Pearl Oyster Pinctada Margaritifera Research Articles

The influence of algal ration and larval density on growth and survival of blacklip pearl oyster Pinctada margaritifera (L.) larvae

This paper reports on two factorial design experiments conducted to examine the combined effects of algal ration and larval density on growth and survival of black lip pearl oyster Pinctada margaritifera (L.) larvae. In the first experiment, 1-day-old larvae were cultured for 7 days at densities of 1, 2 and 5 mL−1 and fed algal rations of 0, 2.5, 5 or 12.5 × 103 cells mL−1. In the second experiment, 13-day-old larvae were cultured for 7 days at the above densities and fed algal rations of 0, 7.5, 15 and 37.5 × 103 cells mL−1. Algal rations in both experiments were composed of a 1:1 mixture of the flagellates Isochrysis aff. galbana clone T.ISO and Pavlova salina. Response surface contour diagrams were generated from growth and survival data to estimate optimal culture conditions. Results showed that, within a suitable larval density range, growth of P. margaritifera larvae was significantly (P < 0.01) influenced by algal ration. At the end of the first experiment, greatest survival occurred at a ration of 4.5–11.5 × 103 cells mL−1 and at a larval density of ≤ 3 mL−1. Greatest antero-posterior shell length was shown by larvae fed between 4.5 × 103 and 11.5 × 103 algal cells mL−1. In the second experiment, greatest antero-posterior shell length occurred within an algal ration range of 15–32 × 103 cells mL−1. The greatest survival occurred below an algal ration of < 2.5 × 103 cells mL−1; however, this algal ration supported poor algal growth. The results indicate that, to maximize growth and survival, P. margaritifera larvae should be fed at an algal ration of ≈ 8 × 103 cells mL−1 and cultured at a density of three larvae mL−1 up to 8 days of age. Older (13- to 20-day-old) larvae should be cultured at a density of < 2 mL−1 and fed an algal ration of ≈ 25 × 103 cells mL−1

The influence of algal ration and larval density on growth and survival of blacklip pearl oyster Pinctada margaritifera (L.) larvae

The influence of algal ration and larval density on growth and survival of blacklip pearl oyster Pinctada margaritifera (L.) larvae

Growth of blacklip pearl oyster ( Pinctada margaritifera) juveniles using different nursery culture techniques

This study was based on blacklip pearl oyster ( Pinctada margaritifera) juveniles, that were hatchery-reared and 8 months old. They were held for 5 months in suspended culture using five culture techniques: in 24-pocket juvenile panel nets (PN24); enclosed within 5-mm plastic mesh ‘inserts’ placed in the pockets of eight-pocket adult panel nets (PN8); in 5-mm plastic mesh inserts without being placed into panel nets (INSERT); in plastic mesh trays (55×30×10 cm) with lids (TRAY); and by ‘ear’ hanging (EAR). Survival was high during the experiment and ranged from 100% in PN24 and PN8 to 90.6% for the INSERT treatment. Juveniles held in 24-pocket nets (PN24) and ear-hung juveniles showed the greatest growth during the experiment, and had significantly greater dorso-ventral height (DVH) and wet weight (WW) than oysters in all other treatments ( P <0.05). Pearl oysters held in inserts within adult panel nets (PN8) and alone (INSERT) showed the lowest mean DVH and WW. This probably resulted from heavy fouling by rock oysters associated with mesh inserts. When other factors such as cost, ease of construction and degree of fouling were considered with growth and survival, the five nursery methods were ranked in decreasing order as follows: PN24>EAR>TRAY>PN8>INSERT.

Ecophysiological model of growth and reproduction of the black pearl oyster, Pinctada margaritifera: potential applications for pearl farming in French Polynesia

