Postlarval Shrimp Research Articles

Effects of dietary astaxanthin supplementation on survival, growth and stress resistance in larval and post-larval kuruma shrimp, Marsupenaeus japonicus

Two trials were conducted to evaluate the effects of chemically synthesized astaxanthin (Ax) on growth performance, survival, and stress resistance in larval and post-larval kuruma shrimp (Marsupenaeus japonicus). Six dietary levels of Ax (0, 50, 100, 200, 400 and 800 mg/kg diet) were added to a baseline diet. As a first study, an 8-day feeding trial was conducted on larval kuruma shrimp, with results showing that larvae-fed diets supplemented with different Ax levels exhibited better performance during developmental and metamorphosis to postlarvae. Broken-line regression analysis indicated that the optimal levels for growth and stress resistance of larvae were 168.9 mg/kg and 82.1 mg/kg diet, respectively. Second, a 30-day feeding trial was conducted on post-larval shrimp. Supplementation with 100 and 200 mg/kg Ax yielded significantly higher final body weight, body weight gain and specific growth rate than that in a control group. A cumulative mortality index for osmotic stress revealed significantly better performance in a group fed 200 mg/kg supplementation than in controls. Broken-line regression analysis indicated that the optimal levels for growth and stress resistance of postlarvae were 108.7 mg/kg and 178.1 mg/kg diet, respectively. Based on these results, we suggest that carefully dosed Ax supplementation is a beneficial nutritional strategy for the early developmental stages of kuruma shrimp.

Effects of partial replacement of fishmeal protein with green seaweed (Cladophora spp.) protein in practical diets for the black tiger shrimp (Penaeus monodon) postlarvae

This study assessed the effects of the green seaweed Cladophora spp. as a protein source to substitute fishmeal protein in practical diets for postlarval tiger shrimp (Penaeus monodon). A control diet without containing seaweed meal was compared with five experimental diets in which fishmeal protein was replaced by increasing the levels of green seaweed protein (10, 20, 30, 40 and 50%) in the diets. All diets were formulated to be equivalent in crude protein (40%) and lipid (7%). Each dietary treatment was replicated in triplicate. After 45 days of the feeding trial, survival of the shrimp was not significantly influenced by the feeding treatments (p > 0.05). Growth rates of the shrimp fed with 10, 20, or 30% replacement levels of green seaweed protein in the diets were superior or similar to those fed with the control diet whereas shrimp fed with the diet containing 40 and 50% substitution levels showed significant reduction in growth (p < 0.05). The feed conversion ratio and protein efficiency ratio exhibited the similar trend as observed for growth performance. Moreover, shrimp fed with the control diet presented the lowest stress tolerance to formalin shock while the best performance was detected in the animals that received the 10 and 20% replacement diet. These results suggested that green seaweed Cladophora could replace up to 30% of fishmeal protein in the tiger shrimp postlarvae diet, and the optimal performance, including growth rate, feed efficiency, and stress resistance, appeared in shrimp fed with the diet of 10 to 20% substitution.

Evaluation of the entry of white shrimp postlarvae (Decapoda: Penaeidae) to a nursery area in the southern Gulf of Mexico

The immigration of white shrimp Penaeus setiferus (Decapoda: Penaeidae) postlarvae (Pls) into the Terminos Lagoon was studied to determine the annual pattern of abundance and its relationship with temperature, salinity, tidal current velocity, and river discharge. Zooplankton samples were simultaneously obtained fortnightly at surface, mid-water, and bottom. The nets used were 50 cm in diameter, 1.5 m in length and 505 μm mesh size. The results indicated a postlarval seasonal immigration pattern, with the lowest average density values from March to May and October to November, and significantly higher values from June to September; maximum peaks occurred in June and September. High Pls densities were obtained between one and three hours after the tidal inflow started. Temperature and salinity varied little during each sampling period and had no apparent effect on immigration, but did have an effect on the seasonal abundance cycle. The multiple regression models indicated that the tidal current velocity and the temperature explained 86% of the variation in Pls abundance during immigration to the Terminos lagoon. The larval migration varied at different levels, with highest densities occurring at a medium depth of 5 m. The Pls entered an optimal range of tidal current velocity (between 0.6 and 0.9 m 3 s -1 ). The main entry mechanism was through the tide current of the Selective Tide Stream Transport, where the Pls could also select an optimum current velocity, avoiding the strata of higher turbulence that would imply higher energy expenditures.

