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Astaxanthin is a ketocarotenoid that is the primary pigment in shrimp and has powerful biological effects. This molecule comprises a 40-carbon chain with multiple double bonds at the end that connects to ketone and hydroxyl groups. The terminal hydroxyl groups can react with fatty acids and form monoester and diester of astaxanthin. Shrimp waste is an inexpensive source of this compound, whose extraction and purification can improve the economy of fishery production and processing in addition to solving the problem of shrimp waste disposal. The efficiency of astaxanthin extraction from Penaeus semisulcatus and Penaeus merguensis wastes was compared for the first time in the present study, employing the fermentation process with two strains of Lactobacillus acidophilus and Lactobacillus plantarum bacteria. The extraction conditions and effects of various treatments on astaxanthin yield were then adjusted using a Box-Benken design with three parameters: fermentation temperature (30–40 °C), fermentation time (12–72 h), and specifically by modifying the waste particle size (40–60 mesh). Following purification of the pigment, H-NMR and FT-IR spectroscopies, as well as Rf values, were clearly utilized to identify the astaxanthin present in the waste. The findings demonstrated that P. semisulcatus shrimp waste had considerably greater extraction yield with both bacterial strains than P. merguiensis shrimp (p<0.05). Also, L. plantarum bacteria had a higher ability to create better fermentation conditions and, as a result, higher extraction of astaxanthin from both shrimp species. Optimum conditions for this bacterium include a fermentation temperature of 35°C, a time of 72 h, and a particle size of 80 mesh. The Rf value for mono (0.59) and diester (0.76) of astaxanthin obtained were in accordance with international standards. FTIR analysis determined the recognizable peaks of mono and diester of astaxanthin, including hydroxyl functional groups and the vibrational mode related to its ester at the end of the polyene chain of astaxanthin. Also, an examination of H-NMR data showed the presence of indicative protons related to astaxanthin and fatty acids attached to it in the chemical shift regions of the spectra of extracted astaxanthin esters. [ABSTRACT FROM AUTHOR]

Reproductive dynamics of commercially important penaeid prawn Penaeus merguiensis was investigated in the coastal waters of Maharashtra during 2002-2003 by collecting data from inshore nearshore and offshore, waters. The size at maturity was 123 mm for males and 133 mm for females. The species spawned throughout the year with two spawning peaks, major one during March-May and minor during October-December and spawning area of the species is offshore waters >40 m depth. Ova diameter study showed tendency to shed all their eggs at one instance, but the progression of modal sizes of mature females demonstrated that females with spawning periodicity of 26±5.5 days could spawn about 12 times during their life span. The sex ratio showed that mainly large sized mature females migrate towards offshore deeper waters. Fecundity was exponentially related to length by F= 0.000000528*TL5.2086. The population fecundity index in nearshore and offshore areas indicated two peaks with major spawning activity during March-April and minor during August-September. The egg production by the surviving population in the sea, gave major peak during April-May and a minor during November. The occurrence of juveniles in the catch was bimodal and their mean size declined twice in inshore, nearshore and offshore waters which pointed to two recruitment pulses in March and November in inshore waters and in March and December in nearshore and offshore waters. The percentage of juveniles was the highest in March which suggested that post-monsoon spawning in November was the most effective. The ratio of juveniles and the egg production gave annual survival rate of 0.03%. The monthly survival showed bimodal trend with peak in April (0.07%) and November (0.03%), which suggested that spawning during November-December and May-June was responsible for the two cohorts, the post-monsoon and pre-monsoon, among which the former was more successful. [ABSTRACT FROM AUTHOR]

در فصل صید سال 1398، اطلاعات صید، اطلاعات جوی و دریایی با هدف بررسی اثر عوامل محیطی بر میزان صید بر واحد تلاش صیادی (CPUE) میگوی موزی (Penaeus merguiensis) و سرتیز (Metapanaeus affinis) در صیدگاه‌های بندرعباس، قشم و بندر کلاهی به وسیله آزمون‌های رج‌بندی، آزمون جایگشتی و محاسبات رگرسیونی جمع آوری شد.طی 49 مرتبه تورکشی، 1932 کیلوگرم میگو شامل 1379 کیلوگرم میگوی موزی با میانگین 56/12 (با حدود اطمینان 95 درصد 68/9 تا 45/15) کیلوگرم بر ساعت و 553 کیلوگرم میگوی سرتیز با میانگین 18/5 (با حدود اطمینان 95 درصد 69/3 تا 68/6) کیلوگرم بر ساعت صید گردید. طبق نمودار رج‌بندی، صید بر واحد تلاش صیادی میگوی موزی با عمق، میزان بارندگی و دمای سطح آب ارتباط مستقیم و معنادار و با سرعت وزش باد، ابرناکی، رطوبت، شوری و ارتفاع موج ارتباط کمی دارد. میزان صید به ازای واحد تلاش صیادی میگوی سرتیز با شوری و دمای سطح آب ارتباط مستقیم و با ارتفاع موج و رطوبت ارتباط معکوس و با عمق، میزان بارندگی، سرعت وزش باد و ابرناکی ارتباطی نداشت؛ اما در نتایج آزمون جایگشتی، این روابط معنی‌دار نبود. طبق مدل دوجمله‌ای منفی در روش رگرسیون، متغیرهای متغیرهای سرعت شناور و میزان شوری (01/0P

β-glucans are produced by many organisms and could be used as supplementary feed to enhance immunity and growth in some aquatic animals. This study aimed to compare the effectiveness of β-glucans derived from two marine diatoms (Chaetoceros muelleri and Thalassiosira weissflogii) as growth promoters and immunity enhancers in banana shrimp (Penaeus merguiensis). Shrimp were divided into 3 groups: the control group was fed without β-glucan; the second and the third group were fed with 2 g kg−1 of β-glucan derived from C. muelleri and T. weissflogii , respectively. Shrimp were fed over a 30-day period to determine growth performance (final weight, weight gain, average daily gain (ADG), and feed conversion ratio (FCR)) at day 15 and day 30, respectively. The immune parameters determined were total hemocyte count (THC), phenoloxidase activity (PO) and immune gene expression. Survival rates were measured after 14 days of the feeding trial and Vibrio parahaemolyticus infection (6, 24, 48 h post infection). There was no significant difference (P > 0.05) for growth stimulation of shrimps between the two types of β-glucans (C. muelleri or T. weissflogii). Notably, shrimps fed with β-glucans had a higher final weight, weight gain, and ADG (P < 0.05) than shrimps fed with the control diet, while FCR of shrimps fed with both β-glucans was lower when compared to the control diet. Immune parameters, THC, PO, and gene expression of anti-lipopolysaccharide factor (ALF) and crustin were significantly higher (P < 0.05) in shrimps fed with β-glucans, especially with β-glucans from C. muelleri than the control group both before and after V. parahaemolyticus infection. Expression of penaeidin 3 and peroxiredoxin genes was significantly higher in shrimps fed with β-glucans after bacterial infection. Histopathology of hepatopancreas revealed an increase in blasenzellen hepatopancreatic epithelial cells (B cells) after 14 days of feeding which remained higher following infection with V. parahaemolyticus. The survival rate of shrimps fed with the diet containing β-glucan derived from either C. muelleri (82.2%) or T. weissflogii (77.8%) after V. parahaemolyticus infection was significantly higher than for the control group (51.1%) (P < 0.05). In conclusion, we propose that feeding banana shrimps with β-glucans derived from marine diatoms either C. muelleri or T. weissflogii at a 2 g kg−1 diet can significantly improve their growth performance and immunity. • β-glucans from diatom either C. muelleri or T. weissflogii had no toxicity and could be use as supplement for shrimp. • β-glucans derived from marine diatoms (C. muelleri and T. weissflogii) can improve banana shrimp growth and immunity. • β-1,3/1,6-glucan from C. muelleri is superior to β-1,3-glucan from T. weissflogii to promote shrimp growth and immunity. [ABSTRACT FROM AUTHOR]

