Variation in clearance and ingestion rates by larvae of the black-lip pearl oyster (Pinctada margaritifera, L.) feeding on various microalgae

Clearance rate (CR) and ingestion rate (IR) of different sizes (89, 125 and 188 μm shell length) of Pinctada margaritifera larvae were determined when feeding on various microalgae. The microalgae tested were the diatoms, Chaetoceros muelleri and C. simplex, and flagellates, Tahitian Isochrysis aff. galbana, Pavlova lutheri and P. salina at 5 or 10 cells μL^–1. Both CR and IR of microalgae tested in this study increased with increasing larval size; but at all larval sizes, diatoms resulted in lower CR and IR. Of the microalgae tested, P. margaritifera larvae showed greatest CR and IR with the two Pavlova spp. Maximum CR for P. salina was 10.5, 21.2 and 29.7 μL h^–1 for larvae with shell lengths of 89, 125 and 188 μm, respectively. The highest IR values for P. margaritifera larvae with shell lengths of 89, 125 and 188 μm were 8.7, 81.0 and 165.7 cells·larva^–1 h^–1, respectively. CR and IR of P. salina were approximately five times higher than those recorded for C. muelleri and C. simplex.     

Growth and biometric relationships of the pearl oyster Pinctada fucata (Gould) on transplanting from the Gulf of Mannar to the Arabian Sea

Comparative studies were made on the growth and biometric relationships of the pearl oyster Pinctada fucata (Gould) Tuticorin stock at (Tuticorin (TST) – parent stock) transplanted from the Tuticorin Bay (8.7°N; 78.2°E) in the Gulf of Mannar along the Indian southeast coast to Kollam Bay (8.8°N; 76.5°E) in the Arabian Sea along the Indian southwest coast (Tuticorin stock at Kollam (TSK) – transplanted stock). At the time of transplantation, Kollam Bay did not have a native stock, however, within a year, the transplanted stock spawned and oyster spats were collected from within the farm (Kollam stock (KS) – progeny stock). The growth in dorso‐ventral measurement and total weight in Kollam Bay was 1.4–1.6 times and 3.1 to 6.8 times respectively greater than that observed at Tuticorin. Furthermore, at Kollam Bay, the thickness observed at the end of first year was similar to that obtained at the end of second year in Tuticorin. Both the TSK and KS had significantly higher instantaneous growth rates (IGR) than TST. All the stocks displayed significantly different biometric relationships. The increased growth in Kollam Bay is attributed to the almost double productivity in the Arabian Sea compared with the Bay of Bengal. It is concluded that in the case of P. fucata, the site and its interaction with environment are important determinants of growth and shell dimensions. The present study clearly indicates that the environmental conditions prevailing along the southeast Arabian Sea are congenial for the growth, gametogenesis, spawning and settlement of P. fucata larvae. In spite of strong monsoonal influences in the hydrology of Kollam Bay, the growth and reproduction of P. fucata stocks indicates its relative hardiness and ability to adapt to a changed environment.     

Excavating sponges that are destructive to farmed pearl oysters in Western and Northern Australia

Species of the family Clionaidae (Porifera: Demospongiae) that excavate shell of the silver‐lip pearl oyster, Pinctada maxima, in north Western and Northern Australia are described. Two species belong to the genus Cliona and one species to the closely related genus Pione. Cliona orientalis has only recently been reported from Australia in living and dead coral on the Great Barrier Reef, and this is the first report of this species from north Western and Northern Australia. Cliona dissimilis is reported from Australia for the first time. Pione velans was first described from Shark Bay, Western Australia and this study extends its distribution from Albany, south Western Australia to Port Bremer in the Northern Territory. The most common species found was C. dissimilis. Pione velans and C. orientalis were also present, although the latter species was rare. Cliona dissimilis and P. velans were found to be sexually reproductive in some shells with specimens of C. dissimilis with oocytes in May and P. velans in September 1999. Egg development was synchronous, indicating that the sponges were oviparous and would broadcast gametes in a spawning event.     

Fouling and predation; how do they affect growth and survival of the blacklip pearl oyster, Pinctada margaritifera, during nursery culture?

This paper reports on 5 experiments conducted to assess the effect of cleaning regime and predation on growth and survival of blacklip pearl oyster (Pinctada margaritifera) juveniles in north Queensland, Australia. P. margaritifera juveniles with a mean (±SE) dorso-ventral shell height (DVH) of 4.5 ± 0.1 mm were placed into plastic mesh trays and cleaned either every 4 or 8 weeks or left uncleaned for 16 weeks. Cleaning regime had a significant effect on growth and survival (P < 0.005). Lowest DVH (16.2 ± 1.0) was shown by oysters in uncleaned trays during 16 weeks compared to oysters in cleaned trays; however, there was no significant difference in DVH between oysters held in trays cleaned every 4 (19.4 ± 1.2) or 8 weeks (21.2 ± 0.8). In contrast lowest survival was shown by oysters held in trays that were cleaned every 4 weeks (30 ± 5%), but no differences were noted between oysters cleaned every 8 weeks (63 ± 4%) and oysters that were left uncleaned for 16 weeks (75 ± 8%). Predators of P. margaritifera in northern Australia included crabs, stomatopods, flatworms, gastropods and fish. The stomatopod, Gonodactylus falcatus, was the most destructive predator with individuals consuming in excess of 20 juvenile pearl oysters per week. The leather jacket, Paramonocanthus japonicus, did not kill pearl oysters, but trimmed the margin of oysters shells significantly reducing DVH when compared to control groups cultured without fish. Removing predators monthly had a significant effect on growth of pearl oysters compared to oysters in non-inspected trays; however monthly inspection of culture trays did not significantly improve oyster survival. This revised version was published online in August 2006 with corrections to the Cover Date.     

