Shrimp and fish pond soils: processes and management

The pond bottom soil and the accumulated sediments are integral parts of ponds. Concentrations of nutrients, organic matter and microorganism density in the pond bottom are several orders of magnitude greater than in the water. The accumulation of organic sediments may limit pond intensification. The intensive organic matter degradation at the pond bottom and high sediment oxygen demand exceeds the oxygen renewal rate. This leads to the development of anoxic conditions in the sediments and at the sediment–water interface. A series of anaerobic processes, affected by the redox potential of the system, are taking place. A large number of potentially toxic materials are generated. Among those are organic acids, reduced organic sulfur compounds, reduced manganese and sulfides.

Shrimp, as animals that normally live on or near the bottom, are exposed to conditions on the pond bottom. Exposure to toxic materials endanger the well being of the cultured shrimp. Reduced feeding, slower growth, mortality and possibly higher sensitivity to disease are reported.

The rational use of aerators to minimize the area of sludge accumulation, construction of ponds to trap sludge, stirring sediments, chemical poising of the redox system and environmentally accepted treatment and reuse of drained sediments are means to control the conditions at the pond bottom.     

Effect of Water Exchange Rate on Production, Water Quality, Effluent Characteristics and Nitrogen Budgets of Intensive Shrimp Ponds

Water exchange is routinely used in shrimp culture. However, there are few, if any, systematic investigations upon which to base exchange rates. Furthermore, environmental impacts of pond effluent threaten to hinder further development of shrimp farming in the U.S. The present study was designed to determine effects of normal (25.0%/d), reduced (2.5%/d) and no (0%/d) water exchange on water quality and production in intensive shrimp ponds stocked with Penaeus setiferus at 44 postlarvae/m². Additional no-exchange ponds were stocked with 22 and 66 postlarvae/m² to explore density effects. Water exchange rates and stocking density influenced most water quality parameters measured, including dissolved oxygen, pH, ammonia, nitrite, nitrate, Kjeldahl nitrogen, soluble orthophosphate, biochemical oxygen demand, phytoplankton and salinity. Reduced-exchange and no-exchange treatments resulted in reduced potential for environmental impact. Mass balance of nitrogen for the system indicates that 13–46% of nitrogen input via feed is lost through nitrification and atmospheric diffusion. Growth and survival were excellent in ponds with normal exchange, reduced exchange, and a combination of low density with no water exchange. A combination of higher stocking density and no water exchange resulted in mass mortalities. Mortalities could not be attributed to a toxic effect of any one water quality parameter. Production was 6,400 kg/ha/crop with moderate stocking density (44/m²) and reduced (2.5%/d) water exchange and 3,200 kg/ha/crop with lower stocking density (22/m²) and no water exchange. Results indicate that typical water exchange rates used in intensive shrimp farms may be drastically reduced resulting in a cost savings to farms and reduced potential for environmental impact from effluent.     

The effects of zeolites and other alumino-silicate clays on water quality at various salinities

Intensive marine and brackishwater shrimp farms commonly use large quantities of zeolites in ponds with the aim of removing ammonia through ion exchange, providing physical cover over sediments to prevent leaching of metabolites into the water column, removing suspended solids, and improving water colour and diatom blooms. Zeolites have the capacity to remove ammonia and other nutrients/ metabolites from fresh waters by ion exchange and absorption. However, there are doubts as to their efficacy and cost-effectiveness in saline waters. This research was conducted to investigate the effect of zeolites on water quality under a range of conditions in seven laboratory-based trials and one pond trial. These investigated the effects of six types of commercially available zeolites and three other alumino-silicate clays at levels from one to 26 times the recommended dose rate (380 kg ha^-1 month^-1) in water at salinities of 0-30%o for periods of 3-19 days. The results indicated that none of the zeolites or natural alumino-silicate clays from Thailand had any significant effects on the removal of nutrients from water at salinities of 0-30%. Neither were these able to prevent nutrient emission from shrimp pond sediments in water at 20-2l%o salinity. Furthermore, none of the other suggested functions of reducing levels of particulate nutrients, enhancing algal biomass, or affecting oxygen and pH dynamics were evident. This study could not establish any useful, cost-effective role for zeolites in shrimp pond culture.     

