Trends of interpopulation variation in meristic characters of seismosensory canals on the head of roach, <Emphasis Type="Italic">Rutilus rutilus</Emphasis> (L.), in anthropogenically polluted environments

Patterns in the quantitative manifestation of meristic characters of seismosensory canals on the head of roach have been studied in fish from populations inhabiting ten river and pond water areas of the Udmurt Republic exposed to different kinds and levels of anthropogenic pollution. Trends of interpopulation variation in the average numbers of pores in some seismosensory canals have been revealed, and their statistical relationship with the level of pollution has been evaluated.     

Fish Communities of Small Ponds in the Udmurt Republic: Structural Features and Trends in Anthropogenic Successions

The ichthyofauna of 20 small ponds in the Udmurt Republic was studied to estimate the dependence of fish species abundance on pond size and anthropogenic load, as well as trends in the succession of dominant species complexes in ponds exposed to the prevailing impact of agricultural activity. Changes in the ecological structure of fish communities in small ponds upon an increase in the anthropogenic load were analyzed. Some specific features of the species composition of ichthyofauna in technogenic pond biocenoses were revealed.     

Contamination of fish by organochlorine pesticide residues in the Ouémé River catchment in the Republic of Bénin

In the Republic of Bénin, aquatic ecosystems are subject to poisoning risks due to the inappropriate use of pesticides, such as washing of empty bottles in rivers and using pesticides to catch fish. In some areas, cotton fields are located near riverbanks, increasing the probability of pesticide emission to the river. To assess contamination levels in the Ouémé River catchment area, different fish species were collected from different geographical areas along the river. DDT, its metabolites and isomers were the most frequently identified pesticides in fish flesh, alpha-endosulfan, beta-endosulfan, dieldrin, telodrin, lindane and octachlorostyrene were also detected. Concentrations of pesticide residues in fish ranged from 0 to 1364 ng/g lipid. A preliminary risk assessment indicated that the daily intake of chlorinated pesticides by people consuming fish from the Ouémé River still is rather low and does not present an immediate risk.     

Activity of Beavers as an Ecological Factor Affecting the Zooplankton of Small Rivers

The role of beavers in the transformation of small rivers is elucidated by analyzing the taxonomic and trophic structure of zooplankton in ponds differing in age, water flow rate, and the degree of overgrowing with higher aquatic plants. The building activity of beavers in the river system promotes the formation of biotopes of the ecotone type, in which the planktonic invertebrate community develops some features similar to or different from those of zooplanktonic communities from lakes and rivers undergoing anthropogenic eutrophication. The main distinctive feature of response to this activity in zooplankton is that its development reaches a plateau at the early and middle stages of succession, compared to that under conditions of anthropogenic eutrophication. For small rivers, the concept of zoogenic eutrophication (in addition to anthropogenic) is proposed.     

Effect of three georges reservoir (Yangzi River) on the plant species richness in drawdown zone downstream the tributary river (Pengxihe River)

In order to understand the spatial pattern of plant community and the maintenance mechanism of biodiversity in littoral zone of Three Gorges Reservoir, 110 km stretches of Pengxihe River (from estuary to the backwater of Three Gorges) were chose to study. We investigated species composition and environmental variables along 50 m long stretches of riverbank between the high-water level and the lowest summer water level, at a 5 km interval. The results showed that: (1) along longitudinal gradients, longitudinal species richness, longitudinal shrub species richness and longitudinal herb species richness were significantly related to distance to estuary; (2) along lateral gradient, there were visible different changes in all kinds of types (lateral species richness, lateral tree species richness, lateral shrub species richness, lateral herb species richness). Along lateral gradient, species richness and herb species richness first increased with the elevation then reduced with it, trees and shrubs species richness increased with the elevation. (3) Correlation analyses showed that substrate types were correlated with the longitudinal species richness, without considering the distance to estuary. Soil moisture and substrate heterogeneity were correlated with lateral, species richness. These results indicated that, along longitudinal gradient of the river, distance to estuary plays an important role in species richness, and along lateral gradient spatial heterogeneity due to inundation and flooding plays an important role in forming a new pattern of plant community in the littoral zone of Three Gorges Reservoir Region. Because of special hydrological dynamics, plant in the littoral zone of Three Gorges, are gradually form a unique spatial pattern to some extent, though it had the same change law with riparian plant of a natural river.     

Macrozoobenthos as an indicator of the ecological state of mountain watercourses

Structural characteristics of benthic macroinvertebrate communities in mountain watercourses of different sizes have been studied in the Upper Ob basin. It has been found that species richness, diversity of zoobenthos, and most biotic indices in the background areas increase in the series from the smallest watercourses to large rivers. On the contrary, the values of the above parameters in areas polluted with mercury has proved to decrease, thereby indicating a significant transformation of the benthic communities. Approaches are proposed to select reference indices for assessing the ecological state of watercourses in the basin with regard to the size of the river, the structure of benthic communities, and variability of biotic indices along the background cross sections.     