Effect of 17β-Estradiol on Feminization, Growth Rate and Survival Rate of Pacific White Shrimp (Litopenaeus vannamei, Boone 1931) Postlarvae

This study was therefore aimed to determine the effect of different concentration of estrogen hormone, 17β-estradiol (E 2 ) on feminization for the production of all female, growth rate and survival rate of Pacific white shrimp ( Litopenaeus vannamei ) postlarvae (PL). L. vannamei PL 1 were stocked randomly at a density of 10 ind.L -1 into a 10 L of seawater for each experimental flask with three replicates each. PL 1 was immersed in seawater containing 0.5, 1.0 and 1.5 mg.L -1 estrogen hormone, E 2 for 4 hours. The experiment was continued for 30 days for larval rearing. At the termination of experiment, the specimens in each treatment groups were weighed and measured individually for their wet body weight (BW) and total length (TL) for the mean weight gain, length gain, and the specific growth rate (SGR) estimation. The mean sex ratio values of male to female postlarvae obtained from control till the highest E 2 hormone concentration of 0, 0.5, 1.0 and 1.5 mg.L -1 were 1:1, 1:2, 1:9 and 0:1 respectively. The weight gain and length gain were 40605% and 606% for control, 46310% and 647% for 0.5 mg.L -1 concentration, 49310% and 663% for 1.0 mg.L -1 concentration and 45048% and 628% for 1.5 mg.L -1 . The mean SGR BW and SGR TL for control till the highest E 2 hormone concentration of 0, 0.5, 1.0 and 1.5 mg.L -1 were 20.00 and 6.51, 20.46 and 6.70, 20.67 and 6.77 and 20.37 and 6.62 respectively. The mean survival rate for E 2 hormone concentration of 0, 0.5, 1.0 and 1.5 mg.L -1 were 52.67%, 54.33%, 54.67% and 52.33% respectively. The study shows that while the concentration of E 2 hormone increased, the female sex ratio of L. vannamei PL also increased but the growth rate and survival rate decreased at concentration of 1.5 mg.L -1 . Thus the optimum concentration of this hormone usage was 1.0 mg.L -1 immersed for 4 hours. Keywords: 17β-estradiol, feminization, growth rate, Litopenaeus vannamei , postlarvae, survival rate.

Effect of selenium on Penaeus monodon and Perna viridis: Enzyme activities and histopathological responses

The study was carried out to evaluate enzyme activities and histopathological changes due to the effect of acute and chronic definitive toxicity of selenium (Se) on the post larvae (PL) of giant tiger shrimp (Penaeus monodon), and green mussel (Perna viridis). The 96-h Median Lethal concentration (LC50) for the PL of shrimp was 3.36 mg L−1 and the chronic value for the long-term survival endpoint in a 21-d exposure was 0.10 mg L−1. The green mussel 96-h LC50 was 28.41 mg L−1 and the chronic value for the long-term survival endpoint in a 30-d exposure was 3.06 mg L−1. Native polyacrylamide gel electrophoresis revealed altered diverse isoforms of esterase, superoxide dismutase and malate dehydrogenase activities in the PL of shrimp and green mussel exposed to sublethal concentration of Se. Cellular anomalies such as deformation and fusion of corneal cells, detachment of corneal cells from cornea facet and increased space between ommatidia were observed in the compound eye of PL of shrimp exposed to Se for 21-d. Shrinkage and clumping of mucous gland, degenerative changes in phenol gland, and ciliated epithelium were observed in the foot of green mussel exposed to Se for 30-d. This study shows that cellular anomalies in the compound eye of PL of P. monodon and foot tissues of P. viridis described would affect the vision of shrimp and byssus thread formation in green mussel.