A model of bioenergetics of the black pearl oyster ( Pinctada margaritifera) was built to simulate growth, reproduction and spawning in suspended culture at field sites in Takapoto lagoon (French Polynesia). This model was based on allometric scaling of physiological functions and scope for growth (SFG) calculations. The input functions were clearance rate (CR, l day −1), retention efficiency (RE, %) for each kind of particle encountered in suspended matter, pseudofaeces and faeces productions (PF and F, mg C day −1), excretion and respiration rate (U and R, mg C day −1). The assimilated carbon (i.e., SFG, mg C day −1) was partitioned to the three internal state variables (somatic tissue, shell and gonad) according to the asymptotic increase of the reproductive effort (ER, %) with the age. Given organic and mineral particulate matter in suspension in lagoon water (POM and PIM, mg L −1) and assuming that the taxonomic composition of POM was fairly constant throughout the year, the model predicted annual evolution of total tissue weight ( W Tissue, g dry weight), shell weight ( W Shell, g DW) and gonad weight ( W Gonad, g DW) of pearl oysters at various ages. Data on tissue and shell growth, but also on gonad development of cultivated pearl oysters, acquired in 1997–1998 in Takapoto lagoon, were used to validate the model outputs. Results of the simulations indicated that the P. margaritifera growth model provided realistic growth trajectories for shell, somatic tissue and gonad, for pearl oysters aged from 1 to 4 years. For scientists, this validated model is very useful to understand more extensively feeding processes and reproduction features of P. margaritifera in Polynesian lagoons. It provides also valuable information for pearl farmers and for management of cultured populations, especially concerning the time to produce a pearl, spat collection, density in system culture, choice of farming site and carrying capacity of the whole lagoon. In this respect, the model demonstrates that local overdensity must be avoided especially when water current is low (<1 cm s −1) and that global consumption of the cultivated pearl oyster stocks plays a insignificant role in comparison with the consumption of all the natural bivalves occurring in the lagoon. Nevertheless, this first growth model developed for P. margaritifera was only validated for a Takapoto atoll and presents several limitations concerning especially the temperature effect and the range of food concentration. Consequently, some improvements will be necessary to apply this work to other pearl farming sites in French Polynesia.

La matière particulaire des eaux du lagon de Takapoto: nourriture potentielle pour les élevages d’huı̂tres perlières

Particulate matter in Takapoto lagoon waters: potential food for cultivated pearl oysters. Results of research concerning the food of the pearl oyster Pinctada margaritifera are presented, by taking Takapoto atoll (Tuamotu archipelago, French Polynesia) as a study site. Monthly sampling of several parameters representative of bivalve environment and food (water temperature, salinity, mineral and organic matter, proteins, lipids and carbohydrates, chlorophyll a and phaeopigments) confirm and increase knowledge of the Takapoto lagoon hydrobiology. The variability of these parameters was analysed. Takapoto lagoon showed a remarkable spatial stability. Temporal variations showed a low seasonal trend. Local meteorology (wind, precipitation) had an influence on short-term variability (especially for mineral matter). Night and day rhythm also affected some parameters (temperature, chlorophyll a, lipids and carbohydrates). In this shellfish environment, carrying capacity appears to be low: organic matter is around 0.35 mg·L −1, chlorophyll a concentration is below 0.30 μg·L −1 and energetic content of particulate material in waters, approx. 2 J·L −1, is ten times lower than in temperate areas. On the other hand, seasonal effect is reduced and particulate food is always available. Preliminary results on carrying capacity show that cultivated pearl oysters play an insignificant role on the system in comparison with the natural trophic bivalve population. © 2000 Ifremer / CNRS / IRD / Éditions scientifiques et médicales Elsevier SAS Pinctada margaritifera / suspended matter / carrying capacity / pearl oyster / atoll

Heterotrophic protists as a trophic link between picocyanobacteria and the pearl oyster Pinctada margaritifera in the Takapoto lagoon (Tuamotu Archipelago, French Polynesia)

