【作者】 黄志涛；

【导师】 万荣； 宋协法； Eric Hallerman；

【作者基本信息】 中国海洋大学 ， 捕捞学， 2013， 博士

【摘要】 北美地区是世界上淡水贝类资源最丰富的地区，共有淡水贝类近300种，然而在过去的三十年间，72%（213种）淡水贝类的生存受到了严重的威胁，部分品种处于濒危状态。随着美国淡水贝类资源的衰退，淡水贝类的人工繁育、养殖和增殖放流已经成为保护和恢复淡水贝类资源的一种重要手段。本文详细综述了美国淡水贝类的现状，以及淡水贝类的养殖设施、养殖技术的研究进展，并以具有代表性的淡水彩虹贝类为研究对象，设计了一套封闭式彩虹贝循环水养殖系统，对钩介幼虫2日龄的彩虹贝幼贝进行了为期60天的养殖，同时还将藻类过滤器（Algal turf scrubber）技术应用于该循环水养殖系统，分析比较了加入藻类过滤器的循环水养殖系统和不加入藻类过滤器的循环水养殖系统的水质及彩虹贝幼贝生长率、存活率情况；分析比较了投喂三种不同微藻饵料对彩虹贝幼贝生长率和存活率的影响；还分析比较了采用不同厚度的底质对彩虹贝幼贝生长率和存活率的影响。本研究得到美国渔业和野生动物服务（USFish and Wildlife Service）的Clinch河段淡水贝类种群恢复项目（Restorationof Freshwater Mussel Populations in the Upper Clinch River Watershed）的资金支持，本文的主要研究结果如下：1.彩虹贝循环水养殖系统的设计根据物质平衡原理，设计并构建了一个小型的封闭式淡水彩虹贝循环水养殖系统，该系统由养殖池、生物过滤器、蓄水池、循环水泵、充氧系统和自动投饵装置组成。养殖池为长方形池（300cm×70cm×30cm），有效养殖水体约为350L，补水量50L/d，循环量1394L/h，循环次数48次/d，设计养殖彩虹贝数量为8000只；生物过滤器为圆形浸没式生物过滤器（1.2m i.d.×1m），垂直浸没式分配管进水，共5个喷嘴进水口，底部中央排水，采用的生物滤料为kaldnes K1，体积为2L；蓄水池中加入气石对系统进行空气充氧，日充氧量为22.8g。循环水泵为扬程6m、流量52L/min的磁力泵，功率为130W；自动投饵装置为体积1L的塑料瓶，底部中心出口装有电磁阀门，通过设定重复计时器来控制饵料的投喂频率和投喂量。系统中水管的材料均为PVC，所有阀门处均安装蝶阀。2.彩虹贝循环水养殖系统的应用本实验对钩介幼虫2日龄的彩虹贝幼贝进行了为期2个月（2011年6月20日到2011年8月20日）的养殖。整个养殖周期内，彩虹贝幼贝循环水养殖系统水质稳定良好。彩虹贝幼贝壳长日增长量为16.4μm/d，最大相对增长率发生在第40天到50天，其相对生长率为32.4%，与传统的池塘流水养殖和跑道式养殖系统相比，该系统养殖的彩虹贝幼贝获得了更高的生长率。实验结束时，彩虹贝幼贝的存活率为54.6%。3.藻类过滤器（ATS）在彩虹贝类循环水养殖系统中的应用效果研究本实验比较了加入藻类过滤器的循环水养殖系统和不加入藻类过滤器的循环水养殖系统的水质及彩虹贝幼贝生长率、存活率情况。设置加入藻类过滤器的系统为实验组，未加入藻类过滤器的系统为对照组。实验结果显示，实验组与对照组的水温、溶解氧、pH、总氨氮、亚硝酸氮等水质参数没有显著性差异（P>0.05）;对照组的硝酸氮和无机磷的浓度要显著高于（P<0.05）实验组，经过为期13周的养殖，对实验数据进行多变量方差分析（MANOVA）处理，结果显示，在时间和处理的共同作用下（time×treatment interaction），两组之间的彩虹贝幼贝的壳长差异极显著(Ptime×treatment=0.001)。实验组和对照组中彩虹贝幼贝的平均存活率分别高达96.7%和96.1%，两组之间彩虹贝幼贝的存活率差异不显著（P>0.05）。以上结果表明：在该养殖系统中添加藻类过滤器可以显著降低水体中硝酸盐和无机磷，还可以提高彩虹贝幼贝的生长率。4.不同微藻饵料对彩虹贝幼贝生长影响的研究实验分析比较了在彩虹贝幼贝循环水养殖系统中，分别投喂富油新绿藻（Neochloris oleoabundans）、微拟球藻（Nannochloropsis)和融合微藻（Tetraselmis sp）等三种微藻对彩虹贝幼贝生长率和存活率的影响，实验设3个处理组，分别投喂三种不同的微藻饵料，每组3个重复，每个重复养殖淡水彩虹贝幼贝200只，实验用彩虹贝幼贝平均壳长为16.4mm，实验周期为13周，实验结束时，三个饵料处理组的彩虹贝幼贝最终壳长差异显著（P<0.05）。在特定生长率方面，富油新绿藻处理组彩虹贝幼贝的特定生长率低于微拟球藻和融合微藻（P<0.05），微拟球藻和融合微藻组之间的特定生长率差异不显著（P>0.05）；三个饵料处理组彩虹贝幼贝均保持较高的存活率（90.3%、91.8%和87.7%），各处理组之间彩虹贝幼贝的存活率差异不显著（P>0.05）。5.不同底质厚度对彩虹贝幼贝的生长率和存活率的影响研究实验分析比较了彩虹贝循环水养殖系统中，养殖池底质厚度对彩虹贝幼贝生长率和存活率的影响，实验设3个处理组，各组底质厚度分别为4-6cm（D1），9-11cm（D2）和无底质（D3），每组3个重复，每个重复养殖淡水彩虹贝幼贝约155只，实验用彩虹贝幼贝平均壳长为16.7mm，实验周期为13周。实验结果表明，D1和D2处理组彩虹贝幼贝的最终壳长没有显著差异（P>0.05），这表明两种不同厚度的底质并没有给彩虹贝幼贝的生长带来不同的影响。D1和D2处理组的最终壳长显著长于D3处理组。三个处理组（D1，D2，D3）彩虹贝幼贝的平均存活率分别为94.7%,92.5%和72.6%,有底质的处理组D1和D2中彩虹贝幼贝的存活率要显著高于没有底质的处理组D3（P<0.05）。可见在养殖池中添加底质能够提升彩虹贝幼贝的生长率和存活率。更多还原

【Abstract】 North America contains the greatest diversity of freshwater mussels in the world,nearly300species. However, bivalve mollusks of the superfamily Unionacea are themost imperiled group of animals in the United States, with213species (72%) listed asendangered, threatened, or of special concern. Already, approximately35species areconsidered extinct. With the decline of native North American freshwater mussels,United States has brought about the need for facilities in which endangered musselscan be held for purposes of relocation, research, and propagation.I reviewed the status of freshwater mussels in United States, and also culturetechnology of freshwater mussel in the