Experimental Studies to Evaluate Larval Survival of the Fire Shrimp, Lysmata debelius, to the Juvenile Stage

Many coral reefs are threatened because of anthropogenic impacts such as destructive fishing methods for marine ornamentals. The marine ornamental industry is currently almost completely dependent upon wild collections. The development of commercially feasible methods to culture ornamental species could help to reduce the need for wild‐collected specimens and reduce pressure on coral reefs. Advances in larval rearing and nutrition would help overcome the bottlenecks that impede the commercial production of many marine ornamental species. This article focuses on research for improving the production of the fire shrimp, Lysmata debelius. Experiments were performed with larval fire shrimp to evaluate (1) the importance of essential fatty acid enrichment of live prey (rotifers and Artemia) and (2) feeding penaeid shrimp muscle tissue to improve survival to metamorphosis. We also provide the fatty acid composition of Day‐1 posthatch fire shrimp larvae. The enrichment of live prey with docosahexaenoic acid did not improve larval growth, survival, or time to metamorphosis, but larvae fed live prey together with pureed penaeid shrimp muscle had survival rates of 9.8 ± 1.2%. The data and protocols developed in this study provide a foundation and baseline for future fire shrimp larval studies.     

The effects of artificial substrate and stocking density on Pacific white shrimp (Litopenaeus vannamei) performance and water quality dynamics in high tunnel-based biofloc systems

The use of artificial substrates in shrimp aquaculture may allow for production of shrimp at increased densities while providing a growth medium for microbes that assist with water quality processes and provide supplemental nutrition for shrimp. Greenhouse-based shrimp production systems can extend the shrimp production season in temperate climates while conserving water and energy. For this study, we evaluated the effects of providing extra substrate and shrimp density on water quality and shrimp production in greenhouse-based biofloc systems. Four 11-m³, wood framed, and rubber-lined tanks were constructed in each of four high tunnel greenhouses (for a total of 16 tanks). Four treatments were evaluated: high-density stocking with substrate (HDS), high-density stocking with no substrate (HDNS), low-density stocking with substrate (LDS), and low-density stocking with no substrate (LDNS). Each treatment was randomly assigned to one tank in each tunnel to block for location. No artificial heat was used, and shrimp were grown for 120 days. High-density systems were stocked at 200 shrimp/m³ while low-density tanks had 100 shrimp/m³. Adding substrate increased total in-tank surface area by 13.4%. The addition of substrate had no significant effect on any shrimp production or standard water quality parameters. Shrimp had significantly greater final weight, faster growth rate, and lower feed conversion rate in low-density treatments (P ≤ 0.02 for all). Total shrimp biomass production was significantly higher in high-density treatments (HD: 4.0 kg/m³; LD: 2.3 kg/m³; P < 0.05). There were no significant differences in survival between densities (HD: 91.3%; LD: 94.5%; P = 0.43). Peak and overall mean nitrite levels were significantly higher in high-density treatments compared to low-density treatments. Dissolved oxygen levels and pH over the course of the study were significantly lower in high-density treatments, likely due to increased respiration rates in the water column. This project shows the feasibility of shrimp production in temperate climates with no artificial heat using high tunnel greenhouses, few impacts of added substrate on shrimp production, and increased shrimp density can result in much larger harvests with few negative impacts on production metrics.     