Benefits of stocking white spot syndrome virus infection free shrimp (Penaeus monodon) post larvae in extensive ghers of Bangladesh

Shrimp farming is an important income generating activity for hundreds of thousands of small scale farmers operating extensive ghers in Bangladesh. White spot syndrome virus (WSSV) has caused major shrimp production losses globally including Bangladesh. This study investigated the benefits of stocking WSSV infection free (WSSVF) Penaeus monodon post larvae (PL) to extensive gher holders of southwest Bangladesh and considered different parameters of the farming system. The longitudinal observational study included 636 gher holders comprising two distinct PL user types; 312 gher holders had stocked polymerase chain reaction (PCR) tested WSSVF and 324 non-tested (NT) PL. Data on explanatory and outcome variables were collected fortnightly during April–October 2015. The major findings were: (i) gher holders who stocked WSSVF PL had significantly higher survival, less disease, higher shrimp production and increased profitability compared to NT PL users, (ii) WSSVF PL stocking had an influence in strengthening the resilience, overall management and economic performance of the extensive gher holders.The study showed that WSSVF PL users had significantly small ghers, higher levels of better management practices (BMP) compliance such as nursery rearing of PL, double netting at inlet, periodic sampling, net fencing and bird netting, significantly higher application rates and usage amount of inputs (lime, inorganic fertilizer, feed) compared to NT PL users. It also found that gher size, water depth, stocking density, stocking frequency, cropping patterns affected levels of shrimp survival, production and disease incidence of the overall population. The results suggested that improving the availability of WSSVF PL through a PCR testing service, production of specific pathogen free PL and limit/stop the sale of WSSV infected PLs could significantly increase shrimp production of extensive gher holders.

Physical and chemical characteristics of soil from tiger shrimp aquaculture ponds at Malacca, Malaysia

ABSTRACTSoil physicochemical properties of the growout ponds of black tiger shrimp (Penaeus monodon) were examined in relation to shrimp yields for one production cycle. The culture ponds were old (>5 years) and new (newly constructed) types. Soil texture was silty clay with low sand content and high proportion of clay for both the pond types with alkaline soil pH (7.87–9.71). Organic matter (OM) concentration was higher (7.48 ± 0.01%) in old ponds and positively related (r = 0.58, P < 0.05) with total nitrogen (TN). The major cations (Ca, Mg, and Na) were higher in the soil of old ponds and did not fluctuate significantly during culture. The majority of trace elements, i.e., Fe (349.22 ± 35.7 ppm), Mn (56.19 ± 30.2 ppm), Zn (88.56 ± 8.09 ppm), Al (454.3 ± 200.6), Pb (1.3 ± 0.96 ppm), Co (3.4 ± 0.2), V (6.56 ± 1.79 ppm), Cr (19.32 ± 0.63 ppm), Ti (82.78 ± 54.3 ppm), As (5.60 ± 0.28 ppm), Ag (0.38 ± 0.5 ppm), and Sb (3.89 ± 0.48 ppm) were found to be higher in new pond soils than the old ponds. Except for soil manganese, no major fluctuations in trace elements were observed during the culture period. Shrimp growth was not significantly different in the two types of ponds, and no distinct correlation between shrimp growth and element content of soils could be drawn. The results indicate that shrimp pond age may not affect production of shrimp if soils are properly managed pre- and postculture. The differences in production in different ponds might be the result of management practice such as quality of shrimp post larvae, pond preparation, water and feed quality, and available live feed in the pond bottom or other environmental factors like water nutrients and physicochemical parameters.

