.16 - - TP (%) 1.52 1.52 1.52 - -Medium size Moisture (%) 10.16 10.16 10.16 - - TN (%) 5.34 5.34 5.34 - - TP (%) 1.02 1.02 1.02 - -FERTILIZER

Urea Moisture (%) 0.00 0.00 0.00 - - TN (%) 46.00 46.00 46.00 - -TSP Moisture (%) 0.00 0.00 0.00 - - TP (%) 20.00 20.00 20.00 - -

Table 3. Moisture (%), TN and TP contents in prawn, tilapia, mimosa, sediment, feeds and fertilizers in the experiment.


ParametersTOTAL NITROGEN

Open System

Closed System

Recycle systemPrawn Tilapia Mimosa

InputsWater 32.2±0.0 8.7±0.0 8.7±0.0 8.7±0.0 8.7±0.0Fertilizer 27.6±0.0 27.6±0.0 27.6±0.0 - -Feed 140.3±0.9a 159.7±2.0b 159.2±5.8b - -Prawn 6.8±0.1 6.7±0.0 6.6±0.0 - -Tilapia - - - 2.3±0.0Mimosa - - - - 5.2±0.0Total 206.9±0.8 202.6±2.0 202.1±5.8 11.0±0.0 13.9±0.0

OutputsWater 75.1±9.0a 42.8±8.5b 21.7±1.4c 19.2±4.3 18.1±1.1Prawn 27.0±0.6a 54.0±2.4b 54.6±3.0b _ _Tilapia -- - - 15.8±2.5 -Mimosa - - - - 17.8±9.9Soil 20.6±22.0 64.4±23.6 62.7±26.4 33.3±54.3 83.6±96.7Total 122.7±7.4 161.2±13.4 139.0±24.8 68.2±47.5 119.5±85.8

GainsPrawn 20.2±5.6a 47.3±2.4b 48.0±2.9b - -Tilapia - - - 13.5±2.5 -Mimosa - - - - 12.7±9.9Water 42.9±9.0a 34.1±8.5a 13.0±1.4b 10.5±4.3 9.4±1.1Soil 20.6±22.0 64.4±23.6 62.7±26.4 33.3±54.3 83.6±96.7

UNACCOUNTED 84.2±6.6 41.4±12.7 63.1±19.0 -57.2±47.5 -105.6±85.8

Table 4. Nitrogen and phosphorous budgets in different treatments over the experiment.


ParametersTOTAL PHOSPHORUS

Open System

Closed System

Recycle systemPrawn Tilapia Mimosa

InputsWater 0.9±0.0 0.3±0.0 0.3±0.0 0.3±0.0 0.3±0.0Fertilizer 8.0±0.0 8.0±0.0 8.0±0.0 - -Feed 27.5±0.2a 31.3±0.4b 31.2±1.1b - -Prawn 0.9±0.0 0.8±0.0 0.8±0.0 -Tilapia - - - 0.5±0.0 -Mimosa - - - - 1.3±0.0Total 37.3±0.2a 40.4±0.4b 40.3±1.1b 0.8±0.0 1.5±0.0

OutputsWater 19.6±0.3a 8.8±1.5b 6.7±0.1b 7.1±0.1 5.2±0.2Prawn 3.3±0.1 6.2±1.0 5.6±0.9 - -Tilapia - - - 3.6±0.5 -Mimosa - - - - 3.3±1.4Soil 51.7±26.3 28.8±13.7 -25.7±22.7 -76.8±12.56 -53.1±8.2Total 74.7±26.9 43.8±12.4 -13.4±23.6 -66.1±11.9 -44.6±9.4

GainsPrawn 2.5±0.9 5.4±1.0 4.8±0.9 - -Tilapia - - - 3.2±0.5 -Mimosa - - - - 2.1±1.4Water 18.7±0.3a 8.6±1.5b 6.4±0.1b 6.8±0.1 5.0±0.2Soil 51.7±26.3 28.8±13.7 -25.7±22.7 -76.8±12.56 -53.1±8.2

UNACCOUNTED -37.4±27.1 -3.4±12.6 53.7±24.7 66.9±11.9 46.1±9.4

Table 4. Continued.

Mean values with different superscript letter in the same row for prawn tanks were significantly different (P < 0.05).