Larval settlement of the silver- or goldlip pearl oyster Pinctada maxima (Jameson) in response to natural biofilms and chemical cues

This paper presents the first laboratory study investigating larval settlement and metamorphosis of Pinctada maxima in response to both natural and artificial inducers. Natural biofilms induced larval settlement and the inductive effect appears to be closely associated with the bacteria in the biofilm. This result indicates that, in nature, bacteria may play an important role in the settlement of P. maxima larvae. Various pharmacological agents were also tested in this study and the results were generally similar to those found with other marine invertebrates, particularly molluscs. The results show that some pharmacological agents are potent artificial inducers of larval settlement for P. maxima. The findings of this study provide valuable information for understanding the mechanism of the larval settlement of this species, which is useful information for the hatchery industry of this pearl oyster.     

利用微卫星标记分析马氏珠母贝4个养殖群体遗传结构

2007年4月,从马氏珠母贝基础群体选取2、4、32和158个亲本分别繁殖4个子代群体,分别命名为P1、P2、P3和P4。2009年7月,从这4个子代群体随机取样30个个体,利用7对微卫星引物分析其遗传结构。结果表明,7对微卫星引物共检测到22个等位基因,每个座位的等位基因数目为2~4个,平均等位基因数为3个,平均有效等位基因数为2.3193。P1、P2、P3和P4群体平均观测杂合度分别为0.4737、0.5489、0.6767和0.7143;P1、P2、P3和P4群体平均期望杂合度分别为0.4737、0.5489、0.6767和0.7143;P1、P2、P3和P4群体的多态信息含量分别为0.4472、0.4224、0.4726和0.4930。本结果表明4个养殖群体均具有较高的遗传多样性,而且有效亲本数目对子代遗传结构有较大的影响,这为马氏珠母贝的遗传育种提供依据。     

东亚钳蝎疾病与天敌的防治

本文介绍了东亚钳蝎在人工养殖条件下 ,一些疾病与天敌发生的原因、临床症状及防治方法。     

合浦珠母贝抗菌肽粗提液制备方法的优化

研究了不同处理方法制备合浦珠母贝外套膜和鳃组织抗菌肽粗提液的抗菌活性,结果表明：以1.0×106cfu·mL^-1无乳链球菌刺激合浦珠母贝14 h以内对其粗提液抗菌活性无显著影响;合浦珠母贝外套膜或鳃组织抗菌肽粗提液制备时,IKAT-18匀浆机的匀浆效果要优于组织匀浆器和研钵。100℃水浴处理组织粗提液10 m in可显著提高其对溶藻弧菌的抗菌活性;反复冻融则会显著降低外套膜组织粗提液的抗菌效果。     

马氏珠母贝两个不同地理种群的形态性状

在“珍珠贝育种规划（Pearl Oyster Breeding scheme,POBs）”中,马氏珠母贝的两个地理种群——印度养殖种群和三亚野生种群正在作为两个基础群（Basic population）建立专门化品系,通过杂交获得杂种优势,构建杂交配套系以培育优良品种。从形态上看,印度养殖种群体个体大,而三亚野生种群体个体小;三亚野生种群的壳宽系数为0．18,大于印度养殖种群的0．15,三亚野生种群的贝体外形较凸,而印度养殖种群的贝体外形扁平。三亚野生种群的壳重指数（25．30）大于印度养殖群体（18．80）。通过成像色度检测分析系统分析,每个种群都有自己的颜色特征值——三刺激值和颜色参数;比较两个种群颜色参数Lab时表明,三亚野生种群贝壳珍珠质颜色的明度（L）大于印度养殖种群,色品比印度养殖种群更偏向绿色（-a）和黄色（b）,印度养殖种群色品偏向蓝色和红色。两个种群间贝壳珍珠质的色差（△XEab）为10．69,属于大色差,感觉强烈。     

马氏珠母贝转录组数据的重新组装

对本实验室和其他学者已经发表的马氏珠母贝外套膜和珍珠囊的454焦磷酸测序转录组数据以及NCBI中的EST数据进行了重组装、同源序列比对和GO注释分析。重组装获得了30266个contig,平均长度522 bp,其中最长的contig为4144 bp;NR数据库BLAST分析获取了2310个相似性contig(E≤10?5),其中1902个在模式动物(人、小鼠、海胆、线虫、斑马鱼、果蝇或者太平洋牡蛎和珠母贝)中可以查找到同源序列。基因注释(GO)结果表明,注释到生物学过程的3846个contig可分为23个亚类,其中代谢过程蛋白、细胞过程蛋白和生物学调控蛋白为contig数量最多的3个亚类;注释到分子功能的4601个contig共分为11个亚类,其中结合蛋白的contig数量最多,其次是具有催化活性的蛋白和结构分子活性蛋白;注释到细胞成分的2992个contig分为17个亚类,其中细胞和细胞组成部分的contig数量最多,其次分别是细胞器和大分子复合体contig数量。本研究结果有助于开展外套膜和珍珠囊特异性表达基因的大规模筛选。