The Effects of Water Exchange on Production of Metapenaeus macleayi and Water Quality in Experimental Pools

Two experiments in 4 m diameter, plastic lined pools were conducted nt two densities, 20 shrimp/ m² and 47 shrimp/m², to determine the effects of water exchange rate on the production of the penaeid shrimp Metapenaeus macleayi (Haswell) and on water quality variables. Water exchange rates ranged from 0–40%/d for the 9 wk low density experiment and 0–20%/d for the 8 wk high density experiment. With the exception of mass mortality after prawns escaped from one pool (0% water exchange) on the last day of the high density experiment, shrimp performance indices (survival, weight gain, biomass gain and food conversion ratio) were not significantly affected by water exchange rate. During both experiments water exchange significantly reduced the concentrations of phosphorus and plant pigments (chlorophyll a, b and c and pheophytin) but had no significant effect on pH or the concentration of ammonia or nitrite plus nitrate. Data from this study suggest that while production ponds should not be managed for extended periods without water exchange, simply increasing daily water exchange rates may not necessarily increase shrimp growth or survival. Water exchange can reduce nutrient concentrations and phytoplankton densities but most of the reduction occurs at water exchange rates of between 0–5%/d.     

The Potential Use of Mangrove Forests as Nitrogen Sinks of Shrimp Aquaculture Pond Effluents: The Role of Denitrification

A generalized nitrogen budget was constructed to evaluate the potential role of mangrove sediments as a sink for dissolved inorganic nitrogen (DIN) in shrimp pond effluents. DIN concentrations were measured in pond effluents from three semi-intensive shrimp ponds along the Caribbean coast of Colombia between 1994–1995. Mean NH₄⁺ concentrations in the discharge water for all farms were significantly higher (67 × 12 μg/L) than in the adjacent estuaries (33 × 8 μg/L). Average NH₄⁺ concentrations in the pond discharge over all growout cycles were similar, representing an approximate doubling in relation to estuarine water concentrations. In contrast, NO₂^-+ NO₃^- concentrations were similar in both pond effluent and estuarine waters. Dissolved inorganic nitrogen loading of the ponds was similar. The estimated reduction of DIN in pond effluents by preliminary diversion of outflow to mangrove wetlands rather than directly to estuarine waters would be × 190 mg N/m² per d. Based on this nitrogen loss and depending upon the enrichment rate, between 0.04 to 0.12 ha of mangrove forest is required to completely remove the DIN load from effluents produced by a 1-ha pond.     

对虾池塘水质调节措施

本文综述了对虾池塘人工调节水质措施的生态作用，旨在为养殖者提供有效的调节水质方法，并兼顾养殖的经济效益和环境效益，为养殖业的可持续发展提供技术保障。本文将水质调节措施分为物理、化学和生物三大类别，每一个类别双包含了若干具体的方法。     

Management Strategies for Production of the Atlantic White Shrimp Penaeus setiferus as Bait Shrimp in Outdoor Ponds

Abstract The geographic distribution of the Atlantic white shrimp Penaeus setiferus is in coastal waters from New York to Florida and around the Gulf of Mexico. Beside its value to commercial fisheries, this shrimp is sold as bait for recreational fishing. Previous data suggest that demand for live bait shrimp cannot be satisfied by commercial fleets. A 120-d trial was designed to study production of bait size P. setiferus at high densities in eight small outdoor ponds in south Texas. A 2^4–1 fractional factorial design was applied to study the effects of postlarval (PL) density (350 and 700 shrimp/m²), feed type (A and B), and water circulation methods (with and without airlift pumps or center pond dividers) on shrimp growth, survival and yield. No significant differences in survivals or yields were found between treatments (P = 0.2). Feed type ( P = 0.011), airlift pumps ( P = 0.021), and center dividers ( P = 0.026), had significant impacts on shrimp growth rates. Density effect on growth was not statistically significant ( P = 0.055). This study demonstrated that 6-d-old postlarvae can be stocked at 700 per square meter and reached a bait size (6.2 g) in 94 d with a 73.6% survival and a yield equivalent to 31,300 kg/ha when offered a commercial shrimp feed. A preliminary economic analysis based on this data suggests that operating a bait shrimp farm in Texas with two crops/yr will show profitability within 7 to 12 yr with an internal rate of return of 6.5 and 17.6%, respectively.     