A study was carried out to determine the maturation period, quality and quantity of sperms production in Banana shrimp male broodstock, Penaeus merguiensis fed different natural diets. The three different natural diets namely; squid, fish and shrimp flesh used in this study were obtained from known sources and fed to the tested shrimp in triplicate groups. Based on the results obtained, squid seem to be the most effective natural diet as it enhances the sperms maturation within 20 days. Feeding fish and shrimp flesh as diets for the Banana shrimp broodstock resulted in the observation of maturation in 22 and 24 days, respectively. Similarly, squid diet also recorded the highest (p = 0.002; p < 0.05) sperms count (58.6 to 74.5) as compared to fish diet (44.0 to 61.3) or shrimp diet (28.0 to 42.8). Also, feeding squid diet resulted in a higher percentage of live sperms with ranged between 97.75% to 98.80%. On the other hand, broodstocks fed fish and squid flesh was observed with ranges of between 96% to 97.86% and 92.54% to 96.06%, respectively. It was therefore concluded that squid diet was most effective to improve sperm quality, quantity and maturation period in male broodstock of P. merguiensis. Further study should be carried on the reproductive performance of broodstock fed with squid as diets and it effect on the performances of post larvae obtained. [ABSTRACT FROM AUTHOR]

Study on ovarian maturation stages were carried out using external morphological assessment of ovarian colourations and histological assessment of Oocyte structure for broodstock selection purpose. Stage 1 to Stage 4 of female shrimps broodstock were sampled from Kuala Muda, Kedah, Malaysia. Four obvious colourations of ovary stages were identified which are: yellow (Stage 1), green yellowish (Stage 2), light greenish (Stage 3) and dark green (Stage 4) through the morphological assessment. The Gonadosomatic Index (GSI) showed significant increment as the gonad reach advance stages. Histological assessment of Stage 1 ovary identified perinucleolar oocyte (PO) with small size oocytes. Stage 2 ovary was identified with yolkless oocyte (YO), Stage 3 ovary was identified with late stage of yolky globules and Stage 4 ovary was identified with fully yolky globules. From the results achieved, it can be concluded that the ovarian colourations and GSI can be applied to identify the ovarian maturation stages, meanwhile, the histology assessment is the most precise method to determine the ovarian maturation stages in more details and accurate for each of the ovarian maturation stages. [ABSTRACT FROM AUTHOR]

The water quality supporting the growth of aquatic animals on the surface is usually better than that those accumulated at the seabed and more bottomless sea. Since water usually brings many materials along the path all the way to reaching its end, their quality varies in places and seasons as area it passes also influences the possessed quality. By employing Penaeus merguiensis larvae produced by the Jepara's Marine Center for Brackishwater-Aquaculture Development owned by Jepara's government, this study analyzes varying effects in three nominal salinities (28, 32, and 36 ppt) and types of diets (Diet A: 100% live feed; Diet B: 100% FRIPPAK; Diet C: a combination of Diet A and Diet C, 50 % each) and finds the optimum water quality parameters such as dissolved oxygen, pH, and temperature on the growth of the newly introduced Penaeus merguiensis larvae. The results show that salinity of 28 and 32 ppt with Diet A works well in supporting the growth from Zoea to Postlarvae-1: Zoea-1 at 28 ppt with Diet A; Zoea-2 at 32 ppt with Diet A; Zoea-3 at 32 ppt with Diet A; Mysis-1 at 28 ppt with Diet A; Mysis-2 at 28 ppt with Diet C; Mysis-3 at 28 ppt with Diet A; Postlarva-1 at 28 ppt with Diet A. All shrimp prefers temperature ranging from 31-32.4°C with dissolved oxygen of 4.9-5.74 ppm and pH 7.0-8.1. [ABSTRACT FROM AUTHOR]

Illegal tin mining or unconventional mining activities produce tailings. Tailings contain dangerous heavy metals one of which is Lead (Pb). The increasing concentration of Pb in the waters will also increase its concentration in the body of the biota, one of which is shrimp. The purpose of this study was to analyse the Pb content in gills, hepatopancreas and muscle in Penaeus merguiensis, analyse the Pb content in water and sediments, measure the ability of Penaeus merguiensis in accumulating Pb in water and sediments, and determine the safe limit for consumption. Shrimp, water and sediment samples were analysed using AAS. The results showed that the highest Pb concentration in Penaeus merguiensis was hepatopancreas> gill> meat, with an average range of 0,1897–0,4064 mg/kg, gills 0,2424-0,4770 mg/kg, and meat 0,1348-0,1636 mg/kg. The average Pb concentration in water ranged from 0,2624 to 0,5713 mg/L, while the sediment ranged from 0,2783 to 0,9760 mg/kg. The ability of Penaeus merguensis to accumulate Pb included in the low category. The value of daily intake is around 9,760-11,128 kg/week. Aktivitas penambangan timah illegal atau tambang inkonvensional menghasilkan sisa limbah buangan (Tailing). Tailing mengandung logam berat berbahaya salah satunya Timbal (Pb). Meningkatnya konsentrasi Pb di perairan akan meningkat pula konsentrasinya dalam tubuh biota, salah satunya udang. Tujuan dilakukannya penelitian ini adalah menganalisis kandungan Pb pada insang, hepatopankreas dan daging pada Penaeus merguiensis, menganalisis kandungan Pb pada air dan sedimen, mengukur kemampuan Penaeus merguiensis dalam mengakumulasikan Pb di air dan sedimen, dan menentukan nilai batas aman konsumsi. Sampel udang, air dan sedimen dianalisis menggunakan AAS. Hasil penelitian menunjukkan bahwa konsentrasi Pb tertinggi pada Penaeus merguiensis adalah hepatopankreas>insang>daging, dengan kisaran rata-rata 0,1897–0,4064 mg/kg, insang 0,2424-0,4770 mg/kg, dan daging 0,1348-0,1636 mg/kg. Konsentrasi Pb rata-rata dalam air berkisar antara 0,2624-0,5713 mg/L, sementara sedimen berkisar dari 0,2783-0,9760 mg/kg. Kemampuan Penaeus merguensis untuk mengakumulasi Pb termasuk dalam kategori rendah. Nilai asupan harian sekitar 9,760-11,128 kg/minggu.