The impacts of modern-use pesticides on shrimp aquaculture: An assessment for north eastern Australia

The use of pyrethroid and neonicotinoid insecticides has increased in Australia over the last decade, and as a consequence, increased concentrations of the neonicotinoid insecticide imidacloprid have been measured in Australian rivers. Previous studies have shown that non-target crustaceans, including commercially important species, can be extremely sensitive to these pesticides. Most shrimp farms in Australia are predominantly located adjacent to estuaries so they can obtain their required saline water, which support multiple land uses upstream (e.g. sugar-cane farming, banana farming, beef cattle and urbanisation). Larval and post-larval shrimp may be most susceptible to the impacts of these pesticides because of their high surface area to volume ratio and rapid growth requirements. However, given the uncertainties in the levels of insecticides in farm intake water and regarding the impacts of insecticide exposure on shrimp larvae, the risks that the increased use of new classes of pesticide pose towards survival of post-larval phase shrimp cannot be adequately predicted. To assess the potential for risk, toxicity in 20day past hatch post-larval Black Tiger shrimp (Penaeus monodon) to modern use insecticides, imidacloprid, bifenthin, and fipronil was measured as decreased survival and feeding inhibition. Post-larval phase shrimp were sensitive to fipronil, bifenthrin, and imidacloprid, in that order, at concentrations that were comparable to those that cause mortality other crustaceans. Bifenthrin and imidacloprid exposure reduced the ability of post-larval shrimp to capture live prey at environmentally realistic concentrations. Concentrations of a broad suite of pesticides were also measured in shrimp farm intake waters. Some pesticides were detected in every sample. Most of the pesticides detected were measured below concentrations that are toxic to post-larval shrimp as used in this study, although pesticides exceed guideline values, suggesting the possibility of indirect or mixture-related impacts. However, at two study sites, the concentrations of insecticides were sufficient to cause toxicity in shrimp post larvae, based on the risk assessment undertaken in this study.

Non-lethal heat shock induces Hsp70 synthesis and promotes tolerance against heat, ammonia and metals in post-larvae of the white leg shrimp Penaeus vannamei (Boone, 1931)

Exposure to temperatures above ambient compromises normal physiological processes and adversely affects aquatic organisms. Nonetheless, non-lethal heat shock (NLHS) protects aquatic organisms against abiotic and biotic stress, perhaps due in part to the accumulation of heat shock protein 70 (Hsp70), a well conserved molecular chaperone. Hsp70 protects cells against stress-induced damage by assisting in the recovery of misfolded proteins, facilitating the folding of nascent proteins and promoting protein degradation. In this study, the immunoprobing of western blots containing protein extracts from the caudal muscle of heated and non-heated post-larvae (PL) of the shrimp, Penaeus vannamei with an antibody specific to Hsp70 revealed that NLHS enhanced Hsp70 build-up in the caudal tissues of shrimp PL. Moreover, exposure to NLHS protected P. vannamei PL against heat, ammonia and heavy metals. The findings in this paper indicate that Hsp70 synthesized in response to NLHS contributed to the protection of P. vannamei PL against several different abiotic stressors. Such findings are potentially useful in the formulation of strategies to protect Penaeid shrimps against environmental stresses during aquaculture.

Microbiome Dynamics in a Shrimp Grow-out Pond with Possible Outbreak of Acute Hepatopancreatic Necrosis Disease

Acute hepatopancreatic necrosis disease (AHPND) (formerly, early mortality syndrome) is a high-mortality-rate shrimp disease prevalent in shrimp farming areas. Although AHPND is known to be caused by pathogenic Vibrio parahaemolyticus hosting the plasmid-related PirABvp toxin gene, the effects of disturbances in microbiome have not yet been studied. We took 62 samples from a grow-out pond during an AHPND developing period from Days 23 to 37 after stocking white postlarvae shrimp and sequenced the 16S rRNA genes with Illumina sequencing technology. The microbiomes of pond seawater and shrimp stomachs underwent varied dynamic succession during the period. Despite copies of PirABvp, principal co-ordinates analysis revealed two distinctive stages of change in stomach microbiomes associated with AHPND. AHPND markedly changed the bacterial diversity in the stomachs; it decreased the Shannon index by 53.6% within approximately 7 days, shifted the microbiome with Vibrio and Candidatus Bacilloplasma as predominant populations, and altered the species-to-species connectivity and complexity of the interaction network. The AHPND-causing Vibrio species were predicted to develop a co-occurrence pattern with several resident and transit members within Candidatus Bacilloplasma and Cyanobacteria. This study’s insights into microbiome dynamics during AHPND infection can be valuable for minimising this disease in shrimp farming ponds.

