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Paul C Southgate - One of the best experts on this subject based on the ideXlab platform.

  • economic feasibility of small scale mabe pearl production in tonga using the winged pearl oyster Pteria Penguin
    Aquaculture Reports, 2020
    Co-Authors: William Johnston, Sophie E Gordon, Max Wingfield, Tuikolongahau Halafihi, Damian Hine, Paul C Southgate
    Abstract:

    Abstract Mabe pearl culture is an increasingly important rural livelihood in south Pacific countries as it offers a low-cost, low-tech alternative to round pearl culture. Mabe pearl production can be achieved by local people with appropriate training, and the products offer further livelihood opportunities through value-adding and local production of jewellery and handicraft items. The Kingdom of Tonga is unique among south Pacific pearl producing countries in focusing primarily on mabe pearl, not round pearl, culture using the winged pearl oyster, Pteria Penguin. The Tongan mabe pearl sector has developed rapidly over recent years and is sustained by routine hatchery production of spat and recently improved pearl culture methods. This study determined establishment and operational costs of a subsistence-level mabe pearl farm in Tonga and developed an economic model to assess potential profitability of such operations. The representative mabe pearl farm modelled in this study targeted annual mabe pearl production from 100 oysters. Estimated capital cost (US dollars; USD) was USD 2,027 and major production costs were labour (29%), marketing (24%), and capital purchase and replacement (16%). Annual production of 231 saleable mabe pearls generated a net present value (NPV) of USD 107,101. The modified internal rate of return (MIRR) and benefit-cost ratio of the modelled mabe pearl farm were 20.46% and 4.86, respectively, with a payback period of 4 years. Given the average annual income in Tonga is USD 4,020, the modelled mabe pearl farm offers significant economic opportunity (USD 9,338 annual profit after all costs, including owner/operator wages) and supports additional socio-economic benefits for rural communities involved in downstream activities relating to handicraft and jewellery production, and tourism. The findings of this study assist stakeholder understanding of costs, risks and production levels required for profitable mabe pearl production.

  • Economic assessment of community-based pearl oyster spat collection and mabé pearl production in the western Pacific
    Aquaculture, 2020
    Co-Authors: Bill Johnston, Damian Hine, Pranesh Kishore, Gary Bingnald Vuibeqa, Paul C Southgate
    Abstract:

    Abstract Cultured pearl production, and associated activities, are of crucial social and economic importance to remote coastal communities in Polynesia and the western Pacific. This study determined the potential profitability of (1) community-based pearl oyster spat collection operations targeting Pinctada margaritifera, and the subsequent sale of pearl oysters to round pearl farms; and (2) the use of Pteria Penguin, collected incidentally from P. margaritifera spat collection operations, for mabe pearl production. The spat collection farm modelled in this study comprised four 100-m longlines supporting 1240 commercial spat collectors, with an estimated capital cost of $1245 (all figures in USD). The spat collection operation produced 2332 saleable P. margaritifera pearl oysters (sold to round pearl culture operations) with estimated NPV of $10,439. The MIRR generated was 12.24%, with a benefit-cost ratio was 1.52, and a payback period of 4 years. The downstream mabe pearl farm modelled in this study comprised two 100-m longlines supporting 2000 implanted Pt. Penguin oysters with an estimated capital cost of $7319. Annual production of 5400 mabe pearls generated an NPV of $491,864. The MIRR and benefit-cost ratio of the modelled mabe pearl farm were 22.64% and 7.24, respectively, with a payback period of 3 years. Incorporating production and price risk into the model reduced the expected NPV of the mabe pearl farm to $297,507. The models developed in this study provide valuable new information for prospective pearl oyster spat and mabe pearl farming community groups, donors, funding bodies and other stakeholders, and provide a valuable extension tool supporting further development of the pearl sector in Fiji and the broader Indo-Pacific region.

  • effects of nucleus position profile and arrangement on the quality of mabe pearls produced by the winged pearl oyster Pteria Penguin
    Aquaculture, 2019
    Co-Authors: Sophie E Gordon, Max Wingfield, Siolaa Malimali, Ipek D Kurtboke, Paul C Southgate
    Abstract:

    The position and arrangement of nuclei is the most important technical aspect of mabe pearl (half-pearl) production. This study examined the effects of nucleus arrangement, profile (height) and position, on quality, nacre thickness and shape of mabe pearls produced by Pteria Penguin. Oysters implanted with three nuclei produced a greater proportion of saleable mabe pearls with more regular shapes than oysters implanted with five nuclei. Use of low profile nuclei resulted in mabe pearls with increased nacre thickness and produced mabe pearls of significantly higher quality, with more regular shapes than high profile nuclei. Nucleus position significantly influenced mabe pearl quality, nacre thickness and shape. The posterior-ventral position of the left shell valve produced mabe pearls of the highest quality with the thickest nacre and was the best location for mabe pearl culture. Based on the results of this study, it is recommended that P. Penguin is implanted with a maximum of three nuclei to increase the production of regular-shaped mabe pearls, and that low profile nuclei are used to improve quality and nacre thickness of mabe pearls produced in less favourable nucleus positions. An optimal nucleus arrangement for P. Penguin of 130–150mm dorso-ventral height would include one high profile nucleus in the posterior-ventral position of the left shell plus additional low profile nuclei in both the anterior-ventral position of the left shell valve and, the center of the right shell. Based on the quality grading system used in this study, a minimum commercial nacre thickness of 0.25mm is recommended for mabe pearl production using P. Penguin.