paper. A recirculating aquaculture system forfreshwater Rainbow mussel (Villosa iris) was designed and evaluated in FreshwaterMollusk Conservation Center at Virginia Tech.2days old juvenile rainbow musselwas cultured in the recirculating system for60days. Algal turf scrubber was added inthe system to improve the water quality, growth rate of juvenile rainbow mussels.Growth and survival of juvenile rainbow mussel was compared under three differentspecies of algae. Growth and survival of juvenile rainbow mussel was comparedunder different depth of sediment in the culture tanks. Funding was provided byRestoration of Freshwater Mussel Populations in the Upper Clinch River Watershed，US Fish and Wildlife Service.Virginia Department of Game and Inland Fisheries,Cooperative Endangered Species Conservation Fund. The main results are as follows:1. Design of recirculating aquaculture system for rainbow musselsTo develop a system supporting rapid growth of juvenile freshwater mussels, arecirculating aquaculture system for freshwater rainbow mussel was designed basedon the mass balance in Freshwater Mollusk Conservation Center (FMCC) at Virginia Tech. The RAS included a plastic stock-watering tank utilized as the container forsubstrate and cultured mussels, submerged biofilter（1.2m i.d.×1m）, sump, pump, airdelivery system and automatic micro-algae drip feeder (1L). The mussel culture tankwas made of polyethylene and was300cm long,70cm wide,30cm deep along themidline, and held approximately350L of water at a depth of16-18cm. The amountwater of making up was50L daily. The vertical influent injection piped with orificeswas used in the submerged biofilter, and water flushed out of the biofilter from thecenter bottom drain. Kaldnes K1bio-media (2L) was suspended in the biofilter.22.8goxygen was aerated into the system by the air delivery system. A magnetically-drivenpump drove water flow at the flow rate of1394L/h. A solenoid valves was installed onthe outlet tube of the automatic feeder to control the feeding frequency and feedingamount by a repeat-cycle timer. All valves installed were PVC butterfly valves.2. Evaluation of the recirculating aquaculture system for rainbow musselsThe recirculating aquaculture system was evaluated as culture environment forjuvenile rainbow mussel.2days old juvenile rainbow mussel was reared in the systemfor60days. Throughout the experiment, water quality parameters were stable andremained within ranges suitable for juvenile survivals. Mean growth rate of thejuvenile rainbow mussel16.4μm/d. The relatively best growth rate was32.4%，which attained from the40thto50thdays during the study. The survival rate was54.6%at the end of the study. The recirculating system improved the growth ratecompared the previous study in pond and raceway culture systems.3. Performance of a recirculating aquaculture system utilizing an algal turfscrubber for scaled-up captive rearing of rainbow musselsAn algal turf scrubber (ATS) was installed in the recirculating system andevaluated for its potential to maintain and improve water quality. Growth and survivalrates of juvenile rainbow mussels (Villosa iris) were compared at90days