The two banana prawns Penaeus merguiensis and P. indicus are arguably the most commercially important species of penaeid prawns in the tropical and sub-tropical Indo-West Pacific region. They are fecund, short-lived, and have a complex life history involving offshore spawning, inshore mangrove-lined nursery grounds, and migrations between the two locations. We have reviewed and assessed published research on: the fisheries and aquaculture; taxonomy and identification; distribution and habitat preferences; growth; mortality; food and feeding; predation, and the importance of the mangrove habitat to banana prawns. We have examined the life history patterns of these two banana prawns and the many environmental and biological factors that affect different life history stages, often resulting in large interannual variations in abundances of adult prawns and commercial catches. We have also reviewed research on the ecosystem relationships involving these prawns, including fishery impacts on the environment and other species caught as bycatch. In reviewing the published information on factors affecting recruitment dynamics and variability, we have sometimes found contrasting and confounding results, suggesting that these factors are not yet fully understood. Therefore, for each aspect of the prawns' biology we have pointed to areas with incomplete or conflicted understanding, which will hopefully guide future research on these extremely valuable prawn species. [ABSTRACT FROM AUTHOR]

Modification of freshwater flow regimes can impact estuarine ecosystems at the receiving end of these flows. This is particularly true in tropical areas, such as the wet-dry tropics, where major freshwater flows in the wet season may result in prolonged and large-scale flooding, followed by periods of little or no flow during an extended dry season. Estuarine species, such as the commercially important prawn Penaeus merguiensis, have lifecycles adapted to seasonal flows. The potential effects of flow regulation on estimated catches of P. merguiensis were explored using a Bayesian belief network (BBN) model. Probability statements were generated about the ecological implications of different magnitudes of natural flow, as well as three water-extraction scenarios: 1) reduced flow in the wet season; 2) the introduction of flow in the dry season; and 3) the combination of scenario one and two. Thresholds of freshwater flow that affect the likelihood of high prawn catches in the fishery were identified, and the cumulative effects explored. This is the first time that these thresholds have been identified and the model suggests there is little capacity to regulate or modify the freshwater flow without reducing the probability of high prawn catches. [ABSTRACT FROM AUTHOR]

Mosquito cell lines (C6/36) were reported in the literature to support the propagation of Penaeus monodon hepandensovirus (PmoHDV). We aim to evaluate the susceptibility and viral propagation of P. merguiensis hepandensovirus (PmeHDV) which is ∼22% different to PmoHDV in Aedes albopictus cell line (C6/36). Cellular changes in the infected cell culture were detected. Vacuole formation was seen in both infected and uninfected cell cultures. The average number of disrupted cellular membranes in the infected cells (presumptive dead cells) was significantly higher than that of uninfected cells at passage two (F = 9.749, d.f. 1, 22, p < 0.05). Using a proliferation assay, light absorption of infected cells peaked at 2 weeks post-infection (O.D. = 0.27) but was significantly lower than that of the uninfected groups (O.D. = 0.37) (F = 6.879, d.f. 1, 94, p < 0.05) suggesting hindered cell growth. PCR of the serial passages of the infected cell cultures indicated weak positive results for PmeHDV infection and TaqMan quantitative PCR confirmed that the average number of viral copies declined from 3.8 × 10 5 to 5.69 × 10 2 copies per μL and the mean of cycle times increased from 19.26 to 27.63. These results are interpreted to mean C6/36 allows the initial stage of PmeHDV replication, but the virus was incapable of using C6/36 for patent replication of its’ virions. [ABSTRACT FROM AUTHOR]

Decapod Hepandensovirus 1 (HDV), formerly known as hepatopancreatic parvovirus, has been associated with stunting, lowered production and outright mortalities in prawns in aquaculture. Despite the fact that broodstock are sourced and aquaculture farms are planned in the regions of northern and Western Australia, data on these parvoviruses from this region are limited. The prevalence of HDV in Penaeus esculentus and Penaeus merguiensis is moderate (34–51%) in southern Western Australia, Exmouth Gulf and the Gulf of Carpentaria but statistically higher (P < 0.05) in Shark Bay (82%). We speculate this is due to the topography of Shark Bay combined with the currents of the Indian Ocean gyre (IOG). Despite an on average 8–12% genomic heterogeneity, the nucleotide sequences of HDV in WA most closely align with HDV in regions associated with the IOG; Thailand, India, Tanzania, Madagascar; eastern Asia, Korea and less commonly, with sequences from the eastern coast of Australia. This potentially changes the paradigm of a single strain of HDV being ubiquitous in Australia and there was little risk in moving broodstock from WA to the eastern states, so there was no testing of broodstock for HDV. There is no strong evidence to clarify whether the strain of HDV in WA P. esculentus came from either its' nearest genetic relatives, P. monodon or P. semisulcatus or from P. merguiensis from the Solanderian province of Australia. P. esculentus HDV appears to be most related to strains within the IOG. The HDV nucleotide heterogeneity of wild prawns contrasts strongly to studies undertaken with prawns from aquaculture where genetic selection may have occurred. [ABSTRACT FROM AUTHOR]

Biotechnology of enzyme has gained popularity due to the growing need for novel environmental technologies and the development of innovative mass-production. The work describes the original application of biosensors based on Penaeus merguiensis alkaline phosphatase (PM ALP) immobilized on gold nanorods (GNRs) to heavy metal determination. Penaeus merguiensis alkaline phosphatase (PM ALP) was immobilized on gold nanorods (GNRs) by ionic exchange and hydrophobic interactions. The optimum pH and temperature for maximum enzyme activity for the immobilized PM ALP are identified to be 11.0 and 60 °C, respectively, for the hydrolysis of para-Nitrophenylphosphate ( p- NPP). The kinetic studies confirm the Michaelis–Menten behavior and suggests overall slightly decrease in the performance of the immobilized enzyme with reference to the free enzyme. K m and V max values were 0.32 µm and 54 µm. min −1 for free and 0.39 µm and 48 µm min −1 for immobilized enzymes, respectively. Similarly, the thermal stability, storage stability and stability at extreme pH of the enzyme is found to increase after the immobilization. The inhibitory effect heavy metal ions was studied on free and immobilized PM ALP. The bi-enzymatic biosensor were tested to study the influence of heavy metal ions and pesticides on the corresponding enzyme. The obtained high stability and lower decrease in catalytic efficiency suggested the great potential and feasibility of immobilized PM ALP nanobiocatalyst in efficient and apply the biosensor in total toxic metal content determination. [ABSTRACT FROM AUTHOR]

Sinus gland from Penaeus merguiensis De man, 1888 was extracted and proteins were fractionated on a HPLC column (μBondapack-phenyl column, 9 mm i.d., 10 μm particle size, Waters). Three major peaks (peaks 3, 5 and 6) were collected and investigated for crustacean hyperglycemic hormone (CHH) and gonad inhibiting hormone activity (GIH). The CHH activity of the peak 5 fraction was significantly higher than the control while peak 6 did not have significant CHH activity. No CHH activity was found in the peak 3 fraction. GIH activity was determined by inhibition of total protein and vitellin synthesis in ovarian tissue. An antivitellin antibody was prepared and used for immunoprecipitation in the GIH activity assay. Hence GIH activity was detected in peaks 5 and 6 while peak 3 had gonad stimulating hormone like activity (GSH-like activity).

It has been established that baculovirus-insect cell line is applicable for shrimp virus replication, propagation and secretion in the in vitro culture system. We thus aimed to produce Macrobrachium rosenbergii nodavirus (MrNV) clone within S2 cell to improve viral production over the previous model using Sf9 cell. Upon the transfection of genomic RNA1 and RNA2 into S2 cells, the recognizable cellular changes including cytoplasmic swelling and clumping of cells were observed within 24 h. The culture media containing secreted MrNV particles were re-transfected into healthy S2 cells and similar cellular changes as with the first transfection were observed. Immunohistochemistry analysis of the re-infecting S2 cell revealed an intense immunoreactivity against MrNV capsid protein confirming that S2 cell was permissive cells for MrNV. In vivo infectivity test using P. merguiensis as a model animal exposed to the secreted MrNV revealed the presence of RNA2 fragment in shrimp tissue accompanied with the sign of whitish abdominal muscle at 24 h post-infection (p.i.). In addition, the number of shrimp hemocytes decreased at 6–24 h p.i. and returned to the normal level at 48 h p.i., whereas a significant up-regulation of immune-related genes including HSP70 and trypsin was noted. These data suggested that rescued MrNV produced in S2 is practically useful for MrNV infection test in which their natural virion inoculae are difficult to obtain. In addition, the molecular basis of viral pathogenesis can further be investigated which should be beneficial for any antiviral therapy developments in the future. • S2 cells improved production of MrN infectious virions over Sf9 cells. • MrNV could infect P. merguiensis in vivo and cause white tail disease. • MrNV infection decreased number of hemocyte and altered the expression of immune-related gene of P. merguiensis. [ABSTRACT FROM AUTHOR]

