Egg Thiamine Status of Lake Ontario Salmonines 1995–2004 with Emphasis on Lake Trout

Alewives (Alosa pseudoharengus), the major prey fish for Lake Ontario, contain thiaminase. They are associated with development of a thiamine deficiency in salmonines which greatly increases the potential for developing an early mortality syndrome (EMS). To assess the possible effects of thiamine deficiency on salmonine reproduction we measured egg thiamine concentrations for five species of Lake Ontario salmonines. From this we estimated the proportion of families susceptible to EMS based on whether they were below the ED20, the egg thiamine concentration associated with 20% mortality due to EMS. The ED20s were 1.52, 2.63, and 2.99 nmol/g egg for Chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch), respectively. Based on the proportion of fish having egg thiamine concentrations falling below the ED20, the risk of developing EMS in Lake Ontario was highest for lake trout, followed by coho (O. kisutch), and Chinook salmon, with the least risk for rainbow trout (O. mykiss). For lake trout from western Lake Ontario, mean egg thiamine concentration showed significant annual variability during 1994 to 2003, when the proportion of lake trout at risk of developing EMS based on ED20 ranged between 77 and 100%. Variation in the annual mean egg thiamine concentration for western Lake Ontario lake trout was positively related (p < 0.001, r² = 0.94) with indices of annual adult alewife biomass. While suggesting the possible involvement of density-dependent changes in alewives, the changes are small relative to egg thiamine concentrations when alewife are not part of the diet and are of insufficient magnitude to allow for natural reproduction by lake trout.     

Effect of Channel Changes in the St. Clair River During the Present Century

Periodic man-made changes in the outlet of Lake Huron through the St. Clair River date back to the middle of the last century. These artificial channel changes have been well documented during the present century. They consist of dredging for commercial gravel removal in the upper river during 1908–25 and uncompensated navigation improvements for the 7.6-m (25-ft) and 8.2-m (27-ft) projects completed in 1933 and 1962, respectively. The total effect of these changes on the levels of Lakes Michigan and Huron (hydraulically one lake) and on the upper St. Clair River profile was determined with dynamic flow models. The ultimate effect of the above dredging was a permanent lowering of the Lake Michigan-Huron levels 0.27 m (0.89 ft), which represents a tremendous loss of freshwater resource [32 km³ (7.7 mi³)].     

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.     

长江与洞庭湖关系变化初步分析

长江中游枝城至城陵矶河段称工南岸洞程有松滋口、太平口、藕池口和调弦口分流入洞庭湖,洞庭湖又集湘、资、沅、澧四水经湖区调节后于城陵矶汇入长江,形成了复杂的江湖关系。受自然的和人为的因素影响,江湖关系不断地发生调整变化,这直接关系到长江和洞庭湖的演变及其治理,因此,深入分析江湖关系变化的规律及其影响,对研究三峡工程修建后江湖关系调整趋势于江、湖的治理均有重要意义。实测资料分析有松滋口近几十年来,长江与     

Lake management organizations in China

The paper analyses the range of lake management organizations (LMOs) established in China and proposes management recommendations for different lake types and contexts. Based on functions, regional coverage and sectoral focus, nine LMO patterns are identified, ranging from existing agency approaches in which there is no specific lake focus or institutional responsibility to comprehensive and powerful lake basin authorities. LMO development in China faces many challenges, including a preoccupation with organizational form rather than function and objectives, duplication with existing agency functions, and insufficient lake basin management and trans-jurisdictional coordination. We therefore propose that LMOs should be tailored to specific situations and problems, drawing distinctions between plateau, urban, plain, inland and wetland lakes as well as other contexts.     

太湖五里湖生态恢复的理论与实践

在针对太湖五里湖水质严重污染和生态严重退化的情况,从分析浅水湖泊生态恢复的理论入手,提出生态恢复过程中控源减污、生境改善、生态重建、稳态调控的四个关键步骤,评价了西五里湖生态恢复示范工程的效果,计算了示范工程区水生植物覆盖度和生物多样性指数,指出达到景观要求的草型清水稳态湖泊还需要一个漫长的演替过程。     

一种湖泊浮标近距离无线调制解调器设计

从千米级近距离通信具体要求出发,选择低功率甚高频无线电通信模块,设计1200bit/s调制解调器,集成到湖泊水文监测浮标终端机中,完成浮标站到岸站的遥测数据近距离传输,通信协议符合 CCITT-V23标准。应用实践表明通信链路稳定可靠,还可以在水库、入海口和近海进行水文水生态测验推广应用。     

Anaerobic methane oxidation and aerobic methane production in an east African great lake (Lake Kivu)

We investigated CH₄ oxidation in the water column of Lake Kivu, a deep meromictic tropical lake with CH₄-rich anoxic deep waters. Depth profiles of dissolved gases (CH₄ and N₂O) and a diversity of potential electron acceptors for anaerobic CH₄ oxidation (NO₃^?, SO₄^2?, Fe and Mn oxides) were determined during six field campaigns between June 2011 and August 2014. Denitrification measurements based on stable isotope labelling experiments were performed twice. In addition, we quantified aerobic and anaerobic CH₄ oxidation, NO₃^? and SO₄^2? consumption rates, with and without the presence of an inhibitor of SO₄^2?-reducing bacteria activity. Aerobic CH₄ production was also measured in parallel incubations with the addition of an inhibitor of aerobic CH₄ oxidation. The maximum aerobic and anaerobic CH₄ oxidation rates were estimated to be 27?±?2 and 16?±?8?μmol/L/d, respectively. We observed a difference in the relative importance of aerobic and anaerobic CH₄ oxidation during the rainy and the dry season, with a greater role for aerobic oxidation during the dry season. Lower anaerobic CH₄ oxidation rates were measured in presence of molybdate in half of the measurements, suggesting the occurrence of linkage between SO₄^2? reduction and anaerobic CH₄ oxidation. NO₃^? consumption and dissolved Mn production rates were never high enough to sustain the measured anaerobic CH₄ oxidation, reinforcing the idea of a coupling between SO₄^2? reduction and CH₄ oxidation in the anoxic waters of Lake Kivu. Finally, significant rates (up to 0.37?μmol/L/d) of pelagic CH₄ production were also measured in oxygenated waters.     

First genetically verified occurrence of Ligula pavlovskii outside its native range and characteristics of its infection in Neogobius fluviatilis

In this study, we provide the first genetically verified distribution record beyond its native range of Ligula pavlovskii, a high-impact endoparasite of Ponto-Caspian gobies. According to parasitological surveys, ligulosis was detected for the first time in monkey goby individuals collected from Lake Balaton in 2004, 34 years after the first record of monkey goby in the lake. During a Lake Balaton survey in 2018, we detected tapeworms in 44.4% of the sampled monkey gobies. This prevalence is about two to ten times higher than it was reported from within the native range of the fish hosts. The same survey revealed an uneven spatial distribution of the ligulosis in the monkey gobies inhabiting different shoreline sections of the lake. We assume that the occurrence and recent distribution data of this high-impact endoparasite may provide useful information for potential biocontrol measures of invasive Ponto-Caspian gobies in the future.