Effects of rearing conditions on growth and survival in juvenile blacklip pearl oyster Pinctada margaritifera (L.) in subtropical Japan.ABSTRACT Spat of blacklip pearl oyster, Pinctada margaritifera (L.), recently have been found to suffer mass mortalities every autumn in farms in subtropical sub·trop·i·cal adj. Of, relating to, or being the geographic areas adjacent to the Tropics. subtropical Adjective of the region lying between the tropics and temperate lands Japan. We investigated what rearing conditions improve growth and survival of the spat in one of the farms. From September 2002, spat with mean [+ or -] SD dorsoventral dorsoventral /dor·so·ven·tral/ (-ven´tral) 1. pertaining to the back and belly surfaces of a body. 2. passing from the back to the belly surface. dorsoventral 1. measurement 14.5 [+ or -] 2.4 mm were reared in trays (33 cm x 21 cm x 8 cm) with combinations of different spat densities (12, 24, 36, 72 or 144 spat tray-l), tray partitioning (trays with or without partitions) and suspension depths (2 or 6 m). Three months later, spat densities and tray partitioning significantly affected the growth: greater for 12-36 spat [tray.sup.-1] (mean [+ or -] SD: 12.2 [+ or -] 3.5 mm) than for 72-144 spat [tray.sup.-1] (7.7 [+ or -] 4.3 mm) and for partitioned trays (12.2 [+ or -] 4.1 mm) than for nonpartitioned trays (8.5 [+ or -] 4.0 mm). Yet, no set of rearing conditions significantly explained the great variation in the survival rate (mean: 51.4%, range: 0.0% to 100.0%). When two groups of spat reared separately in the farm and laboratory were transferred to the same aquarium, cross infection occurred. It is possible that spat-density and tray-partitioning dependent factors (e.g., food abundance and space per spat) affected mainly the growth, whereas other factors including a putative Alleged; supposed; reputed. A putative father is the individual who is alleged to be the father of an illegitimate child. A putative marriage is one that has been contracted in Good Faith and pursuant to ignorance, by one or both parties, that certain infectious agent infectious agent Pathogen, see there affected mainly the survival rate. KEY WORDS: Pinctada margaritifera; growth; survival; rearing condition; Japan, pearl oyster INTRODUCTION The blacklip pearl oyster, Pinctada margaritifera (L.), is cultured in tropical and subtropical Indo-Pacific regions to produce black pearls The Black Pearl, originally HEIC Wicked Wench, is a fictional ship in , , and . The Black Pearl is easily recognised by her distinctive black hull and sails. This turns out to be an advantage in more than one way. (Coeroli et al. 1984, Shokita et al. 1991). The oyster is economically important in some areas (e.g., 86 million yen per company year in subtropical Japan; Okinawa General Secretariat 2003). To improve aquaculture aquaculture, the raising and harvesting of fresh- and saltwater plants and animals. The most economically important form of aquaculture is fish farming, an industry that accounts for an ever increasing share of world fisheries production. techniques and management of natural populations, the physiology and ecology of the oyster have been intensively studied (Coeroli et al. 1984, Shokita et al. 1991). Few studies, however, have examined how rearing conditions change growth and survival rates in P. margaritifera spat (Southgate & Beer 1997, Southgate & Beer 2000, Friedman & Southgate 1999). Further, no such studies have been made at pearl farms with spat showing mass mortality. Studies to improve rearing conditions should be made at farms experiencing mass mortality, because P. margaritifera spat often shows mass mortality (Alagarswami et al. 1989, Sano 1998; see also Nasr 1982 for mass mortality of adult oyster). In pearl farms in subtropical Japan, over the last decade mass mortalities of P. margaritifera spat tended to occur in a short period, typically from September to December (Katsumata & Nakamori 2002). An effective countermeasure coun·ter·meas·ure n. A measure or action taken to counter or offset another one. countermeasure Noun action taken to counteract some other action Noun 1. is to rear spat in aquariums with