Tetraselmis chuii biomass as a potential feed additive to improve survival and oxidative stress status of Pacific white-leg shrimp Litopenaeus vannamei postlarvae

Shrimp is an important traded fishery commodity. When subjected to stress, shrimp usually suffers from oxidative stress, which leads to cell injury, senescence, and death. To maintain shrimp good health, performance and production, antioxidant and immune systems are important. Natural antioxidants found in microalgae may be used to increase the cell protection against oxidative damage, being a promising alternative to the carcinogenic synthetic antioxidants. In this study, Tetraselmis chuii was evaluated for its effect on survival, growth and oxidative stress biomarkers on Litopenaeus vannamei postlarvae (PL). The antioxidant properties of the formulated feed with T. chuii inclusion were determined using four antioxidant chemical assays. Meanwhile, the oxidative stress biomarkers on PL were analyzed by hydrogen peroxide, membrane stability and lipid peroxidation assays. Results showed that PL reared on diets supplemented with 50% T. chuii had a significantly higher (P ≤ 0.05) survival (97.6 ± 1.4%) and lower oxidative stress in terms of hydrogen peroxide content (10.08 ± 0.4 mM g−1 FW) and electrolyte leakage (10.8 ± 0.3%). The result of this study also showed that shrimp PL reared on diets supplemented with microalgal, T. chuii have high resistance to reverse salinity stress test (76.7–100%). However, no significant differences (P ≥ 0.05) were found in the growth and lipid peroxidation. Due to the positive effect on oxidative stress status, survival and resistance to salinity stress, the feeding of L. vannamei PL with diet containing at least 50% of T. chuii is recommended as a natural source of antioxidant for PL.

Replacement of fishmeal by two types of fish protein hydrolysate in feed for postlarval shrimpLitopenaeus vannamei

After filleting of tilapia, the material remaining is discarded and this waste represents about 700 g/kg of fish body volume, corresponding to carcass and viscera. These leftovers are important sources of proteins that can be used as feed in aquaculture industry by producing protein hydrolysates. In this study, two protein hydrolysates of tilapia were produced, with one (FPH1) and two (FPH2) hours of hydrolysis. The nutritional composition of the hydrolysates showed desirable levels of crude protein and essential amino acids. Electrophoresis revealed peptides ranging from 10 to 250 kDa. In addition, caseinolytic activity was recorded by zymogram. The hydrolysates were incorporated separately in experimental diets to replace fishmeal at distinct levels: 0, 40, 80 and 120 g/kg, totalizing seven diets named 0 (control), 40H1, 80H1, 120H1, 40H2, 80H2 and 120H2. A 45-day feeding trial was carried out to evaluate the zootechnical performance of postlarvae fed these diets. In conclusion, the use of FPH2 as a substitute for fishmeal promotes better shrimp growth than FPH1 and allows higher levels of substitution. In addition, it is recommended a 60 g/kg fishmeal replacement by FPH2 to improve growth.