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 22:215-226 (2000) - doi:10.3354/ame022215 Heterotrophic protists as a trophic link between picocyanobacteria and the pearl oyster Pinctada margaritifera in the Takapoto lagoon (Tuamotu Archipelago, French Polynesia) Pascale Loret1,*, Solange Le Gall2, Christine Dupuy2,3, Jean Blanchot4, Annie Pastoureaud2, Bruno Delesalle1, Xavier Caisey5, Gérard Jonquières5 1EPHE, URA-CNRS 1453, Université de Perpignan, 66860 Perpignan Cédex, France 2CREMA, BP 5, 17137 L¹Houmeau, France 3LBEM, Université de La Rochelle, Pôle Science, Avenue Michel Crépeau, 17042 La Rochelle, France 4IRD, Station Biologique de Roscoff, BP 74, 29682 Roscoff, France 5IFREMER/COP, BP 7004 Taravao, Tahiti, French Polynesia *Present address: Department of Oceanography, Texas A&M University, 3146 TAMU, College Station, Texas 77843-3146, USA. E-mail: ploret@ocean.tamu.edu ABSTRACT: Pearl oysters are farmed in oligotrophic tropical atoll lagoons where planktonic communities are dominated by production from cyanobacteria smaller than 2 μm. Paradoxically, the pearl oyster Pinctada margaritifera only retains particles larger than 2 μm. In this study, we assess the relative contribution of hetero/mixotrophic microbiota to the available planktonic resource. In Takapoto Atoll, picocyanobacteria are the dominant biomass (20 μg C l-1). The carbon biomass of ciliates and dinoflagellates ranges from 1 to 24 and 0.5 to 5 μg C l-1 respectively, with a mean of 6 μg C l-1 for ciliates and 2 μg C l-1 for dinoflagellates. The possible retention by P. margaritifera on a natural protist suspension was investigated. Due to its high clearance rates (ca 20 l h-1 g-1) the pearl oyster retained 85 μg C h-1 g-1 from ciliates and 65 μg C h-1 g-1 from dinoflagellates. Conversely, cyanobacteria were not efficiently retained by the bivalve and did not efficiently contribute to its diet. From our experiments, we concluded that hetero/mixotrophic protists rapidly and efficiently process the picoplanktonic resource towards filter-feeders, particularly pearl oysters. KEY WORDS: Protists · Atoll lagoon · Pearl oysters · Pinctada margaritifera · Picoplankton · Trophic resource Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 22, No. 3. Online publication date: October 26, 2000 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2000 Inter-Research.

Phytoplankton composition and selective feeding of the pearl oyster Pinctada margaritifera in the Takapoto lagoon (Tuamotu Archipelago, French Polynesia):in situ study using optical microscopy and HPLC pigment analysis

The in situ diet of the pearl oyster Pinctada margaritifera was determined in the lagoon of Takapoto Atoll by comparing the phytoplankton composition of water and bivalve gut contents using 2 different methods, optical microscopy and HPLC pigment analysis. In order to evaluate the available food resources for pearl oysters in the water column, a new method for estimating the pigment/chloro- phyll a (chl a) ratio (based on an inverse analysis) was developed which allowed us to determine the contribution of the main phytoplanktonic groups in terms of chl a. In the water, picocyanobacteria and nanoflagellates predominated, the latter being mainly chlorophytes and prymnesiophytes. Compar- isons between the results obtained by the 2 methods of investigation indicated that most of the dinofla- gellates are unpigmented and, therefore, heterotrophic. An examination of the gut contents showed that picocyanobacteria were only weakly ingested by the oyster and, thus, nanoflagellates constituted the main food resource. Cryptophytes, although poorly represented in the water, were preferentially ingested. Chlorophytes were inefficiently hgested since they were found alive and motile in the faeces of the oyster. The ecological implications of this feeding behaviour are discussed.

Comparative effects of temperature on suspension feeding and energy budgets of the pearl oysters Pinctada margaritifera and P. maxima

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 195:179-188 (2000) - doi:10.3354/meps195179 Comparative effects of temperature on suspension feeding and energy budgets of the pearl oysters Pinctada margaritifera and P. maxima H. Yukihira1, J. S. Lucas2,*, D. W. Klumpp3 1Department of Zoology and Tropical Ecology, School of Biological Sciences, James Cook University, Townsville, Queensland 4811, Australia 2School of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland 4811, Australia 3Australian Institute of Marine Science, PMB 3, Townsville MC, Queensland 4810, Australia *Corresponding author. E-mail: john.lucas@jcu.edu.au ABSTRACT: This study assessed the effects of seasonal temperatures on suspension feeding, related physiological parameters and energy budgets in 2 pearl oysters, Pinctada margaritifera and P. maxima. Pearl oysters that were acclimatised at approximately 19, 23, 28 and 32°C in the field were tested in the laboratory at these temperatures. Clearance rate (CR), absorption efficiency (ae), absorbed energy (AE), respired energy (RE), excreted energy (EE) and the value of (AE - RE) were significantly affected by temperature. They usually increased with increasing temperature. ae, RE, EE and the value of (AE - RE) differed significantly between the pearl oyster species. P. margaritifera had a significantly higher CR than P. maxima at 19°C. P. maxima had higher ae than P. margaritifera at 28 and 32°C. As a result, P. margaritifera had greater AE than P. maxima at 19°C, but the latter species had greater AE at 32°C. Temperature significantly affected the RE of P. margaritifera over a wider temperature range (19 to 32°C) than P. maxima (19 to 23°C). However, interspecific differences in RE were only significant at 32°C. P. maxima had significantly higher EE at 32°C than P. margaritifera, although this energy accounted for a very small portion of AE (<5%). P. maxima exceeded P. margaritifera in Scope for Growth [SFG = (AE - RE) - EE] at 32°C, but the latter species had greater SFG at 19°C. These results agree with observations of the occurrence of P. margaritifera at higher latitudes and lower temperature habitats. The temperature effects on suspension feeding, related physiological parameters and SFG indicate that there will be marked seasonal variations in growth in both species in environments where water temperatures vary seasonally. In bioenergetic terms, the optimum temperature ranges for these pearl oysters are approximately 23 to 28 and 23 to 32°C for P. margaritifera and P. maxima, respectively. KEY WORDS: Pearl oyster · Temperature · Energy budget · Pinctada margaritifera · Pinctada maxima · Scope for Growth · Physiology Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 195. Publication date: March 31, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