filtered seawater seawater Water that makes up the oceans and seas. Seawater is a complex mixture of 96.5% water, 2.5% salts, and small amounts of other substances. Much of the world's magnesium is recovered from seawater, as are large quantities of bromine. in this period (Kurihara in preparation), but this requires much labor. Therefore, to improve the growth and survival of spat in the pearl farms, we conducted a rearing experiment, keeping spat in trays with various spat densities, tray partitionings and suspension depths. We expected better growth and survival for lower spat densities and partitioned trays, which prevent spat from clumping clumping /clump·ing/ (klump´ing) the aggregation of particles, such as bacteria, into irregular masses. clump·ing n. The massing together of bacteria or other cells suspended in a fluid. together (Southgate & Beer 1997, Southgate & Beer 2000, Friedman & Southgate 1999). We expected depth-dependent changes in growth and survival because of depth-dependent changes in environmental factors (e.g., water temperature and food abundance; Vacelet et al. 1996, Yukihira et al. 1998, Yukihira et al. 2000). In addition, we conducted infection experiments to determine whether spat survival is affected by an infectious agent, a plausible factor of P. margaritifera mass mortality (Nasr 1982, Dauphin Dauphin, town, Canada Dauphin (dô`fĭn), town (1991 pop. 8,453), SW Man., Canada, on the Vermilion River. It is the retail and distribution center for an agricultural, lumbering, and fishing area. & Cuif 1991, Marin & Dauphin 1991). MATERIAL AND METHODS Study Site We conducted the experiment at a pearl farm in Kabira Bay (24[degrees]27.3'N, 124[degrees]8.7'E; Ishigaki Island, Okinawa, subtropical Japan) where pearl producers rear artificially-produced P. margaritifera. The producers keep the oysters at depths of 2-6 m in lantern lantern held by Judas, leading officers to Christ. [N.T.: John 18:3] See : Passion of Christ nets, trays and panel nets, which are suspended from headlines near the sea surface. Dissolved-oxygen levels range from approximately 6-8 mg [1.sup.-1] at 6 m depth (Katsumata & Nakamori 2002, Katsumata & Nakamori 2003). Chlorophyll a Noun 1. chlorophyll a - a blue-black plant pigment having a blue-green alcohol solution; found in all higher plants chlorophyl, chlorophyll - any of a group of green pigments found in photosynthetic organisms; there are four naturally occurring forms concentrations show a small spatial variation (mean = 0.57 [micro]g [1.sup.-1], range = 0.31 [micro]g [1.sup.-1]). During the study period, the water temperature decreased from 26.8[degrees]C to 23.5[degrees]C at 2 m depth and from 26.4[degrees]C to 23.6[degrees]C at 6 m depth. Rearing Experiment We reared artificially-produced spat from September 13 to December 19, 2002, which includes the period with many spat dying (Katsumata & Nakamori 2002). In total we kept 3,456 spat with dorsoventral measurements (Sims 1993) of 14.5 [+ or -] 2.4 mm (mean [+ or -] SD) in perforated per·fo·ra·ted adj. Pierced with one or more holes. trays with a lid (33 cm W x 21 cm L x 8 cm H, covered with a 2 mm x 2 mm mesh). We used 60 trays to prepare 3 replicates for each of the 20 experimental conditions. The conditions consisted of 5 spat densities (12, 24, 36, 72 or 144 individuals per tray) x2 suspension depths (2 or 6 m) x2 forms of tray partitioning. Spat density and suspension depth were within the range used by local pearl producers. Tray partitioning was modified with the tray divided or not divided by resinous partitions into 4 cells of 16.5 cm W x 10.5 cm L x 8 cm H. Each cell within a tray held the same number of spat, so that more spat could clump together in nonpartitioned trays than in partitioned trays. For each of the 20 experimental conditions, 3 replicate trays were suspended from different headlines. Under each headline, the trays were arranged in a random order at 1.4 m intervals in a horizontal direction. These trays were cleaned weekly to remove fouling and predators (ranellid gastropods, portunid crabs, polyclads). At the end of the experiment, each tray was brought to the laboratory to record the number