Distinguishing Wild vs. Stocked Lake Trout (Salvelinus namaycush) in Lake Ontario: Evidence from Carbon and Oxygen Stable Isotope Values of Otoliths

We investigated the potential for using carbon and oxygen isotope values of otolith carbonate as a method to distinguish naturally produced (wild) lake trout (Salvelinus namaycush) from hatchery-reared lake trout in Lake Ontario. We determined δ ¹³C_(CaCO3) and δ ¹⁸O_(CaCO3) values of otoliths from juvenile fish taken from two hatcheries, and of otoliths from wild yearlings. Clear differences in isotope values were observed between the three groups. Subsequently we examined otoliths from large marked and unmarked fish captured in the lake, determining isotope values for regions of the otolith corresponding to the first year of life. Marked (i.e., stocked) fish showed isotope ratios similar to one of the hatchery groups, whereas unmarked fish, (wild fish or stocked fish that lost the mark) showed isotope ratios similar either to one of the hatchery groups or to the wild group. We interpret these data to suggest that carbon and oxygen isotope values can be used to determine the origin of lake trout in Lake Ontario, if a catalogue of characteristic isotope values from all candidate years and hatcheries is compiled.     

鄱阳湖控制工程对自然保护区生态环境的影响

鄱阳湖是长江流域的一大淡水湖泊，其水旱灾害相当频繁，长期以来，国家和地方政府十分重视鄱阳湖洪涝灾害的治理研究工作，逐步形成了以鄱阳湖控制工程为代表的治理方案，该控制工程实施后，其水位将常年维持在16．0－18．0m之间，这将直接淹没16．0m以下的然状态下随着枯洪季节在而变化形成的的草滩、沼泽和浅水洼地等独特湿地自然景观，其自然环境将发生变化，使湖泊水域增大，洲滩，湿地大面积减少，从而对国家级鄱阳湖候鸟自然保护区生态环境带来严重不利影响。     

洞庭湖区挖泥船筑堤技术

用挖泥船吹填堵口复堤，具有施工简便、速度快、质量好等优点，此法自９０年代以来在洞庭湖区得到较多应用。施工程序是首先水下冲填，接着分池分边、轮回冲填，最后进行人工填筑、整形结顶，此法１９８４年在汉寿县马家铺堤段试验成功后，进而在许多地方推广。洞庭湖区多数用此法堵口复堤段在１９９８年特大洪水时，在挡水深１０ｍ以上情况下，安全无恙，没有参漏管涌和滑坡险情。用挖泥船吹填筑堤应注意做好泥沙沉淀池的设计和排大     

三峡工程对洞庭湖典型洪水的防洪作用分析

根据三峡工程建成后对荆江和城陵矶地区补偿的调度方式,采用大湖演算模型对1996、1998、1999年洞庭湖区3种不同来水组合的典型洪水进行了分析计算.计算结果表明,三峡工程不同的实时调度方案,其作用相差大,且对于不同的来水组合类型的洪水,不同的调度方式其作用大小不一样,对于历时不长,长江干流洪水与湖南省"四水"恶劣遭遇的湖区洪水,作用较大;对于湖南省"四水"来水为主的典型洪水和长江干流与"四水"长历时复峰恶劣遭遇的湖区洪水其作用较小.     

松嫩平原湖泡湿地浮游植物调查与研究

松嫩平原扎龙、向海国家级自然保护区是我国中温带最完整的湿地生态系统。本文以扎龙、向海、莫莫格、查干泡湿地保护区为例,对湿地浮游植物的种类组成和数量变化进行了详细调查与研究。     