  • Using microradiography to assess nacre thickness of mabé pearls: Technique suitability and insights
    Aquaculture, 2018
    Co-Authors: Sophie E Gordon, Pranesh Kishore, Max Wingfield, Siolaa Malimali, 'ana 'akau'ola, Paul C Southgate
    Abstract:

    Abstract Nacre thickness is a major factor influencing the quality and value of half-pearls (‘mabe’), yet accurate determination of nacre thickness, in a non-destructive manner, is problematic. Microradiography is commonly used to measure the nacre thickness of round pearls, however the suitability of this technique for mabe has not previously been assessed. Mabe were cultured in winged pearl oysters (Pteria Penguin) for periods of 200 to 380 days to produce pearls with a range of nacre thicknesses. The nacre thickness of each pearl was quantified using microradiography and standard micrometer techniques. A strong, significant relationship was observed between measurements obtained using both techniques (R2 = 0.88, P ≤ 0.001). Microradiography produced defined, measureable images, with a resolution of ±0.04 mm, for mabe pearls with nacre thicknesses between 0.1 and 1.3 mm. Mabe nacre thickness and pearl quality were significantly influenced by the position of the pearl nucleus within the shell (T(95) = 7.14, P

  • morphometric relationships and shell form of cultured winged pearl oysters Pteria Penguin in tonga
    Journal of Shellfish Research, 2017
    Co-Authors: Sophie E Gordon, Poasi Ngaluafe, Max Wingfield, Paul C Southgate
    Abstract:

    Shell dimensions of 588 hatchery-produced Pteria Penguin (Roding, 1798) were measured and analyzed to describe morphometric changes in shell form of this species over its life cycle. Oysters ranged from 9.4 to 202.2 mm in dorsoventral height (DVH), 0.1–1,526.9 g in weight and spanned 0.5–5 y of age. Significant positive curvilinear relationships were observed between shell width (SW) and DVH (R2 = 0.99, P < 0.001), diagonal length (DL) and DVH (R2 = 0.99, P < 0.001), shell thickness (ST) and DVH (R2 = 0.98, P < 0.001), and wet weight (WW) and DVH (R2 = 0.99, P < 0.001). Trends in the morphometric ratios of P. Penguin indicated a proportional decrease in SW and DL with increasing DVH, resulting in a shift from a horizontally elongate to a vertically elongate shell form. The ST of P. Penguin remained proportionally stable over its life cycle, whereas its WW increased proportionally by more than two orders of magnitude. Based on the results of this study, future research should examine (1) the relationship between the external shell dimensions and internal nacreous area, (2) changes in nacre deposition rate in different shell locations, and (3) the relationship between soft tissue weight, shell weight, nacre thickness, and DVH of P. Penguin. The description of the growth form of P. Penguin represents an important first step toward determining optimum half-pearl (mabe) culture procedures for P. Penguin in Tonga.

Michael Milione - One of the best experts on this subject based on the ideXlab platform.

  • reproductive cycle of the winged pearl oyster Pteria Penguin roding 1793 pteriidae in north eastern australia
    Invertebrate Reproduction & Development, 2012
    Co-Authors: Michael Milione, Paul C Southgate
    Abstract:

    The spawning cycle of the winged pearl oyster, Pteria Penguin, was studied at Orpheus Island, north-eastern Queensland to observe seasonal changes in gonad development, mean oocyte diameter and sex ratio over time. A total of 201 oysters were collected over 10 sampling periods, approximately every 5–6 weeks (mean = 20 oysters/sample). Histological analysis of gonads showed that spawning activity occurred mainly through the austral mid-spring to late summer (November to March), when mean monthly water temperature ranged between 27.5°C and 29.4°C. There was a primary spawning peak at the beginning of the spawning season in December, followed by a secondary peak in March. Mean oocyte diameter (µm) was highest during the warmer months, ranging from 31.2 ± 2.4 in November to 36.2 ± 3.2 in March, and sex ratio analysis showed the percentage of females in the population also peaked between 30% and 50% during this period.

  • growth of the winged pearl oyster Pteria Penguin at dissimilar sites in northeastern australia
    Journal of Shellfish Research, 2012
    Co-Authors: Michael Milione, Paul C Southgate
    Abstract:

    Growth of Pieria Penguin pearl oysters was monitored for 20 mo, from April 2009 to November 2010, to investigate differences in growth performance at three dissimilar sites: Pioneer Bay, Cape Ferguson, and Horseshoe Bay in the Great Barrier Reef lagoon. Growth parameters generated with the von Bertalanffy growth function ranged from K = 0.09-0.32 and L-infinity = 283.6-822.5. Overall growth performance (Phi') ranged from 4.40-4.77. Time to reach commercial size (T-100) was between 1.38 y and 1.54 y, and T-120 was between 1.74 and 1.92 y. A more accurate estimate of the L-infinity = 213.4-mm dorsoventral measurement (DVM) was obtained at Pioneer Bay by using a larger data set that incorporated a wider size range of oysters. Overall monthly increase in DVM of oysters held at Horseshoe Bay (5.3 +/- 0.2 mm) was more than that at Pioneer Bay (4.7 +/- 0.2 mm) and Cape Ferguson (4.9 +/- 0.2 mm), and there were significant differences in the monthly DVM increase among the sites during growth measurement periods (P < 0.05). Monthly DVM growth was fastest (7.2 +/- 0.2 mm) in small oysters (DVM, 50-70 mm) in the spring and summer and was lowest (2.4 +/- 1.4 mm) in larger oysters (DVM, 105-110 mm) during the spring. Regression analysis showed anteroposterior measurement (A PM), shell thickness (ST), and whole weight (WW) were significantly correlated with DVM for all groups (P < 0.001). In the commercial size class of 100-120 mm DVM, mean WW of oysters at Cape Ferguson was significantly greater (P < 0.01), and the APM-to-DVM ratio was also significantly greater for oysters at Cape Ferguson and Horseshoe Bay (P < 0.01), whereas there were no significant differences among groups with regard to the ST-to-DVM ratio. At all 3 sites, the highest mortalities (measured as a percentage) were recorded for small oysters (DVM, 25-50 mm) during the winter period. Suspended particulate inorganic matter (measured in grams) levels were significantly different among sites (P < 0.001). Comparison among growth rates obtained during this study demonstrate that there is significant variability in growth between sites in the Great Barrier Reef lagoon, and that P. Penguin are able to tolerate-and even thrive-under a wide range of turbidity levels.

