Penaeid Prawns Research Articles

Vertical migration of postlarval penaeid prawns in two Australian estuaries: the effect of tide and day/night

Knowledge of the vertical migration behaviour of postlarval penaeid prawns is important in understanding postlarval migration from offshore spawning grounds to estuarine nursery areas. We sampled throughout several 24-h periods in two estuaries in Australia to assess the distribution of postlarvae in the water column. We used four trawl nets: one net in the top 0.5 m of the water column and three nets one above the other, from the seabed to 0.72 m above the seabed. Penaeus plebejus was abundant in catches in the Nerang River, southern Queensland, while Penaeus semisulcatus, Penaeus esculentus and Penaeus merguiensis were caught in the Embley River, northern Queensland. For all species, the highest catches at the surface were on night flood tides. Many postlarvae in the Embley River were caught in nets above the seabed on ebb tides, suggesting that net migration patterns cannot be determined simply by sampling surface waters. The vertical distribution of penaeid postlarvae is determined primarily by tide and day/night; however, water turbidity and cloud cover, factors that reduce light at the seabed, are also likely to be important. All these aspects of postlarval behaviour should be included in hydrodynamic models of larval advection from spawning grounds to inshore nursery areas.

Contribution to Some Biological and Fishery Aspects of Commercial Penaeid Prawns in Mersin Bay (Northeastern Mediterranean, Turkey)

Contribution to Some Biological and Fishery Aspects of Commercial Penaeid Prawns in Mersin Bay (Northeastern Mediterranean, Turkey)

Trophodynamics of the Spotfin Flathead Grammoplites suppositus (Troschel 1840) from the Southeast Arabian Sea

The dietary habits of the spotfin flathead, Grammoplites suppositus which inhabits the southeast Arabian Sea was studied. The stomach contents of 581 specimens were analysed between September 2001 and May 2002. G. suppositus preyed primarily on crustaceans. The most important preys were benthic crabs and penaeid prawns, and fishes were next in rank. During premonsoon, fishes and crustaceans were equally important, whereas in monsoon and postmonsoon benthic crabs and penaeid prawns were the predominant prey. There were significant (p165 mm) ate crustaceans such as the benthic crabs, penaeid prawns, the paste shrimp, Acetes indicus and the mantis shrimp, Oratosquilla nepa. Highest similarity in diet was observed between 216- 240 and 241-265 mm length groups. Diet breadth was higher during the monsoon season; however, the trophic level which had a mean value of 3.79 ± 0.13 peaked during the postmonsoon season. Maximum diet breadth was for 191-215 mm length groups. The length of the prey Solenocera choprai had a linear positive correlation to the predator length (r2 = 0.72). Electivity studies showed that G. suppositus has a strong preference for low trophic level animals such as benthic crabs and Solenocera choprai. The Amundsen plot showed that G. suppositus is a specialized feeder on benthic crustaceans.

Molecular cloning and characterization of cortical rod protein in the giant freshwater prawn Macrobrachium rosenbergii, a species not forming cortical rod structures in the oocytes

The formation of cortical rod structures is a characteristic of fully mature oocytes in penaeid prawns, but such structures are absent from oocytes of giant freshwater prawn Macrobrachium rosenbergii. In the present study, we first demonstrated the presence of a 30-kDa protein, which was immunologically related to kuruma prawn cortical rod protein (CRP), in the ovary of giant freshwater prawn, and subsequently purified this protein. Furthermore, a cDNA encoding the CRP-like protein was isolated. Based on the high homology (98%) in the amino acid sequence with kuruma prawn CRP, the 30-kDa protein has been identified as a CRP homologue of giant freshwater prawn, designated mrCRP. The RT-PCR analysis revealed that mrCRP mRNA was present in the ovary from a prawn with a gonadosomatic index (GSI) of 0.2. Western blot analysis revealed the presence of a CRP-immunoreactive band of 30kDa in the ovary with GSI of 1.6. By immunocytochemistry, CRP-immunopositive signals were detected in the ovary with GSI of 0.9, that had started to accumulate considerable amounts of vitellins and lipids in the peripheral cytoplasm. With progress of vitellogenesis, mrCRP was apparently accumulated in the mature oocytes, although it was not detectable, presumably because a relatively small amount of mrCRP was masked with large amounts of vitellin and lipids. In giant freshwater prawn without forming cortical rod structures, our findings indicate that the oocytes produce mrCRP, a homologue of CRP found in penaeid prawns.

