拆坝对河流生态系统的影响及评估方法综述

为研究拆坝对河流生态系统造成的影响,从短期和长期两个时间尺度综合分析了河流水文情势、地形地貌、岸边带植物、鱼类和底栖动物等关键生态因子对拆坝的响应,并总结了目前拆坝对生态系统影响的两种主要评估方法。认为根据实际拆坝情况进行评估和基于数值模型进行预测两种评估方法中,实地观测是最直接、最有说服力的研究方法,但受成本和一些不可控因素限制;数值模拟具有速度快、费用低、无比尺影响等优点,可对拆坝影响进行预测,为管理者提供参考,但精度和准确性有待提高。指出后续研究中应综合考虑拆坝过程中各生态因子间的耦合效应,需对不同拆坝时机和分阶段拆坝方式对河流生态系统的影响进行深入研究。     

Stay with the flow: How macroinvertebrate communities recover during the rewetting phase in Alpine streams affected by an exceptional drought

Droughts are affecting an increasing number of lotic ecosystems worldwide due to the combined effects of climatic and anthropogenic pressures. Unlike naturally intermittent rivers, where the drying phase is a part of the annual flow regime, water scarcity in Alpine rivers represents a relatively recent phenomenon and, therefore, a major threat for the biodiversity of these lotic ecosystems. However, Alpine stream community response to drought is still poorly investigated. Here, we assess the recovery of macroinvertebrates in two Alpine streams after a supraseasonal drought. As water returned, a total of 10 sampling sessions were carried out, and temporal patterns in diversity, density, and taxonomic composition of benthic communities, as well as in the percentage of functional feeding groups, were investigated. We found that the resistance of invertebrate communities in Alpine streams is generally low: drought markedly reduced the diversity and density of macroinvertebrates. Conversely, our results suggest that the passive dispersal by drift from the upstream river sections seems the most probable mechanism promoting the post‐drought recovery. Nevertheless, this resilience ability appears to be stream specific and influenced by intrinsic stream characteristics, including the flow permanence and distance from the nearest upstream perennial reach. This work sheds light on the ecological consequences of droughts on macroinvertebrate communities. As flow intermittency in Alpine areas is expected to intensify under current global change scenarios, results of this study provide important information to predict changes in the taxonomic composition and diversity of macroinvertebrate communities.     

Downstream Ecological Impacts of Controlled Sediment Flushing in an Alpine Valley River: A Case Study

Sediment flushing may be effective to tackle the loss of reservoir storage as a result of siltation. When operationally possible, the impact of this practice on the downstream aquatic environment can be mitigated by limiting the sediment concentration of the discharged waters (controlled sediment flushing). However, this topic is poorly documented, and concerns arise when limits are discussed. We present the results of a 3‐year field investigation concerning the controlled sediment flushing of a small reservoir on the Adda River, the main tributary of Lake Como—Italy. Two limits for suspended solid concentration (SSC) were adopted: 1.5 g L^?1, as average value throughout the whole working day, and 3.0 g L^?1, as alert threshold to adjust the ongoing activity. These constraints were essentially fulfilled in the course of the documented operations. The first year sediment flushing was more significant than the following year: 25 000 tons of fines below 2 mm in diameter were flushed in six non‐consecutive days in summer 2010, while, one year earlier, 75 000 tons were flushed in 16 non‐consecutive days. In the third year of investigation (2011), no sediment evacuation took place. The benthic macroinvertebrate and the fish communities were surveyed a short distance below the reservoir, that is, in the potentially more affected river reach. Clear pieces of evidence of environmental quality degradation were not detected; the adopted strategies can therefore be considered to be appropriate when planning sediment flushing management in comparable contexts. Copyright © 2014 John Wiley & Sons, Ltd.     

Development of Habitat Suitability Criteria and In‐Stream Habitat Assessment for the Benthic Cyanobacteria Phormidium

Global demand for freshwater has led to unprecedented levels of water abstraction from riverine systems. This has resulted in large alterations in natural river flows. The deleterious impacts of reduced flows on fish and macroinvertebrate abundances have been thoroughly investigated; in contrast, there is a limited understanding of the potential for changes in the abundance of nuisance benthic algal/cyanobacterial blooms. In New Zealand, Phormidium sp. blooms are common in numerous rivers during summer low flows. In this study, an in‐stream habitat assessment is used to examine the relationship between Phormidium habitat availability and reducing flows. Over 650 observations of Phormidium mats, from seven sites (Hutt River, lower North Island, New Zealand), were used to construct habitat suitability curves for depth, velocity and substrate. Preference curves were fitted using both the ‘forage ratio’ and ‘quantile regression’ methods. Phormidium growth, observed at all seven sites, increased significantly from upstream (uppermost site, 5.2% mat cover) to downstream (63.5%). The habitat suitability curves revealed Phormidium had a large tolerance to velocity, depth and substrate type. Consequently, decreases in flow had only negligible effects on available Phormidium habitat. During periods of stable flow, Phormidium abundance positively correlated with increased nitrogen concentrations, potentially explaining the large variation in Phormidium cover from upstream to downstream. Quantile regression generated habitat suitability criteria were a more accurate predictor of available Phormidium habitat than the forage ratio criteria. Copyright © 2013 John Wiley & Sons, Ltd.     