Changes to lake ecosystem structure resulting from fish cage farm emissions

This study demonstrates how a given lake (Lake S. Bullaren, Sweden) would respond to emissions from a fish cage farm. The main questions to be answered are: How would emissions of feed spill and faeces from a fish farm influence the production and biomass of key functional organisms and how long would such changes remain if the fish farm is closed down? The work is based on a comprehensive lake ecosystem model, LakeWeb, which accounts for production, biomass, predation, abiotic/biotic interactions of nine key functional groups of organisms, phytoplankton, bacterioplankton, two types of zooplankton (herbivorous and predatory), two types of fish (prey and predatory), as well as zoobenthos, macrophytes and benthic algae. The LakeWeb model gives seasonal variations (the calculation time is one week). It has been calibrated and critically tested using empirical data and regressions based on data from many lakes. These tests have demonstrated that the model can capture typical functional and structural patterns in lakes very well, lending credibility to the results presented in this study. To the best of the author's knowledge, this is the first time that effects from fish cage farm emissions on lake ecosystem structure have been quantified at the ecosystem scale. To carry out studies such as these in the traditional manner, by extensive field work in one or a few lakes, would be very demanding, in terms of costs, personnel and time. This work has demonstrated that fish farm emissions would cause significant increases in the biomass of wild fish, without corresponding increases in algal volume. Thus, it is concluded that the fish farm emissions influence the lake's secondary production more markedly than primary production. Although this finding might seem to be a paradox, it is related to the fact that wild fish directly consume food spill and faeces from the fish farm, thereby creating a specific foodweb pathway, as described in this study.     

基于WebGIS的洞庭湖湿地资源信息共享系统研究

本文结合开源软件开发了基于WebGIS的洞庭湖湿地资源信息共享系统,使公众、湿地资源管理者和决策人员可以通过Web浏览器访问洞庭湖湿地资源信息,进行湿地空间信息的叠加显示、放大、缩小、漫游、信息查询等操作。     

鄱阳湖渔业资源的利用现状及其应采取的保护措施

本文简要介绍了鄱阳湖渔业资源的现状,分析了渔业资源存在的优势以及目前对其利用的不合理现象,并进一步从渔民思想的“惯性”、保护资源政策的落实情况、资源开发缺乏整体规划等方面分析了不合理利用渔业资源的深层次原因,文章的最后提出了保护鄱阳湖渔业资源的可行性对策。     

环艾比湖农场生态环境建设研究

艾比湖区生态环境极其脆弱，尤其建国以后的大规模开垦，减少了入湖水量，导致湖面萎缩，风沙危害严重，对沿岸团场的生产和生活产生了较大的影响，针对近年来日益严重的生态环境问题，对艾比湖流域自然资源的合理开发和利用，生态环境的防治与保护提出了相应的措施，搞好生态环境建设，对保证该区绿洲农业的可持续发展具有重要意义。     

Macrobenthic fauna in Thale Sap Songkla, a brackish lake in southern Thailand

The macrobenthic fauna in Thale Sap Songkhla was investigated at 2–3 month intervals from October 1991 to October 1993. The abundance of the benthic fauna ranged from 53 to 9529 individuals m^?2. The abundance and species composition were generally higher during the late southwest monsoon (October) than during the mid-northeast monsoon (December). One hundred and twenty-two species belonging to six phyla were found. Three major groups of macrobenthic fauna consisted of 44 species of Polychaeta (36%), 44 species of Crustacea (36%) and 28 species of Mollusca (28%). The other six species (5%) were minor groups belonging mainly to the Nematoda, Oligochaeta, Sipunculida and Pisces (fish larvae). The predominant polychaetes were Diopatra neapolitana and Heteromastus filiformis. Diopatra neapolitana was found only at two stations close to the sea (20–1440 individuals m^?2), while H. filiformis was found at all stations (6-2255 individuals m^?2). Apseudes sp. 1 (Tanaidacea), Apanthura africana (Isopoda), Amphipoda (many species) and Eupogebia sp. (Anomura) were the main groups of Crustacea. The most abundant crustacean was Apseudes sp. 1., with a maximum density of 5726 individuals m^?2. The dendrogram of Jaccard's coefficient shows two clusters of communities. An increase of polychaetes was observed in the second year of the study.