YQ—80D型远控潜吸式水下清淤机

YQ－80D型远控潜吸式水下清淤机是根据专利实施的专利产品。它冲破“车入泥潭”不能行走的禁区，一改水力清塘机组、船舶式带泵抽吸和岩拖潜水泥泵，在出入水域、转移清淤地点需肩扛手拉，操作时劳动强度大，能耗大的缺点。本肖淤机构思独特，只需一人在岸上操纵电气开关，就能控制其在水下、陆上多地形中独立行走，并可爬坡46度，前进后退，顺逆时针施转。转弯半径为零，在转移工作地点时全部自动行走。该专利发明项目第六届全国发明展览会金牌奖。     

SQY7型潜式池塘清淤机的应用和推广

近年来,广东省的水产养殖业发展迅猛,但鱼塘的淤积相当严重,淤泥厚度普遍达到五十厘米,有的甚至达到1米以上,万亩水田淤积每年要减少放养面积30～33.33公顷,并且会使水质恶化,增加鱼群发病率,致使鱼塘单产下降,因此,各地对鱼     

基于水力推进的渔药自动喷施装置设计

针对人工泼洒渔药工作劳动强度大、施药效率低、对人身危害大等问题,设计了一种新型的基于水力推进的渔药自动喷施装置。该装置以玻璃钢船为载体,由直流自吸水泵驱动,采用锂电池供电,利用喷水推进原理行进。整机由船体、推进装置、转向系统、施药系统、无线遥控系统以及配套的管路系统组成。样机测试结果表明,该装置作业平均前行速度为1.0 m/s,总体混药稀释比例整数范围达1∶1000~1∶5000,实际施药效率达460 m~2/min,较传统人工泼洒效率提升160%。通过遥控渔药喷施作业,可以保证操作人员的安全,也可避免喷施药液配置过多造成浪费和污染环境。研究表明,该装置提供了一种移动式在线混药水下施药方法,对精准化水产养殖具有促进作用。     

冰冻杂鱼切块机精准自动控制技术研究

为提高渔业养殖效率,改变现有杂鱼块不平整和破碎率较高等缺点,研制了一种自动化程度较高的冰冻杂鱼切块机。采用变频调速技术,以通用串行通信接口通讯协议实现西门子PLC与MM440变频器通讯,用普通齿轮减速电机进行杂鱼切块宽度调节,用测距传感器进行精确测距,对射式光电计数器进行切块计数。通过PLC控制变频器参数,设置减速电机的运行参数,再运用PLC与上位机之间的串口通讯,实现良好的人机交互,从而完成切块机精准自动控制。性能测试结果显示,在额定电压400 V条件下,切块速度25~35块/min,可将600 mm×400 mm×80 mm的杂鱼板切成宽60~90 mm,宽度可调;空载状态下,功率0.26 k W,负载运行时的转速、功率、扭矩成正比。在指定宽度下,切块精度为±5%,切块个数准确。研究表明,该控制系统可靠,适合在沿海渔业养殖中应用推广。     

投饲范围可控的自动投饲机研究

为解决水产养殖用投饲机投饲范围固定、投饲不均匀、饲料利用率低及污染严重等问题,提出并研制了基于气力输送和单片机控制的投饲范围可控的自动投饲机.根据其工作原理,对该自动投饲机的供料系统、抛撒系统和控制系统进行了设计,采用气力作为供料能源,喷嘴和凸台组合作为抛撒机构,选用STC90C516RD+作为控制单元.工作过程表明,与传统投饲机相比,该自动投饲机具有结构简单、饲料不易破碎、饲料利用率高、噪声污染小等特点,并可实现对投饲范围的调节和控制,达到预期投饲范围调节和均匀投饲的效果.     