The ability of three proteases producing bacteria such as Pseudomonas aeruginosa , Serratia marcescens , and Bacillus pumilus on the demineralization and deproteinzation efficiency of shrimp waste, for chitin extraction, was investigated. Statistical analysis of data was showed a significant difference between the percentage of demineralization and deproteinization in different bacteria species ( p < 0.05). The highest deproteinization (74.76%) and demineralization rate (78.46%) was obtained with P. aeruginosa and the lowest was observed in the treatment of S. marcescens . Then, chitin was converted to chitosan by deacetylation in the presence of NaOH 50%. The antioxidant activity of chitosan solution was determined using different tests. The highest activity (DO 700 nm = 0.74, DO 695 nm = 0.31) was observed for chitosan sample at concentration of 1000 μg/ml. The antioxidant potential of the hydrolysates was also evaluated. The highest reducing power in a volume of 400 μl hydrolysate of S. marcescens and the highest total antioxidant capacity in a volume 100 μl hydrolysate of B. pumilus were observed. These results indicated that the P. aeruginosa bacterium in comparison with other bacterial strains, higher ability to remove proteins and mineral from shrimp waste. Therefore, the use of this bacterium is recommended for protein and mineral removal from marine crustaceans. [ABSTRACT FROM AUTHOR]

Hemocyanin (HC) was purified from hemolymph of Fenneropenaeus merguiensis (de Man, 1888). Purified HC showed one band in non-denaturing PAGE with a molecular mass of 457 kDa, determined by gel filtration. Using an ELISA, HC content was 85.6% of total hemolymph protein. HC's hexamer form contained no phenoloxidase activity under trypsin or SDS activation. FmHC, cloned from F. merguiensis, had a full-length cDNA comprised of 2128 bp with an open reading frame encoding a peptide of 661 amino acids with two Cu-binding sites. Expression of FmHC was found only in the hepatopancreas where it was up-regulated after exposure to Vibrio harveyi injection into shrimp and with tissue incubations. HC protein levels in the hemolymph of bacterial injected shrimp also increased. FmHC expression was also up-regulated after shrimp were challenged with a lipopolysaccharide, which is a surface component of gram-negative bacteria. These results indicate that HC is inducible and up-regulated in response to pathogenic challenge, confirming that HC participates in the innate immune response in F. merguiensis. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the population dynamics ofPenaeus merguiensisstock in the coastal waters of the Persian Gulf. A total of 4994 male and 5264 female prawns were collected monthly by a bottom-trawl net, from July 2010 to September 2012. The carapace length and weight relationship demonstrated that growth in both sexes was allometric. The asymptotic carapace length (CL∞) was estimated at 48 mm for males and 54 mm for females. The growth parameterKwas calculated as 1.6 Yr− 1for males and 1.8 Yr− 1for females. The total mortality rate for males was more than that for females. And the exploitation rates were 0.75 for males and 0.69 for females. The sex ratio identified that it was not a constant 1:1 throughout the year, with 51.3% females. Banana prawns can spawn all year round and have a spawning peak from February to May. The Lm50%was estimated at a carapace length of 33.64 mm. The exploitation ofP. merguiensisin the area is intended to protect spawners and juvenile stock for renewal. Also, the results showed that long-term monitoring is still required to better understandP. merguiensispopulation dynamics. [ABSTRACT FROM PUBLISHER]

Penaeus merguiensis hepandensovirus (PmeDV) is a strain of the hepatopancreatic parvoviruses that causes overt mortalities and stunting in survivors in many penaeids around the tropical and temperate world. This study was to investigate if RNA interference (RNAi) could be used to ameliorate pre-existing PmeDV infection in a therapeutic manner rather than in a simultaneous exposure when delivered via live bacteria in pelleted food. One hundred and fifty Australian Penaeus merguiensis testing positive for PmeDV by PCR were divided into 5 treatment groups which were bled weekly for viral copies measured by real time PCR and treated for 5 weeks with the appropriate RNAi. The treatments were no treatment control, carrier fish oil, plasmid delivered nonspecific RNAi, plasmid delivered specific RNAi and plasmid delivered specific RNAi in live Escherichia coli . Statistically, the specific RNAi microencapsulated in live E. coli was the best overall treatment against pre-existing PmeDV when delivered in the food. Specific RNAi in bacterial cells had the lowest mortality (P < 0.0001), the highest relative percentage survival (68%), most prawns with no detectable viral copies (53%) and it was equal to the nonspecific RNAi with the lowest viral copies when virus was detected (P < 0.0001). The naked plasmid, specific RNAi and the nonspecific RNAi as plasmids were very similar being the next most protective across all measures. The week of the trial was not significant (P > 0.05), but the week by treatment interaction was (P < 0.05) with the number of RNAi-control prawns significantly increasing viral copies at week 2 whilst copies in other treatments fell. Also, fish oil lost its protective effects by 5 weeks as evidenced by statistically increased number of viral copies. Overall, this study showed that RNAi microencapsulated in live E. coli and fed via pelleted feed could increase survival of P. merguiensis and lower viral copies in pre-existing infections of PmeDV. This methodology herein should be the simplest for farmers to apply and when utilized, these results should allow farmers to increase yields, profitability and therefore, sustainability. [ABSTRACT FROM AUTHOR]

Biomass, catchability, and natural mortality are key parameters in fish stock assessment. Yet, it is difficult to estimate these quantities, especially natural mortality, when only fishery data are available. Using a method of population depletion analysis, we estimated these population and biological quantities for the white banana prawn (Penaeus merguiensis) in Australia's valuable Northern Prawn Fishery. In addition, we directly included fishing power change over time. The models were implemented in a Bayesian framework by incorporating process error, observation error, and random variability for the underlying parameters. The posterior median initial fishable biomass ranged from ∼2000 to 7000 t year−1, and the median catchability varied from ∼3.8 × 10−4 to 7.3 × 10−4 boat-day−1, resulting in an average fishing power increase of 2.6% per year. An unexpected result is the estimate of exponential natural mortality rate of ∼0.03 week−1. This value is substantially lower than an earlier estimate of 0.05 week−1, which was based on a single year's fishery data in one stock region and has been widely used for over four decades without validation. We attribute this low natural mortality estimate mainly to prawn aggregation behaviour. [ABSTRACT FROM PUBLISHER]

A major decline in the catch of the banana prawn [shrimp], Penaeus (Fenneropenaeus) merguiensis, occurred over a six-year period in the Weipa region of the northeastern Gulf of Carpentaria, Australia. Three main hypotheses have been developed to explain this decline: (1) prawn recruitment collapsed due to overfishing; (2) recruitment collapsed due to a change in the prawn's environment; and (3) adult banana prawns were still present, but fishers could no longer effectively find or catch them. Qualitative mathematical models were used to link population biology, environmental factors, and fishery dynamics to evaluate the alternative hypotheses. This modeling approach provides the means to rapidly integrate knowledge across disciplines and consider alternative hypotheses about how the structure and function of an ecosystem affects its dynamics. Alternative models were constructed to address the different hypotheses and also to encompass a diversity of opinion about the underlying dynamics of the system. Key findings from these analyses are that: instability in the system can arise when discarded fishery bycatch supports relatively high predation pressure; system stability can be enhanced by management of fishing effort or stock catchability; catch per unit effort is not necessarily a reliable indicator of stock abundance; a change in early-season rainfall should affect all stages in the banana prawn's life cycle; and a reduced catch in the Weipa region can create and reinforce a shift in fishing effort away from Weipa. Results from the models informed an approach to test the hypotheses (i.e., an experimental fishing program), and promoted understanding of the system among researchers, management agencies, and industry. The analytical tools developed in this work to address stages of a prawn life cycle and fishery dynamics are generally applicable to any exploited natural resource. [ABSTRACT FROM AUTHOR]