Trophic structure of invertebrate communities in ecosystems of salmon rivers in the southern Far East

The formation of trophic structure has been studied in communities of amphibiotic insects (mayflies, stoneflies, caddis flies, and dipterans) and gammarids accounting for 90% of the total benthos biomass. The results show that the trophic groups prevailing by biomass in the metarithral subzone of small rivers are as follows: filtering collectors in rivers of the moderately cold-water type, collectors and scrapers in rivers of the cold-water type, and scraping predators and scrapers in rivers of the moderately warm-water type. Predators, scraping predators, and scrapers show seasonal changes in abundance and biomass. In the rithron of Far Eastern rivers, the abundance of predators regularly decreases in a south-north direction. The change of dominant groups along the longitudinal profile of the river is related to its zones and subzones. In the trophic structure of rivers exposed to anthropogenic impact, the number of trophic groups decreases and the remaining groups undergo changes in their qualitative composition and the ratio of their individual members.     

Specific features of immune status and lipid metabolism in bream, Abramis brama L. from the Kuban River

Antimicrobial properties of blood serum and contents of immune complexes, total lipids, and lipid peroxidation products have been analyzed in bream from segments of the Kuban River with different levels of anthropogenic pollution. The results show that the test parameters vary depending on the river segment inhabited by the fish.     

Faunal diversity and dynamics of species richness and dominance of parasite communities in age series of the perch (<Emphasis Type="Italic">Perca fluviatilis</Emphasis>)

Changes in parameters of species richness and dominance in parasite communities of perch have been analyzed in the age series of hosts from two water bodies, Lake Gusinoe and Chivyrkui Bay (Lake Baikal), at the levels of a host individual (infracommunity) and a host age group (set of infracommunities). The species richness of parasite infracommunities has been found to increase in both age series due to decreasing proportions of fish affected by no more than three to four parasite species and increasing proportion of fish parasitized by more than four to five species.     

巢湖流域河流鱼类群落的时空分布

基于2013年4月和10月对巢湖流域66个河道样点的调查数据,初步研究了巢湖流域河流鱼类群落的时空变化特征。主要研究结果显示,鱼类多样性无显著性的水系间、生态分区间的变化,但随季节和河流级别显著变化:10月份的个体数显著高于4月份,2级河流的物种数和个体数均显著大于1级、3级和4级河流。鱼类群落结构的季节动态显著,随生态分区显著变化,但不受水系、河流级别的显著影响。在二级生态分区水平上,仅西南森林生态亚区的鱼类群落结构与其他5个生态亚区的显著差异;宽鳍鱲、吻虾虎鱼等在西南森林生态亚区具有更高多度,而鲫、鰐、鲤等物种在其他生态亚区多度更高。     

Changes in the structure of ichthyofauna in water bodies of Kaluga oblast over the past few decades

The structure of the ichthyofauna in water bodies of Kaluga oblast has undergone significant rearrangements over the past 20 years. The abundance of some species has increased, while that of other species has decreased; spontaneous dispersal of some fishes is underway. Synchronous fluctuations of fish abundance (“waves of life”) take place simultaneously in the Western Dvina, Dnieper, and Volga basins. These processes differ in intensity depending on fish species and are conditioned by a number of factors, including changes in hydrological regimes of rivers, improvement of the ecological state of small rivers, and increased poaching pressure. The results of monitoring the ichthyofauna fauna of small rivers are used as an example to trace the routes of fish dispersal and discuss changes in the composition of fish communities.     

长湖鱼类群落结构的时空变化

为系统阐明长湖鱼类群落结构特征,2014年3~11月对长湖鱼类群落结构的空间差异和季节动态进行了较为全面的调查。结果表明,长湖共调查到鱼类43种,隶属于7目14科37属,主要为湖泊定居型鱼类;大湖区和海子湖区鱼类优势种组成虽存在一定的差异,但鲫、鰐、鲤和达氏鲌为两个湖区的共同优势种;长湖鱼类群落的Margalef丰富度指数、Shannon-Wiener多样性指数和Pielou均匀度指数分别为0.53~2.30、0.52~2.02和0.24~0.66,除丰富度指数外,均表现为5月或8月相对较高;聚类和MDS排序分析结果表明长湖鱼类群落分为两大类群,呈现显著的时空异质性;ABC曲线显示长湖优势鱼类以小型鱼类或大型鱼类的幼体为主,且已受到不同程度的干扰。针对长湖鱼类资源已出现衰退,建议在拆除围网/拦网养殖、取缔有害渔具的同时,考虑增殖放流、栽种水生植物等措施来达到长湖鱼类资源保护和可持续利用的目的。     