Sydney rock oyster, Saccostrea commercialis (Iredale & Roughley), filtration of shrimp farm effluent: the effects on water quality

Shrimp pond effluent water can contain higher concentrations of dissolved nutrients and suspended particulates than the influent water. Consequently, there are concerns about adverse environmental impacts on coastal waters caused by eutrophication and increased turbidity. One potential method of improving effluent water quality prior to discharge or recirculation is to use bivalves to filter the effluent. In this study, we examined the effects of the Sydney rock oyster, Saccostrea commercialis (Iredale & Roughley), on the water quality of shrimp pond effluent. Effluent from a shrimp farm stocked with Penaeus japonicus (Bate) was pumped directly into 34-L tanks stocked with different densities of oysters. Combinations of live and dead oysters were used to test the effects of three different densities of live oysters (24, 16 and 8 live oysters per tank). The concentrations of total suspended solids, the proportion of organic and inorganic matter, total nitrogen, total phosphorous, chlorophyll a and the total number of bacteria in the pond effluent water were determined before and after filtration by oysters. The oysters significantly reduced the concentration of all the parameters examined, with the highest oyster density having the greatest effect. Shrimp pond effluent contained a higher proportion of inorganic matter (72%) than organic matter (28%). The organic component appeared to be mainly detritus, with chlorophyll a comprising only a minor proportion. Filtration by the high density of oysters reduced the effluent total suspended solids to 49% of the initial level, the bacterial numbers to 58%, total nitrogen to 80% and total phosphorous to 67%. The combined effects of settlement and oyster filtration reduced the concentration of chlorophyll a to 8% of the initial effluent value.     

Testing the potential for improving quality of sediments impacted by mussel farms using bioturbating polychaete worms

Biodeposits from farmed mussels severely influence the biogeochemistry of sediments by increasing the levels of organic matter (OM). Mitigation of such negative impacts is important for the development of sustainable aquaculture operations. As a step towards developing methods for remediation of coastal sediments affected by mussel farming, the effects of the polychaete, Hediste diversicolor was evaluated experimentally. In a series of field‐ and laboratory experiments we tested hypotheses about the effects of polychaetes on sediment oxygen consumption, nutrient fluxes and sulphide pools under different polychaete densities and sedimentation regimes. The experimental results support the idea that polychaetes can mitigate negative effects on the benthic environment beneath mussel farms. H. diversicolor oxidized the sediment and generally enhanced the oxygen consumption, and thus the decomposition of OM. The accumulation of pore water sulphides were reduced and fluxes of nutrients across the sediment‐water interface increased. Additional calculations suggest that the effects of polychaetes were mainly indirect and driven by increased microbial activity due to the borrowing activity of the polychaetes. Trends of increasing decomposition with increasing polychaete density suggest that the decomposition could be further enhanced by higher densities. Overall, we concluded that H. diversicolor is a potentially strong candidate for remediation of mussel farm sediments. The results show that sediments inhabited by H. diversicolor have high assimilative capacity of OM and oxygen conditions are significantly improved following the addition of polychaetes at naturally occurring densities. However, technological developments are needed in order to allow the approach to be used in practice.     