Factors affecting the distribution of commercially exploited penaeid prawns (shrimp) (Decapod:Penaeidae) across the northern Great Barrier Reef, Australia

In the far northern Great Barrier Reef, Australia, the spatial distribution of commercially important penaeid prawns (shrimp) can be coarsely differentiated by a combination of three factors; water depth, mud content of the sediment, and seafloor rugosity. Penaeus esculentus (brown tiger prawn) was associated with high mud content sediments of the inshore reef lagoon. Melicertus longistylus (red spot king prawn) was associated with the coralline sand sediments of the reef–shoal matrix, and Metapenaeus endeavouri (true endeavour prawn) straddled both sediment and bottom types but was concentrated over the inshore mud to mud–sand sediments. Melicertus latisulcatus (western king prawn) occurred in small numbers concentrated on pockets of terrigenous silica sand, close to the shoreline. Apart from these silica sand pockets, cross-shelf surficial sediment were dominated by the sand fraction (>0.063 mm particle size), high in CaCO 3 (>80%) and were mainly biogenic in origin, except for a band of terrigenous muddy sediment close to the coast. Seafloor topography followed similar zonation with the highest complexity in the reef–shoal matrix (rugosity index 11.24, fractal dimension D = 1.052), grading back to a flat mud–sand plain (rugosity index 3.88, fractal dimension D = 1.005) in the inner reef lagoon close to shore. Multi-dimensional Scaling (MDS) analysis indicated an “offshore” grouping of species that was associated with low mud and high rugosity, and an “inshore” grouping that tended towards the opposite combination. The currently accepted regression model for the distribution of penaeids in the Gulf of Carpentaria was modified to reflect this dual effect of the sediment and three-dimensional complexity of reef-associated habitats. The new model significantly improved the amount of variation explained in biomass estimates for P. esculentus, Melicertus longistylus, and Metapenaeus endeavouri, but not for Melicertus latisulcatus.

Molecular characterisation of hepatopancreatic parvovirus ( PmergDNV) from Australian Penaeus merguiensis

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.

Microbial flora associated with submerged mangrove leaf litter in India

We studied the microbial flora in decomposing mangrove leaves in relation to changes in nitrogen and tannin levels, and in penaeid prawn assemblages. Senescent leaves of two mangrove species (Rhizophora apiculata and Avicennia marina) kept in nylon bags, were separately immersed for 80 days in five tanks full of mangrove water. A known amount of decomposing leaves was collected every ten days from each tank for microorganism counts, total nitrogen and tannin measurement, and juvenile penaeid prawn counts. Five genera of total heterotrophic bacteria (THB), three species of azotobacters and 19 species of fungi were identified. The azotobacters showed a significant peak around 40-50 days after the beginning of decomposition, similar to the trend for total nitrogen and for prawn assemblages.

The importance of estuarine gravitational circulation in the early life of the Bohai Penaeid Prawn

Estuaries along the southern shore of the Bohai Sea are the major habitat of the Bohai Penaeid Prawn ( Penaeus chinensis). Since the 80's, however, many of the rivers have been dammed. Field observations, as well as laterally integrated 2-D numerical experiments, were conducted to understand both the role of estuarine gravitational circulation and the impact of the damming of the rivers on the early life of the Bohai Penaeid Prawn. For a river with runoff, especially for small discharge, the gravitational circulation tends to transport the planktonic larvae in their metamorphosis phase near the river mouth where condition is favorable for survival. The gravitational circulation inside the estuary tends to transport the mysis phase larvae towards the upstream end of the estuary when the most part of the larvae suspended in the bottom layer, and it transports the post larvae to the low salinity near upstream side of the estuary when the larvae become benthic, if the larvae enter the estuary. Damming causes long periods of zero runoff in the river, resulting in the alteration of the estuarine circulation and in the change of the estuarine environment. In addition, excess evaporation may prematurely transport the planktonic larvae into the estuary. On the other hand, sudden release of a large volume of freshwater from behind the dam may exert undesirable stress on the larvae.

