山东省中小河流生态环境问题及对策研究

山东省中小河流的资源利用及其非生态治理模式等问题已经导致河流生态环境不断恶化,水资源紧缺的现象日益凸显.通过对山东省中小河流当前的生态环境现状进行梳理,阐述山东省中小河流生态环境存在的主要问题,结合国内外目前中小河流的生态治理模式提出相应的对策建议,以期尽快改善山东省中小河流生态环境,更好地建设生态山东.     

天津市河流和水库浮游植物群落与水环境因子关系的研究

为探明天津市河流、水库浮游植物群落结构及其与环境因子的关系,于2009年5月、7月、9月对天津市的5条河流和4个水库进行采样分析。结果表明,天津市河流浮游植物为7门100种,优势种为绿藻、蓝藻;水库为8门81种,优势种为硅藻、蓝藻。环境因子在河流和水库间差异极显著的为透明度、pH、总磷和重碳酸盐碱度(P<0.01)。影响浮游植物群落结构的环境因子,河流依次为:浮游动物丰度、高锰酸盐指数、氨氮、碳酸盐碱度、磷酸盐浓度、总磷;水库依次为:重碳酸盐碱度、钙离子浓度、氨氮、透明度、溶解氧、水深、叶绿素(a、b)、总碱度、总硬度、pH。     

Foraging mode variation in three stream‐dwelling salmonid fishes

Despite long‐standing interest in foraging modes as an important element of animal space use, few studies document and compare individual foraging mode differences among species and ecological conditions in the wild. We observed and compared foraging modes of 61 wild Arctic charr, Salvelinus alpinus, 42 brown trout, Salmo trutta, and 50 Atlantic salmon, Salmo salar, in their first growing season over a range of habitats in 10 Icelandic streams. We found that although stream salmonids typically sit‐and‐wait to ambush prey from short distances, Arctic charr were more mobile during prey search and prior to prey attack than Atlantic salmon, whereas brown trout were intermediate. In all three species, individuals that were mobile during search were more likely to be moving when initiating attacks on prey, although the strength and the slope of this relationship differed among species. Arctic charr also differed from salmon and trout as more mobile individuals travelled longer distances during prey pursuits. Finally, coupled with published data from the literature, salmonid foraging mobility (both during search and prior to attack) clearly decreased from still water habitats (e.g., brook charr), to slow‐running waters (e.g., Arctic charr) to fast‐running waters (e.g., Atlantic salmon). Hence, our study suggests that foraging mode of young salmonids can vary distinctly among related species and furthers our understanding of the behavioural mechanisms shaping the geographical distribution of wild salmonids.     

刈割对江河源区混播草地牧草产量及品质的影响

在江河源区"黑土型"退化草地上用垂穗披碱草Elymus nutans+冷地早熟禾Poa crymophila+中华羊茅Festuca sinensis+碱茅Puccinellia tenuiflora混播建植栽培草地,自生长第2年起连续2年于7月26日-10月6日进行间隔10d的刈割试验。结果表明:2龄草地8月26日刈割牧草鲜草产量最高,为31933kg/hm2,3龄草地8月16日最高,为9520kg/hm2。营养物质的测定表明,8月16日刈割牧草粗蛋白产量最高,2龄为5683kg/hm2,3龄为2189kg/hm2。研究得出8月16-26日是该地区多年生栽培草地的最佳收割时期。     

干旱河谷地区退耕还林调查与生态还林分析

退耕还林工作全面展开已经有4~5年,其执行效果如何?如何及时总结退耕还林中存在的问题和经验进行更好的退耕还林决策呢?利用遥感和地理信息系统技术结合采访调查,及时的、客观反映了退耕还林的执行情况。本文以长江上游生态脆弱区——川藏边缘的横断山区X县为例,应用“3S”技术对退耕还林的成果进行了监测,得出:由于种种原因,该地区退耕还林中可能上报的退耕面积不实,超出实际退耕面积;耕地中很大比例的坡度小于25o的耕地纳入到退耕地中。研究也分析了退耕还林对当地社会、经济等影响,调查和有关研究证实,大面积退耕还林使该地区财政收入大比例较少,农民对国家的补贴依赖性强,一旦停止钱粮补助,农民将失去生活来源,很可能导致毁林复耕。多数农户强烈表达了希望延长粮食补助的愿望,本研究认为经济补偿机制的关键应该放在如何调动农民调整产业结构和发展后续产业的积极性上,否则再长时间的连续补偿也无济于事。对已经大面积退耕的区域,加紧发展后续产业和产业结构调整势在必行,对正在计划退耕的地区,应该将退耕还林作为一个系统工程考虑,退耕还林应该是一个长期的、逐步实施的过程,必须综合各种原则和因素、分清楚轻重缓急,一步步实施,相应的经济补偿机制也需要调整。     

Distribution of economically important fish larvae (Characiformes,Prochilodontidae) in the Central Amazonia,Brazil