Mangroves are traditionally considered to provide important nutrition to tropical estuarine consumers. However, there is still controversy about this, and the extent and importance of these inputs are largely unquantified. In particular, there is no information for food webs of small estuaries that dominate wet-dry tropical coasts, where freshwater inflow is intermittent, leading to highly seasonal inputs of nutrients from terrestrial systems. Since the relative importance of the different sources depends on the type and extent of different habitats and on hydrological and topographic conditions, results from other regions/type of systems cannot be extrapolated to these estuaries. Here, δC is used to determine the importance of mangrove-derived carbon for Penaeus merguiensis (detritivore; shrimp), Ambassis vachellii (planktivore; fish), and Leiognathus equulus (benthivore; fish) from six small wet-dry tropical estuaries that differ in mangrove (C) cover and in type of terrestrial vegetation adjacent to the estuary. Bayesian mixing models confirmed that mangrove material was important to consumers in all estuaries. There was a gradient in this importance that agreed with the extent of mangrove forests in the estuaries, as C sources were the most important contributors to animals from the three estuaries with the greatest (>40 %) mangrove cover. There was also evidence of incorporation of C material for the three estuaries with lower (<30 %) mangrove cover. Since these latter estuaries had no adjacent terrestrial C forests, the detected C influence can only be of mangrove origin. This shows that mangroves are important contributors to these food webs, underlining the importance of mangroves in supporting estuarine nursery ground value and fisheries productivity. [ABSTRACT FROM AUTHOR]

The levels of mercury in tissues of Penaeus merguiensis from Musa estuary, northwest of the Persian Gulf, were investigated. This study assessed the relationship between mercury levels in hepatopancrea, gill, and muscle with sex, size, and season. The order of mercury concentrations in tissues of the shrimp P. merguiensis was as follows: hepatopancreas > gill > muscle. There was a positive correlation between mercury concentrations in shrimp species with sex and size of its food items. We expected to see higher mercury levels in tissues of female species because they are larger and can eat larger food items. Also, there was a positive correlation between mercury concentrations in shrimp species with its food source. Therefore, female species feed more on shrimp and plant and are contaminated with high levels of mercury. There was significant difference ( p < 0.05) in mercury levels between different seasons; higher mercury levels were found in July (summer season). [ABSTRACT FROM AUTHOR]

The study investigates the vital aspects of reproductive biology: maturation stages of ovaries, spawning season and size at sexual maturity of Penaeus merguiensis. The sampling of Penaeus merguiensis De man, 1887 was conducted from the coastal waters of Pakistan during the period July 2006 to June 2007, from the Damb Bunder, Sonmiani Bay Lagoon locally known as Miani Hor (25° 27' N/ 66° 33' E). Five maturation stages were recognized by the variations in colour as well as development and arrangements of cells. These stages were designated as undeveloped, developing, nearly ripe, ripe and spent. The data show P. merguiensis spawn throughout the year with 2 or 3 peaks being different in different years. The peak spawning activity was observed in NE monsoon and pre monsoon. The results of one way ANOVA showed significant differences for ovarian developmental stages (colouration) and morphological parameters. The size at onset of sexual maturity at when fifty percent of the population was morphologically mature was estimated as (TL50 =15.50 cm), and can be significantly utilized in fisheries management as an indicator for minimum permiöible capture size. [ABSTRACT FROM AUTHOR]

The rod-shape virus particles were found in the hyperthrophied nucleus and cytoplasm of diseased white shrimpPenaeus merguiensis naturally infected by White spot syndrome (WSBV). In natural infection cumulative mortality of shrimp werevery high, 95% of population were dead in 3-7 days, and 5% of shrimp population survived. The disease was outbreak in intensiveculture farms used the closed circulation sea water system. Others crustacean such as crabs and bentatos were not infected by WSBVat time of sampling. The virus particle were rod-shape ranging from 78 ± 10 nm in diameter and 280 ± 10 nm in length. The pathogenicbacteria mainly dominated by genus Vibrio sp were isolated from shrimp.

Abstract: Penaeus merguiensis densovirus (PmergDNV) is a serious pathogen of the banana prawn, Penaeus merguiensis leading to at least 28% production loss due to reduced growth rates and mortality of juveniles. In the present study, we reduced PmergDNV titres and subsequent mortality by feeding Acheta domesticus (previously determined as an appropriate animal model for P. merguiensis) with dsRNA specific to the capsid protein by mixing it into their food. Feeding A. domesticus with PmergDNV-specific dsRNA in advance of viral challenge increased their longevity, decreased mortality by 84.4% and reduced viral loads 24-fold below the threshold level required for mortality. Mortalities and viral loads were significantly (both P <0.001) lower in treatments challenged with PmergDNV following exposure to bacterially expressed PmergDNV–dsRNA. This is the first study to demonstrate gene silencing via RNAi against PmergDNV in vivo through oral administration of live bacteria expressing dsRNA in a model system. [Copyright &y& Elsevier]

Abstract: Offshore catches of banana prawns, Penaeus merguiensis, are correlated with the extent of mangrove forests. However, recent evaluation has questioned whether the apparent relationship between juvenile penaeids and mangroves reflects specific utilisation of mangroves or just the use of shallow, organically rich, muddy habitats. We investigated this by focussing on juvenile P. merguiensis within 30 mangrove estuaries spanning 650 km of the coast of north-eastern Australia. We investigated a range of hierarchically clustered spatial scales and within-estuary spatial resolutions, as well as variables representing a variety of estuary structural factors, anthropogenic impacts, and particular hypotheses about the ways in which mangroves could influence P. merguiensis catch per unit effort (CPUE). Estuary to estuary differences, rather than climatic zone or the proximity of other estuaries, was the major large scale spatial influence on CPUE. At the among-estuaries scale mangrove extent appeared to influence CPUE but was extensively confounded with the effects of two non-mangrove variables; intertidal extent and substrate type. The fact that 3 alternative measures of connectivity with mangrove forests were not influential, points to the importance of the non-mangrove variables rather than mangrove extent. At the within-estuary scale, P. merguiensis CPUE was correlated with the extent of shallow water but not with mangrove variables. The spatial and temporal extent of sampling support a strong conclusion that factors associated with mangroves alone do not drive abundances of juvenile prawns. Nevertheless, despite being the dominant habitat, mangroves are only one of a mosaic of interacting habitats occurring in the tropical estuaries inhabited by juvenile penaeids (Sheaves, 2009), so causal relationships are complex and difficult to define unambiguously. [Copyright &y& Elsevier]