Isolation and expression analysis of multiple isoforms of putative farnesoic acid O-methyltransferase in several crustacean species

Farnesoic acid O-methyltransferase (FaMeT) is the enzyme responsible for the conversion of farnesoic acid (FA) to methyl farnesoate (MF) in the final step of MF synthesis. Multiple isoforms of putative FaMeT were isolated from six crustacean species belonging to the families Portunidae, Penaeidae, Scyllaridae and Parastacidae. The portunid crabs Portunus pelagicus and Scylla serrata code for three forms: short, intermediate and long. Two isoforms (short and long) were isolated from the penaeid prawns Penaeus monodon and Fenneropenaeus merguiensis. Two isoforms were also identified in the scyllarid Thenus orientalis and parastacid Cherax quadricarinatus. Putative FaMeT sequences were also amplified from the genomic DNA of P. pelagicus and compared to the putative FaMeT transcripts expressed. Each putative FaMeT cDNA isoform was represented in the genomic DNA, indicative of a multi-gene family. Various tissues from P. pelagicus were individually screened for putative FaMeT expression using PCR and fragment analysis. Each tissue type expressed all three isoforms of putative FaMeT irrespective of sex or moult stage. Protein domain analysis revealed the presence of a deduced casein kinase II phosphorylation site present only in the long isoform of putative FaMeT.

Assimilation efficiency of zinc and cadmium in the decapod crustacean Penaeus indicus

The assimilation of trace metals from food can be the main route of metal uptake into aquatic invertebrates. The assimilation efficiencies of zinc and cadmium from muscle tissue of a cephalopod mollusc (40% to 70% Zn, 64% to 83% Cd) and from a macrophytic alga (50% to 69% Zn, 39% to 50% Cd) were measured in juvenile penaeid prawns Penaeus indicus. Assimilated Zn and Cd were retained mostly in the hepatopancreas of the prawns, some metal being excreted (Zn k e 0.10 and 0.11 and Cd k e 0.004 and 0.009, from cephalopod muscle and alga, respectively). There were no significant differences between k es (efflux rate constants) of one metal from either diet. Given the high trace metal assimilation efficiencies measured here, it is highly probable that metal assimilation from food plays an important role in Zn and Cd accumulation in the body of P. indicus, particularly in estuarine stages of the life cycle, for estuaries are particularly prone to metal pollution and are likely to offer the prawns abundant metal-rich diets such as detrital material derived from local macrophytes.

Development of a spatial Decision Support System (DSS) for the Spencer Gulf penaeid prawn fishery, South Australia

The Spencer Gulf penaeid prawn fishery in South Australia has undergone a substantial increase in fishing efficiency (and profitability) mainly due to the implementation of adaptive harvest strategies requiring rapid response for change to harvesting plans. This paper describes the management background and the decision-making process leading to the development of a basic Decision Support System (DSS) that uses spatial information techniques and near real-time fishery-independent survey data. The system is implemented through linking an Oracle database to ArcGIS, Genstat and Splus. Two examples show the application of the DSS for optimal harvest timing and assessment of fishery sustainability. Fishery-independent survey data are used to assess stock and model population growth. The first example shows the information flow leading to a dynamic stock model and the estimate of value change as a function of harvest time. The second example shows how the DSS is used to validate and refine existing biological reference limits by evaluating long-term detailed data sets of the prawn population structure and catch dynamics. We conclude that it is important for the economic benefit and sustainability of the fishery to maintain and improve the collection of long-term data sets that are independent of commercial fishery statistics.