A probiotic Bacillus strain containing amorphous poly-beta-hydroxybutyrate (PHB) stimulates the innate immune response of Penaeus monodon postlarvae

In this study, the PHB-accumulating Bacillus sp. JL47 strain (capable of accumulating 55% PHB on cell dry weight) was investigated for its effects on the immune response of giant tiger shrimp (Penaeus monodon) postlarvae (PL) before and after the Vibrio campbellii challenge. Briefly, shrimp PL were cultured and fed with Artemia nauplii enriched with Bacillus sp. JL47. Shrimp receiving the Artemia nauplii without JL47 enrichment were used as control. After 15 days of feeding, the shrimp were challenged with pathogenic V. campbellii LMG 21363 at 106 cells mL−1 by immersion. Relative expression of the immune related genes encoding for prophenoloxidase (proPO), transglutaminase (TGase) and heat shock protein 70 (Hsp70) in the shrimp were measured before (0 h) and after (3, 6, 9, 12, 24 h) the Vibrio challenge by quantitative real-time PCR using β-actin as the reference gene. The expressions of TGase and proPO were significantly up-regulated (p < 0.05) within 9 h and 12 h, respectively after challenge in shrimp receiving the Bacillus sp. JL47 as compared to the challenged and non-challenged controls. Hsp70 expression was significantly increased (p < 0.05) at 3 h post-challenge in all challenged shrimp. Interestingly, proPO and TGase genes were significantly up-regulated (p < 0.05) in Bacillus sp. JL47 treated shrimp even before the Vibrio challenge was applied. No up-regulation in the Hsp70 gene, however, was observed under these conditions. The data suggest that the protective effect of the PHB-accumulating Bacillus sp. JL47 in shrimp was due to its capacity to stimulate the innate immune related genes of the shrimp, specifically the proPO and TGase genes. The application of probiotic Bacillus species, capable of accumulating a significant amount of PHB, is suggested as potential immunostimulatory strategy for aquaculture.

Bacterial Loads in Shrimp and Fish Hatchery Environments of Bangladesh

Artemia hatching tank of Cox’s Bazar hatchery had similar total bacterial build up (2.59 ± 0.10×107cfu/g) in the water sampled and in the shrimp post larvae (PL) sampled at stage 10 and 12 (2.37 ± 0.11×107cfu/g and 2.42 ± 0.10×107cfu/g, respectively). In MA plate, no significant differences was observed in the bacterial count of these samples. Similar result was observed for the total presumptive vibrio count in TCBS plates ranging from 3.8 ± 0.60×103cfu/g to1.62 ± 0.50×103cfu/g.Total bacterial load (7.5 ± 0.11×107) measured in the water sampled from 25 day old fry rearing pond of tilapia from Mymensingh Hatchery, was similar to that of 33 day old fry (8.6 ± .66×107). The bacterial density found in the 25 (1.6 ± 0.50×107), 28 (3.12 ± 0.14×107) and 40 day old fry (6.46 ± 1.52×106) samples was similar but significantly different from the sample of 33 day old fry and the water sample of the pond of 25 day old fry. In TCBS plate, bacterial abundance detected in the samples across all four age groups was similar (25 day old fry: 4.21 ± 3.79×103; 28 day old fry: 4.90 ± 3.50×103; 33 day old fry: 1.08 ± 0.12×103; 40 day old fry: 7.04 ± 2.08×103). In finfish hatchery of Bogra, the overall bacterial build up (2.03 ± 0.31×108) found in the samples of zeol fish fry in NA plate was significantly higher than that of the corresponding rearing pond water (2.11 ± 0.459×107) and the water of the live food rearing tank ( 8.43 ± 0.57×106). Similar to that, TCBS plates had 2.3-, and 5.09-folds higher bacterial load (1.08± 0.25×103) in the samples of fish fry than in the samples of the corresponding water samples and water samples of the live food rearing tank, respectively (4.70 ±w 1.67×102 and 2.12 ± 0.28×102).&#x0D; Asiat. Soc. Bangladesh, Sci. 43(1): 37-47, June 2017

Isolation and risk assessment of Geotrichum spp. in the white shrimp (Litopenaeus vannamei Boone, 1931) from culture ponds

The present study was done in order to identify the fungus invading some of the supralittoral ponds used for shrimp aquaculture in the CIBNOR facilities in La Paz, Baja California Sur (BCS), México during the summer season. From the walls and bottoms of the ponds, two strains of Geotrichum spp. were isolated and morphologically identified. Fungal adhesion towards hemocytes and primary cultures of various white shrimp (Litopeneaus vannamei) tissues (gill, tegument, and gut) was analyzed to determine infectivity. Extracellular protease, lipase, and amylase activity were evaluated as virulence factors. Survival of shrimp postlarvae (PL8) exposed to fungal culture supernatant or to their filaments was also investigated. The results showed that shrimp tegument cells and hemocytes were very susceptible to Geotrichum spp. invasion, and that this fungus provokes great mortality of post-larvae. Hence, Geotrichum spp. could be considered an opportunistic pathogen that might represent a serious health risk to shrimp in culture.