网箱真空活鱼起捕机的研究

采用真空负压原理,利用负压抽吸与零压排放交替起捕的方法,研制了由真空泵、耐压集鱼罐和全自动控制电路等组成的网箱活鱼起捕机。起捕试验结果表明,在1：1的鱼水比例时,该机的活鱼起捕量可达(15～20)t／h,且对鱼体无伤害,其设备技术性能稳定可靠、自动化程度高,可广泛应用于网箱养殖生产。     

锯缘青蟹血细胞的形态及分类

对锯缘青蟹（Scylla serrata）血细胞染色的抗凝剂、染色方法进行筛选。蟹样品体质量约250g。采用亚甲基蓝、瑞氏法染色后，在Olympus油镜下观察、记数、测量，再结合电镜超薄切片观察结果对锯缘青蟹血细胞进行分类。根据血细胞质中颗粒的有无、大小、折光性、染色特性及细胞的大小、核质比等，将锯缘青蟹血细胞分为4种：（1）无颗粒细胞，细胞质中无颗粒；（2）小颗粒细胞，细胞质中有深蓝色小颗粒；（3）中间型细胞，细胞质中既有深蓝色小颗粒，又有折光性红色大颗粒；（4）大颗粒细胞，细胞质中充满了具有折光性的红色大颗粒。4种血细胞的大小顺序从小到大依次为无颗粒细胞、小颗粒细胞、中间型颗粒细胞、大颗粒细胞；核质比则相反，分别为54．01％、37．13％、25．37％、17．49％；其数量百分比分别占20．92％、40．30％、19．39％、19．39％。根据伪足的多少。对4种血细胞在机体的免疫防御机制中所起的不同作用进行了简单探讨。     

长江口底泥浸出液和悬浮液对叶绿素a含量的影响

以微绿球藻(Nannochloropsis oculata)和牟氏角毛藻(Chaetoceros muelleri)为受试生物,检验不同浓度的底泥浸出液和悬浮液对其叶绿素a含量的影响试验,探讨长江口底泥污染物析出对浮游植物生长的影响。研究结果表明,浓度低于或等于20%时,底泥浸出液对牟氏角毛藻和微绿球藻生长影响不显著;高于20%时,浓度越高,抑制作用越加明显。悬浮液抑制作用强于浸出液。浸出液对叶绿素a含量增长的抑制作用,在牟氏角毛藻试验的第4天开始显现,在微绿球藻试验和悬浮液试验中,第3天就开始显现。在较低浓度中,微绿球藻对污染物的反应更加灵敏,而牟氏角毛藻是适合较高浓度的受试物种。底泥重金属溶出是影响浮游植物生长的主要原因之一。     

Effects of tank colour on larval survival and development of mud crab Scylla serrata (Forskål)

Hatchery culture of mud crabs has not yet achieved commercial viability despite decades of research efforts. Further research is therefore needed to better understand larval culture requirements of the crab. Based on anecdotal observations, an experiment was carried out to test whether the background colour of the culture vessel affected larval culture success. Newly hatched larvae of Scylla serrata were reared in culture vessels of five colours, i.e., black, dark green, maroon, sky blue and white. Larval survival and development were monitored daily until all of them either moulted to the first crab stage or died. The results showed clear effects of background colour on larval survival. A general tendency of higher larval survival in darker‐coloured backgrounds was evident. In particular, overall zoeal survival for larvae reared in black vessels was significantly higher than those reared in white ones. Background colour also appeared to affect larval development. Larvae reared in darker backgrounds generally had shorter development times and more synchronized moulting. A significant delay in zoeal development was observed in larvae reared in white vessels. Dark backgrounds possibly facilitated more efficient feeding, reduced settlement of larvae at the bottom of the vessels as well as minimized stress. This result appears to be the first to demonstrate that background colour can significantly affect larval survival and development of a crustacean species.     