of surviving spat and the dorsoventral measurement ([+ or -] 0.1 mm). Although to clarify the density effect on spat, specimens should be added to trays with spat having died, we did not for 2 reasons: (1) we aimed to develop a method available for pearl producers who cannot afford to regulate density frequently, and (2) they should not often add spat into trays, because spat possibly die of infectious agents (see Results) and should not be mixed with other spat. Infection Experiments We conducted infection experiments in November 2001 (Run 1) and 2002 (Run 2). Just after P. margaritifera spat began to show mass mortality in the pearl farm, the spat group reared there (possibly infected with a contagious contagious /con·ta·gious/ (-jus) capable of being transmitted from one individual to another, as a contagious disease; communicable. con·ta·gious adj. 1. Of or relating to contagion. factor), and the group reared in the laboratory (unlikely to be infected) were transferred into the same aquarium (10-60 individuals [group.sup.-1] [aquarium.sup.-1]). The two groups were then reared for 30-40 d. If the spat group from the pearl farm were infected with a contagious factor then both groups in the same aquarium would show high mortalities. Data Analyses For the rearing experiment, growth (i.e., increase in mean dorsoventral measurement) and arcsine-transformed survival rate were analyzed by a 3-way orthogonal At right angles. The term is used to describe electronic signals that appear at 90 degree angles to each other. It is also widely used to describe conditions that are contradictory, or opposite, rather than in parallel or in sync with each other. ANOVA anova see analysis of variance. ANOVA Analysis of variance, see there (analysis of variance) with spat density, suspension depth and tray partitioning as fixed factors (see Underwood 1997 and Zar 1999 for this and subsequent analyses). Differences in variances between treatments were not significant (P > 0.05; Cochran test). For posthoc comparisons a Tukey test was performed at 5% level. When comparing survival rates of P. margaritifera spat between different experimental periods, we calculated survival rate for 100 d as: [(survival rate for an experimental period).sup.(100/ experimental period)]. We calculated variances between spat rearing units for the present and previous survival data (Tables 5 and 6 in Southgate & Beer 1997; Figures 7 and 8 in Friedman & Southgate 1999) from the means, standard errors and sample sizes. [FIGURES 7-8 OMITTED] RESULTS Rearing Experiment Spat growth significantly depended on spat densities and tray partitionings (P < 0.001 for both; Tables 1 and 2). Growth was greatest at densities of 12, 24 or 36 spat [tray.sup.-1] and lowest at 144 spat [tray.sup.-1] within each combination of tray partitioning and suspension depth. In a Tukey test, growth significantly differed in general between densities of 12-36 spat [tray.sup.-1] (mean [+ or -] SD across these levels: 12.2 [+ or -] 3.5 mm) and 72-144 spat [tray.sup.-1] (7.7 [+ or -] 4.3 ram). Growth was always greater in the partitioned tray (12.2 [+ or -] 4.1 ram) than the nonpartitioned tray (8.5 [+ or -] 4.0 mm) within each combination of spat density and suspension depth. Spat numbers per cell for both nonpartitioned and partitioned trays (i.e., spat density and the quarter of spat density, respectively) gave a similar effect on spat growth (Fig. 1): the mean growth decreased as 2.78 mm (12 spat [cell.sup.-1]), 2.42 mm (24 spat [cell.sup.-1]) and 2.29 mm (36 spat [cell.sup.-1]) for nonpartitioned trays and as 2.74 mm (9 spat [cell.sup.-1]), 2.66 mm (18 spat [cell.sup.-1]) and 2.14 mm (36 spat [cell.sup.-1]) for partitioned trays. [FIGURE 1 OMITTED] In contrast to growth, survival rate was not significantly dependent on either spat density or tray partitioning (P = 0.141 and 0.522, respectively; Table 2). Survival rate peaked at different spat densities, depending on tray partitioning and suspension depth (Table 1). Similarly, survival rate peaked for different partition patterns, depending on spat density and suspension depth. Survival rates in trays varied from 0.0% to 100.0% (mean [+ or -] SD = 51.4 [+ or -] 41.7%; variance = 1723.2 [[% 100 [d.sup.