Sunlight and sediment improve the environment of a litter biofilm-based shrimp culture system

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 9:73-85 (2017) - DOI: https://doi.org/10.3354/aei00213 FEATURE ARTICLE Sunlight and sediment improve the environment of a litter biofilm-based shrimp culture system Charles Gatune1,*, Ann Vanreusel2, Marleen De Troch2 1School of Natural Resources and Environmental Studies, Karatina University, PO Box 1957─10101, Karatina, Kenya 2Biology Department, Marine Biology, Ghent University, Campus Sterre, Krijgslaan 281-S8, 9000 Ghent, Belgium *Corresponding author: kgatune@yahoo.com ABSTRACT: In silvofishery, where shrimp culture is integrated with mangrove trees, the mangrove leaf litter may modify the environment in these culture systems. This study tested the potential of submerged leaf litter of Rhizophora mucronata and associated biofilm in providing a favorable environment for post-larval shrimp Penaeus monodon. Litter decomposition and assembly of microalgae and epifauna were assessed under exposure to sunlight or shade, and presence or absence of sediment. Litter incubated with sediment and exposed to sunlight was rapidly decomposed and supported the highest biomass and diversity of microalgae and epifauna. The litter also supported the highest abundance of diatoms, polychaetes and nematodes during the 4th week of decomposition. Cyanobacteria of the genus Microcystis dominated litter incubated without sediment, in sunlight, after decomposition for 5 wk. Under shaded conditions, diatoms of the genus Navicula and the Cyanobacteria Anabaena spp. and Oscillatoria spp. continued to grow at high total ammonium nitrogen, low dissolved oxygen, low temperature and low pH. Our study illustrates synergy between sediment and direct sunlight in promoting diversity of microalgae and polychaetes (of dietary benefit to shrimps), inhibiting growth of Cyanobacteria and maintaining water quality at levels favorable to culture of post-larval shrimp. Our findings support 4 practices for a healthy environment in fish ponds: (1) locating ecological shrimp culture in less forested areas, (2) promoting sediment conditions in artificial shrimp culture systems, (3) exposing litter-derived biofilm within ponds to sunlight and incubating with sediment to maintain favorable water quality and control Cyanobacteria blooms, and (4) minimizing the use of pond liners and related sludge removal. KEY WORDS: Shrimp culture · Sunlight · Sediment · Mangrove litter · Microalgae · Epifauna · Biofilm Full text in pdf format Information about this Feature Article PreviousNextCite this article as: Gatune C, Vanreusel A, De Troch M (2017) Sunlight and sediment improve the environment of a litter biofilm-based shrimp culture system. Aquacult Environ Interact 9:73-85. https://doi.org/10.3354/aei00213 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 9. Online publication date: February 08, 2017 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2017 Inter-Research.

Abundance of Shrimp (&lt;i&gt;Penaeus Monodon&lt;/i&gt;) Post Larvae (PL) and to Quantify the Damage of Different Aquatic Fauna during Shrimp PL Collection in Mongla Tidal River (Rampal), Bagerhat

