Physiological mechanisms of degradation of fish populations in acidified water bodies

Disturbances in fish that result from water acidification and related factors are analyzed in the context of generalizations based on the results of experimental and field studies. It is shown that low pH, monomeric aluminum, and other metal ions have an adverse effect on physiological processes in fish and are a major cause of their death in acidified lakes and rivers. The vulnerability of fish to low water pH at different stages of their life cycle and mechanisms of delayed mortality are discussed.     

鱼类洄游通道恢复——国外的经验及中国的对策

简要介绍了鱼类洄游和鱼类洄游通道恢复的概念及类型。从法律与政策、资金筹措、恢复方法、恢复效果监测评估、信息交流与公众参与等5个方面介绍了欧盟、美、日、澳大利亚等国在鱼类洄游通道恢复方面积累的先进经验和成功实践,并在此基础上提出了我国鱼类洄游通道恢复应采取的对策：开展鱼类洄游通道恢复的立法和政策制定工作,加强鱼类洄游通道恢复工作的法律保障力度;开展流域阻碍鱼类洄游的障碍物调查和影响评价,制定流域鱼类洄游通道恢复规划;探索建立和完善多元化投入机制;加强鱼类洄游通道恢复研究能力建设,建立科学的技术支撑体系;开展鱼类洄游通道恢复关键技术研究;重视河流鱼类洄游通道恢复效果的监测评估工作;开展信息交流和公众教育,积极营造全社会参与的良好氛围。     

南沙港网箱养殖水域沉积环境质量评价

2007-01至2007-11分4个航次对宁波南沙港网箱养殖区沉积物环境质量状况进行了现场调查,利用MOM—B系统的三个子集参数对沉积环境质量进行了评价。结果表明：子集1得出2007-01的平均分数小于0．5,而-2007—04、2007—07以及2007—11的平均分数均大于0．5;子集2得出4个季节沉积物的pH和氧化还原电位变化范围分别为7．15—8．33和-197．5m～-105my;子集3得出4个航次得到的平均分数介于4和10之间;综合3个子集的结果来看,南沙港网箱养殖区沉积物环境质量状况冬季为2级,春季、夏季和秋季均属于4级严重污染状态。     

异龙湖湖周鱼塘排水污染物排放总量研究

在进行现场调查的基础上,对异龙湖湖周的鱼塘排水水量进行估算,并在鱼塘排水前采集鱼塘水样进行监测分析,确定异龙湖湖周鱼塘的主要污染物浓度,计算异龙湖湖周鱼塘排水污染物排放总量。     

基于鱼类保护目标的太子河环境流量研究

环境流量是流域水资源合理配置的基础.因此,本文借鉴FLOWS法,以太子河重要鱼类为保护目标,构建了流量组分与鱼类生态需求关系模型.同时,结合栖息地指标与流量关系曲线,计算了包含基流、脉冲流、平滩流和漫滩流4种组分在内的太子河环境流量.结果表明：太子河本溪、辽阳、唐马寨河段鱼类保护年基流量分别为2.93×108、3.12×108、2.88×108m3;现状径流总体可以满足年基流量的要求,但水文过程需要通过水库调度以匹配鱼类生态过程.推荐的各河段脉冲流、平滩流和漫滩流的量级、频率、历时、出现时间等水文参数,可以体现环境流量组分与自然径流过程的一致性要求.该研究可为太子河流域水库生态调度提供理论依据.     

Climate variability,water levels,and fish catch in the Upper East Region of Ghana

The aim of the research was to investigate the effects of climate variability on selected water bodies in the Upper East Region of Ghana using time series decomposition and simple linear regression analyses. Data on temperature and rainfall (1960–2015), annual total fish catch (1996–2016), and the recorded water levels (1987–2015) of a major reservoir, the Tono, were used. Time series decomposition analyses were performed on the rainfall, temperature, and water level data to identify their trends. While temperature was increasing, rainfall was decreasing and resulted in a decrease in the water level in the Tono Reservoir. The decreasing water level in the reservoir made fish catch easier, which led to overfishing. Out of the other 39 dugouts studied, 8 (21%) were silted. Also, rainfall was decreasing at 4.4% per decade and minimum and maximum temperatures were increasing at 2.5% and 0.03% per decade, respectively. The minimum, maximum, and mean water levels of the Tono Reservoir were 3.7, 8.0, and 4.9 meters (m), respectively. The water level of the Tono Reservoir was decreasing by ?0.08 m per year. It is concluded that the water level in the Tono Reservoir was continually decreasing as a result of decreasing rainfall and increasing maximum and minimum temperatures. To maintain a much more stable microclimate and decrease the siltation rate of the reservoirs, farmers are advised to stop farming along the banks of water bodies and avoid clearing vegetation. Fishermen are also encouraged to adopt fish farming in enclosed areas within the reservoir to meet the growing protein demands in the Upper East Region of Ghana.     