NITROGEN

Total Input (g) 167.9±0.9a 187.3±2.0b 186.8±5.8b

Recovered by prawn(g/tank) 20.2±5.6a 47.3±2.4b 47.9±2.9b

(%) 12.02±3.40a 25.26±1.37b 25.74±2.38b

Recovered by tilapia(g/tank) - - 13.5±2.5(%) - - 7.19±1.10

Recovered by mimosa(g/tank) - - 12.7±9.9(%) - - 6.62±5.08

Total Recovered(g/tank) 20.2±5.6a 47.3±2.4b 74.1±9.4c

(%) 12.02±3.40a 25.26±1.37b 39.55±3.81c

Total Wasted(g/tank) 147.7±6.5a 140.0±3.5a 112.7±3.6b

(%) 87.98±3.40a 74.74±1.37b 60.45±3.81c

PHOSPHOROUS

Total Input (g) 35.5±0.18a 39.3±0.40b 39.2±1.1b

Recovered by prawn(g/tank) 2.5±0.9 5.4±1.0 4.8±0.94(%) 7.01±2.50 13.67±2.41 12.31±2.76

Recovered by tilapia(g/tank) - - 3.2±0.5(%) - - 8.01±1.13

Recovered by mimosa(g/tank) - - 2.1±1.4(%) - - 5.20±3.41

Total Recovered(g/tank) 2.5±0.9a 5.4±1.0a 10.0±1.0b

(%) 7.01±2.50a 13.67±2.41a 25.53±1.78b

Total Wasted(g/tank) 33.0±1.1 33.9±0.7 29.2±0.1(%) 92.99±2.5a 86.33±2.41a 74.47±1.78b

Mean values with different superscript letters in the same row were significantly different (P < 0.05).

Table 5. The efficiency of nutrient recovery from feed and fertilizer input in different treatments over the experiment.



GROSS REVENUE

Prawn 3.88±0.84a 7.20±0.66b 7.07±1.67b

Tilapia - - 0.37±0.06Mimosa - - 0.70±0.32Total Revenue 3.88±0.84a 7.20±0.66b 8.14±1.29b

Mean revenue per tank 3.88±0.84a 7.20±0.66b 2.71±0.43a

OPERATION COST

Prawn juveniles 2.01±0.02 1.98±0.01 1.96±0.01Tilapia fingerlings 0.25±0.00Mimosa seedlings 0.25±0.00Feeds 2.07±0.01a 2.37±0.03b 2.36±0.09b

Urea 0.01±0.00 0.01±0.00 0.01±0.00TSP 0.01±0.00 0.01±0.00 0.01±0.00Electricity 0.24±0.00a 1.45±0.00b 1.68±0.00c

Cost of working capital 0.12±0.00a 0.15±0.00b 0.17±0.00c

Total Cost 4.45±0.00a 5.97±0.02b 6.69±0.08b

Mean cost per tank 4.45±0.00b 5.97±0.02c 2.23±0.03a

NET RETURN PER TANK -0.57±0.84 1.23±0.64 0.48±0.46

Mean values with different superscript letters in the same row were significantly different (P < 0.05).

Table 6. Economic performance of the three systems in US$.


Figure 1. Changes of DO concentrations at 0600 h, 0900 h, and 1800 h in prawn tanks of the three systems over the experiment.


Figure 2. Changes of pH, temperature, and total alkalinity at 0900 in prawn tanks of the three systems over the experiment.


Figure 3. Changes of total ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, and total Kjeldahl nitrogen at 0900 h in prawn tanks of the three systems over the experiment.


Figure 4. Changes of total phosphorous and soluble reactive phosphorus at 0900 h in prawn tanks of the three systems over the experiment.

TWENTY-SECOND ANNUAL TECHNICAL REPORT80

Figure 5. Changes of chlorophyll a, total suspended solids, and total volatile solids at 0900 h in prawn tanks of the three systems over the experiment.

Cite as: [Author(s), 2005. Title.] In: J. Burright, C. Flemming, and H. Egna (Editors), Twenty-Second Annual Technical Report. Aquaculture CRSP, Oregon State University, Corvallis, Oregon, [pp. ___.]

p s d i r aquaculture crsp 22nd annual...

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