  • Sexual development, sex ratio and morphometrics of Pteria Penguin (Bivalvia: Pteriidae), in North-Eastern Australia
    Molluscan Research, 2011
    Co-Authors: Michael Milione, Pedro E. Saucedo, Paul C Southgate
    Abstract:

    Pteria Penguin were collected at Orpheus Island, north-eastern Queensland to observe sexual development, sex ratio and changes in morphometric relationships during growth. P. Penguin are protandrous hermaphrodites, with all sexually mature oysters below 88.8 mm dorso-ventral height (DVH) being males. Evidence of male primary gonad development was seen in oysters with a DVH of ≥33.9 mm. Sexual maturity of males was first seen in oysters at ≥56.0 mm DVH, but was common in oysters at ≥70.0 mm DVH. Mean female size was 150.1 (±3.6) mm DVH, and mean male size was 111.3 (±2.2) mm DVH. In oysters 180 mm DVH. Significant linear correlations were found between anterior-posterior length of the shell (APL) and DVH (r2 = 0.97, p

  • sexual development sex ratio and morphometrics of Pteria Penguin bivalvia pteriidae in north eastern australia
    Molluscan Research, 2011
    Co-Authors: Michael Milione, Pedro E. Saucedo, Paul C Southgate
    Abstract:

    Pteria Penguin were collected at Orpheus Island, north-eastern Queensland to observe sexual development, sex ratio and changes in morphometric relationships during growth. P. Penguin are protandrous hermaphrodites, with all sexually mature oysters below 88.8 mm dorso-ventral height (DVH) being males. Evidence of male primary gonad development was seen in oysters with a DVH of ≥33.9 mm. Sexual maturity of males was first seen in oysters at ≥56.0 mm DVH, but was common in oysters at ≥70.0 mm DVH. Mean female size was 150.1 (±3.6) mm DVH, and mean male size was 111.3 (±2.2) mm DVH. In oysters 180 mm DVH. Significant linear correlations were found between anterior-posterior length of the shell (APL) and DVH (r2 = 0.97, p <0.001) and between shell thickness (ST) and DVH (r2 = 0.95, p <0.001), and a curvilinear relationship was recorded between adductor muscle weight (AW) and DVH (r2 = 0.93, p <0.001). These findings have industry applications for collection of juvenile stock, spawning induction procedures and determining optimal shell size for pearl nucleus implanting.

  • environmental conditions and culture method effects on growth and survival of juvenile winged pearl oyster Pteria Penguin
    Journal of Shellfish Research, 2011
    Co-Authors: Michael Milione, Paul C Southgate
    Abstract:

    Juvenile winged pearl oysters, Pteria Penguin, were cultured for 6 mo in three commonly used culture units (panel nets, plastic mesh trays, and pyramidal pearl nets) at two dissimilar sites—Pioneer Bay (a coral reef environment in which P. Penguin are naturally present) and Cape Ferguson (a coastal semiestuarine area with high levels of silt deposition)—to determine the effects of site and culture method on growth, survival, and fouling. Mean growth increases were recorded for the dorsoventral measurement (DVM), anteroposterior measurement (APM), shell thickness, and whole weight. At Pioneer Bay, five replicates for each of the three culture unit types were suspended at 3 m and at 6 m, and mean initial DVM was 28.0 ± 0.6 mm (n ¼ 190). At Cape Ferguson, there were five replicates for each culture unit at 3 m only, and mean initial DVM was 28.0 ± 0.6 mm (n ¼ 86). Mean growth increase at the end of the experiment for oysters at Pioneer Bay and Cape Ferguson, respectively, were 26.6 ± 1.0 mm and 32.6 ± 2.4 mm DVM, 29.6 ± 1.2 mm and 34.0 ± 2.9 mm APM, 6.7 ± 0.3 mm and 9.7 ± 0.5 mm shell thickness, and 16.5 ± 0.7 g and 23.0 ± 2.1 g whole weight. For all growth parameters, mean increase was significantly higher under high-turbidity conditions at Cape Ferguson (P < 0.05). Culture unit also affected growth, with oysters held in mesh trays showing significantly more growth at both sites (P < 0.05). Mean survival of oysters at Cape Ferguson (96.5%) was significantly higher than at Pioneer Bay (79.4%). Depth had no significant effect on growth, survival, or fouling. The results indicate that site selection and culture unit are important parameters for optimizing growth and survival during nursery phase culture of P. Penguin.

Matthew Wassnig - One of the best experts on this subject based on the ideXlab platform.

  • the effects of stocking density and ration on survival and growth of winged pearl oyster Pteria Penguin larvae fed commercially available micro algae concentrates
    Aquaculture Reports, 2016
    Co-Authors: Matthew Wassnig, Paul C Southgate
    Abstract:

    Abstract Commercially available micro-algae concentrates have been successfully used as an alternative to live micro-algae as a food source during routine larval culture of the winged pearl oyster, Pteria Penguin . This supports the development of simplified hatchery facilities and larval rearing protocols that are more appropriate to Pacific island nations. An optimal feeding regime based on these products that also accounts for larval stocking density is yet to be developed. Two experiments were conducted at a commercial pearl oyster hatchery facility in the Kingdom of Tonga to examine the combined effects of stocking density and ration on survival and growth of both D-stage (from 1 to 8 days post-fertilsation) and umbo-stage (from 8 to 17 days) P. Penguin larvae. Both experiments used a factorial design combining three larval stocking densities (D-stage: 2, 6 & 10 larvae mL −1 ; umbo-stage: 1, 3 & 5 larvae mL −1 ) and three rations (D-stage: 5, 10 & 15 cells mL −1 ; umbo-stage: 10, 15 & 20 cells mL −1 ). Survival during D-stage was significantly improved in aquaria stocked below 10 larvae mL −1 , whereby a density of 6 mL −1 maximised larval production. An intermediate ration of 10 × 10 3 cells mL −1 maximised both survival and growth during D-stage. Increasing the initial stocking density of umbo-stage larvae from 1 to 3 mL −1 resulted in significant reductions in both survival and growth. Growth of umbo-stage larvae stocked at a density of 1 mL −1 increased significantly when ration remained below 20 × 10 3 cells mL −1 . The results of this study provide a basis for optimised hatchery culture protocols for P. Penguin that are more appropriate to Pacific island nations.