Haemagglutination as a low-cost detection method for gill-associated virus and by inference, yellowhead virus in Penaeus monodon Fabricius, 1798

A quantitative, low-cost test based on haemagglutination (HA) using chicken erythrocytes was developed to indicate the viral load of Australian yellowhead-like virus, gill-associated virus (GAV), in Penaeus monodon. The study tested the haemolymph, gill, lymphoid organ, heart, sub-cutaneous tissue, eye stalk, pleopods, uropods and the central nerve cord for agglutination activity in 100 prawns, with the haemolymph and gill tissue giving the highest end-point titres of 1:1370 and 1:361 respectively. The sensitivity of the test was demonstrated by testing two different populations of P. monodon, which showed a highly significant difference (P<0.001) in HA activity, indicating a difference in viral load. By testing three other penaeid prawn species (n=20), Penaeus esculentus, Penaeus merguiensis and Penaeus longistylis, and the crayfish Cherax quadricarinatus, it was demonstrated that natural agglutinins were not causing the high agglutination in the population of P. monodon being tested. It was also demonstrated that there was no effect of freezing and thawing of samples on HA activity. The speed and low cost of this test makes it a very useful tool, particularly in the developing world, for on-farm testing of penaeid prawns to indicate yellowhead virus and GAV loads which can contribute to management practices with respect to harvesting of ponds.

Creel survey based estimation of recreational harvest of penaeid prawns in four southeastern Australian estuaries and comparison with commercial catches

Stratified, roving creel surveys done at night, provided estimates of the quantity caught, and information about species, sex and size composition of the catches of penaeids by recreational fishers in four New South Wales (NSW) estuaries during the spring–summer seasons of 1991–1992, 1992–1993 and 1993–1994. Overall, recreational catches were estimated to be 30% (±12%) of the total commercial catch of all prawn species from these estuaries over the 3 years of the study, but there was great variability between estuaries. Recreational catches represented 57% (±5%) of the commercial catch for Lake Illawarra, 36% (±4%) for Tuggerah Lakes, 17% (±3%) for Wallis Lake and 10% (±2%) for Coila Lake. The species composition of the recreational catch differed from the commercial catch, with the recreational fishery taking a larger proportion of eastern king prawns Penaeus plebejus than school prawns Metapeneaus macleayi and few greasyback prawns Metapenaeus bennettae. The size distributions of eastern king prawns were similar between recreational and commercial catches in three of the four estuaries. Mean catch rates (kg/h) of recreational prawners varied between estuaries and between harvest methods. Recreational prawning on the ebb-tide in the dark of the moon was strongly favoured by prawners, particularly in the areas of the estuaries affected by tides. Our results showed that the recreational fishery is a significant harvester of the prawn resources of NSW. The impact of the recreational fishery, therefore, needs to be incorporated into stock assessments of the prawn resources and it needs to be considered during any determinations about the optimal biological conditions for harvesting these resources. This study demonstrated that it is possible to do surveys at night using intercept techniques on fisheries where artificial lighting is used.

The value of patches of intertidal seagrass to prawns depends on their proximity to mangroves

Penaeid prawns were sampled with a small seine net to test whether catches of postlarvae and juveniles in seagrass were affected by the distance of the seagrass (mainly Zostera capricorni) from mangroves and the density of the seagrass in a subtropical marine embayment. Sampling was replicated on the western and eastern sides of Moreton Bay, Queensland, Australia. Information on catches was combined with broad-scale spatial information on the distribution of habitats to estimate the contribution of four different categories of habitat (proximal dense seagrass, distal dense seagrass, proximal sparse seagrass, distal sparse seagrass) to the overall population of small prawns in these regions of Moreton Bay. The abundance of Penaeus plebejus and Metapenaeus bennettae was significantly and consistently greater in dense seagrass proximal to mangroves than in other types of habitat. Additionally, sparse seagrass close to mangroves supported more of these species than dense seagrass farther away, indicating that the role of spatial arrangement of habitats was more important than the effects of structural complexity alone. In contrast, the abundance of P. esculentus tended to be greatest in sparse seagrass distal from mangroves compared with the other habitats. The scaling up of the results from different seagrass types suggests that proximal seagrass beds on both sides of Moreton Bay provide by far the greatest contribution of juvenile M. bennettae and P. plebejus to the overall populations in the Bay.