Tilapia–Shrimp Polyculture in Negros Island,Philippines: A Review

Tilapia–shrimp polyculture has played an important role in current efforts to control luminous bacterial disease caused by Vibrio harveyi. At present, green water technology is most extensively used by shrimp farmers in Negros Island in the central Philippines. While the contribution of tilapia as a biomanipulator is highlighted in the literature, the mechanism of action is not well understood. Data were gathered from shrimp ponds practicing two production systems: (a) green water system (probiotics + tilapia) and (b) closed/semiclosed system (probiotics alone). There was no difference between luminous Vibrio count (P < 0.05) in both systems, and water quality was found to be similar (P < 0.05). Because the green water system uses a bigger reservoir to raise the tilapia biomass, the net shrimp production was lower. In terms of direct cost of production, however, the green water system was 10–15% lower than the closed/semiclosed system because of significantly less aeration required. The polyculture maintained a more stable plankton environment during the early months of culture, which increased survival of shrimps. Various pathways are presented for the control of luminous bacterial growth in polyculture ponds: (a) fish feeding on organic wastes and conversion to feces; (b) selective fish foraging to increase the dominance of beneficial phytoplankton; (c) bioturbation of pond sediments; and (d) release in the water column of antimicrobials, fungi, or competing bacteria from the skin and gut mucus of tilapia.     

Biosecurity and Genetic Improvement of Penaeid Shrimp: Applications to the Marine Ornamental Industry

The marine ornamental industry relies almost exclusively on wild-caught fish, invertebrates, and live rock to meet the market demands of aquarium hobbyists. For the industry to expand, appropriate technologies are needed to mitigate disease problems and reduce the dependence on wild stocks. Biosecurity protocols and techniques for genetic improvement have recently been applied to the culture of penaeid shrimp for human consumption, and these approaches may be applicable to an emerging marine ornamental industry. Biosecure production systems for penaeid shrimp are being developed in response to disease problems and growing concerns about environmental pollution from pond effluent. Biosecure systems rely on minimal water exchange and provide shrimp farmers with an opportunity to move production away from the coastline. In addition to the development of biosecure production systems, researchers at the Oceanic Institute have established a selective breeding program for the Pacific white shrimp, Litopenaeus vannamei. To date, significant improvements in shrimp growth and disease resistance have been made through selective breeding. It is likely that advances in biosecure technologies and genetic improvement will be applicable to the culture of marine ornamental shellfish and finfish and will contribute to an economically viable and environmentally sustainable industry.     

Comparison of methods for sampling populations of ghost shrimp, Trypaea australiensis (Decapoda: Thalassinidea: Callianassidae)

Coring and pumping methods, commonly used to determine the abundance and population parameters of burrowing ghost shrimp, were assessed in three widely separated south-eastern Australian estuaries. First, a comparison of two sizes of coring tube (0.04 and 0.07 m²) revealed no significant differences in catches of the ghost shrimp Trypaea australiensis Dana, nor differences in precision. However, the smaller sized core was consistently more cost effective. Second, when sampling a 0.1 m² quadrat, it was found that 12 “pumps” of a suction pump produced significantly higher numbers of individuals at most sites than using either four, eight or 16 pumps. In a third set of experiments, the coring method was compared to the pumping method, in terms of sampling efficiency, abundance estimates and sex ratios of captured ghost shrimp. Pumping was found to be more efficient, catching significantly greater numbers of ghost shrimp per minute than the coring. In addition, pump catches displayed a more normal size distribution than catches from the core and included a wider range of sizes. Sex ratios of catches from coring was 1:1, while catches from pumping were significantly biased toward females (0.71:1). Since female-biased sex ratios are characteristic of many thalassinid populations, this latter result probably reflects actual sex ratios for T. australiensis and not method based size selectivity.     

Brown shrimp (Farfantepenaeus aztecus) density distribution in the Northern Gulf of Mexico: an approach using boosted regression trees

