虾塘沉积物—水界面的营养盐扩散通量及其在养殖季节的变化

以自行设计的方法测定了对虾养殖环境中沉积物-水界面的营养盐扩散通量。结果表明，营养盐自底质向养殖水体的扩散贯穿于整个对虾养殖季节；该扩散通量的最大值出现在养殖后期的有机质污染区，即投铒区；在污染区，养殖后期的扩散通量大大高于养殖前期，但在非污染区却未见其随养殖季节的明显差异；污染区的扩散通量始终高于非污染区，且随养殖时间的推移，该差异逐渐增大。此外，还比较了新、旧虾塘之间的营养盐扩散通量的差异。初步探讨了底质溶出营养盐对对虾养殖环境的影响。     

Growth patterns of reed (Phragmites australis): the development of reed stands in carp ponds

Reed stands exhibit apparent differences of stem diameter, shoot length, density, and invasiveness. In carp ponds, five characteristic growth patterns can be distinguished. These growth patterns are ontogenetic states of a time-dependent stand development. Invasive reeds with short shoots are found in newly occupied habitats. With continuing establishment of the stand, the shoots in the inner regions become taller and fewer, a growth pattern described as central reed. Later, only a few shoots with thick stems remain. Two alternative pathways of stand development exist: steep shore reed and reed tussocks. By mowing, the directional development of reed stands can be turned into a circulation of growth patterns. The growth patterns have implications for the selection of reed stand areas for conservation purposes.     

锯缘青蟹苗池微生态环境影响因素的初步探讨

通过对锯缘青蟹苗池微生态环境和水质环境的全过程检测,探讨了总菌数、弧菌数及弧菌数/总菌数的消长规律,并对苗种培育阶段涉及的各种外源因素及控制苗池微生态环境的相关手段的有效性作了初步的探讨。结果表明:苗池水体中总菌数在Z1~Z2少量添加水不换水阶段,呈相对稳定状态,进入Z3后总菌数逐渐增加,最高达3.5×106cfu/m l;弧菌数在Z1培育阶段出现2×102cfu/m l激增至5×104cfu/m l的峰值,第二峰值出现在Z5阶段,达6×105cfu/m l;弧菌数/总菌数比值在育苗起始时仅为0.4%,之后迅速升至30%~40%,在Z5阶段,由于弧菌数量急剧上升,达到50%的高比值;NH4-N与COD检测值在育苗过程中变动较大,两者与弧菌数/总菌数比值呈正相关关系。现行育苗方式中对苗池微生态环境产生影响的主要因素是苗种培育密度,海水、饵料的处理方式和抗生素;净化功能菌和蛭弧菌应用于育苗水体具有抑制弧菌繁殖的效果。     

“Summer syndrome” in Litopenaeus stylirostris grow out ponds in New Caledonia: Zootechnical and environmental factors

The “Summer Syndrome”, a septicemic vibriosis caused by Vibrio nigripulchritudo, is responsible for one of the two main seasonal mortalities which affect shrimp aquaculture in New Caledonia. It was identified for the first time in December 1997 in an intensive shrimp farm (called farm DF) and has been enzootic ever since. The “Summer syndrome” affects shrimp during warm-season growout. Although the geographic area concerned is limited, it is a potential threat for the industry in that the disease could spread. Analysis of grow out data from 1991 to 2002 in this farm was carried out in order to characterize the disease and the environmental conditions in relation to mortality. Results of farm DF were compared to data from farms not affected by the disease (called farms HC). The “Summer syndrome” occurs during the warm season which is characterized by an increase in water temperature and sunny duration. This disease is characterized by simultaneously highest densities and weakest drying duration between crops in the farms studied. Between 1991 and 2002, the increase of feed input and nitrogen rate in feed has led to a significant increase of the growth rate over the years in farm DF. At the same time, water management has not changed and has induced an increase in environmental waste production. In consequence, an early eutrophication of water is observed, which is concomitant with the beginning of the mortality outbreaks. This could play a role by inducing directly or indirectly a stress for shrimp and/or a growth and/or virulence factors of the pathogen.     