玉符河生态修复目标及方案研究

分析济南市玉符河存在的主要生态环境问题,采取样点调查方法,寻找玉符河生态水文规律,提出玉符河生态修复的目标和方案,建议在玉符河生态恢复过程中进行长期的水文与生物监测,注重本底资料的完善与积累,以便为我国河流生态修复提供借鉴。     

A Chamber for Testing the Release of Volatile Substances Secreted by Animals,Especially Mammals,as Exemplified by Substances Released by Rats in Response to Stress

Abstract

The success of the testing of volatile organic compounds emitted by animals is dependent on the creation of appropriate conditions for air sampling subsequently used to assay and identify the compounds. These conditions play a particularly important role in the investigation of pheromones, which are secreted in extremely low concentrations. The authors have not come across any previous work which offers constructional solutions, which would allow avoidance of contamination of the air samples containing volatile substances secreted by animals.

A constructional solution was developed, which provides optimal conditions for their sampling and isolation. Its main advantages are as follows: the exposure chamber (the chamber in which the animal is studied) is filled with synthetic air; the exposure chamber is separated from the atmospheric air with a synthetic air “jacket”; the exposure chamber has been constructed using materials which do not release chemicals and absorb them in trace quantities.     

水产动物自溶研究进展

水产动物资源由于水分含量大、自身酶系非常丰富,极易发生自溶,给其储藏、运输和加工过程带来很大不便,是制约水产加工业快速发展的重要瓶颈。本文重点从自溶影响因素、自溶过程生化变化、自溶机理和自溶技术应用四个方面对水产动物自溶的研究现状进行综述,并对未来的发展趋势和研究方向进行了展望,旨在为水产动物自溶的进一步研究提供理论参考。      

东江河流生态评价及其修复方略

本文通过对大型无脊椎底栖动物状况的调查对东江河流水生态状况进行了分析,并在此基础上提出了生态修复方略。从上游到河口选12个点采集底栖动物样本,发现东江流域底栖动物生物多样性在上游和中游保持在较高水平,而到下游则迅速降低到零。对增江湾、西枝江牛轭湖等处的取样进行分析并探讨改善东江生态的方法。针对不同生态应力提出了3种生态修复方略:1.创造多样性的生物栖息地,开发和形成一系列类似增江湾那样的缓流滞流区,把已经隔离的牛轭湖和江边湖泊湿地重新与江水连通;2.调整大坝运用方式,采取大坝泄放的流量逐渐增加和减少的方式,给生物发出流速增大和降低的信号,使其得以准备和躲避;3.稳定岸坡、控制侵蚀、保护和发育河边植被。     

涡河（安徽段）底栖动物时空分布及河道健康评价

底栖动物类群位于腐食食物链的关键一环,在水生态系统中扮演重要角色,其群落组成可以表征河道的健康状况。根据2016年冬季、2017年夏季两个季度对涡河（安徽段）的两次底栖动物的数据采集,对底栖动物群落的时空分布进行分析,同时采用多样性指数对河道开展分段健康评价。结果表明：涡河流域共发现底栖动物3门17属种,冬季以节肢动物和环节动物为主,夏季各物种相对平均。底栖动物的种类数群随季节变化较为明显,两次采样共发现17个属种,两个季节中种类最多的均为节肢动物。涡河（安徽段）干流底栖动物主要表现出生物多样性低、种类分布不均匀、不同河段差异性大等特点,整体来说尚需加强保护。     

High prevalence of antimicrobial‐resistant Escherichia coli from animals at slaughter: a food safety risk

BACKGROUND: There has been concern about the increase of antimicrobial resistant bacteria and protection of animal and public health, along with food safety. In the present study, we evaluate the incidence of antimicrobial resistance among 192 strains of Escherichia coli isolated from faecal samples of healthy food‐producing animals at slaughter in Portugal. RESULTS: Ninety‐seven % of the pig isolates, 74% from sheep and 55% from cattle were resistant to one or more antimicrobial agents, with the resistances to ampicillin, streptomycin, tetracycline and trimethoprim–sulfamethoxazole the most common phenotype detected. Genes encoding resistance to antimicrobial agents were detected in most of the resistant isolates. Ninety‐three % of the resistant isolates were included in the A or B1 phylogenetic groups, and the virulence gene fimA (alone or in association with papC or aer genes) was detected in 137 of the resistant isolates. Five isolates from pigs belonging to phylogroup B2 and D were resistant to five different antimicrobial agents. CONCLUSION: Our data shows a high percentage of antibiotic resistance in E. coli isolates from food animals, and raises important questions in the potential impact of antibiotic use in animals and the possible transmission of resistant bacteria to humans through the food chain. © 2012 Society of Chemical Industry