岷江下游干流段鱼类资源现状及其多样性分析

2014~2016年在岷江下游干流开展了4次鱼类资源调查，共采集到鱼类71种（亚种），隶属于3目11科51属，其中包括长江上游特有鱼类16种。不同调查江段鱼类组成相似性指数分析结果显示，宜宾和乐山江段相似性指数最低，70%；宜宾和屏山江段相似性指数最高，9219%。岷江下游干流江段主要经济鱼类为鲤（Cyprinus carpio）、光泽黄颡鱼（Pelteobaggrus nitidus）和瓦氏黄颡鱼（Pelteobagrus vachelli），在岷江下游整个江段渔获物中各占1610%、1396%和1232%。对调查到的71种鱼类产卵类型进行分析结果显示，产粘性卵鱼类和漂流性卵鱼类分别占渔获物总重量的6828%和2707%。不同调查时间和不同江段多样性指数存在差异，其中5~7月份调查到的鱼类多样性指数高于10~12月份调查结果；乐山和犍为江段间鱼类均匀度Pielou指数存在显著差异（P<005）。从调查结果看，岷江下游干流段鱼类种类丰富，渔获物数量较高，但受岷江下游梯级开发的影响，资源前景不容乐观，需加强保护措施。     

Cladocerans under conditions of small river damming by man and beavers

In beaver ponds, the species diversity, abundance, biomass, and production of cladocerans and the amount of food consumed by them have increased and the composition of dominant species has changed as compared to those in the stretches of small rivers with running water or dammed by man. The stimulating effect of water from a beaver pond has been confirmed in laboratory experiments. The average number of juvenile Ceriodaphnia affinis produced by one female was considerably greater in this water than in the water from flowing and dammed (by man) river stretches.     

Distribution and sources of (129)I in rivers of the Baltic region

The concentration of (129)I was measured in 54 river waters discharging into the Baltic Sea from Sweden, Finland, Estonia, Latvia, Lithuania, Poland and Germany. Sample collection was performed during a well-bracketed time interval (June-July 1999), thus allowing comparison of the rivers over a wide latitude range without the effect of long temporal spread. Although there is no direct input of anthropogenic (129)I in the watersheds, the concentration of the isotope is about two to three orders of magnitude higher than the expected pre-nuclear era natural values in the rivers of Finland and northern Sweden, and in the rivers of southern Sweden, Lithuania, Estonia, Latvia, Poland and Germany; the (129)I concentration may reach five orders of magnitude higher. Furthermore, there are significant correlations between the (129)I concentration and latitude and/or distance from the North Sea and between (129)I and Cl. These findings suggest seawater as a main source of (129)I to the rivers through atmospheric transport. Of the many chemical parameters investigated, the pH may account for some of the variability in (129)I concentrations of the rivers. The contribution from nuclear weapon tests and the Chernobyl accident to the riverine (129)I is insignificant compared to the releases from the nuclear fuel reprocessing facilities. The total flux of (129)I by rivers to the Baltic Sea and related basins represents minor amounts of the isotope pool in these marine waters. External radioactivity hazards from (129)I are considered to be negligible in the Baltic region. However, as the main (129)I intake to the human body is likely through water, due to the large amount of daily water consumption, more concern should be given to internal radioactivity hazard that may be associated with the isotope's localized elevated concentration in the human organs.     

三峡库区重要支流鱼类多样性初探

为了解三峡库区重要支流鱼类多样性情况，于2015年和2016年对三峡库区36条支流各进行了一次调查。长度〖JP〗小于50 km的河流设置4个调查断面，长度为50～100 km的河流设置6个调查断面、长度为100～300 km和超过1 000 km的河流均设置8个调查断面。共统计渔获物685.5 ，测量鱼类标本 35 507 尾，鉴定鱼类121种，分属于9目22科78属，种类组成以鲤形目及鲤科为主，其中中国特有种68种，长江上游特有种26种，外来物种9种。小江渔获物种类、中国特有种和长江上游特有种都最多，其次为綦江。研究表明：该区域鱼类以产粘性卵和底栖为主，食性以肉食性和杂食性为主；按照河流的长度分为4组，长度超过 1 000 km 的河流与另外3个河流长度组的平均分类差异指数（Δ+）有显著性差异（P<0.05），各河流长度组分类差异变异指数（Λ+）无显著性差异（P>0.05），Δ+和Λ+与河流长度无显著性相关性（P>0.05）；库区支流主要经济鱼类是鲤（Cyprinus carpio）、鲫（Carassius auratus）和光泽拟鲿（Pseudobagrus nitidus）。建议严防引进种逃逸，加大对珍稀特有鱼类的基础生物学研究，特别是人工繁殖工作，将对支流鱼类多样性保护发挥重要作用。     

An evaluation of a river health using the index of biological integrity along with relations to chemical and habitat conditions