  • effects of settlement cues on behaviour and substrate attachment of hatchery reared winged pearl oyster Pteria Penguin larvae
    Aquaculture, 2012
    Co-Authors: Matthew Wassnig, Paul C Southgate
    Abstract:

    Successful hatchery production of commercial bivalve species requires optimal recruitment of larvae to substrates. This study used two experiments to investigate the effects on recruitment of Pteria Penguin pediveliger larvae of (1) treating the culture medium with alternate concentrations of three chemical compounds both in the presence/absence of a bio-film and (2) exposure to five substrate types both in the presence/absence of a chemical cue. Small 10 mL aquaria were stocked with 1 larvae mL⁻¹ and given a 25x25 mm piece of horizontally-oriented flat substrate. The proportion of larvae within each treatment that displayed various behaviours (swimming/sitting/crawling), had settled using byssal attachment or had undergone mortality was recorded at 24, 48 and 72 h. After 48 h, settlement of P. Penguin was 65% greater in aquaria containing a substrate covered by a naturally formed bio-film than in control aquaria. The neuroactive compounds 5-hydroxytryptamine (serotonin) and γ-aminobutyric acid (GABA) and the chemical compound potassium chloride (KCl) all acted to decrease larval swimming behaviour when compared to controls with untreated seawater. Exposure to KCl (20 mM) also resulted in more larvae crawling over the substrate surface. After 72 h, settlement of larvae in aquaria treated with serotonin (10⁻³ M) or KCl (20 mM) was significantly greater than in control aquaria by 75% and 84%, respectively, while exposure to GABA had no effect. The positive effect of a bio-film on settlement did not change significantly according to chemical treatment of the culture medium, suggesting that the techniques can be used in conjunction. Settlement in response to 20 mM KCl was enhanced by the presence of a red nylon mesh substrate with 5 mm between filaments. Roughly three times more larvae settled onto this substrate during the first 24 h when compared to the same material with a smaller mesh size, black fibreglass screen and smooth plastic substrates. Comparisons with settlement behaviour of other bivalves and the commercial implications of this research are discussed.

  • embryonic and larval development of Pteria Penguin roding 1798 bivalvia pteriidae
    Journal of Molluscan Studies, 2012
    Co-Authors: Matthew Wassnig, Paul C Southgate
    Abstract:

    This study describes the processes of embryogenesis, shell formation and larval development of the winged pearl oyster, Pteria Penguin. Broodstock were induced to spawn using the standard method of thermal stimulation and fertilized eggs were incubated at a density of 50 ml−1 and a temperature of 27 ± 1°C. After an incubation period of 24 h, shelled larvae were stocked at 3 ml−1 and fed a mixed microalgae diet until reaching settlement age. Embryos and larvae were sampled periodically for examination by scanning electron microscope. The resulting high-resolution images were used to record the timing of developmental stages including the first cleavage (1 h postfertilization, hpf), morula (2.5 hpf), blastula (4.5 hpf), gastrula (5.5 > hpf), trochophore (7 > hpf), D-stage (20–22 hpf), prodissoconch II (3–6 days posthatching, dph), umbone (10–12 dph) and pediveliger (22 dph). Comparison with other oviparous oyster species revealed a similar sequence of key events, with differences occurring in the timing of developmental stages, shell structure and shell shape. This study is the first to describe early shell formation for a species belonging to the family Pteriidae. Shell development begins with formation a shell-field invagination (sfi) at the dorsoposterior end of the embryo (7 hpf), indicating the creation of a shell gland. The sfi stretches laterally to create a deep crevice (9 hpf) before eventually everting to form a flat central hinge linking the two expanding shell valves (12 hpf).

  • Developing hatchery culture techniques for the winged pearl oyster, Pteria Penguin (Röding, 1798)
    2011
    Co-Authors: Matthew Wassnig
    Abstract:

    Pearl culture has traditionally relied on collecting juvenile pearl oysters (family: Pteriidae) from the wild and growing them to an appropriate size to be used in pearl production; a method that has become increasingly less viable due to a corresponding depletion in wild populations. Hatchery propagation of juvenile pearl oysters is now a necessity in regions where collection from the wild can no longer sustain commercial pearl production. The cultured pearl industry in the Indo-Pacific includes production of half-pearls or 'mabe' from Pteria Penguin (Roding 1798). Pearl production from P. Penguin has become progressively more reliant on hatchery culture of oysters; however, efficient production is constrained by a lack of knowledge regarding optimal culture techniques. This study aimed to develop hatchery culture techniques that could be implemented by industry to improve the prospects for pearl production from P. Penguin and decrease the fishing pressure currently placed on wild populations. The natural spawning season for P. Penguin typically spans only a few months of each year, providing a short window for hatchery production of juveniles. A lack of knowledge regarding the diet and conditions required to optimise energy uptake by adult P. Penguin has impeded the development of brood-stock conditioning programs that could be used to encourage gametogenesis outside of the natural spawning season. This study examined the pattern of suspension feeding by P. Penguin in response to variations in microalgae diet, food concentration and water temperature. Brood-stock were placed in temperature controlled flow-though chambers that supplied individual oysters with a constant concentration of suspended microalgae. Feeding behaviour was quantified as the rate at which water was cleared of algae cells (clearance rate; CR) and the fraction of organic carbon absorbed during digestion (absorption efficiency; AE). The results showed that CR was greater when feeding on the two flagellate species Isochrysis sp. Tahitian (T-Iso) and Pavlova sp. (mean = 32 L h⁻¹ oyster⁻¹) when compared to the diatom Chaetoceros muelleri (27 L h⁻¹ oyster⁻¹). At temperatures of 24-28°CP. Penguin maintained a stable CR with increasing food availability up to the maximum concentration tested (50 x 10³ cells mL⁻¹). Mean AE was highest for T-Iso (61%) and not influenced by food concentration. Decreased CR and AE in response to a rapid reduction in water temperature during summer, reflected the 35% lower CR and 47% lower AE observed during the colder austral winter, suggesting temperature contributes to differences in suspension feeding between seasons. The high feeding capacity of P. Penguin raised the issue that in order to undertake brood-stock conditioning, hatcheries would require the facilities to culture large volumes of live microalgae. Pearl farms that use P. Penguin are typically located in regional areas where the technical capacity for mass algae culture is not available. An experiment was conducted to assess the viability of using commercially available concentrated microalgae and a unique flow-though aquarium system to condition brood-stock prior to the natural spawning season. Fifteen P. Penguin of a similar size were distributed between 5 identical 30 L 'flow-though aquaria'. A mixed diet of concentrated microalgae from the Instant Algae® range was supplied to brood-stock for a period of 40 days with periodic increases (10 day intervals) in food concentration and water temperature up to a maximum of 40 x 10 cells mL⁻¹ and 28°C. Histological examination of gonad tissue was conducted at the conclusion of the study so that the reproductive condition of each oyster could be categorized using the five stages for pearl oyster gonad development, ranging from inactive to ripe. The same process was conducted for 15 similar sized P. Penguin that were held in ocean culture for the same time period. The reproductive state of conditioned animals suggested that male P. Penguin produced spermatozoa at a rate exceeding that observed in a wild environment over the same time period. The production of mature oocytes in experimental females was less reliable, attributable to the period for conditioning being too short for the production of energetically expensive ooyctes. In order to develop techniques for hatchery culture of juvenile P. Penguin, it was first necessary to understand the processes of embryogenesis and larval development for this species. Following standard methods used in the hatchery culture of other pearl oyster species, P. Penguin eggs were spawned, fertilized and incubated until they hatched into shelled veliger larvae. Larvae were then fed a diet of live microalgae until developing a foot and being deemed competetent to settle. Embryos and larvae were sampled periodically during hatchery culture to be examined under scanning electron microscope (SEM). The resulting high resolution images were then used to map the approximate timing of developmental stages. These stages included the first cleavage (1 h post-fertilisation; hpf), morula (2.5 hpf), blastula (4.5 hpf), gastrula (5.5> hpf), trochophore (7> hpf), D-stage (20 - 22 hpf), prodissoconch II (3 - 6 days post-hatching into D-stage; dph), umbone (10 - 12 dph) and pediveliger (22 dph). Comparison with patterns of embryogenesis and larval development in other oviparous oyster species revealed a similar sequence of key events, with differences occurring in the timing of developmental stages, shell structure and shell shape. Embryo incubation is a period of pearl oyster culture that is typically characterised by excessive mortality. This study addressed the issue of embryo mortality by examining the effects of egg stocking density and the application of antibiotics during incubation. A factorial experimental design combined three egg densities (10, 50 and 100 mL⁻¹) and three antibiotic treatments (Control - no antibiotic; 5 mg mL⁻¹ streptomycin-sulfate; 5 mg mL⁻¹ tetracycline:erythromycin 2.5:2.5 mg mL⁻¹). Antibiotics were added to the culture medium as a single dose and fertilised eggs were incubated for a period of 24 h. Tetracycline:erythromycin (1:1) improved mean survival (23%), but yielded an average of only 9% more veliger larvae than control aquaria due to interference with development. The antibiotic streptomycin-sulfate improved mean survival by 16% when compared to control aquaria, without significantly compromising development. A high egg density of 100 mL⁻¹ did not significantly reduce survival, but resulted in a 5% reduction in normal development to D-stage. It is recommended that eggs be stocked at a density ≤50 mL⁻¹ and mortality be minimised by treating the culture medium with the antibiotic streptomycin-sulfate. Hatchery culture in regional areas is often impossible because farms cannot afford the facilities required to produce the live microalgae used as a food source for larvae. Concentrated algal paste supplied by Instant Algae® has been successfully trialled as an alternative food source during hatchery culture of P. Penguin, but the feeding regime that promotes optimal larval growth and development is yet to be determined. Experiment 1 assessed the combined effects of stocking density and feed ration on the survival and growth of P. Penguin larvae during D-stage (1-8 days post-fertilisation). Experiment 2 examined the effects of the same treatments on the survival and growth of larvae during umbo-stage (8 - 17 days post-fertilisation). Both experiments used a factorial design combining 3 egg stocking densities (Experiment 1: 2, 6 and 10 larvae mL⁻¹; Experiment 2: 1, 3 and 5 larvae mL⁻¹) and 3 levels of feed ration (Experiment 1: 5, 10 and 15 x 10³ cells mL⁻¹; Experiment 2: 10, 15 and 20 x 10³ cells mL⁻¹). Survival during D-stage was significantly enhanced (by 105%) in aquaria stocked at

  • developing hatchery culture techniques for the winged pearl oyster Pteria Penguin roding 1798
    2011
    Co-Authors: Matthew Wassnig
    Abstract:

    Pearl culture has traditionally relied on collecting juvenile pearl oysters (family: Pteriidae) from the wild and growing them to an appropriate size to be used in pearl production; a method that has become increasingly less viable due to a corresponding depletion in wild populations. Hatchery propagation of juvenile pearl oysters is now a necessity in regions where collection from the wild can no longer sustain commercial pearl production. The cultured pearl industry in the Indo-Pacific includes production of half-pearls or 'mabe' from Pteria Penguin (Roding 1798). Pearl production from P. Penguin has become progressively more reliant on hatchery culture of oysters; however, efficient production is constrained by a lack of knowledge regarding optimal culture techniques. This study aimed to develop hatchery culture techniques that could be implemented by industry to improve the prospects for pearl production from P. Penguin and decrease the fishing pressure currently placed on wild populations. The natural spawning season for P. Penguin typically spans only a few months of each year, providing a short window for hatchery production of juveniles. A lack of knowledge regarding the diet and conditions required to optimise energy uptake by adult P. Penguin has impeded the development of brood-stock conditioning programs that could be used to encourage gametogenesis outside of the natural spawning season. This study examined the pattern of suspension feeding by P. Penguin in response to variations in microalgae diet, food concentration and water temperature. Brood-stock were placed in temperature controlled flow-though chambers that supplied individual oysters with a constant concentration of suspended microalgae. Feeding behaviour was quantified as the rate at which water was cleared of algae cells (clearance rate; CR) and the fraction of organic carbon absorbed during digestion (absorption efficiency; AE). The results showed that CR was greater when feeding on the two flagellate species Isochrysis sp. Tahitian (T-Iso) and Pavlova sp. (mean = 32 L h⁻¹ oyster⁻¹) when compared to the diatom Chaetoceros muelleri (27 L h⁻¹ oyster⁻¹). At temperatures of 24-28°CP. Penguin maintained a stable CR with increasing food availability up to the maximum concentration tested (50 x 10³ cells mL⁻¹). Mean AE was highest for T-Iso (61%) and not influenced by food concentration. Decreased CR and AE in response to a rapid reduction in water temperature during summer, reflected the 35% lower CR and 47% lower AE observed during the colder austral winter, suggesting temperature contributes to differences in suspension feeding between seasons. The high feeding capacity of P. Penguin raised the issue that in order to undertake brood-stock conditioning, hatcheries would require the facilities to culture large volumes of live microalgae. Pearl farms that use P. Penguin are typically located in regional areas where the technical capacity for mass algae culture is not available. An experiment was conducted to assess the viability of using commercially available concentrated microalgae and a unique flow-though aquarium system to condition brood-stock prior to the natural spawning season. Fifteen P. Penguin of a similar size were distributed between 5 identical 30 L 'flow-though aquaria'. A mixed diet of concentrated microalgae from the Instant Algae® range was supplied to brood-stock for a period of 40 days with periodic increases (10 day intervals) in food concentration and water temperature up to a maximum of 40 x 10 cells mL⁻¹ and 28°C. Histological examination of gonad tissue was conducted at the conclusion of the study so that the reproductive condition of each oyster could be categorized using the five stages for pearl oyster gonad development, ranging from inactive to ripe. The same process was conducted for 15 similar sized P. Penguin that were held in ocean culture for the same time period. The reproductive state of conditioned animals suggested that male P. Penguin produced spermatozoa at a rate exceeding that observed in a wild environment over the same time period. The production of mature oocytes in experimental females was less reliable, attributable to the period for conditioning being too short for the production of energetically expensive ooyctes. In order to develop techniques for hatchery culture of juvenile P. Penguin, it was first necessary to understand the processes of embryogenesis and larval development for this species. Following standard methods used in the hatchery culture of other pearl oyster species, P. Penguin eggs were spawned, fertilized and incubated until they hatched into shelled veliger larvae. Larvae were then fed a diet of live microalgae until developing a foot and being deemed competetent to settle. Embryos and larvae were sampled periodically during hatchery culture to be examined under scanning electron microscope (SEM). The resulting high resolution images were then used to map the approximate timing of developmental stages. These stages included the first cleavage (1 h post-fertilisation; hpf), morula (2.5 hpf), blastula (4.5 hpf), gastrula (5.5> hpf), trochophore (7> hpf), D-stage (20 - 22 hpf), prodissoconch II (3 - 6 days post-hatching into D-stage; dph), umbone (10 - 12 dph) and pediveliger (22 dph). Comparison with patterns of embryogenesis and larval development in other oviparous oyster species revealed a similar sequence of key events, with differences occurring in the timing of developmental stages, shell structure and shell shape. Embryo incubation is a period of pearl oyster culture that is typically characterised by excessive mortality. This study addressed the issue of embryo mortality by examining the effects of egg stocking density and the application of antibiotics during incubation. A factorial experimental design combined three egg densities (10, 50 and 100 mL⁻¹) and three antibiotic treatments (Control - no antibiotic; 5 mg mL⁻¹ streptomycin-sulfate; 5 mg mL⁻¹ tetracycline:erythromycin 2.5:2.5 mg mL⁻¹). Antibiotics were added to the culture medium as a single dose and fertilised eggs were incubated for a period of 24 h. Tetracycline:erythromycin (1:1) improved mean survival (23%), but yielded an average of only 9% more veliger larvae than control aquaria due to interference with development. The antibiotic streptomycin-sulfate improved mean survival by 16% when compared to control aquaria, without significantly compromising development. A high egg density of 100 mL⁻¹ did not significantly reduce survival, but resulted in a 5% reduction in normal development to D-stage. It is recommended that eggs be stocked at a density ≤50 mL⁻¹ and mortality be minimised by treating the culture medium with the antibiotic streptomycin-sulfate. Hatchery culture in regional areas is often impossible because farms cannot afford the facilities required to produce the live microalgae used as a food source for larvae. Concentrated algal paste supplied by Instant Algae® has been successfully trialled as an alternative food source during hatchery culture of P. Penguin, but the feeding regime that promotes optimal larval growth and development is yet to be determined. Experiment 1 assessed the combined effects of stocking density and feed ration on the survival and growth of P. Penguin larvae during D-stage (1-8 days post-fertilisation). Experiment 2 examined the effects of the same treatments on the survival and growth of larvae during umbo-stage (8 - 17 days post-fertilisation). Both experiments used a factorial design combining 3 egg stocking densities (Experiment 1: 2, 6 and 10 larvae mL⁻¹; Experiment 2: 1, 3 and 5 larvae mL⁻¹) and 3 levels of feed ration (Experiment 1: 5, 10 and 15 x 10³ cells mL⁻¹; Experiment 2: 10, 15 and 20 x 10³ cells mL⁻¹). Survival during D-stage was significantly enhanced (by 105%) in aquaria stocked at <10 larvae mL⁻¹, whereby a density of 6 mL⁻¹ maximised larval production per volume of culture medium. An intermediate feed ration of 10 x 10³ cells mL⁻¹ maximised both survival and growth during D-stage. Increasing the initial stocking density of umbostage larvae from 1 to 3 mL⁻¹ resulted in a significant reduction of both survival (360%) and growth (16%). Growth of umbo-stage larvae stocked at 1 mL⁻¹ increased significantly (7%) when feed ration remained below 20 x 10³ cells mL⁻¹. Optimising the rate of larval settlement during pearl oyster hatchery cultivation is critical to maximising the production of juvenile spat for commercial use and is reliant on providing suitable stimuli. This study used two experiments to investigate the effects of (1) treating the culture medium with alternate concentrations of three chemical compounds (Serotonin; GABA; KCl) both in the presence/absence of a bio-film and (2) exposure to five substrate types (red nylon mesh with 5 mm and <1 mm pore sizes; black fibreglass mesh with 3mm and 1mm pore sizes; transparent smooth plastic) both in the presence/absence of a chemical cue (KCl), on recruitment of P. Penguin pediveliger larvae. After 48 h, settlement was 65% greater in aquaria containing a substrate covered by a naturally formed bio-film than in control aquaria. After 72 h, settlement of larvae in aquaria treated with serotonin (10⁻³M) or KCl (20 mM) was significantly greater than in control aquaria by 75% and 84%, respectively, while exposure to GABA had no effect. Settlement in response to 20 mM KCl was enhanced by the presence of a red nylon mesh substrate with 5 mm pore size. The findings of this PhD project provide practical knowledge regarding techniques for efficient hatchery culture of P. Penguin. The specific aims of this study place emphasis on facilitating hatchery propagation in regional communities within the Indo-Pacific. This research will aid in increasing pearl production from hatchery bred P. Penguin and therefore alleviate much of the pressure currently being placed on overexploited wild populations.

