Viable aquaculture development in the U.S. affiliated islands‐lessons from giant clam and sponge farming

Abstract

The Center for Tropical and Subtropical Aquaculture (CTSA), which is funded by the U. S. Department of Agriculture as one of its Regional Aquaculture Centers, has assisted giant clam and sponge fanning technology development and technology transfer within the region since 1989. Six species of giant clam and one species of bath sponge can currently be commercially produced in the region. After over 12 years of intensive effort by CTSA to develop and transfer technology, the production of giant clam and bath sponges has yet to make any significant contribution to the local economy.

By self‐evaluation of our efforts and the continuing efforts of others, this paper provides possible solutions on aquaculture development related factors, which include biological, technological, environmental, and socioeconomic. Recommendations are made on viable aquaculture development in the region based on our experiences. Amongst other factors, the government's commitment to aquaculture and the resulting actions are vital. Farming technology for giant clams and sponges are also briefly reviewed.     

鸭—鱼—蚌—树生态种养模式及其效益分析

为探索水体养殖减排增产增效的新方法,提出采用水上养鸭、水中养鱼、水底养蚌、周边栽树的生态模式。通过鸭粪肥水、育珠净水、鱼食残饵达到空间与资源循环利用的目的。探索并总结了鸭-鱼-蚌-树生态种养模式的主要技术要点及模式运行成效。结果表明,处理出水基本满足《城市污水再生利用城市杂用水水质》(GB/T l8920—2002)标准,同时可产出肉鸭、鱼、珍珠、蚌肉和贝壳等副产品,经济效益和生态效益显著。     

辐照控制菲律宾蛤仔中治病菌及其在贮藏期的生长情况

研究了菲律宾蛤仔经60Coγ射线辐照后,其中的菌落总数、大肠肝菌和副溶血性的D₁₀值及辐照后在贮藏期的变化。结果表明,经60Coγ射线辐照后菲律宾蛤仔中的菌落总数、大肠肝菌、副溶血性的D₁₀值分别为：0.70、0.56和0.20kGy;真空包装的菲律宾蛤仔在0°C~4°C贮藏条件下,3kGy剂量辐照贮藏28d后菌落总数为4.46log(CFU/g),符合水产品卫生要求;而0.4kGy剂量辐照贮藏7d后大厂肝菌、副溶血性弧菌后检测未检出。由此可见,3kGy以上剂量辐照处理菲律宾蛤仔,能有效杀灭其中的微生物,且其贮藏期可达28d,用辐照方法保鲜菲律宾蛤仔具有一定实际意义。     

河蚌的生物学特性及人工育珠技术

介绍了河蚌的生物学特性,阐述了人工育珠技术及珍珠的采集与加工方式。     

Preliminary study on zeolite materials used to control of heavy metal pollution during the culture of mud clam Tegillarca granosa L.

To control heavy metal pollution during the culture of the mud clam, Tegillarca granosa L., the isothermal static adsorption capacities of three adsorption materials [natural zeolites, zeolites synthesized from kaolin and zeolites synthesized from coal fly ash (ZFA)] towards Cu²⁺, Cd²⁺, Cr⁶⁺, Zn²⁺, Pb²⁺ and Hg²⁺ in seawater were investigated. The adsorption capacity of the best material was investigated during the culture of mud clam in an artificially polluted environment. Results showed that the ZFA adsorption capacity was the highest and conformed to the Freundlich model. The theoretical maximum adsorption capacities of the adsorbent towards Cu²⁺, Cd²⁺, Cr⁶⁺, Zn²⁺, Pb²⁺ and Hg²⁺ in seawater were 3.057, 1.123, 0.325, 13.101, 6.116 mg g^?1 and 6.527 μg g^?1 respectively. For seawater artificially polluted by six heavy metals, heavy metal adsorption by ZFA followed the order Zn²⁺ > Cd²⁺ > Hg²⁺ > Cu²⁺ > Pb²⁺ > Cr⁶⁺. For the mud clam culturing experiment that simulated a continuously polluted water source, the Cu²⁺, Cd²⁺, Cr⁶⁺, Zn²⁺, Pb²⁺ and Hg²⁺ contents of mud clam tissues decreased by 40.9%, 25.8%, 9.6%, 28.2%, ?27.8% and 25.7%, respectively, after 21 days of culturing compared with the contents before the experiment.     