betweensystem units with and without ATS. Results showed ammonia and nitrite levels werelow and not different among treatments. However, systems with ATS exhibited significantly (P<0.05) lower levels of nitrate and phosphate than systems withoutATS. The average survival rates in the systems with and without ATS were96.7%and96.1%, respectively. No statistically significant difference on survival rates(P>0.05) of juvenile mussel reared in systems with or without ATS. Based on theMANOVA, the growth rate of the juvenile mussels was extremely (Ptime×treatment=0.001) different under time×treatment interaction between systems with or withoutATS. Our results show that freshwater mussel culture systems can be scaled up toincrease production and suggest that ATS may help maintain water quality inrecirculating aquaculture systems in long-term culture of freshwater mussels.4. An evaluation of three algal diets for juvenile rainbow mussel in recirculatingsystemThe experiment lasted13weeks was conducted to assess the effects of threedifferent diet treatments on the survival and growth of juvenile rainbow mussel. Thethree macroalgae were Neochloris oleoabundans, Nannochloropsis and Tetraselmissp.as three treatments. Each treatment replicated3times.200rainbow mussels werereared in each system. The results showed that the final length of the juvenile rainbowmussels was significant different among the treatments (P<0.05). The SGR of thejuvenile rainbow mussels fed with Nannochloropsis and Tetraselmis sp. wassignificantly higher than the treatment fed with Neochloris oleoabundans. Nostatistically significant difference on survival rates (P>0.05) of juvenile mussel amongthe treatments. The juvenile rainbow mussel under different diet treatments allmaintained high survival rate (90.3%、91.8%and87.7%, respectively).5. An evaluation of different sediment depths for the culture of juvenile rainbowmussels in recirculating systemTo develop a suitable sediment depth for rearing freshwater juvenile rainbowmussels in the recirculating system, grow and survival rate of juvenile rainbowmussels was evaluated on different depth of sediment for13weeks. There were threetreatments (D1,4-6cm; D,29-11cm; D3, no sediment). Each treatment replicated3times. Approximate155rainbow mussels were reared in each system. The average length was16.7mm. The results showed that no significant difference on finial lengthof juvenile mussel between treatment D1and D2(P>0.05). And the finial length ofjuvenile rainbow mussel in treatment D1and D2were significant greater thantreatment D3(P<0.05). That means it is benefit for the growth of the rainbow musselto add the sediment in the culture tank. The growth rate can be improved by addingthe sediment in the culture tank in the recirculating system. No statistically significantdifference on survival rates (P>0.05) of juvenile mussel between treatment D1and D2.The survival rate of juvenile rainbow mussel reared under no sediment was significantlower than under the treatments (D1and D2) with sediment. The results show thatadding sediment in the culture tanks was really important to rear the freshwaterrainbow mussel in recirculating system.更多还原