Feifei Yu - One of the best experts on this subject based on the ideXlab platform.

  • pax3 gene regulated melanin synthesis by tyrosinase pathway in Pteria Penguin
    International Journal of Molecular Sciences, 2018
    Co-Authors: Feifei Yu, Bingliang Qu, Yuewen Deng, Ronglian Huang, Zhiming Zhong
    Abstract:

    The paired-box 3 (Pax3) is a transcription factor and it plays an important part in melanin synthesis. In this study, a new Pax3 gene was identified from Pteria Penguin (Roding, 1798) (P. Penguin) by RACE-PCR (rapid-amplification of cDNA ends-polymerase chain reaction) and its effect on melanin synthesis was deliberated by RNA interference (RNAi). The cDNA of PpPax3 was 2250 bp long, containing an open reading fragment of 1365 bp encoding 455 amino acids. Amino acid alignment and phylogenetic tree showed PpPax3 shared the highest (69.2%) identity with Pax3 of Mizuhopecten yessoensis. Tissue expression profile showed that PpPax3 had the highest expression in mantle, a nacre-formation related tissue. The PpPax3 silencing significantly inhibited the expression of PpPax3, PpMitf, PpTyr and PpCdk2, genes involved in Tyr-mediated melanin synthesis, but had no effect on PpCreb2 and an increase effect on PpBcl2. Furthermore, the PpPax3 knockdown obviously decreased the tyrosinase activity, the total content of eumelanin and the proportion of PDCA (pyrrole-2,3-dicarboxylic acid) in eumelanin, consistent with influence of tyrosinase (Tyr) knockdown. These data indicated that PpPax3 played an important regulating role in melanin synthesis by Tyr pathway in P. Penguin.

  • identification of a tyrosinase gene and its functional analysis in melanin synthesis of Pteria Penguin
    Gene, 2018
    Co-Authors: Feifei Yu, Bingliang Qu, Yuewen Deng, Xiangyong Yu, Kaihang Xu, Feilong Liang
    Abstract:

    Abstract Tyrosinase is a key rate-limiting enzyme in melanin synthesis. In this study, a new tyrosinase gene ( Tyr ) was identified from Pteria Penguin and its effect on melanin synthesis was deliberated by RNA interference (RNAi). The cDNA of PpTyr was 1728 bp long, containing a 5′untranslated region (UTR) of 11 bp, a 3′UTR of 295 bp, and an open reading fragment of 1422 bp encoding 473 amino acids. Amino acid alignment showed PpTyr had the highest (50%) identity to tyrosinase-like protein 1 from Pinctada fucata . Phylogenetic tree analysis classified PpTyr into α-subclass of type-3 copper protein. Tissue expression analysis indicated that PpTyr was highly expressed in mantle, a nacre formation related tissue. After PpTyr RNA interference, PpTyr mRNA was significantly inhibited by 71.0% ( P PpCreb2 and PpPax3 expression showed no significant change, but PpBcl2 was obviously increased. By liquid chromatograph-tandem mass spectrometer (LC-MS/MS) analysis, the total content of PDCA (pyrrole-2, 3-dicarboxylic acid) and PTCA (pyrrole-2,3,5-tricarboxylic acid), as main markers for eumelanin, was sharply decreased by 66.6% after PpTyr RNAi ( P P . Penguin .

Y U Xiangyong - One of the best experts on this subject based on the ideXlab platform.