Ovary maturation, oocyte differentiation, and embryonic development in shrimp are highly dependent on nutritional lipids taken up by female broodstocks. These lipids are important as energy sources as well as for cell signaling. In this study, we report on the compositions of major lipids, i.e. phosphatidylcholines (PCs), triacylglycerols (TAGs), and fatty acids (FAs), in the ovaries of the banana shrimp, Penaeus merguiensis, during ovarian maturation. Thin-layer chromatography analysis showed that the total PC and TAG signal intensities increased during ovarian maturation. Further, by using gas chromatography, we found that (1) FAs 14:0, 16:1, 18:1, 18:2, 20:1, and 22:6 proportionally increased as ovarian development progressed to more mature stages; (2) FAs 16:0, 18:0, 20:4, and 20:5 proportionally decreased; and (3) FAs 15:0, 17:0, and 20:2 remained unchanged. By using imaging mass spectrometry, we found that PC 16:0/16:1 and TAG 18:1/18:2/ 22:6 were detected in oocytes stages 1 and 2. PCs 16:1/20:4, 16:0/22:6, 18:3/22:6, 18:1/22:6, 20:5/22:6, and 22:6/22:6 and TAGs 16:0/16:1/18:3, 16:0/18:1/18:3, 16:0/18:1/18:1, and 16:0/18:2/22:6 were present in all stages of oocytes. In contrast, the PC- and TAG-associated FAs 20:4, 20:5, and 22:6 showed high signal intensities in stage 3 and 4 oocytes. These FAs may act as nutrition sources as well as signaling molecules for developing embryos and the hatching process. Knowledge of lipid compositions and localization could be helpful for formulating the diet for female broodstocks to promote fecundity and larval production. [ABSTRACT FROM AUTHOR]

Abstract: Two hundred and two strains of lactic acid bacteria (LAB) isolated from digestive tracts of cultivated and wild adult shrimp, including Litopenaeus vannamei, Metapenaeus brevicornis and Penaeus merguiensis were selected based on their antibacterial activity against Vibrio harveyi. LAB strain of MRO3.12 exhibiting highest reduction of V. harveyi was identified as Lactobacillus plantarum MRO3.12 based on the nucleotide sequence of its 16S rDNA, which showed 99% (780/786 bp) homology to L. plantarum strain L5 (GenBank accession number DQ 239698.1). Co-cultivation of V. harveyi and L. plantarum MRO3.12 showed complete reduction of V. harveyi at 24 h under aerobic and anaerobic conditions, whereas L. plantarum increased from 5.29 to 9.47 log CFU ml−1. After 6-week feeding trial with L. plantarum supplemented diet, white shrimp (L. vannamei) exhibited significant differences (p < 0.05) in relative growth rate (% RGR), feed conversion ratio (FCR) and survival compared to the control group fed with non-supplemented diet. LAB-fed group showed 98.89% survival, whereas only 68.89% survival was observed in the control group. LAB from the digestive tract of probiotic-fed shrimp showed higher level of 5.0 ± 0.14 log CFU/g than the non-supplemented ones (3.34 ± 0.21 log CFU/g). However, total bacterial and non-fermenting vibrios counts decreased in shrimps fed on L. plantarum. Ten days after infection with V. harveyi (5.3–5.5 log CFU ml−1), significant survival (p < 0.05) of 77% was observed in LAB supplemented shrimp, while only 67% survival was observed in the control. [Copyright &y& Elsevier]

Penaeus merguiensis densovirus (PmergDNV) is currently present on several Queensland prawn farms culturing Penaeus merguiensis. Densoviruses have been linked to mortality and stunting that has caused significant financial loss to prawn farms in Asia. A histopathological study for PmergDNV was initially undertaken to compare broodstock to grow out factors from 60 broodstock animals from each of 22 ponds. There was a significant negative correlation ( r = −0.61) between the number of animals with PmergDNV lesions and healthy animals. Furthermore, a higher number of septic hepatopancreatic tubules was correlated ( r = 0.48) to high PmergDNV loads. Hence, a polymerase chain reaction analysis of 10-day-old post-larvae (PL) was conducted to determine whether PmergDNV infection was resulting in production losses. An attributable risk analysis of PL from 190 ponds over a 2-year period revealed that 28-29% of ponds with below average survival will have at least average survival following the removal of or decreased levels of PmergDNV. P. merguiensis culture facilities in Queensland should have at least a 14.5% increase in production, equating to an increase of $2.25 million within the first year alone, following the removal or reduction of PmergDNV in their ponds. Hence, focussing efforts on prevention, better management practices and maintaining healthy stock should be of top priority. [ABSTRACT FROM AUTHOR]

The bycatch in a tropical Australian banana prawn, Penaeus merguiensis (de Man), fishery is described and contrasted with the closely related tiger prawn, Penaeus semisulcatus De Haan and Penaeus esculentus Haswell, fishery. Most of the similarity between banana prawn fishery catches was accounted for by three teleost species constituting 51.4% of the total bycatch weight. The bycatch assemblage structure of this fishery was significantly different ( P < 0.05) from the adjoining tiger prawn fishery. The banana prawn fishery had a higher mean bycatch catch rate from shorter duration trawls, but lower estimated total annual bycatch (1502 t yr−1) than the longer duration trawls of the tiger prawn fishery (20 073 t yr−1). This study provides new data for quantifying bycatch and improving the accuracy of quantitative risk assessments currently being used to demonstrate sustainability of bycatch populations. The information will be incorporated into collaborative development of a long-term monitoring programme. [ABSTRACT FROM AUTHOR]

Abstract: The lack of available cell lines has hampered the study of viral diseases in crustaceans. This is particularly important for aquaculture which has been plagued by viral diseases since its rapid expansion to meet with the growing demand for seafood products. This study was designed to find an alternative bioassay to cell lines by investigating the use of insects as potential animal models for Penaeus merguiensis densovirus (PmergDNV). Acheta domesticus (house cricket) and Tenebrio molitor (mealworms) were challenged with approximately 1×106 virions of PmergDNV by inoculation. PmergDNV was detected in 20% of Tenebrio molitor and 86.6% of Acheta domesticus challenged with PmergDNV. During a subsequent time course experiment, there was a non significant increase in PmergDNV titres (104–5 virions), reaching a maximum peak at day 5 (106 copies). A threshold of PmergDNV DNA level equal to or greater than 103 virions was necessary for mortality in Acheta domesticus. As the inoculum increased from 103 DNA copies to 104, 105, 106, mortality increased from 20% to 60%, 80% and 100%, respectively. This is the first evidence that insects may be directly used to study viruses from crustaceans and concludes Acheta domesticus may be used as a potential model to study Penaeus merguiensis densovirus. [Copyright &y& Elsevier]

This study found no evidence that turbidity influenced the distribution of fishes in four tropical estuaries in north-eastern Queensland. When both more turbid and less turbid environments were immediately available to Ambassis vachelli and Leiognathus equulus there was no difference in abundance between the more and less turbid environments and no correlated change in abundance as the difference in turbidity increased. A similar outcome was evident for an additional six species of fish. Furthermore, the distribution of fishes was not correlated with the distribution of an important prey species, juvenile banana prawns Penaeus merguiensis, which exhibited a clear response to differences in turbidity level with higher abundance in the more turbid samples, however, the magnitude of the difference did not alter with changes in the magnitude of the differences in turbidity. [ABSTRACT FROM AUTHOR]

Abstract: Hepatopancreatic parvovirus infection is associated with reduced growth rates of prawns during the juvenile stages and overt mortalities. Hepatopancreatic parvovirus was purified from Penaeus merguiensis from northern Queensland and a partial consensus sequence of 5.9 kb was obtained. Nucleotide comparisons revealed that the Australian isolate of HPV has a nucleotide similarity (87%) closer to HPVchin and the full sequence of HPV Penaeus monodon (PmDNV) (6321 bp) than to HPVsemi (83%). Three putative open reading frames were identified. The first open reading frame encoded a nonstructural protein (NS2) and shared an amino acid similarity of 86% with PmDNV. The second ORF overlapped the first open reading frame and shared 93% and 26% amino acid similarity with PmDNV and PstDNV, respectively, and encoded NS1. The third ORF encoded the viral structural protein and shared an amino acid similarity of 73% with the capsid protein of PmDNV and HPVchin. The phylogeny suggests that the Australian HPV isolate is closely related to the Korean HPVchin isolate than to the Indian HPVsemi and Thai PmDNV isolates. HPV strains may be following the phylogenetic relationship of penaeid prawn hosts rather than their geography. [Copyright &y& Elsevier]