-1].sup.2]), showing little correlation with growth rate (Spearman's [rho] = 0.156; Fig. 2). [FIGURE 2 OMITTED] Neither growth nor survival rate was affected significantly by suspension depth or any interaction between treatments: P = 0.093-0.886 for growth rate; and P = 0.117-0.814 for survival rate (Table 2). It should be noted, however, that growth was often larger at greater depth (for 7 of 10 combinations of spat density and tray partitioning), showing a low significance level (0.093). Infection Experiments Survival rates (% 100 [d.sup.-1]) were positively correlated between the two spat groups transferred from the pearl farm and laboratory tanks, showing nonsignificant non·sig·nif·i·cant adj. 1. Not significant. 2. Having, producing, or being a value obtained from a statistical test that lies within the limits for being of random occurrence. but high correlation coefficients Correlation Coefficient A measure that determines the degree to which two variable's movements are associated. The correlation coefficient is calculated as: (Fig. 3): [rho] = 0.825 for Run 1 (P = 0.086) and [rho] = 0.445 for Run 2 (P = 0.317). [FIGURE 3 OMITTED] DISCUSSION Growth and survival rate in P. margaritifera spat varied independently. Hence, they may be affected mainly by different mechanisms. Only growth significantly varied between spat densities and tray partitioning and thus may be affected by some factors related to these rearing conditions. Such factors appear to include the availabilities of food (i.e., suspended particulate matter particulate matter n. Abbr. PM Material suspended in the air in the form of minute solid particles or liquid droplets, especially when considered as an atmospheric pollutant. Noun 1. ; Yukihira et al. 1999) and space per individual spat. Increases in food and space are reported to improve growth of P. margaritifera (Southgate & Beer 1997, Friedman & Southgate 1999) and many other bivalves (e.g., mytilids; Gosling 2003). Food and space available for each spat may increase for lower densities and partitioned trays because of a mechanism that fewer spat clump together with byssus threads in each cell of trays (Crossland 1957, Southgate & Beer 1997, Friedman & Southgate 1999). This mechanism is plausible, because similar spat numbers per cell led to similar spat growth rates Growth Rates The compounded annualized rate of growth of a company's revenues, earnings, dividends, or other figures. Notes: Remember, historically high growth rates don't always mean a high rate of growth looking into the future. , independent on volume of cell. In contrast to growth, survival rate is unlikely to be affected mainly by food and space in our experiment. When the survival rate of spat dropped in the studied farm, it was nearly 100% in laboratory tanks where food and space were less abundant (Kurihara, personal observation). In the studied farm, food abundance appears to be similar between trays, considering the small spatial variation in chlorophyll a content (an index of food abundance, Loret et al. 2000; mean = 0.57 [micro]g [1.sup.-1], range = 0.31 [micro]g [1.sup.-1]) and rapid current (Kubo et al. 2004), which transports suspended food. The similarity in food abundance does not explain the large tray-to-tray variance of survival rate, 1723.2 [[% 100 [d.sup.-1]].sup.2], which exceeds <92.2 in North Queensland North Queensland is the northern part of the state of Queensland in Australia. Queensland is a massive state, larger than most countries, and the Tropical northern part of it has been historically remote and underdeveloped, resulting in a distinctive regional character and (Southgate & Beer 1997) and <131.6 in the Solomon Islands Solomon Islands, independent Commonwealth nation (2005 est. pop. 538,000), c.15,500 sq mi (40,150 sq km), SW Pacific, E of New Guinea. The islands that constitute the nation of the Solomon Islands—Guadalcanal, Malaita, New Georgia, the Santa Cruz Islands, (Friedman & Southgate 1999). Space is also unlikely to have affected the spat survival, because spat survived well (74.8 to 90.8% 100 [d.sup.