Abnormal periostracum secretion during the mineralization process of the pearl in the blacklip pearl oyster Pinctada margaritifera

Whitish parasite-like bodies (PLBs), 0.5–2 μm in size, were detected within the pearl bag of some grafted pearl oysters, Pinctada margaritifera, from Takapoto island (French Polynesia). Histological and ultrastructural investigations have revealed that these bodies consisted of lamellar organic material locally secreted by some epithelial cells of the pearl bag. The fine structure and the formation of these bodies are described. The causes of this abnormal secretion of organic mater, which actually corresponds to periostracum, are not presently known. No parasite nor infectious micro-organism was found associated with the PLBs.

Feeding adaptations of the pearl oysters Pinctada margaritifera and P. maxima to variations in natural particulates

The tropical pearl oysters Pinctada margaritifera (Linnaeus) and P. maxima Jameson are suspension feeders of major economic importance. P. margaritifera occurs in coral reef waters characterised by oligotrophy and low turbidity. P. maxima habitats are generally characterised by high terrigenous sediment and nutrient inputs, and productivity levels. These differences in habitat suggest that P. margaritifera will feed more successfully at low food concentrations, while P. maxima will cope with a wider range of food concentrations and more silty conditions. The effect of varying concentrations of natural suspended particulate matter (SPM) on clearance rate (CR), pseudofaeces production, absorption efficiency (abs.eff.), respired energy (RE) and excreted energy (EE) was determined for P. margaritifera and P. maxima. The resultant scope for growth (SFG) was determined and related to habitat differences between the oysters. There was no selective feeding on organic particles in either species. P. margaritifera had higher CR at low SPM concentration ( 3 µm) and P. maxima (SPM = ca 3 to 15 mg l⁻¹, size > 4 µm) may be used for selection of optimum pearl culture sites.

Evaluation of a partial flow-through culture technique for pearl oyster (Pinctada margaritifera L.) larvae

This study evaluated a partial flow-through culture system for larvae of the blacklip pearl oyster (Pinctada margaritifera, L.). Water flowed through the 500-l larval rearing tanks for 12 h day−1 and provided a 100% water exchange during this period. Larvae were prevented from leaving the culture tanks by a conical mesh screen placed over a central stand-pipe. Tanks were completely drained every 7 days to prevent build-up of debris on the tank bottom. First `eyed' larvae were seen on day 23 and, by day 28, approximately 5% of the larvae initially stocked had reached the `eyed' stage and were removed into settlement tanks. Larval growth and survival compared favourably with previous studies in which P. margaritifera larvae were cultured using conventional static culture methods. However, when compared to static culture systems, the partial flow-through system described in this study requires less labour and, as such, is likely to be more appropriate for hatchery culture in developing Pacific nations.

