Water circulation induced by mechanical aerators in a rectangular vessel for shrimp aquaculture

A water streamer was designed for the purpose of enhancing cost-efficient circulation between the water surface and bottom of shrimp aquaculture ponds. We took direct measurements of the water current field induced by the designed aerator in a large rectangular reservoir of dimensions (L)50 × (W)19 × (D)1.3 m³ and compared the results with those of a standard Taiwanese paddle-wheel aerator. Vertical circulation between the surface and the bottom induced by the paddle wheel aerator was less than that by the designed aerator. Furthermore, the paddle-wheel aerator consumed more electric power than the designed aerator. The structures of water current induced by the two aerators are elucidated, and the advantages and disadvantages of the aerators are discussed.Auxiliary employment of the designed aerators may contribute to delivery of high DO water throughout the pond, which is more efficient than a paddle wheel aerator.     

我国内陆水域增殖渔业发展存在的问题

我国内陆水域渔业是我国渔业发展的重要内容,内陆水域增殖渔业经过多年的发展,取得了很大的成绩,但是在发展过程中也表现出多种问题,如增殖品种不合理,不重视遗传多样性的保护。本文对这些问题作具体的分析,同时提出相应的对策。     

福建省内陆捕捞渔具的作业类型及其数量组成分析

本文根据2009年8月至12月福建省捕捞业渔具渔法普查资料,分析整理了福建内陆地区捕捞业渔具渔法现状调查数据.结果表明:福建内陆地区捕捞渔具有刺网类、钓具类、笼壶类、拖网类、张网类、陷阱类、耙刺类、地拉网类、敷网类、掩罩类、抄网类和杂渔具等12个类别、21种作业型式、渔具总数量123204张(个、顶等).按渔具类别划分...     

基于人工神经网络的CHRIS数据内陆水体叶绿素浓度反演研究

利用BP神经网络和CHRIS高光谱数据反演了富营养化非常严重的太湖梅梁湾地区叶绿素A浓度。首先计算了CHRIS模式2的18个波段与叶绿素A浓度的皮尔森相关系数,选择CHRIS的前5个波段和第13波段的反射率值作为神经网络的输入,以野外测量的叶绿素A浓度为神经网络的输出。实验表明,BP神经网络具有很好的非线性拟合能力,叶绿素A浓度的反演精度相对误差仅为22%,明显优于传统的多项式模型,显示BP神经网络与CHRIS高光谱数据结合的方法在内陆水体水质参数反演领域的应用具有相当的优势。     

日本对虾内陆养殖的实验室模拟研究

我们将日本对虾进行实验室桶养作模拟内陆养殖试验。发现日本对虾可以顺利地养殖到体长５－７厘变,然后短人存活率急剧降低,这一现象与我们海边虾塘养殖所得到的结果极为一致,我们称之为“５－７”现象。     

Elemental analysis of otoliths of Japanese anchovy: trial to discriminate between Seto Inland Sea and Pacific stock

The ability to discriminate local stocks of Japanese anchovy Engraulis japonicus was assessed based on data from four elements (K, Na, P, and Sr) using an electron probe micro analyzer (EPMA) and data from three elements (Ba, Mn, and Sr) using inductively coupled plasma mass spectrometry (ICP-MS) from the otoliths of 40 anchovy (23.6–47.0 mm body length). Anchovy were caught at three sites (Aki-nada, Hiuchi-nada, and Osaka Bay) in the Seto Inland Sea, and one site (Kuroshio extension) in the Pacific Ocean in 2002. In order to discriminate different spawning grounds, EPMA data from the core portion (from core to 30 μm in the core-posterior axis) were used. Results showed that it was difficult to discriminate between the Seto Inland Sea and the Pacific anchovy by EPMA data. Conversely, it was possible to discriminate between the Seto Inland Sea and the Pacific anchovy by ICP-MS data from bulk otoliths. Our results showed that Mn contents of otoliths using ICP-MS discriminate between spawning grounds most, and Ba and Sr discriminate less. The difference in elemental compositions in anchovy otoliths between the Seto Inland Sea and the Pacific Ocean might be reflected by cumulative experienced elemental composition of ambient sea water during life history between the Seto Inland Sea and the Pacific anchovy.     