  • anaesthesia effect of two anaesthetic chemicals 2 phenoxyethanol and benzocaine on the winged pearl oyster Pteria Penguin rding
    Journal of Tropical Organisms, 2012
    Co-Authors: Y U Xiangyong
    Abstract:

    Anaesthetics,as a means of reducing stress reaction,may have a role in the pearl seeding process.Anaesthetic chemicals were identified to facilitate the safe and effective anesthetization of wing pearl oysters(Pteria Penguin(Rding)) in seeding.Two anaesthetic chemicals,2-phenoxyethanol and benzocaine,were assessed for their ability to relax the wing pearl oyster.These reagents of different concentrations were added into containers of the oysters to observe their reactions at the temperatures ranging from 21,23,25 and 27 ℃.At 25 ℃ 2-phenoxyethanol of 0.1%—0.3%(V/V) and benzocaine of 500,800,1 000 mg·L-1 appeared promising.And 2-phenoxyethanol and benzocaine were selected to determine their effects on the time to relaxation and to recovery and on survival of the oysters after 7 days of relaxation.It was found that as anesthetic concentrations of the reagents increased,the time to relaxation of the oysters decreased while the time to recovery tended to increase.Increased duration of exposure to the relaxants increased the time to recovery.When the temperature increased both the time to relaxation and to recovery of the oysters decreased.The highest proportion of the relaxed oysters(100%) within 30 min and the shortest exposure time required for anaesthesia were recorded in the treatments of the oysters with 0.2% 2-phenoxyethanol or 1 000 mg·L-1 benzocaine,and the treated oysters had no mortalities after 7 days of the treatment.

  • seasonal variation of major fouling organisms of Pteria Penguin rding and its effects on the growth performance of the shell
    Journal of Tropical Organisms, 2011
    Co-Authors: Y U Xiangyong
    Abstract:

    The species, biomass, infection rate, infection position of biofouling at Pteria Penguin and its effect on their growth performances were analyzed at different seasons. The results showed that ① the species and the biomass of fouling organisms on the Pteria Penguin varied with seasons significantly, which were significantly higher in summer and autumn than that in spring and winter (that in summer was the highest)(P0.05); the common dominant species of biofouling in summer and autumn were sponge (phylum porifera), polydora, hydroides, serpula, balanus and sea squirt, however, they were horny coral, balanus and bugula in spring, they were sea squirt, balanus and bugula in winter; in winter, the attachment situation of wild Pteria Penguin were similar to that of cultured Pteria Penguin, however, the parasitic load of polydora, hydroides and serpula in wild Pteria Penguin were significantly lower than that in cultured Pteria Penguin. ②the cultured Pteria Penguin were infected by polychaete parasitosis in all seasons, and the infection rates of spring, summer, autumn and winter were 11.76%, 36.51%, 27.58%, 19.56%, respectively; in winter, the infection rate of cultured Pteria Penguin was higher than that of wild Pteria Penguin; the infection rates of surface shell were higher than that of the inner shell as well as both surface and inner shell in all seasons; in spring and winter, the infection rates of the inner shell were higher than that of both surface and inner shell, while in summer and autumn the results were opposite. ③ the growth performances of healthy Pteria Penguin were higher than that of the infected one, especially in summer, the difference was significant.

  • genetic markers studies based on est ssr primer relative to Pteria Penguin of farming and wild populations
    Journal of Guangdong Ocean University, 2011
    Co-Authors: Y U Xiangyong
    Abstract:

    Amplifying the DNA of Pteria Penguin(R?ding) from the Pinctada martensii’s EST-SSR primers,7 pairs of utilizable EST-SSR markers were found.The DNA of wild individuals from Guangxi Weizhou Island(YS) and cultured individuals from Guangdong Liusha Bay(YZ) were amplified under the optimal reaction condition.And genetic diversity of the two populations was analyzed.The results showed that 26 alleles were detected across the 7 loci.The number of alleles for the two populations ranged from 3 to 5(3.7 on average) and 3 to 4(3.4 on average),respectively.The expected heterozygosity(He) was 0.623 5 and 0.496 8,and observed heterozygosity(Ho) was 0.431 8 and 0.302 8 respectively.Polymorphism Information Content(PIC) values of two populations at all loci were exceeded 0.50 except for locus HNUPM047 suggesting high polymorphism at microsatellite markers.Compared with the wild populations,genetic variance in the cultivated population was lower.

  • gametogenesis in Pteria Penguin rding mollusca bvalvia
    Journal of Guangdong Ocean University, 2009
    Co-Authors: Y U Xiangyong
    Abstract:

    The gonad and gametocyte of Pteda (Magnavicula) Penguin (Rding) were observed under microscope with the method of historical section, and the morphology and the distribution of oogametes and spermatogonia at different development stages were described. The results showed that the germ cells in the scallop could be divided into several stages. Female germ cells could be divided into oogonium, yolkless vitellogenisis stage, yolk-fomation vitellogenesis stage, mature oocyte srage, and degenerate oocyte stage, and male germ cells into spermatogonium stage, primary spermatocyte stage, secondary spermatocyte stage, spermatid stage and spermatozoan stage. Moreover, the spermatogonium were divided into A and B style. Furthermore, a sex reversal specimen was discovered.

  • culture of half_pearls mabe from the winged pearl oyster Pteria Penguin
    Journal of Guangdong Ocean University, 2007
    Co-Authors: Y U Xiangyong
    Abstract:

    During the blister pearl cultivating, pearl nucleus made from polyethylene plastics and surgical pearl oysters chosen from both normal and malformation in shape were used. After six months of culture ,survival and pearl formation rate of oysters in normality shape was 73.3%～93.8% and 55.0%～82.0%,respectively. The survival rate and the percentage of pearl formation of the malformed was 60% and 53.3% respectively. The experiments indicated that the height of pearl nucleus had a significant influence on the survival and percentage of pearl formation of pearl producing shell. The higher pearl nucleus was, the lower survival rate and percentage of pearl formation of the oysters would be. There was highly significant(P0.01) difference between the pearl producing shell of normality and malformation in shell shape in survival rate and percentage of pearl producing. Furthermore, the malformaed oysters should not be used for the production of blister pearl.