-1]) in previous experiments (Southgate & Beer 1997) in which the space available for spat (1 cell for 10-200 spat) was approximate to that in our experiment (1 cell for 3-144 spat). It is possible that, even if food and space influenced spat survival, their effects were masked by a stronger factor. Such a factor could be an infectious agent. Its existence in the studied farm is indicated from the cross infection in laboratory aquariums. Infectious agents (i.e., gregarine greg·a·rine n. Any of various sporozoan protozoans of the order Gregarinida that are parasitic within the digestive tracts of various invertebrates. adj. Of or belonging to the order Gregarinida. parasite parasite, plant or animal that at some stage of its existence obtains its nourishment from another living organism called the host. Parasites may or may not harm the host, but they never benefit it. , Chagot et al. 1993; prokaryote prokaryote: see Monera. prokaryote Any cellular organism that lacks a distinct nucleus. Organisms classified in the domains Bacteria (including blue-green algae, or cyanobacteria) and Archaea are prokaryotes; all other organisms are eukaryotes and , Comps et al. 1998; "unidentified spherical spher·i·cal adj. Having the shape of or approximating a sphere; globular. parasite," Nasr 1982) have been suggested to kill many P. margaritifera in French Polynesia French Polynesia, officially Territory of French Polynesia, internally self-governing overseas country (2002 pop. 245,516) of France, consisting of 118 islands in the South Pacific. The capital is Papeete, on Tahiti. (Dauphin & Cuif 1991, Marin & Dauphin 1991) and the Red Sea (Nasr 1982). Infectious agent may spread rapidly between spat within a tray, independent of spat density and tray partitioning, because trays possess enclosed en·close also in·close tr.v. en·closed, en·clos·ing, en·clos·es 1. To surround on all sides; close in. 2. To fence in so as to prevent common use: enclosed the pasture. environments caused by their cover of fine mesh (2 mm x 2 mm); and many mobile animals (polyclads, polychaetes, isopods, crabs, gastropods, fishes) intrude intrude, v to move a tooth apically. into each tray and might transmit infectious agent between spat, as reported for oysters Crassostrea virginica (White et al. 1987, White et al. 1989, Powell et al. 1987, Gosling 2003). In conclusion, spat may grow well for densities less than 36 spat [tray.sup.-1] and partitioned trays, even when showing mass mortality. Because this is attributable to the decrease of spat clumping in a cell, trays with many partitions and smaller trays, including fewer spat, possibly improve spat growth further. The effect of suspension depth on spat growth is unclear and should be further examined. ACKNOWLEDGMENTS We thank S. Chiba and Y. Nakamura for their comments on the manuscript; K. Ashida, T. Katsumata, Y. Shimadzu, K. Tamai and the staff of the Okinawa Prefecture Fisheries fisheries. From earliest times and in practically all countries, fisheries have been of industrial and commercial importance. In the large N Atlantic fishing grounds off Newfoundland and Labrador, for example, European and North American fishing fleets have long Experimental Station and Seikai National Fisheries Research Institute for their advice on our study; Hayashibara, M. Katoh, K. Kiso, M. Tamaki, H. Yamada and the local pearl producers for their help in the pearl farm. This study was financially supported by the SNFRI Project Fund. LITERATURE CITED Alagarswami, K., S. Dharmaraj, A. Chellam & T. S. Velayudhan. 1989. Larval larval 1. pertaining to larvae. 2. larvate. larval migrans see cutaneous and visceral larva migrans. and juvenile rearing of black-lip pearl oyster, Pinctada margaritifera (Linnaeus). Aquaculture 76:43-56. Chagot, D., A. Fougerouse, M. Weppe, A. Marques Marques may refer to:
Coeroli, M., D. De Gaillande & J. P. Landret. 1984. Recent innovations in cultivation of molluscs in French Polynesia. Aquaculture 39:45-67. Comps, M., A. Fougerouse & D. Buestel. 1998. A procaryote pro·car·y·ote n. Variant of prokaryote. pro  car·y·ot ic adj. infecting the black-lipped pearl oyster Pinctada margaritifera. J.
Invertebr. Pathol. 72:87-89.