Particulate material as an indicator of pearl-oyster excess in the Takapoto lagoon (Tuamotu, French Polynesia)

The aquatic environment of black-lipped pearl oysters ( Pinctada margaritifera) in the Takapoto lagoon was studied to determine the cause of their recent diseases. Both N and P limitations were observed, and the oligotrophy was known from previous reports. The low N concentration appeared to affect the volumes of the various picoplankton compartments more than their numbers, whereas the P concentration affected phytoplankton, estimated as chlorophyll a. The values for the resulting biomasses of phytoplankton (3.8 μg C l −1) and bacteria (2.8 μg C l −1) were amongst the lowest reported values, as were the respective production rates (2.2–3.5 μg C l −1 reported and 1.22 μg C l −1 current work). Although unexpectedly low, the values for biomass and production of bacteria are consistent with the close relationship observed between phytoplankton and bacteria. Waste products from the reared P. margaritifera stock enhanced the growth rates of phytoplankton and picoplankton as shown when incubating in unpoisoned sediment traps, even though the concentrations of both populations were lower than those achieved in the surrounding water. Oyster filtering affected not only phytoplankton, but also smaller-sized plankton, including flagellates and the viable heterotrophic bacteria, but had a significant impact on total counts of bacteria only in the 0–7 m layer. The density of the pearl oysters appeared to exceed the nutritional potential of the lagoon. Owing to the oligotrophic conditions, phytoplankton and even bacteria were unable to sustain their grazing. The 0–7 m depth appeared to be more favourable to oyster growth than the bottom, despite the higher amount of pigments collected in bottom traps. The suspended material in the upper layer was less degraded and showed a higher potential for microbial multiplication. The lack of exchange between the intermediate layer of 18 m and the upper and lower levels suggested that during our study, the suspended material at the bottom did not originate directly from the 0–7 m level owing to the particular circulation of water in the lagoon.

Trichromatic characterization of the “black pearls” from aquaculture centers of French Polynesia

In the pearl production centers of French Polynesia, which are specialized in “black pearl” production, a statistical shift in pearl color has been noted, possibly resulting from exchanges between populations of the pearl oyster Pinctada margaritifera. Spectral analyses were carried out on pearls covering the whole spectrum of currently observed colors. This paper presents a simplified method making possible a control of the pearl oyster farming and a regulation of pearl production.

Genetic differences among black-lipped pearl oyster (Pinctada margaritifera) populations in the western Pacific

Seven populations of the black-lipped pearl oyster, Pinctada margaritifera, from the western Pacific were assayed for allozyme variation at 17 polymorphic loci from mantle biopsies. Levels of within population variation were high (mean number of alleles per locus averaged 6.8, mean direct-count heterozygosities averaged 0.575). Gene frequencies within populations conformed to those expected under random mating. Significant genetic differentiation between populations within reef groups and additionally between the Great Barrier Reef (GBR) and the Pacific islands (Kiribati and the Cook Islands) was revealed by hierarchical FST analysis. The average numbers of migrants per generation (Nem) among the Pacific islands and among the GBR populations was 6–8 and twice that between the Pacific islands and the GBR. This suggests a relatively high gene flow among populations in Kiribati and the Cook Islands on an evolutionary time scale. However, the occurrence of significant differences in gene frequencies among populations within reef groups suggests that genetic surveys of local populations should be undertaken prior to making any transfers of pearl oysters from other reefs in order to protect these genetic resources.

Fatigue fracture of mother‐of‐pearl and its significance for predatory techniques

Specimens of nacre from the pearl oyster Pinctada margaritifera were loaded in bending to various fractions of the load needed to cause fracture. For a small number of cycles, less than about 1000, no changes in compliance or strength were found if the load was less than about 60% of the load necessary to cause failure. Above this fraction the compliance increased, the strength usually decreased but occasionally increased.We conclude that, because the loading of a shell by a predator is likely to be far less controlled than loading by a machine, causing a shell to break by fatigue fracture is unlikely to be a tactic employed by a predator, though it may happen fortuitously.

Recent innovations in cultivation of molluscs in French Polynesia

Until recently, mollusc production in French Polynesia was based on fishing to satisfy local consumption of edible bivalves (mainly the oyster Saccostrea cuccullata) and to export pearl-oyster shells. Because of parasite problems in the local oyster population, a mollusc culture program was initiated. Hatchery techniques were developed for introduced species of edible bivalves, Saccostrea echinata and Perna viridis, and cultivation methods were developed in specially fitted-up areas. Traditional shell production concerning the pearl oyster Pinctada margaritifera was recently reorganized to produce black cultured pearls, causing an increased demand for young, implantable pearl oysters. Hatchery spat production proved to be unsuccessful, and techniques of collection and cultivation in lagoons were set up to supply the pearl-oyster farming industry, and to address the problems of depleted natural stock.