The spatio‐temporal patterns of three species of Prochilodontidae larvae that are intensely used as fishery resources in Central Amazonia are analysed. Sampling was conducted during 2011 at four stages of the hydrological cycle (flood, high water, falling and low water phases). Sixteen collecting stations were located in different habitats (mouths of lake channels, “barrancos,” sandbars and the main river channel) along the Solimões and Japurá rivers. A total of 4,322 Prochilodontidae larvae were collected during this investigation, with most captures occurring in the Japurá River (76.3% of larvae), while only 23.7% of the samples were caught in the Solimões River. Most captures occurred during rising water, indicating a strong reproductive seasonality in these three species. Rainfall and water level, along with dissolved oxygen, water temperature and electric conductivity, determined the larvae's spatio‐temporal distribution. These results confirm the importance of várzea areas along white water rivers for the conservation, preservation and maintenance of heavily used fishery resources in the Brazilian Central Amazonia.     

Patterns of diel activity and species richness in young and small fishes of European streams: a review of 20 years of point abundance sampling by electrofishing

Originally developed to assess the relative abundance of ≥1+ fishes in large rivers, point abundance sampling by electrofishing (PASE) was adapted for 0+ fishes in the mid‐1980s. Being both economical and widely applicable, PASE for 0+ fish has become a commonly used sampling approach in Europe, but its use for estimating 0+ fish density and species richness has attracted particular concern because of size and species selectivity. As such, this review is both timely and necessary. It summarizes the development of PASE and evaluates its various applications: studies of 0+ fish community composition, relative abundance and density, species richness (S), population size structure, larval and juvenile growth dynamics, microhabitat use, diel dynamics of species–species and species–microhabitat interactions, and the analysis of data emanating from PASE databases. The use and potential misuse of replicate sampling in estimates of S are examined, with PASE data from various European rivers re‐analysed to assess geographical patterns in 0+ fish S. Comparisons of PASE and other approaches for estimating 0+ fish density and species richness have all demonstrated PASE to be cost‐effective and relatively reliable, but sampling accuracy and precision do decrease as fishes enter the juvenile period of development.     

2-D water quality numerical simulation of the river by using stream tube-FVM

The contamination transplant-diffuse mechanism in shallow river is analysed. FVM is applied to the stream tubes, according to mass conservation principle and established the 2-D finite volume model in the contamination concentration field (CCF). This method is applied to simulate water quality of some section of Yangtze River and Jialing River around Chongqing city, which is simple and effective.     

Effects of heavy metals in river waters in Japan on immobility and mortality of <Emphasis Type="Italic">Daphnia magna</Emphasis> and <Emphasis Type="Italic">Oryzias latipes</Emphasis> larvae

ABSTRACT:   Samples of river waters containing high concentrations of zinc and other heavy metals but low concentrations of other anthropogenic contaminants were collected to investigate the relationship between toxicity of heavy metals and naturally present organic matters or hardness, as well as the effects of heavy metals on aquatic organisms. Acute toxicity tests were conducted for the water samples using Daphnia magna and medaka Oryzias latipes . Almost all the D. magna died in river waters containing high concentrations of zinc, but O. latipes in the same waters were hardly affected. Since the test organisms were not only exposed to zinc but also other heavy metals in the river waters, we examined the toxicity using toxic units composed of zinc, copper, lead, and cadmium. The results of a bioassay with the river waters showed that the mortality of D. magna did not depend solely on the total number of toxic units of heavy metals. The organic matters and the hardness of the river waters could decrease the acute toxicity of zinc and other heavy metals to D. magna .     

Brook trout occupancy in rivers and streams of the Mixedwood Plains Ecozone,Ontario

Brook trout (Salvelinus fontinalis) are an iconic freshwater salmonid native to northeastern North America. They prefer cold, clean rivers and lakes, and have been culturally, socially and economically valued for decades. Overharvest and deforestation associated with European settlement in southern Ontario, Canada led to notable declines in brook trout abundance in rivers and streams by the late 1800s. Today, they are threatened by further habitat degradation, non-native species, and climate change. In this study, we document brook trout occupancy in rivers and streams of the Mixedwood Plains Ecozone in southern Ontario, between 1970–1980 and 2000–2010. We used generalised linear models to determine occupancy variation between the two time periods at five spatial scales spanning multiple watershed levels. We detected a decline in occupancy between time periods for the tertiary (from 23% to 17%) and quaternary (from 35% to 22%) watershed scales. In the Credit River-Sixteen Mile Creek watershed, mean occupancy decreased to a third of past estimate (from 31% to 10%). For a subset of 86 sites with overlapping sampling in both periods no temporal trend was detected, but a post-hoc analysis indicated low statistical power (0.07), which suggested that more intensive sampling would be needed to better quantify brook trout occupancy changes at this scale. The occupancies quantified for the past period in our study may serve as benchmarks for brook trout restoration efforts.