The estuarine‐dependent brown shrimp, Farfantepenaeus aztecus, is a significant commercial fishery and important species in the Gulf of Mexico (GOM) ecosystem as well as being a key component in energy transfer between benthic and pelagic food web systems. Because of the economical and ecological importance of brown shrimp, we developed a spatial population model to identify places of high shrimp density under a set of spatial, environmental and temporal variables in the Northern Gulf of Mexico (NGOM). We used fisheries‐independent data collected by the Southeast Area Monitoring and Assessment Program (SEAMAP) from 1992 to 2007 (summer and fall seasons). The relationship between the predictor variables and shrimp density was modeled using Boosted Regression Trees (BRT). Within the environmental variables included in the model, bottom type and depth of the water column were the most important predictors of shrimp density in the NGOM. Spatial predictions performed using the trained BRT model for summer and fall seasons showed a spatial segregation of shrimp density. During the summer, higher densities were predicted near the Texas and Louisiana coast and during the fall, higher densities were predicted further offshore. The model performed well and allowed successful prediction of brown shrimp hot spots in the NGOM. Model results allow fisheries managers to evaluate the potential impact from fisheries on the resource and to develop future fisheries management strategies, understand the biology of brown shrimp as well as assess the potential impacts of oil spills or climate change.     

Performance of Larval and Postlarval Pacific White Shrimp,Litopenaeus vannamei (Boone), Fed Two Commercial Liquid Diet Supplements

Abstract

Two commercial liquid diet supplements were evaluated as a partial replacement for live foods fed to larval and postlarval Pacific white shrimp, Litopenaeus vannamei. Larvae were stocked in 20-L buckets at a density of 113 shrimp/L and fed one of four diets (5 replicate buckets per diet): (1) a control diet consisting of the diatom, Chaetoceros neogracile, and live Artemia; (2) the control diet plus Treflan (a fungicide); (3) LiquaLife liquid larval diet supplements with reduced concentrations of C. neogracile and Artemia; and (4) Epifeed liquid larval diet supplements with reduced concentrations of Artemia. Diets were evaluated by comparing shrimp rostro-caudal length and survival to PL-8, survival to osmotic and pH stress, as well as shrimp gut fullness, gut lipid content, and fouling. Rostro-caudal length and survival to PL-8 were not significantly different among the four treatments. However, mean survival to PL-8 was 12-34% greater in the Epifeed treatment than in the other three treatments. Shrimp fed Epifeed exhibited greater survival (P < 0.05) when exposed to 7 ppt water for two hours than shrimp in the control treatments. In contrast, there was no significant difference in survival (P > 0.05) among the four treatments when shrimp were exposed to apH of 3.35 for two hours. Although shrimp fed liquid diet supplements had more fouling (P < 0.05) than shrimp in either of the control treatments, commercial liquid diet supplements can be used in penaeid shrimp hatcheries to partially replace Artemia without compromising shrimp growth or survival.     

Accumulation of Chemical Elements in Texas Shrimp Pond Soils

Abstract— This study evaluated changes in chemistry of shrimp pond soils over one production cycle. Several soil nutrients, pH, organic matter, and total soluble salts were analyzed in the upper 10 cm of pond-bottom soil on two Texas shrimp farms in two consecutive years. Soil concentrations of S, P, Ca, Mg, K, Na, Mn, and Zn increased from one year to the next, S increased by 400 ppm. Organic matter did not accumulate. The pH decreased in all pond soils, owing perhaps to the oxidation of organic matter and/or inorganic compounds. There was no statistical difference in shrimp yield between the two consecutive years. These results indicated that the accumulation of S and soluble salts derived from seawater and feed should be monitored and evaluated to prevent excessive chemical element loading of pond soil and discharge water.     

Compensatory growth and feed restriction in marine shrimp production,with emphasis on biofloc technology

In Brazil, studies and production of penaeid shrimp in a biofloc technology (BFT) system are recent, but the results point to a promising future. Research with feed restriction inducing compensatory growth in shrimps has been shown to be a technique that allows a saving of around 25% in the use of feed for shrimp production. It also allows the reduction of costs with salaries and adapts shrimp farming to the world demand for environmentally friendly production, with the reduction of nitrogen and phosphorus levels in its effluents, as well as lower water use in shrimp farming. In crustaceans, it has been shown that after a period of feed restriction, the animals show a pronounced compensatory growth when they return to a sufficient food source. Studies with the penaeid shrimp Litopenaeus vannamei reported the ability of the species to obtain a complete compensatory growth after short feeding periods (1 to 3 days) followed by feeding; These short periods of fasting presented a greater efficiency in the feed conversion besides the decrease in the concentration of phosphorus present in the aquatic environment, coming from the excreta. The adoption of a restriction program in the feeding using BFT may contribute to a reduction in operating costs, reduction of metabolic nutrients dissolved in water, and, consequently, an increase in the number of cycles in which the same water can be reused for production reducing production costs and improving productivity indices in shrimp farming.     

