西北典型内陆湖泊近40年来的演化特点及机制分析

利用40年来的实测数据研究揭示了西北典型内陆湖泊的演化特点及机制。研究表明:赛里木湖气候向暖湿转变,降水逐渐增加,处于湖面稳定扩张阶段;青海湖降水无明显变化,入湖地表径流却逐年减少,湖泊处于持续萎缩阶段;察尔汗盐湖,入湖水量少,湖面蒸发量大,处于干涸、半干涸状态,更容易萎缩。影响湖泊演化的因子主要是气候变化及人类活动。     

Ecological Engineering for Sustainable Food Production and the Restoration of Degraded Watersheds in Tropics of Low pH Soils: Focus on West Africa

Since upland rice under shifting cultivation is common, the mean paddy yield in sub-Sahara Africa (SSA), especially West Africa, has been stagnated at 1.3–1.7 t ha^?1 during the past 30 years of 1970–2000. There exist numerous small inland valley swamps (IVS), of which 10 million ha is capable of being turned into small scale irrigated rice fields, i.e., sawah* by simple and low cost ecological engineering technology with farmer's self-support efforts. The fertility of lowland soils in West Africa was the lowest, particularly available phosphorous status was extremely poor and low pH as well as low exchangeable bases among the three tropics of Asia, Africa and Latin America. However, because of multi-functional mechanisms of soil and water conservation and replenishment of nutrients, sustainable productivity of 1 ha of lowland sawah system can be equivalent more than 10 ha of upland fields. Geological fertilization, nitrogen fixation, neutralization of pH and increase phosphorous availability are the important functions of the sawah system. Sustainable development of sawah systems in IVSs can contribute to increase food production and to restore the degraded watersheds of SSA. *Sawah: The term sawah refers to leveled rice field surrounded by bund with inlet and outlet connecting irrigation and drainage. The term originates from Malayo-Indonesian. The English term, Paddy or Paddi, also originates from the Malayo-Indonesian term, Padi, which means rice plant. The term, Paddy, refers to rice grain with husk in West Africa of SSA. Most of the paddy fields in the Asian countries correspond to the definition of the term sawah. Paddy field is almost equivalent to sawah for Asian scientists. However, the term paddy fields refers to just a rice field including upland rice field in West Africa of SSA. Therefore in order to avoid confusion between the terms rice plant, paddy, and the improved man-made rice growth environment through ecological engineering, the authors propose to use the term sawah.     

甘肃省棉花生产的自然特点和区域划分及发展思路

通过分析甘肃省棉花生产发展、布局演变和植棉区自然、气候特点等,按照"区域划分同一性"原则,以≥10℃活动积温、7月平均气温、无霜期为主要依据,在全国棉花生产一级区划的框架下,将甘肃省棉花生产划分为黄河流域棉区黄土高原亚区、黄河流域棉区特早熟亚区和西北内陆棉区河西走廊亚区3个二级区;中部沿黄灌区特早熟次亚区、陇东特早熟次亚区、河西走廊早熟棉次亚区和河西走廊特早熟次亚区4个3级区。通过分区评述各级区的气候、生产等特点,指出了在该区发展棉花生产的优势、不利条件和自然灾害,提出了棉花产业发展的思路:如合理规划产业布局,优化种植区域与结构;坚持集中连片,突出规模效益;坚持依靠科技创新,突出经济效益;实施产、学、研相结合,育、繁、推一体化的模式;加强人才队伍建设和科技培训;增加和整合支农投入。     

Change in fisheries access arrangements as a result of hydropower development: The case of reservoir fisheries at the Mount Coffee hydropower scheme in Liberia

Hydropower development can result in both environmental and social change. Modification of riparian environments and the creation of storage reservoirs can alter fish assemblages, change access arrangements and create new opportunities within and outside fishing. These opportunities may be perceived differently by different stakeholders, leading to changes in the fishery and, ultimately, with implications for the nature and distribution of benefits from the fishery. Focusing on a trap fishery for freshwater prawn Macrobrachium vollenhovenii (Herklots), this study examines the way access arrangements changed in response to the rehabilitation of the Mount Coffee run-of-river hydropower scheme on the lower reaches of the Saint Paul River in Liberia. Through the use of interviews and limited participant observation, the study explores the responses to change resulting from the rehabilitation, highlighting the way that agency and bargaining power contributed to shaping the formation of a fisher group and the new access arrangements that they have begun to develop.     

The effect of LED lights on trap catches in Finnish inland fisheries

Trap fisheries can provide catches of high quality, and unwanted bycatch can be released with high survival. Light attraction could be an effective way of increasing trap catches, but research results are largely lacking. Experiments to test the effect of LED lights in trap-net fishing were conducted in two Finnish lakes where fishing targeted Eurasian perch Perca fluviatilis L. and roach Rutilus rutilus (L.). LED lights (white, green, red, blue and combinations) were attached inside the traps. The use of LED lights did not increase fish CPUE. Contrary to expectation, Eurasian perch catches were higher in traps without LED lights. Significant variation in CPUEs was observed, but without interaction with light treatments. The LED lights tested in this study do not increase the effectiveness of trap fishery targeting Eurasian perch and roach in Finnish lakes in the ice-free season.     