Seasonal and Flood‐Induced Variations in Groundwater–Surface Water Exchange in a Northern Coldwater Fishery

Groundwater upwelling is important to coldwater fisheries survival. This study used stable isotopes to identify upwelling zones within a watershed, then combined isotope analyses with reach‐scale monitoring to measure surface water–groundwater exchange over time. Research focused on Amity Creek, Minnesota, a basin that exemplifies conditions limiting coldwater species survival along Lake Superior's North Shore where shallow bedrock limits groundwater capacity, lowering baseflows and increasing temperatures. Groundwater‐fed reaches were identified through synoptic isotope sampling, with results highlighting the importance of isolated shallow surficial aquifers (glacially derived sands and gravels) for providing cold baseflow waters. In an alluvial reach, monitoring well results show groundwater was stored in two reservoirs: one that reacts quickly to changes in stream levels, and one that remained isotopically isolated under most flow conditions, but which helps sustain summer baseflows for weeks to months. A 500‐year flood demonstrated the capacity of high‐flow events to alter surface water–groundwater connectivity. The previously isolated reservoir was exchanged or mixed during the flood pulse, while incision lowered the water table for years. The results here provide insight for streams that lack substantial groundwater inputs yet maintain coldwater species at risk in a warming climate and an approach for managers seeking to protect cold baseflow sources.     

长江江苏段鱼类种类组成和优势种研究

根据2001~2005年对长江江苏段鱼类的调查与监测,结合鱼类学研究的最新观点,对长江江苏段鱼类历史资料进行整理和归并,结果长江江苏段共记录鱼类161种（19目42科）。本次调查采集到鱼类15目31科108种,其中2个新种,2个省新记录,种类组成以鲤科鱼类为主。根据相对重要性指标（IRI）计算,江苏全江段的优势种分别为鳖hemiculter leucisculus、鲫Carassius auratus auratus (Linnaeus)、鳊Parabramis pekinensis (Basilewsky)、鲤Cyprinus capio Linnaeus、刀鲚Coilia nasusSchlegel、贝氏Hemiculter bleekeriWarpachowsky、似鳊Pseudobrama simony (Bleeker)、香斜棘鱼衔Callionymus olidus Günther、鲢Hypophthalmichthys molitrix (Valenciennes)、草鱼Ctenopharyngodon idellus (Valenciennes);优势种平均体重为0.974~292.431 g。江段鱼类小型化、低龄化仍十分严重。     

Streamside Forest Buffer Width Needed to Protect Stream Water Quality,Habitat, and Organisms: A Literature Review

This literature review addresses how wide a streamside forest buffer needs to be to protect water quality, habitat, and biota for small streams (≤~100 km² or ~5th order watershed) with a focus on eight functions: (1) subsurface nitrate removal varied inversely with subsurface water flux and for sites with water flux >50 l/m/day (~40% avg base flow to Chesapeake Bay) median removal efficiency was 55% (26‐64%) for buffers <40 m wide and 89% (27‐99%) for buffers >40 m wide; (2) sediment trapping was ~65 and ~85% for a 10‐ and 30‐m buffer, respectively, based on streamside field or experimentally loaded sites; (3) stream channel width was significantly wider when bordered by ~25‐m buffer (relative to no forest) with no additional widening for buffers ≥25 m; (4) channel meandering and bank erosion were lower in forest but more studies are needed to determine the effect of buffer width; (5) temperature remained within 2°C of levels in a fully forested watershed with a buffer ≥20 m but full protection against thermal change requires buffers ≥30 m; (6) large woody debris (LWD) has been poorly studied but we infer a buffer width equal to the height of mature streamside trees (~30 m) can provide natural input levels; (7, 8) macroinvertebrate and fish communities, and their instream habitat, remain near a natural or semi‐natural state when buffered by ≥30 m of forest. Overall, buffers ≥30 m wide are needed to protect the physical, chemical, and biological integrity of small streams.     

Spatial and Temporal Patterns of Endocrine Active Chemicals in Small Streams Indicate Differential Exposure to Aquatic Organisms

Alkylphenolic chemicals (APCs) and hormones were measured six times from February through October 2007 in three Minnesota streams receiving wastewater to identify spatial and temporal patterns in concentrations and in estrogen equivalency. Fish were collected once during the study to evaluate endpoints indicative of endocrine disruption. The most commonly detected APCs were 4‐tert‐octylphenol and 4‐nonylphenol and the most commonly detected hormones were estrone and androstenedione. Chemical concentrations were greatest for nonylphenol ethoxycarboxylates (NPECs) (5,000‐140,000 ng/l), followed by 4‐nonlylphenol and 4‐nonylphenolethoxylates (50‐880 ng/l), 4‐tert‐octylphenol and 4‐tert‐octylphenolethoxylates with concentrations as great as 130 ng/l, and hormones (0.1‐54 ng/l). Patterns in chemicals and estrogen equivalency indicated that wastewater effluent is a pathway of APCs and hormones to downstream locations in this study. However, upstream contributions can be equally or more important indicating alternative sources. This study indicates that aquatic organisms experience both spatially and temporally variable exposures in the number of compounds, total concentrations, and estrogenicity. This variability was evident in fish collected from the three rivers as no clear upstream to downstream pattern of endocrine disruption endpoints emerged.