Crossland, C. 1957. The cultivation of the mother-of-pearl oyster in the Red Sea. Aust. J. Mar. Freshwater Res. 8:111-130. Dauphin, Y. & J. P. Cuif. 1991. Epizootic ep·i·zo·ot·ic adj. Affecting a large number of animals at the same time within a particular region or geographic area. Used of a disease. ep disease in the "black lip" pearl oyster Pinctada margaritifera in French Polynesia: ultrastructural alterations of the nacreous nacreous /na·cre·ous/ (na´kre-us) having a pearl-like luster. na·cre·ous adj. Resembling mother-of-pearl; lustrous. nacreous having a pearl-like luster. layer. In: S. Suga & H. Nakahara, editors. Mechanisms and phylogeny of mineralization Mineralization The process by which the body uses minerals to build bone structure. Mentioned in: Rickets mineralization, n the bioprecipitation of an inorganic substance. in biological systems. Tokyo: Springer-Verlag. pp. 167-171. Friedman, K. J. & P. C. Southgate. 1999. Growout of blacklip pearl oysters, Pinctada margaritifera collected as wild spat in the Solomon Islands. J. Shellfish shellfish, popular name for certain edible mollusks (see Mollusca), e.g., oysters, clams, and scallops, and for certain edible crustaceans, e.g., crabs, lobsters, and shrimps. All are aquatic invertebrates with shells; they are not fish. Res. 18:159-167. Gosling, E. M. 2003. Bivalve bivalve, aquatic mollusk of the class Pelecypoda ("hatchet-foot") or Bivalvia, with a laterally compressed body and a shell consisting of two valves, or movable pieces, hinged by an elastic ligament. molluscs. Biology, ecology and culture. Oxford: Blackwell Science. 443 pp. Katsumata, T. & J. Nakamori. 2002. Kurochogai chigai no tairyo heishi genninn tyosa (Investigations on factors causing mass mortality in juvenile black-lip pearl oyster Pinetada margaritifera). Annual report from Okinawa Prefecture Fisheries Experimental Station, fiscal year 2000. Itomann City, Okinawa, Japan. 225-229 (in Japanese). Katsumata, T. & J. Nakamori. 2003. Kurochogai chigal no tairyo heishi genninn tyosa (Investigations on factors causing mass mortality in juvenile black-lip pearl oyster Pinctada margaritifera). Annual report from Okinawa Prefecture Fisheries Experimental Station, fiscal year 2001, Itomann City, Okinawa, Japan. pp. 192-196. (in Japanese) Kubo, H., K. Iwai, H. Kureya & S. Takeuchi. 2004. Kabira hogo suimenn kannri jigyo (Observations of sanctuary in Kabira Bay). Annual report from Okinawa Prefecture Fisheries Experimental Station, fiscal year 2002, Itomann City, Okinawa, Japan. pp. 208-212 (in Japanese) Loret, P., A. Pastoureaud, C. Bacher & B. Delesalle. 2000. Phytoplankton phytoplankton Flora of freely floating, often minute organisms that drift with water currents. Like land vegetation, phytoplankton uses carbon dioxide, releases oxygen, and converts minerals to a form animals can use. composition and selective feeding of the pearl oyster Pinctada margaritifera in the Takapoto lagoon lagoon Area of relatively shallow, quiet water with access to the sea but separated from it by sandbars, barrier islands, or coral reefs. Coastal lagoons have low to moderate tides and constitute about 13% of the world's coastline. (Tuamotu Archipelago Tuamotu Archipelago (t  ämō`t) or Low Archipelago, coral island group (2002 pop. ,
French Polynesia): in situ In place. When something is "in situ," it is in its original location. study using optical microscopy microscopy /mi·cros·co·py/ (mi-kros´kah-pe) examination under or observation by means of the microscope. mi·cros·co·py n. 1. The study of microscopes. 2. and HPLC HPLC high-performance liquid chromatography. HPLC high performance liquid chromatography. HPLC High-performance liquid chromatography Lab instrumentation A highly sensitive analytic method in which analytes are placed pigment pigment, substance that imparts color to other materials. In paint, the pigment is a powdered substance which, when mixed in the liquid vehicle, imparts color to a painted surface. analysis. Mar. Ecol. Prog. Ser. 199:55-67. Marin, F. & Y. Dauphin. 1991. Diverse alteration in the amino-acid content of the nacreous organic matrices in the black lip pearl oyster (Pinctada margaritifera) in French Polynesia affected by an epizootic disease. C. R. Acad. Sci. Paris 312:483-488. Nasr, D. H. 1982. Observations on the mortality of the pearl oyster, Pinctada margaritifera, in Dongonab Bay, Red Sea. Aquaculture 28: 271-281. Okinawa General Secretariat. 2003. Dai 31 ji Okinawa Nourinn Suisann Tokei Nennpou (The 31st annual report on agriculture, forestry, and fishery in Okinawa Prefecture). 