Marine shrimp aquaculture: a novel waste treatment system

Ecuadorian Penaeus vannamei were cultured in dirt ponds (each of approximately 163 m²) at four different stocking densities, i.e. 5 shrimp m⁻², 10 shrimp m⁻², 15 shrimp m⁻² and 20 shrimp m⁻². Experiments were carried out over three different periods during the year. Each experiment lasted for 11–14 weeks. No commercial feed was given to the shrimp. The only input to the ponds was about 30 kg of cattle manure per pond per week. Chemical composition of the cattle manure was analyzed. Water quality parameters such as temperature, pH, DO and turbidity were recorded twice daily for each experiment; nutrients (nitrite, nitrate, ammonium and phosphate), water ATP, sediment ATP, H₂S and chlorophyll were measured twice weekly for each experiment. Shrimp were sampled either weekly or bi-weekly for body weight measurements.

The results showed a negative correlation between stocking density and growth. Weekly growth ranged from 0·44 to 1·58 g week⁻¹. Survival was over 50% in all treatments and averaged at 70·8%. Under these stocking densities, shrimp production ranged from 4·4 to 18·8 kg ha⁻¹ day⁻¹. The stocking density of 15 shrimps m⁻² provides better production than the other stocking densities.

Water quality data did not relate to any shrimp growth. Water nutrient levels in pond discharge water were less than or equal to the nutrients in the incoming water in spite of the weekly addition of cattle manure and did not increase with the addition of cattle manure. No coliform bacteria were detected in any pond water samples through the study period. This indicates digestion of cattle manure in marine shrimp ponds would not pollute the environment with high concentrations of dissolved nutrients.

Thus, a marine shrimp pond can be considered a dissolved nutrient marine treatment plant converting unwanted cattle manure (1841 kg cattle manure ha⁻¹ week⁻¹ in this study) into a valuable commodity — shrimp.     

Oral Administration of Hot‐water Extract of Tropical Brown Seaweed,Sargassum cristaefolium,to Enhance Immune Response,Stress Tolerance,and Resistance of White Shrimp,Litopenaeus vannamei,to Vibrio parahaemolyticus

The efficacy of hot‐water extract of tropical brown seaweed, Sargassum cristaefolium (SCE), supplemented in diets on immune response, stress tolerance, and disease resistance of Litopenaeus vannamei to Vibrio parahaemolyticus was evaluated. Shrimp were fed diets containing graded levels of SCE (0, 250, 500, 750, and 1000 mg/kg). The results showed that shrimp fed all diets containing SCE had significantly higher (P < 0.05) immune response in total hemocyte count (THC), differential hemocyte count (granular and hyaline cells), and phagocytic activity than those of shrimp fed the control diet. Similarly, in low dissolved oxygen stress tolerance test and the challenge test with V. parahaemolyticus, survival rates of shrimp fed all diets containing SCE were significantly higher (P < 0.05) (83–93% in stress test and 27–47% in challenge test) than those of shrimp fed the control diet (77 and 3.3%, respectively). These results suggest that oral administration of SCE at 500 and 750 mg/kg can be effectively used to enhance immune response, stress tolerance, and resistance of white shrimp, L. vannamei, against V. parahaemolyticus infection. These findings also confirm that using dietary SCE as immunostimulant is effective at increasing the nonspecific immune system in penaeid shrimp, L. vannamei.