Impact of salinity changes on growth,oxygen consumption and expression pattern of selected candidate genes in the orange mud crab (Scylla olivacea)

Change in environmental salinity level is a major limiting factor for the aquaculture productivity because it imposes severe stress on organisms that in turn retards growth. The orange mud crab (Scylla olivacea) is an important coastal aquaculture species (farming is practised in 10‰–20‰ salinity levels) in Bangladesh. The present study was conducted to investigate the changes in growth, O₂ consumption and mRNA expression levels of five selected genes in the orange mud crab (S. olivacea) exposed to three different experimental salinity levels (0‰, 10‰ and 20‰) for three months. Crabs reared at 10‰ and 20‰, showed significantly higher (p < .05) growth performance and expression of growth regulatory genes (Actin and α‐amylase). The highest levels (p < .05) of O₂ consumption and expression of ion regulatory genes (Na⁺‐K⁺‐ATPase, V‐type H⁺‐ATPase and Diuretic Hormone) were obtained at 0‰. Moderate levels of growth and expression of selected candidate genes were observed at 10‰ treatment while the highest levels of growth and gene expression were obtained at 20‰ (control salinity). Strong interactions were observed between growth performance and expression of growth genes (R² = 0.81–0.91), and rate of O₂ consumption and expression of ion regulatory genes (R² = 0.83–0.93), implying that the selected genes are important candidates for growth and ionic balance in S. olivacea. Growth performance was found to be very low at 0‰ initially, after 30 days crabs showed better growth performance at this salinity level. It is thus inferred that orange mud crab individuals might require 3–5 days for acclimation to salinity stress but it can take at least 30 days for acclimation to regular growth. Results indicate that with proper acclimation, the orange mud crab (Scylla olivacea) can be farmed at low salinity conditions and possibly in freshwater condition.     

Induced out-of-season spawning of the mud crab, Scylla paramamosain (Estampador) and effects of temperature on embryo development

Treated with combined bilateral eyestalk ablation and maintenance of water temperature at 22.5±1.5 °C, mud crab Scylla paramamosain females with mature ovaries were induced to produce eggs outside the natural spawning season in subtropical southern China. Newly extruded eggs from a crab were incubated in vitro at 10, 15, 20, 25, 27, 30, 35 °C, respectively, and the embryonic development was closely monitored. Abnormal cell division was observed at temperatures 10 and 35 °C. At 15 °C, development remained at the gastrula stage by day 32 post‐spawn, at which time the experiment was terminated. Hatching of in vitro incubated eggs occurred between 20 and 30 °C. An increase in incubation temperature from 20 to 25 °C reduced the incubation duration by 14 days, 2.6 times of that measured for a similar 5 °C increase from 25 to 30 °C. Embryonic development of S. paramamosain was divided into stage 0–10, and the duration of each stage was recorded for each incubation temperature. The information obtained allows accurate prediction of hatching time of female crabs incubated under variable temperatures. Larvae hatched from in vitro incubated eggs were reared to reach first juvenile crab stage and their dry weights were similar to those of larvae hatched naturally.     

Stocking density and artificial habitat influence stock structure and yield from intensive nursery systems for mud crabs Scylla serrata (Forsskål 1775)

Intensive nursery systems are designed to culture mud crab postlarvae through a critical phase in preparation for stocking into growout systems. This study investigated the influence of stocking density and provision of artificial habitat on the yield of a cage culture system. For each of three batches of postlarvae, survival, growth and claw loss were assessed after each of three nursery phases ending at crab instars C1/C2, C4/C5 and C7/C8. Survival through the first phase was highly variable among batches with a maximum survival of 80% from megalops to a mean crab instar of 1.5. Stocking density between 625 and 2300 m⁻² did not influence survival or growth in this first phase. Stocking densities tested in phases 2 and 3 were 62.5, 125 and 250 m⁻². At the end of phases 2 and 3, there were five instar stages present, representing a more than 20‐fold size disparity within the populations. Survival became increasingly density‐sensitive following the first phase, with higher densities resulting in significantly lower survival (phase 2: 63% vs. 79%; phase 3: 57% vs. 64%). The addition of artificial habitat in the form of pleated netting significantly improved survival at all densities. The mean instar attained by the end of phase 2 was significantly larger at a lower stocking density and without artificial habitat. No significant effect of density or habitat on harvest size was detected in phase 3. The highest incidence of claw loss was 36% but was reduced by lowering stocking densities and addition of habitat. For intensive commercial production, yield can be significantly increased by addition of a simple net structure but rapidly decreases the longer crablets remain in the nursery.