摄食促进剂对对虾生长的影响

IntroductionMeasures to assure that all feed offered to animals in commercial operation is consumed and to reduceformulated feed waste pollution,have been considered as some of the most relevant for lowering productioncosts in aquaculture.Considering the importance of chemical stimulant in development of the crustacean lifecircle,it is logical to assume that by adding attractants to the feed,the animal would rapidly find potentialfeed and ingest it.Additionally,measures involving the incorpora…     

淡水轮虫土池培育技术研究及应用

淡水轮虫是淡水水产动物育苗的优质饵料之一.在总结传统的土池水花鱼苗培育技术的基础上,确立了土池培育淡水轮虫的技术,旨在建立一种高效低耗的淡水轮虫培育技术.结果表明,在水温22 ～ 25℃下利用豆浆对浮游植物和轮虫进行同步培育,投入豆浆后第6天轮虫密度可达高峰期,所培育的轮虫高峰期时密度可达40 ～50个/ml.将培育的轮虫运用于花鱼骨和黄尾密鲴的苗种培育,取得了较好的效果.因此,在土池中进行淡水轮虫培育是可行的.该研究可使传统的淡水鱼苗培育技术更具有科学性和确定性,同时也可为工厂化的水产动物育苗提供优质、适口的生物饵料.     

池塘轮捕轮放高产高效养殖技术

轮捕轮放是提高养鱼产量的重要技术措施.该文介绍了池塘养殖轮捕轮放高产高效养殖技术,包括池塘选择、清塘、配套设备准备、苗种放养、投喂管理、日常管理、病害防治及成鱼收获等,并分析其经济效益.     

一种新型廉价吸附剂对低浓度 氨氮的吸附特征研究

采用旱伞草为试验原料,通过简单的炭化处理工艺制取一种新型廉价的吸附剂。研究了炭化旱伞草在不 同氨氮浓度下吸附时间、投加量、吸附温度、pH、粒径等因素对其去除效果的影响,并采用傅立叶红外光谱分析对该 种吸附剂及吸附氨氮前后官能团的变化进行检测分析。结果表明院吸附剂制取的最佳炭化温度为450益,炭化时间 40 min;最佳工艺条件为吸附时间60 min,吸附剂投加量为1.50 g,吸附温度30益,pH 为6~8,旱伞草粒径为420~841 滋m。傅立叶红外光谱分析结果表明炭化后旱伞草中含有丰富的羟基和氨基,并与水中氨氮发生氧化反应,使氨氮得 到去除。     

Bacterial diversity of tilapia (Oreochromis niloticus) cultured in brackish water in Saudi Arabia

The bacterial flora occurring in brackish pond water, sediment, gills and intestine of healthy tilapia cultured in Saudi Arabia were estimated both quantitatively and qualitatively, and the isolates were identified to genus or species level. Total viable count of bacteria ranged from 1.4±1.5×10³ to 8.6±2.7×10³ cfu ml⁻¹; 1.2±3.1×10⁶ to 7.3±1.1×10⁷ cfu g⁻¹; 8.7±1.9×10⁵ to 2.1±0.9×10⁶ cfu g⁻¹; and 2.8±2.4×10⁷ to 1.0±1.6×10⁸ cfu g⁻¹ in the pond water, sediment, gills and intestine of brackish water tilapia, respectively. In total, 19 bacterial species were identified. The bacteria were predominantly Gram-negative rods (87%). Pond water and sediment bacteria influenced the bacterial composition of gills and intestine of tilapia. In contrast to gill bacteria, more diversification was observed in intestinal bacteria. The predominant (prevalence >10%) bacterial species were Vibrio parahaemolyticus, Vibrio carchariae, Vibrio alginolyticus, Chryseomonas sp., Vibrio vulnificus, and Streptococcus sp. in all the populations with the exception of the sediment population where Streptococcus sp. was replaced by Shewanella putrefaciens. Vibrio spp. (58% of the total isolates) dominated the total bacterial population.     

Evaluation of shrimp polyculture system in Thailand based on stable carbon and nitrogen isotope ratios

ABSTRACT: To quantify the contribution by cocultured animals to waste assimilation in an intensive shrimp farm in Thailand, the food web structures of the macrobenthos in a reservoir pond, a shrimp culture pond and water treatment ponds were examined using the stable C and N isotope ratio technique. Seawater for aquaculture was drawn from a creek, and stored in a reservoir pond, used for farming the banana prawn Fenneropenaeus merguiensis in culture ponds, and then recycled through treatment ponds where the green mussel Perna viridis was cultured to remove organic wastes discharged from the farming. The clam worm Nereididae sp. and the mud creeper Cerithideopsilla cingulata in the culture pond had δ ¹³C values of −21.0‰ and −18.4‰, respectively, suggesting that shrimp feed (mean δ ¹³C = −20.7‰) was the main food source for these species. The δ ¹³C analysis also suggested that sediments (−23.7‰) in the reservoir pond and particulate organic matter (POM) (−24.0‰) and/or sediments (−25.0‰) in the treatment pond supplied carbon for most macrobenthic animals. However, green mussels in the treatment pond had a mean δ ¹³C value of −20.5‰, suggesting that shrimp feed was the main food source for this species.