264 pp. (in Japanese) Powell, E. N., M. E. White, E. A. Wilson & S. M. Ray. 1987. Changes in host preferences with age in the ectoparasitic pyramidellid snail snail, name commonly used for a gastropod mollusk with a shell. Included in the thousands of species are terrestrial, freshwater, and marine forms. Some eat both plant and animal matter; others eat only one type of food. Boonea impressa (Say). J. Mollus. Stud. 53:285-286. Sano, K. 1998. Minami Marutea kannsyoto ni okeru kuroshinnju bogai tairyo heishi to kaiketsusaku (Countermeasures That form of military science that, by the employment of devices and/or techniques, has as its objective the impairment of the operational effectiveness of enemy activity. See also electronic warfare. against mass mortality of blacklip pearl oyster, Pinctada margaritifera, at South Marutea Island). Youshoku, February 1998:93-95. (in Japanese) Shokita, S., K. Kakazu, A. Tomori, T. Toma & M. Yamaguchi. 1991. Aquaculture in tropical areas. Tokyo: Midori Shobo. 360 pp. Sims, N. A. 1993. Size, age and growth of the black-lip pearl oyster, Pinctada margaritifera (L.) (Bivalvia; Pteriidae). J. Shellfish Res. 12: 223-228. Southgate, P. C. & A. C. Beer. 1997. Hatchery hatchery a commercial establishment dedicated to the hatching of bird eggs to provide day old chicks and poults to the poultry industry. hatchery liquid the contents of unfertilized eggs. Used in petfood manufacture. and early nursery culture of the blacklip pearl oyster (Pinctada margaritifera L.). J. Shellfish Res. 16:561-567. Southgate, P. C. & A. C. Beer. 2000. Growth of blacklip pearl oyster (Pinctada margaritifera) juveniles using different nursery culture techniques. Aquaculture 187:97-104. Underwood, A. J. 1997. Experiments in ecology. Cambridge University Press Cambridge University Press (known colloquially as CUP) is a publisher given a Royal Charter by Henry VIII in 1534, and one of the two privileged presses (the other being Oxford University Press). , Cambridge. 504 pp. Vacelet, E., A. Arnoux & B. Thomassin. 1996. Particulate par·tic·u·late adj. Of or occurring in the form of fine particles. n. A particulate substance. particulate composed of separate particles. material as an indicator of pearl-oyster excess in the Takapoto lagoon (Tuamotu, French Polynesia). Aquaculture 144:133-148. White, M. E., E. N. Powell, S. M. Ray & E. A. Wilson. 1987. Host-to-host transmission of Perkinsus marinus Perkinsus marinus is a prevalent pathogen of oysters, causing massive mortality in oyster populations. The disease it causes is known as "Dermo", and is characterized by proteolytic degradation of oyster tissues. in oyster (Crassostrea virginica) populations by the ectoparasitic snail Boonea impressa (Pyramidellidae). J. Shellfish Res. 6:1-5. White, M. E., E. N. Powell, E. A. Wilson & S. M. Ray. 1989. The spatial distribution of Perkinsus marinus, a protozoan protozoan (prō'təzō`ən), informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple parasite, in relation to its oyster host (Crassostrea virginica) and an ectoparasitic gastropod gastropod, member of the class Gastropoda, the largest and most successful class of mollusks (phylum Mollusca), containing over 35,000 living species and 15,000 fossil forms. (Boonea impressa). J. Mar. Biol. Ass. UK. 69:703-717. Yukihira, H., D. W. Klumpp & J. S. Lucas. 1998. Comparative effects of microalgal species and food concentration on suspension feeding and energy budgets of the pearl oysters Pinctada margaritifera and P. maxima (Bivalvia: Pteriidae). Mar. Ecol. Prog. Ser. 171:71-84. Yukihira, H., D. W. Klumpp & J. S. Lucas. 1999. Feeding adaptations of the pearl oysters Pinctada margaritifera and P. maxima to variations in natural particulates. Mar. Ecol. Prog. Ser. 182:161-173. Yukihira, H., D. W. Klumpp & J. S. Lucas. 2000. Comparative effects of temperature on suspension feeding and energy budgets of the pearl oysters Pinctada margaritifera and P. maxima. Mar. Ecol. Prog. Ser. 195:179-188. Zar, J. H. 1999. Biostatistical analysis, 4th ed. New Jersey: Prentice Hall Prentice Hall is a leading educational publisher. It is an imprint of Pearson Education, Inc., based in Upper Saddle River, New Jersey, USA. Prentice Hall publishes print and digital content for the 6-12 and higher education market. History In 1913, law professor Dr. . 663 pp. TAKEO KURIHARA, (1) * HIDEAKI YAMADA, (1) JUN NAKAMORI, (2) MOTOHIKO SANO (3) AND HIROFUMI SHIMIZU (4) (1) Seikai National Fisheries Research Institute, Fukai-Ota 148-446, Ishigaki City, Okinawa 907-0451, Japan; (2) Okinawa Prefecture Fisheries Experimental Station, Kabira 828-2, Ishigaki City, Okinawa 907-045, Japan; (3) Fisheries Research Agency, 15F Queen's Tower Queen's Tower can refer to:
* Corresponding author. E-mail: takeo@affrc.go.jp
TABLE 1.