Short-term consequences of a benthic cyanobacterial bloom ( Lyngbya majuscula Gomont) for fish and penaeid prawns in Moreton Bay (Queensland, Australia)

This study examined the phenology and ecological consequences of a benthic filamentous cyanobacterial bloom ( Lyngbya majuscula) in Deception Bay (Moreton Bay, Queensland, Australia). Bloom initiation occurred in mid December 1999 and expanded to encompass an 8 km 2 area by April 2000. Small fish and penaeid prawns (<25 cm total length) were quantitatively sampled through periods designated as before, during and after the bloom using a combination of pop-netting within mangroves and beam trawling over adjacent seagrass beds. Data on larger-bodied fish were compiled from daily fishing logs provided by local commercial fishers. Changes in dry mass of bloom material caught in nets and changes in water chemistry were also measured. Mean concentrations of ammonia-N in residual water within mangroves were several orders of magnitude higher in the affected area than in the control and dissolved oxygen was markedly lower in affected areas. Across the study area, mean density, live mass and number of species declined during the bloom, with fish assemblages using mangroves showing greater decline than assemblages using seagrasses. Response at the species level was highly variable; generally, epibenthic species showed a more sustained decline than demersals. Mean monthly fish catch was significantly lower in bloom than non-bloom years. This study has also demonstrated that throughout the bloom, the affected area continued to support a highly diverse and abundant fish and prawn assemblage, and probably maintained its function as an important nursery habitat for many species.

Cadmium uptake and accumulation by the decapod crustacean Penaeus indicus

Juveniles of the dendrobranchiate decapod Penaeus indicus take up radiolabelled cadmium from solution over the exposure concentration range of 1.8-31.5 microg L(-1), with an uptake rate constant of 0.090 L g(-1)d(-1) at 15 salinity and 25 degrees C. New cadmium taken up is added to the existing cadmium content of the prawn with no significant excretion, and the rate of accumulation of radiolabelled cadmium is a measure of the absolute cadmium uptake rate from solution. Moulting had no significant effect on the accumulation of cadmium. Newly accumulated cadmium is distributed to all organs with the highest proportions of body content being found in the hepatopancreas, exoskeleton, gills and remaining soft tissues, the hepatopancreas and gills containing the highest labelled cadmium concentrations. Like other crustaceans, penaeid prawns inhabiting anthropogenically contaminated coastal waters with raised cadmium bioavailabilities can be expected to contain raised body concentrations of cadmium. Cadmium concentrations of most field-collected adult penaeids are relatively low, as a probable consequence of the growth dilution of their cadmium contents as a result of the rapid growth rates of penaeid prawns.

Kinetics of zinc uptake from solution, accumulation and excretion by the decapod crustacean Penaeus indicus

Juveniles of the dendrobranchiate decapod Penaeus indicus take up radiolabelled zinc from solution at all exposure concentrations studied from 5.6 to 100 μg l−1, with an uptake rate constant of 0.045 l g−1 day−1 at 15 salinity and 25°C. Over the first 10 days of zinc exposure, the new zinc taken up is added to the existing zinc content of the prawn with no significant excretion; over this period the rate of accumulation of radiolabelled zinc is a measure of the absolute zinc uptake rate from solution. Over the next 10 days of zinc exposure to 10 μg Zn l−1, however, zinc is excreted at about half the rate of uptake resulting in a raised body concentration of zinc. Moulting had no significant effect on the accumulation of zinc. Newly accumulated zinc is distributed to all organs with the highest proportions of body content being found in the exoskeleton, followed by the muscle, the hepatopancreas and the antennal organs. Radiolabelled zinc is subsequently lost from all organs. Unlike caridean shrimps or prawns (pleocyemate decapods), therefore, penaeids (dendrobranchiate decapods) do not show regulation of zinc body concentrations to a constant level over a range of dissolved zinc bioavailabilities by matching zinc excretion to zinc uptake. Nevertheless, unlike amphipod crustaceans, P. indicus does excrete some of the zinc newly accumulated from solution after a time delay. Unlike their caridean counterparts, penaeid prawns inhabiting anthropogenically contaminated coastal waters with raised zinc bioavailabilities can be expected to contain raised body concentrations of zinc.