Abstract: The ribosomal DNA internal transcribed spacer 1 (ITS1) was investigated in the search for additional genetic marker that is suitable for population studies of the penaeid shrimps. The sequence variations of the ITS1 were determined and found to be informative in estimating phylogenies in that they differentiate four species of penaeid shrimps, namely Penaeus merguiensis, Penaeus silasi, Penaeus monodon and Penaeus semisalcatus and the populations of P. merguiensis collected in the Gulf of Thailand and the Andaman Sea. The length of the ITS1 ranged from 499 to 772 bp, with a GC content of 63.30–67.37%. Four microsatellite loci are found in the ITS1 at 5′ end and the middle of region and seem to be associated with sequence divergence and size variation in Penaeus species. Some microsatellites were found in only one specie, (GCGA)4 in P. semisalcatus and (CGGA)4–9 in P. monodon. These microsatellite regions are considerably long enough and the level of intragenomic variation in P. merguiensis is less than that between different species, hence, provide a great potential use in the population studies. [Copyright &y& Elsevier]

Abstract: Apoptosis is a fundamental cellular process that plays a critical role in normal development and tissue homeostasis, eliminating from an organism unwanted cells, including damaged and virus-infected cells. In order to investigate the significance of apoptosis in response to viral infections in crustacean, we have cloned a caspase gene (cap-3) from the white shrimp, Penaeus merguiensis infected with white spot syndrome virus (WSSV). The deduced amino acid sequence of the protein named CAP-3 was 320 amino acids in length and contained the highly conserved pentapeptide QACRG recognized as the active site of caspase. CAP-3 showed similarities to the insect caspase, Spodoptera frugiperda Sf caspase-1 and the caspases of Spodoptera littoralis, Bombyx mori, Drosophila melanogaster and Anopheles gambiae, which in turn belong to the group of human caspase-3, caspase-7 and CED-3. The recombinant CAP-3 protein prepared from Escherichia coli had enzymatic activity when assayed using a luminescent substrate specific for the cleavage target site for human caspase-3, implying that CAP-3 functioned as caspase-3. There was a high level of expression of this gene product in moribund shrimp infected with WSSV. [Copyright &y& Elsevier]

Abstract: The effects of fish predators, light phase, habitat structure and prawn size on the habitat preferences of juvenile Penaeus (Fenneropenaeus) merguiensis de Man were examined with laboratory experiments. The behaviour of juvenile P. merguiensis within habitats of different structural complexity was also examined. Experiments were carried out in a tank (1.8 m diameter) divided into four habitats representing: bare substratum, leaf litter (little vertical structure), mangrove pneumatophores (regular vertical structure) and mangrove woody debris (heterogeneous vertical structure). The location of 10 prawns was monitored over 270 min (135 min light and 135 min dark), with different prawns five times for each combination of prawn size class, and predator (no predator; Arius graeffei Kner and Steindachner and Lates calcarifer Bloch). In the absence of predators and during the light phase, when observations on prawn behaviour were made, swimming was the most common behaviour (of seven mutually exclusive behavioural categories) with few differences in behaviour between sizes. All size classes of juvenile P. merguiensis selected vertical structure (mangrove debris and pneumatophores) over low vertical structure (leaf litter and bare substratum), in both light and dark conditions and in the presence or absence of predators. When L. calcarifer was present, the selection by prawns of the mangrove-debris habitat increased significantly. This was attributed to an increase in predation risk in the other habitats. L. calcarifer rarely pursued prey amongst the mangrove-debris structure, compared to habitats with less heterogeneous vertical structure (pneumatophores, leaf litter and bare substratum). [Copyright &y& Elsevier]

Abstract: This study investigates the distribution of three trace elements (Cd, Cu and Zn) in tissues (exoskeleton, abdominal muscle and hepatopancreas) of two shrimp species (Penaeus merguiensis and Penaeus semisulcatus). Special emphasis in this study was placed on evaluating the effects of storage conditions on redistribution of the elements and moreover the potential roles of metallothionein in tissue redistribution. The specimens were collected from the northern part of Persian Gulf during September 2001 and January 2002. The concentrations of metals in the tissues were measured using an Inductively Coupled Plasma-Atomic Emission Spectrophotometer (ICP-AES) and an ICP-Mass Spectrometer (ICP-MS). Metallothionein levels were determined using Differential pulse polarography. Results show a similar hierarchy for Cd and Cu concentrations among different tissues as follows: hepatopancreas>exoskeleton>muscle; and for Zn, the hepatopancreas again contained the highest levels, though there were not any significant differences in Zn concentrations between muscle and exoskeleton. Significant differences were found between the species in the case of Cd and Zn concentrations. Cd and Zn levels in P. semisulcatus were markedly higher than in P. merguiensis. In general, there were highly significant differences among the storage conditions from accumulation the selected trace elements and metallothionein in both species point of view, but in most cases, no significant differences could be observed among the fresh, refrigerated and frozen specimens of P. semisulcatus. In regards to Zn and Cu accumulation in edible (muscle) tissues of P. merguiensis, optimum conditions for frozen storage is −30 °C as ice-frozen, and in terms of short-term storage, 1-day refrigeration is recommended. The redistribution of Zn and Cu during the storage period can be attributed to the role of metallothionein in their transport from organ(s) to muscle during storage. The variations in pH values measured in the muscle of P. merguiensis in different storage conditions showed a similar trend with metallothionein, Zn and Cu. In contrast, it appears that cadmium is transported from muscle to the other tissues. Exoskeleton is probably one of the recipient tissues of cadmium. The inter-elemental relationships were assessed for each species, separately. A significant positive relationship was observed between the concentrations of Zn and metallothionein in P. semisulcatus, whereas in P. merguiensis, Cd concentrations decreased significantly with increasing metallothionein. Highly significant differences between the sexes in Cu and Zn contents could be detected. The differences between the sexes in the levels of Zn and Cu were significantly greater in P. semisulcatus. Highly significant size-related differences were found in the levels of Cd, Cu and metallothionein in the selected tissues of the shrimp species. Comparison between the mean concentrations of the elements in muscle tissue and existing guidelines indicate that in nearly all cases, the concentrations were well below permissible levels for human consumption. The only exception was observed regarding mean values of Cd, which was somewhat greater than some of the recommended levels. [Copyright &y& Elsevier]

Polymorphisms of nuclear DNA markers were used to study the genetic variation and differentiation among populations of Penaeus merguiensis in Thailand. The data consisted of three nuclear loci analysed for 163 individuals from five populations collected from the Gulf of Thailand (Trad, Surat Thani and Songkhla) and the Andaman Sea (Satun and Trang). The multilocus FST estimated at three nuclear loci revealed great and highly significant differentiation between the Gulf of Thailand and Andaman Sea (FST=0.203, P<0.001), mostly due to the polymorphism of locus PvAmy. In addition, significant population differentiation was also found within the Gulf of Thailand. These results were compared to that of a previous mitochondrial DNA survey spanning the same geographical range where two divergent mitochondrial clades were reported. The present study brings support to the fact that the existence of these two clades is not due to a mixture of cryptic species but reflects their phylogeographic origin. The strong genetic structure of P. merguiensis on each side of the Thailand peninsula for both mitochondrial and nuclear genes could thus be linked to the phylogeographic divide between Indian Ocean and Pacific forms on the west and east sides respectively. [Copyright &y& Elsevier]