三疣梭子蟹新品种“黄选1号”的选育

2005年收集鸭绿江口、莱州湾、海州湾、舟山4个三疣梭子蟹野生地理群体,构建核心育种群体,评估有效群体含量,制定合理保种模式;在5％留种率下,采用群体选育方法进行新品种培育.到2010年经过连续5个世代选育,形成特征明显、性状稳定的三疣梭子蟹新品种“黄选1号”.在相同养殖条件下与商品苗种进行对比测试.“黄选1号”收获时平均个体体重提高20.12％,成活率提高32.00％,全甲宽变异系数小于5％“黄选1号”新品种2010～2012年进行中试养殖200余hm2,养殖方法以“蟹、虾、贝、鱼”多品种生态养殖为主.结果显示,新品种收获时个体规格大、成活率高、整齐度好,平均单产提高30％;已推广到山东、河北及浙江等地,累计养殖面积6 000余hm2,获得较显著的经济效益和社会效益.     

Expression and localization of MCsialec, a sialic acid-specific lectin in the marine bivalve Manila clam, Ruditapes philppinarum

A novel sialic acid-specific lectin (MCsialec) was detected from an expressed sequenced tag (EST) sequence from Manila clam haemocytes infected with Perkinsus olseni. The cDNA of the lectin was cloned using gene-specific primers based on a previously determined EST and characterized. The full-length cDNA of MCsialec is 603 bp in length and encodes a polypeptide of 200 amino acids with a calculated molecular mass of 21.928 kDa. Sequence alignment and protein motif analyses showed that MCsialec shares identity with sialic acid-specific invertebrate lectins from Cepaea hortensis, Helix pomatia and Haliotis discus discus. The lectin was expressed in Escherichia coli M15 cells and purified using a Ni-NTA His-binding resin matrix for antibody production. The presence of the lectin in various tissues of Perkinsus-infected and uninfected Manila clams was analysed by both PCR and immunohistochemical localization assays. MCsialec was detected in each tissue of the clams; however, upon infection, the level of expression of the lectin increased in each tissue. Vibrio tapetis infection also induced high-level expression of MCsialec in the haemocytes. These data suggest that MCsialec plays a crucial role in the immune system of the Manila clam during pathogenic infection.     

Small-scale variation in feeding environments for the Manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> in a tidal flat in Tokyo Bay

The relative contribution of particulate organic matters (POMs) in water column and sediment as a food source for the Manila clam, Ruditapes philippinarum, was studied using carbon and nitrogen stable isotopic method (δ¹³C and δ¹⁵N) in a tidal flat at Seaside Park, Yokohama, Japan. Comparisons of δ¹³C and δ¹⁵N among R. philippinarum and POMs in surface water, bottom water, and sediment surface indicated that R. philippinarum larger than 5 mm shell length (SL) mainly assimilated benthic POM, and individuals smaller than 5 mm SL assimilated benthic and pelagic POM. Continuous measurements of chlorophyll concentrations in the bottom water revealed tide-driven resuspension of the benthic phytopigments. R. philippinarum showed differences in δ¹³C and δ¹⁵N along an inshore–offshore transect, indicating small-scale spatial differences in POM provision in the tidal flat. These findings suggest that POM in the bottom water, supposedly inhaled by R. philippinarum, is a mixture of a larger proportion of resuspended benthic POM and a smaller proportion of pelagic POM, and that the mixing ratio of the POMs may be affected by the hydrodynamics of flooding water associated with tidal flat topography.     

Growth and kinetics of lipids and fatty acids of the clam Venerupis pullastra during larval development and postlarvae

This study examines the larval development, metamorphosis and postlarval stage of Venerupis pullastra in relation to growth, lipids content and fatty acid composition, specifically those believed to be essential for most bivalves (i.e. 20:5n‐3 and 22:6n‐3). Clam larvae were fed with two species of microalgae supplied individually or mixed –Isochrysis galbana and Tetraselmis suecica–species normally used in bivalve hatcheries. Larvae fed with T. suecica showed a progressive accumulation of lipids and fatty acids but did not survive to metamorphosis. Contrarily, larvae fed with I. galbana or mixed diet showed a progressive decline in lipids and essential fatty acids (20:5n‐3 and 22:6n‐3) from the pediveliger stage onwards, and a survival rate of 95% until the start of metamorphosis. The lower content in n‐6 and the absence of 22:6n‐3 in T. suecica diet might contribute to the massive mortality observed for larvae fed with this diet. That diet seems to fail in the supply of some particular nutrient that allows energetic transformation of reserves for growth and metamorphosis. Nevertheless, larvae fed on mixture diet showed higher weight growth values at postlarval stage than those larvae fed on I. galbana diet.     

单细胞藻类饲养青蛤稚贝的研究

本试验以几种单细胞藻类为饵料,研究青蛤稚贝的生长和成活率。经21天饲养证明,小球藻、扁藻、三角褐指藻、底栖硅藻都是青蛤稚贝的适宜饵料,其成活率均达90％以上,其中又以投喂底栖硅藻生长最快。