Increasing codend mesh openings: an appropriate strategy for improving the selectivity of penaeid fishing gears in an Australian estuary?

This study investigates the effects of increasing the lateral mesh openings in codends on the size and species selectivity of lagoon and river seines and a stow net used to target penaeid prawns (eastern king (Penaeus plebejus), school (Metapenaeus macleayi) and greasyback prawns (M. bennettae)) in Wallis Lake, New South Wales, Australia. Compared with conventional codends made from 36-mm diamond-shaped mesh, new designs made from 25- and 29-mm mesh hung on the bar (i.e. square-shaped mesh) significantly reduced the catches of non-target fish (by between 58 and 95%) and improved size selection for the targeted penaeids in the stow net and lagoon seine. In contrast, owing to gear-specific operational characteristics such as a slower hauling speed, there were few detectable effects of altering mesh openings in the codend of the river seine. The results are discussed in terms of the differences in the gears used and their particular selection mechanisms. We conclude that, pending further trials, codends made from a mesh size approaching 29 mm, hung on the bar, would provide appropriate size- and species-selection for Wallis Lake stow nets and lagoon seines. Further research is required, however, to examine the utility of operational changes to river seines and/or alterations to mesh size and configuration in the wings and body to improve selectivity.

Fishing the marine food web along the Indian coast

The annual mean trophic level (TrL) of marine fish landings along the Indian coast consisting of 53 exploited species/groups was estimated for the period 1950–2002. The landings as well as TrL increased along the northwest (NW) and southwest (SW) coasts. However, increase in the landings was associated with decrease in mean TrL along the east coast, particularly along the southeast (SE) coast at the rate of 0.04 per decade. The increasing trend of the FIB index ceased in the last 5–10 years along three coasts. A backward-bending signature in the landings versus TrL plot for the SE coast in the last 6 years indicates fisheries-induced changes in the ecosystem owing to low productivity of the coastal waters and high density of fishing craft. The landings of most of the large predators increased along the Indian coast, but higher removals appear to have helped proliferation of their prey, the mid-level carnivores. Fishing the food web has been influenced by environmental fluctuations, advanced fishing technologies, and market-driven, deliberate fishing on low-trophic level (TL) invertebrates such as the penaeid prawns.

Interaction of pH with mercuric chloride toxicity to penaeid prawns from a tropical estuary, East Coast of India: enhanced toxicity at low pH

Toxicity tests were conducted to study the interaction of pH and the response of two size groups of penaeid prawns i.e. Penaeus monodon and Penaeus indicus to different sets of five concentrations of HgCl 2 (0.01–0.09 mg l −1) under a broad range of pH conditions (5–9). Behavioural responses varied according to test solution concentration and nominated values of pH. Abnormality was detected in the higher concentrations with lower pH in smaller size group of P. monodon. High mortality was observed at higher concentration of test solution with low pH. Irrespective of species and size group LC 50 demonstrated similar trend of variation with respect to time period. At pH 9 the threshold limit for 65–75 mm size group of P. monodon and P. indicus was 0.043 and 0.049 mg l −1 respectively while it was 0.041 and 0.035 mg l −1 respectively at pH 8; and 0.038 and 0.044 mg l −1 respectively at pH 7. Relative toxicities were significantly varied except for bigger size groups in the studied pH ranges. The result was pronounced at pH 5 with maximum 1.61 times for inter-hour relative toxicity in contrast to all. At pH below 7 of mercury resulted more toxic compared to high pH range (>7) might be due to acid toxicity itself. At each pH smaller size groups were sensitive while bigger shown tolerant. P. monodon were more sensitive than P. indicus. The toxic order of pH effect was 9 < 8 < 7 < 6 < 5. Toxicity increased significantly ( p > 0.01) in acidic medium compared to alkaline.