The study was conducted in Mongla tidal river (Rampal) of Bagerhat district from November 2014 to October 2015 to assess the abundance of black tiger shrimp (Penaeus monodon) post larvae (PL) and to quantify the damage of different aquatic fauna during collection of P. monodon PL. Insignificant variation in water temperature, pH, salinity and hardness were found but salinity and hardness showed great fluctuation during the study period. On average 6.3 million of P. monodon PL were collected annually from the studied area and around 0.16 million man days/year were estimated to be involved in shrimp PL collection activities. It was found that about 412 other shrimp larvae, 391 fin fishes and 1696 other macrozooplankton were killed during the period of collection for only one PL of P. monodon. It was also calculated from the present study that about 29,874 million of other shrimp species, fin fishes and macrozooplankton were destroyed annually by the shrimp seed harvesting process in Mongla river. The study implies that present seed collection practice caused severe damage of other valuable aquatic fauna, which directly affect the biodiversity of tidal waters, natural productivity, improvement of mother stock and environment friendly of coastal and marine water.

Shrimp Post-Larvae Nursing in Earthen Ponds, Bangladesh

In Bangladesh, shrimp post-larvae (PL) are mainly produced in hatcheries. From 2000s shrimp PL are reared in nurseries containing small earthen ponds by relatively poor people for a few days before stocking into the shrimp farms. This study assesses the physical and chemical parameters of five such nurseries at Satkhira district, Bangladesh using scientific instruments and semi-structured questionnaire. The nursing process involved stocking of PL (4151.8 ± 1581.35 PL/m2) in small earthen ponds (&lt;18m2 area/pond) and raring for up to 10 days with feeding. Most of the physico-chemical parameters were within the suitable range recommended for shrimp culture. The survival rate of PL ranged from 80% to 90%. The nursing system was profitable as the average Benefit-Cost Ratio (BCR) was 1.19. The establishment and operation of these nurseries do not require any expensive equipment or complex technology and can be run by less educated and poor people. However, constraints like lack of credit and continuous water supply are hindering the scaling up of these nurseries in size and number. By providing means to overcome the constraints these nurseries can be an excellent income generating source for the poor entrepreneurs as well as contribute in increasing shrimp production in Bangladesh.

Effect of tidal hour on the abundance of penaeid shrimp postlarvae (Decapoda, Penaeidae) along the Mexican Pacific coast

In the present study we explored the effect of the tidal hour on the postlarvae abundance of the penaeid white-leg shrimp (Litopenaeus vannamei (Boone, 1931)) in three Mexican Pacific coastal lagoons. Correlation analysis of tidal hour against the hourly variation of the abundance of postlarvae was conducted in three regions of the Mexican Pacific; the system lagoon Huizache-Caimanero LHC, the region of the “Grandes Lagunas” SGL and the “Mar Muerto” Lagoon LMM. Two peaks were found in L. vannamei abundance in the three locations, at 04:00 and 16:00 of tidal hour in LHC and SGL, and 06:00 and 12:00 of tidal hour in LMM. Significant correlations between postlarvae and the tidal hour for the three regions were found. The tidal hour standardizes the time of ebb and flow. It is concluded that tidal hour can be used as cue for shrimp postlarvae immigration to nurseries.

Impact of farm management on expression of early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) on penaeid shrimp farms in Thailand

Asian shrimp farming industry has experienced massive production losses due to a disease caused by toxins of Vibrio bacteria, known as early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) for the last 5years. The disease can cause up to 100% cumulative pond mortality within a week. The objective of this study was to identify factors associated with AHPND occurrence on shrimp farms. A case-control study was carried out on shrimp farms in four provinces of Thailand. Factors related to farm characteristics, farm management, pond and water preparation, feed management, post-larvae (PL) shrimp and stock management were evaluated. Multivariable logistic regression analysis identified factors affecting AHPND occurrence at the pond level. Chlorine treatment, reservoir availability, use of predator fish in the water preparation, culture of multiple shrimp species in one farm and increased PL stocking density contributed to an increased risk of AHPND infection, while delayed first day of feeding, polyculture and water ageing were likely to promote outbreak protection. Additionally, the source of PL was found to be associated with AHPND occurrence in shrimp ponds, which requires further study at the hatchery level. Identification of these factors will facilitate the development of effective control strategies for AHPND on shrimp farms.