Interannual variability of the ecosystem of the Kii Channel, the Inland Sea of Japan, as influenced by bottom intrusion of cold and nutrient-rich water from the Pacific Ocean, and a recent trend of warming and oligotrophication

Interannual variability of the ecosystem of the Kii Channel, productive shelf water on the Pacific side of south‐western Japan, was analysed based on physicochemical environmental variables and abundance of major zooplankton taxa collected monthly for 12 yr from 1987 to 1999. The Kii Channel experienced both short‐term (i.e. 3–4 yr) cyclical changes and a long‐term (i.e. decadal) environmental trend. The short‐term variability was primarily associated with year‐to‐year differences in intrusion of subsurface, cold nutrient‐rich water along the bottom of the Kii Channel from the Pacific Ocean. When this bottom intrusion was intense, the Kii Channel experienced a cold, new production‐dominated ecosystem. The bottom intrusion, however, has become less intense in recent years, because of the closer proximity of the Kuroshio flow axis to the Kii Channel. Hence, there was a consistent trend towards warming and a regenerated production‐dominated ecosystem. In accordance with such environmental changes, the zooplankton community shifted towards more oceanic conditions; major herbivorous calanoids (i.e. Calanus sinicus, Paracalanus parvus (s.l.), Clausocalanus spp. and Acartia omorii) decreased, while carnivores (i.e. hydromedusae and Sagitta spp.) increased. The amount of total fish catch also decreased, while the catch of subtropical species increased. These findings lead us to conclude that the bottom intrusion from the Pacific Ocean plays a key role in determining the biological production in the Kii Channel.     

地膜植棉喷灌技术研究

根据内陆干旱区的特点，为了充分发挥喷灌节水增产优势，本文提出地膜植棉喷灌技术、干播湿出及栽培配套措施。     

Effects of manganese on juvenile mulloway (Argyrosomus japonicus) cultured in water with varying salinity—Implications for inland mariculture

The effects of 5 mg/L of dissolved manganese on juvenile mulloway at salinities of 5, 15 and 45 ppt were determined by comparing their survival, growth and blood plasma and organ chemistry with those of fish grown at the same salinities without manganese addition. Survival of mulloway at 45 ppt in the presence of 5 mg/L of manganese (73 ± 13%) was significantly lower than all other treatments, which achieved 100% survival. Those fish grown in water without manganese exhibited rapid growth, which was not affected by salinity (SGR = 4.05 ± 0.29%/day). Those fish grown at 5 ppt and 45 ppt in the presence of manganese lost weight over the 2-week trial (SGR − 0.17 ± 0.42 and − 0.44 ± 0.83%/day, respectively), whilst those at 15 ppt gained some weight (SGR 1.70 ± 0.20%/day). Manganese accumulated in the gills, liver and muscle of the fish and significant differences in blood plasma chemistry were observed. Blood plasma sodium and chloride of fish exposed to manganese were significantly elevated in hyperosmotic salinity (45 ppt) and depressed at hyposmotic salinity (5 ppt) compared with unexposed fish at the same salinity; consistent with manganese causing apoptosis or necrosis to chloride cells. We did not, however, observe any gill epithelial damage under light microscopy. Blood plasma potassium was significantly elevated at all salinities in the presence of manganese and liver potassium and glycogen reduced. These findings are consistent with manganese interfering with carbohydrate metabolism.     

基于AHP法对甘肃内陆河流域水资源可持续利用的评价

以甘肃省河西内陆河流域的水资源可持续利用程度为研究对象,选取层次分析法,从水资源状况、水资源开发利用状况、水资源与社会发展协调性、水资源与经济发展协调性、水资源与生态发展协调性5个方面,对河西地区2006～2008年的22个指标进行量化分析及综合评价,基于评价结果,对该地区水资源的可持续利用提出建议。