We evaluated the health condition of a temperate river during June-November 1999 through applications of the index of biological integrity (IBI) using fish assemblages and qualitative habitat evaluation index (QHEI) as well as chemical analyses. Overall IBI values ranged from 13 to 37 and averaged 23 (n = 25, standard error = 1.16), indicating a "poor" or "very poor" condition according to the criteria of modified Karr [Fisheries 6 (1981) 21]. The values of mean IBI declined at a rate of 0.22 km(-1) (R2 = 0.91, p < 0.05) along the longitudinal distance from the headwaters to the downstream sites. Reduced IBI values at downstream sites reflected low forest cover, high population density and high nutrient enrichments. Ecotoxicity tests using the river water also showed that toxic impacts were evident in the downriver sites. These factors resulted in decreases of riffle benthic species and insectivores and increases of tolerant species, anormalies and exotic species in the river. Spatial pattern in IBI agreed with QHEI values, which showed a linear relation (R2 = 0.998, p < 0.001) with species richness. Field measurements of conductivity and pH, an indicators for variation of conservative ions, showed that the river water was diluted by 40% fold by summer monsoon rain and surface run-off from the watershed, resulting in a physical and chemical instability during the monsoon. For these reasons, average IBI values during the monsoon and postmonsoon decreased >20% compared to the premonsoon, indicating that IBI values were also affected by flow regime. Based on the overall physico-chemical data and IBI values, the river health is rapidly degrading due to the combined effect of chemical contaminations and habitat modifications.     

Caddis flies (Trichoptera) in the benthos and food of fish from streams of the Pechora-Ilych State Biosphere Reserve, the northern Urals

Data on the numbers and biomass of caddis fly species (Trichoptera) in the benthos and in the diets of fish from streams of the Pechora-Ilych State Reserve (the northern Urals) are provided. In the diets of grayling and juvenile Atlantic salmon caught in the rivers of the reserve, 17 and 10 species of caddis flies have been identified. As a rule, one to three species (in most cases, two species) prevail in the diet of fish.     

湖南境内澧水鱼类资源现状与多样性研究

作为洞庭湖一级支流,澧水对洞庭湖乃至长江水系鱼类资源的维持或补充有着重要作用。为了了解澧水的鱼类资源现状,于2010年4月~2011年12月,对湖南境内澧水水系鱼类资源进行调查。共采集鉴定鱼类95种（包括1种湖南鱼类新纪录,4种外来种）,隶属于8目19科59属。种类组成以鲤科鱼类为主,占5053%。多样性分析表明,澧水不同江段鱼类群落多样性处于较好或丰富状态,在空间分布上,鱼类物种数按上、中、下游依次增加,多样性指数也呈上升趋势且差异显著（P<005）。相似性及聚类分析表明,澧水鱼类群落可分为3个类群,即：上、中、下游类群;上游与中游类群为中等相似,与下游类群为中等不相似,中游与下游类群相似性总体小于与上游类群相似性。澧水鱼类在洄游、摄食、栖息习性等生态类型上呈现多样化特征。调查江段渔获物组成虽存在差异,但主要以鲤、鲫、翘嘴鲌、蒙古鲌、鲇、黄颡鱼、[XCz1.tif;%85%85,JZ]、银鮈、中华花鳅、子陵吻鰕虎鱼等湖泊定居性或山溪流水性[JP3]鱼类为主,“四大家鱼”等洄游性鱼类所占比例极低,鱼类小型化现象明显,原因分析主要与水工建设和过度捕捞有关。[     

Radionuclides from past uranium mining in rivers of Portugal

During several decades and until a few years ago, uranium mines were exploited in the Centre of Portugal and wastewaters from uranium ore milling facilities were discharged into river basins. To investigate enhancement of radioactivity in freshwater ecosystems, radionuclides of uranium and thorium series were measured in water, sediments, suspended matter, and fish samples from the rivers Vouga, D?o, Távora and Mondego. The results show that these rivers carry sediments with relatively high naturally occurring radioactivity, and display relatively high concentrations of radon dissolved in water, which is typical of a uranium rich region. Riverbed sediments show enhanced concentrations of radionuclides in the mid-section of the Mondego River, a sign of past wastewater discharges from mining and milling works at Urgeiri?a confirmed by the enhanced values of (238)U/(232)Th radionuclide ratios in sediments. Radionuclide concentrations in water, suspended matter and freshwater fish from that section of Mondego are also enhanced in comparison with concentrations measured in other rivers. Based on current radionuclide concentrations in fish, regular consumption of freshwater species by local populations would add 0.032 mSv a(-1) of dose equivalent (1%) to the average background radiation dose. Therefore, it is concluded that current levels of enhanced radioactivity do not pose a significant radiological risk either to aquatic fauna or to freshwater fish consumers.