Growth and survival rate in Pinctada margaritifera spat.
Mean [+ or -] SD across three replication trays are presented.
Spat densities showing no significant difference in growth
were categorized into subgroups a, b, or c (p > 0.05
in a Tukey test).
Spat
Density
([tray.sup.-1]
Growth (mm) 12
24
36
72
144
Survival 12
rate (%) 24
36
72
144
Suspension Depth = 2 m
Non-partitioned Partitioned
Tray Tray
Growth (mm) 12.1 [+ or -] 4.7 12.7 [+ or -] 0.7
8.0 [+ or -] 2.0 12.4 [+ or -] 1.5
8.8 [+ or -] 3.3 14.5 [+ or -] 1.0
5.3 [+ or -] 2.3 12.6 [+ or -] 6.8
3.6 [+ or -] 3.1 6.6 [+ or -] 3.6
Survival 33.5 [+ or -] 51.5 60.8 [+ or -] 41.0
rate (%) 67.7 [+ or -] 52.7 61.9 [+ or -] 50.8
35.6 [+ or -] 43.0 62.0 [+ or -] 51.6
62.7 [+ or -] 54.5 4.0 [+ or -] 4.4
5.3 [+ or -] 4.2 6.2 [+ or -] 6.4
Suspension Depth = 6 m
Non-partitioned Partitioned
Tray Tray
Growth (mm) 14.1 [+ or -] 1.2 16.7 [+ or -] 1.2
12.2 [+ or -] 3.2 15.9 [+ or -] 1.7
8.1 [+ or -] 1.6 11.3 [+ or -] 5.0
7.3 [+ or -] 3.9 11.6 [+ or -] 1.9
6.5 [+ or -] 3.7 7.3 [+ or -] 1.9
Survival 74.7 [+ or -] 21.8 83.0 [+ or -] 9.0
rate (%) 54.2 [+ or -] 50.5 92.7 [+ or -] 6.5
36.2 [+ or -] 50.3 25.4 [+ or -] 26.5
37.0 [+ or -] 46.1 59.4 [+ or -] 48.2
54.8 [+ or -] 48.8 66.6 [+ or -] 50.4
Subgroups
in Tukey
Tests
Growth (mm) a
a, b
a, b
b, c
c
Survival
rate (%) Not performed
TABLE 2.
Analyses of variance for growth and survival rate in
Pinctada margaritifera. Their df are common except for
df of residual and total, which are smaller by
three for growth analyis, because in three trays all
spat died and growth was not determined.
Growth Survival Rate
Growth
Source of Variation df ss F-ratio p
Spat density, Dns 4 4.111 10.811 <0.001
Tray partition, Pt 1 1.763 18.545 <0.001
Suspension depth, Dep 1 0.282 2.970 0.093
Dns x Pt 4 0.350 0.922 0.462
Dns x Dep 4 0.598 1.572 0.202
Pt x Dep 1 0.059 0.625 0.434
Dns x Pt x Dep 4 0.108 0.285 0.886
Residual 37 or 40 3.517
Total 56 or 59 10.933
Survival Rate
Source of Variation ss F-ratio p
Spat density, Dns 2.132 1.835 0.141
Tray partition, Pt 0.121 0.418 0.522
Suspension depth, Dep 0.747 2.572 0.117
Dns x Pt 0.454 0.391 0.814
Dns x Dep 1.326 1.141 0.351
Pt x Dep 0.135 0.465 0.499
Dns x Pt x Dep 1.138 0.979 0.430
Residual 11.621
Total 17.675
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