Effects of different levels of dietary protein on the growth performance,nutrient utilization,digestive enzymes and physiological status of white shrimp,Litopenaeus vannamei juveniles reared in inland saline water

A 60‐day feeding trial was conducted to illustrate the effect of dietary protein levels on the growth and physio‐metabolic responses of juvenile Litopenaeus vannamei reared in inland saline water (ISW). Six isoenergetic (15 MJ/kg) and isolipidic (60 g/kg) diets with graded level of crude protein viz., 240 (T240), 260 (T260), 280 (T280), 300 (T300), 320 (T320) and 340 (T340) g/kg diet were formulated. Significantly higher (p < .05) weight gain (%), specific growth rate, with lower food conversion ratio were found in T320 and T340 groups. The protein utilizing efficiency and whole‐body protein content were significantly higher (p < .05) in the T320 group. Trypsin activity increased with the increasing dietary CP level but amylase activity decreased with the increasing dietary CP level. Transaminase enzymes, haemolymph protein and haemocyanin were elevated in T320 and T340 groups. The lactate dehydrogenase and malate dehydrogenase activities were significantly higher (p < .05) in the T240 group. Shrimp of T240 group had the lowest (p < .05) glycogen and total haemocyte count with highest (p < .05) haemolymph glucose and antioxidant enzymes activities than the other groups. Based on the results, feeding 320 g CP/kg is found to be optimum for supporting maximum growth and health status of L. vannamei reared in ISW at 8 g/L salinity. The finding of the present study will help in developing a low‐cost feed for L. vannamei reared in ISW.     

干旱区滴灌条件下土壤水盐运移规律探析

通过对干旱内陆河灌区田间土壤水、盐及土壤肥力动态监测试验分析,结果表明：在干旱内陆河灌区,棉花全生育期里,灌水前后土壤盐分变化明显,积盐脱盐交替频繁。土壤的肥力对土壤盐分的影响很大。通过对干旱内陆河灌区土壤水盐运移规律的研究和分析,可以为合理灌溉和防止土壤次生盐渍化提供科学依据,为当地农业生产作出指导,具有一定的现实意义。     

干旱内陆河流域水资源管理模式研究

水资源管理是水行政主管部门运用法律、行政、经济、技术等手段对水资源的分配、开发、利用、调度和保护进行管理,以求可持续地满足社会经济发展和改善环境对水的需求的各种活动的总称。通过水资源的有效管理,对提高水资源利用效率,改善区域生态环境,促进区域经济、社会与环境协调与可持续发展具有重要意义。而水资源管理模式是提高水资源动态管理的有效方式,为水资源高效配置和合理利用提供技术支撑。针对内陆河流域水资源供需矛盾突出、水资源配置结构不合理、生态环境仍恶化、用水管理不够完善和管理制度不健全等方面存在问题,分析和探讨了基于"三条红线"、生态环境综合治理、地表水与地下水联合调度和流域水资源集成管理的内陆河流域水资源管理模式。指出在未来应加强流域水资源污染研究,气候变化和人类活动影响下流域水资源研究与流域水资源管理的法律法规和政策体系研究。     

中国北方内陆盐水的浮游植物

1990～1991年在运城、张家口和白城地区盐度为0.57～214g/L的22个内陆水体采集了浮游藻类,共鉴定出100属132种和亚种。能在超盐水体出现的计有60种,种数和多样性指数均与盐度呈显著的负相关。根据出现率和平均密度,下列30种是区系的主要种或较主要种:小颤藻、微小色球藻、细小平裂藻、银灰平裂藻、铜绿微囊藻、针晶蓝纤维藻、大螺旋藻、湖生卵囊藻、普通小球藻、盐藻、衣藻、四角十字藻、扭曲蹄形藻、尖细栅藻、绿球藻、孟氏小环藻、舟形藻、菱形藻、细小桥穹藻、卵圆双眉藻、尖布纹藻、扁圆卵形藻、隐头舟形藻、卵形双菱藻、绿裸藻、卵圆鳞孔藻、矩圆囊裸藻、尖尾蓝隐藻、啮蚀隐藻和光甲藻。文中讨论了内陆盐水浮游植物区系特点、藻类对盐度的耐受性以及种类多样性与盐度、碱度、PH和离子系数之间的关系等问题。     

中国北方内陆盐水水域鱼类的种类和多样性

根据中国北方内陆盐水水域生物资源的调研材料，结合国内已有的报道，试对中国北方内陆盐水水域鱼类种类和分布做初步分析，在已掌握的60多个水域资料中，有鱼生存的21个盐水湖，盐度为1．24－13．00，碱度为3．0－44．5mmol/L,pH8.20-9.45，共见到鱼类74种，隶属8目16科，其中许多是北方区，宁蒙区和华西区鱼类的指示种，也有华东区和华南区的代表种，各湖的鱼类种数在1－27种之间，北方区和宁蒙区各水域鱼类区系的相似系数较高，新疆盐水湖针类种类组成较有特点，作者还讨论了盐度、碱度，pH等生态因子对鱼类的种类和多样性的影响，以及对盐水水域鱼类资源和多样性的保护利用方式。