During October to December 1997, we trawled estuarine habitats in the Joseph Bonaparte Gulf (JBG) to determine the distribution of juvenile red-legged banana prawns, Penaeus indicus (H. Milne Edwards, 1837) and white banana prawns, Penaeus merguiensis (de Man, 1888). We made 229 beam-trawls at 185 sites, mostly over a 100-m path (3-min duration). A Global Positioning System (GPS) receiver was used to verify our location. During October to December 1998, we intensively resampled three of the rivers that were sampled in 1997 to confirm the gulf-wide distribution of P. indicus and P. merguiensis and to investigate the microhabitat use of P. indicus. We chose previously sampled and new sites in Forsyth Creek (eastern JBG), the Lyne River (Cambridge Gulf), and the Berkeley River (western JBG). We made 249 trawls at 21 sites, mostly over 100 m.Juvenile banana prawns were abundant in eastern JBG, Cambridge Gulf and western JBG. They were not abundant in southern JBG, although fewer trawls were made there, due to its inaccessibility. In eastern JBG and Cambridge Gulf, over 96% and 73% (respectively) of juvenile banana prawns were P. indicus and they were more abundant there than in the western JBG. Conversely, in the western JBG over 93% of the juvenile banana prawns were P. merguiensis and they were more abundant than in the eastern JBG and Cambridge Gulf. The Lyne River in the northwestern Cambridge Gulf seems to be the transition zone; both P. indicus and P. merguiensis are equally abundant.P. indicus are most abundant on the mangrove-lined muddy banks of waterways within mangrove forests, similar habitats to P. merguiensis. Within these habitats, they were most abundant in gutters and small creeks, rather than rivers and large creeks. Few P. indicus or P. merguiensis were caught in 100 m2 trawls undertaken midriver (on the channel bottom and on emergent banks), although these habitats may be only 100 m from the mangrove-lined habitats. In all creek and river habitats, both species are most catchable at low tide (irrespective of daylight or darkness) when they move out of the mangrove forests and accumulate in the remnant water bodies.The offshore fishery for P. indicus is in northwestern JBG in waters 50–80 m deep, about 300 and 200 km, respectively, from where juveniles are abundant in their extensive inshore habitats in east JBG and in Cambridge Gulf, demonstrating a geographical separation of the juvenile and adult phases. Postlarval P. indicus, spawned offshore, must use tides and currents to travel south and east to reach nursery habitats. Emigrant subadults must migrate north and west, across relatively shallow inshore sand substrates (30–40 m deep) to reach their offshore habitats. [Copyright &y& Elsevier]

The combined effects of temperature and salinity on the hatching success, survival and development of the larval stages of Penaeus merguiensis were investigated in a 4×2 factorial designed experiment employing two temperatures (29±1 and 33±0.5 °C) and four salinities (25, 30, 35 and 40 ppt). Best percentage of hatch was obtained at 33 °C and 35 ppt (87%) followed by 29 °C and 35 ppt (82%). Similarly during naupliar stages, high survival rate was obtained at 33 °C and 35 ppt (89%). Metamorphosis cycle during the protozoeal stages (protozoea 1 to postlarva 1) was extended and survival rate decreased at 25 ppt. Development to PL1 was faster at 33 °C (7–8 days) as compared to 29 °C (8–10 days) regardless of the salinity levels. Maximum survival during the protozoeal stages was at 35 ppt followed by 48% at 33 °C and 45% at 29 °C. Results showed that salinity exerted a greater influence than temperature on the survival and development of larvae. Based on the results, the best temperature–salinity combination for larval survival and metamorphosis of P. merguiensis is 33 °C and 35 ppt. A salinity range of 30–35 ppt is ideal for larval development. [Copyright &y& Elsevier]

Closely related species, Penaeus merguiensis and Penaeus silasi from Thai waters, were genetically examined using variation observed in 558 base pairs (bp) of sequence from cytochrome oxidase subunit I (COI) gene of mtDNA. The sequence divergences of COI between P. merguiensis and other Penaeus species were 5.76–6.15% (P. silasi), 13.17–13.97% (Penaeus indicus), 16.43% (Penaeus vannamei), 16.63% (Penaeus monodon), and 18.37% (Penaeus japonicus). From the alignment reported that there were four clades on phylogenetic tree, the distinction of the two monophyletic clades was referred as P. merguiensis, one monophyletic clade within P. silasi and P. indicus. These results point toward the possibility of P. merguiensis being a complex of two cryptic species or a single species with strong phylogeographic subdivision. [Copyright &y& Elsevier]

Two environmental manipulation protocols were tested against a current maturation technique (CONTROL) in an 81-day experiment. PROTOCOL 1 mimicked changes in the natural environment from winter to spring when ovarian maturation and spawning in Penaeus merguiensis starts. PROTOCOL 2 evaluated whether a clear improvement of temperature from a fluctuation period to a stable one could help trigger ovarian maturation. In phase A (first 30 days) of the experiment, temperature and day length were gradually increased from 22 to 27 °C and from 10 to 14 h, respectively, while light intensity was stepwise reduced from 360 to 240, 120 and 5 lx for PROTOCOL 1. For PROTOCOL 2, light intensity and day length were manipulated as for PROTOCOL 1, but temperature was cycled from 22 to 27 °C every 3 days. In phase B (the following 30 days) temperature, light intensity and day length were stably maintained at optimal levels (27 °C, 5 lx and 14 h light, respectively). During phase B, the proportion of female prawns reaching stages III and IV was significantly (P<0.05) highest in PROTOCOL 1 and lowest in the CONTROL. Of the total spawns by unablated females recorded in this phase, 55.6% was in PROTOCOL 1, 33.3% in PROTOCOL 2 and only 11.1% in the CONTROL. Mass spawning was induced by unilateral eyestalk ablation on day 60. Spawning performance of prawns were monitored for a further 21-day period (phase C). Overall, PROTOCOL 1, PROTOCOL 2 and the CONTROL produced 2.36, 1.96 and 1.53 million eggs, respectively. The latency period of spawners was shortest (P<0.05), whereas the proportion of spawners, fecundity, spawning rate and egg production/female were all improved in PROTOCOL 1. An improvement of prawn growth was observed in PROTOCOL 2. This study suggested that environmental manipulation could improve ovarian maturation and spawning rate of pond-reared P. merguiensis. [Copyright &y& Elsevier]

The effects of light intensity (I, 750 and 75 lx) and photoperiod (P, 12L/12D and 7L/5D) on moulting and growth of Penaeus merguiensis were investigated over 12 weeks under laboratory conditions. Both light intensity and photoperiod significantly (P<0.05) influenced the percentage weight gain (PWG), but did not influence moult frequency or moult interval. Mean PWG of prawns cultured at 750 lx was 198.4%, significantly (P<0.01) higher than those cultured at 75 lx (168.1%). Imposing two light/dark cycles (7L/5D) in 24 h resulted in a significantly higher growth of prawns (P<0.05) than the normal photoperiod (12L/12D). Prawns cultured at 750 lx had a lower food conversion ratio (FCR, 1.485) than those cultured at 75 lx (1.590, P<0.05). The effect of light intensity on prawn growth was found to be stronger and more immediate than that of photoperiod. There was no interaction between light intensity and photoperiod. Although not significantly different (P>0.05), prawns cultured at 750 lx tended to moult more frequently. Sexual dimorphism was not observed within the range of tested prawns. [Copyright &y& Elsevier]