Range expansion of rotan <Emphasis Type="Italic">Perccottus glenii</Emphasis>, sunbleak <Emphasis Type="Italic">Leucaspius delineatus</Emphasis>, and bleak <Emphasis Type="Italic">Alburnus alburnus</Emphasis> in the Ob River basin

The ranges of three alien fish species (rotan Perccottus glenii, sunbleak Leucaspius delineatus, and bleak Alburnus alburnus) in the Ob River basin, West Siberia, have expanded. Our data prove the expansion of rotan and sunbleak ranges to the north. In particular, for the first time, populations of rotan are reported from the lower section of the Ob. We also present new data about range expansion of the studied fish species southward. All three species have probably reached the southern limits of their possible distribution in the Upper Ob system, entering the potamon/rhithron transition zone, because the species under study prefer lowland waters. The spatio-temporal dynamics of their expansion reveals the role of the Ob River as the main invasion corridor, enhancing their distribution mostly in meridional direction. In the system of the Upper Ob, rotan and sunbleak were found by us in isolated ponds and lakes, as well as in floodplain systems. This is in agreement with the concept of two invasion vectors: the translocation of fish by humans between water bodies and self-distribution along the river courses.     

Distribution of fish in the river system of the Lower Irtysh

We report the results of investigation of fish distribution in water bodies of different types (open floodplain complex, closed lake, floodplain channels, and a riverbed depression) of the river system of the Lower Irtysh obtained by application of differently aimed hydroacoustic complexes and by traditional ichthyological methods. Distribution, composition, and abundance of fish aggregations and their diurnal movements are determined in different water areas. Periodicity, range, and direction of fish migrations, rhythm of downstream migrations of juveniles under various conditions are recorded. Distribution of fish is considered as a continual process controlling the biological integrity of the river system. Significant presence of nomadity (various migrations and local movements) is demonstrated in fish, reflecting multilevel lability of the environment in the floodplain-channel system of the Lower Irtysh. A set of notions is suggested defining application limits of principal terms characterizing fish movements of various scales: migrations, wanderings, and short-term movements.     

Mitochondrial DNA variability in populations and ethnic groups of Tatars of the Tobol-Irtysh basin

The data on mitochondrial DNA diversity in seven local populations (villages) and four territorial groups of Tatars of the Tobol-Irtysh basin are presented. In the Turkic-speaking populations from the Tobol and Irtysh river basins, high levels of intergroup and interpopulation mtDNA variation were observed. It was demonstrated that genetic diversity of the territorial groups of Tatars of the Tobol-Irtysh basin resulted from various interethnic relationships and different ethnic components integrated into these groups.     

新疆阿勒泰地区额尔齐斯河和乌伦古河流域鱼类多样性演变和流域健康评价

为了解阿勒泰地区额尔齐斯河和乌伦古河流域的鱼类多样性现状和历史演变, 本研究于2013-2016年间在该流域的鱼类多样性进行了连续调查, 并结合历史资料和标本, 以Margalef丰富度指数、Shannon-Wiener多样性指数、Pielou均匀度指数分析评估了流域内鱼类的多样性水平和时空变化。该流域历史上分布有土著鱼类23种, 当前记录到19种, 流域内还有外来鱼类15种。阿勒泰鱼类的区系组成以鲤科种类为主, 其中特有和珍稀濒危物种占比高, 具有重要的保护价值。多样性指数计算结果显示, 2013-2016年鱼类多样性情况整体稳定, 额尔齐斯河鱼类物种数多于乌伦古河。研究还基于鱼类生物完整性指数(Fish Index of Biological Integrity, F-IBI)对34个采集点的河流健康状况进行了评价, 结果显示额尔齐斯河流域大多数调查点的健康状况处于“亚健康”或“一般”水平, 乌伦古河流域多数调查点的健康状况处于“健康”水平。水利工程、外来物种、过度捕捞是影响阿勒泰地区鱼类多样性的重要因素。未来应通过水利工程的联合调度、下泄合理生态流量、布设鱼类通道、规范养殖渔业、严控外来物种、本地土著鱼类的人工增殖放流, 以及合理的就地保护措施对阿勒泰地区的鱼类多样性加以保护, 提升水体健康程度。     

The introduced fish, rotan (Perccottus glenii), depresses populations of aquatic animals (macroinvertebrates, amphibians, and a fish)

The fish rotan (Perccottus gleniiDybowski) was accidentally introduced into European Russia from the Amur River basin. Rotan is capable of colonising small waterbodies – favourable breeding sites of native amphibians. To reveal its influence on the native aquatic fauna, monitoring of small waterbodies has been carried out since 1994 in the region of Lake Glubokoe Reserve (Moscow Province, Russia). The fish's diet includes a wide range of animal species of all trophic levels. Rotan considerably decreases the species richness of aquatic macroinvertebrates and larval amphibians. As a rule, most amphibian species (Triturus cristatus, T. vulgaris, Rana temporaria, R. arvalis, R. lessonae) and the fish Carassius carassius failed to breed successfully in ponds inhabited by rotan. In contrast, the toad Bufo bufo bred successfully in such sites because its larvae are distasteful to rotan. Rotan–amphibian interactions are discussed.     

Peculiarities of the biotope distribution of click beetle larvae (Coleoptera, Elateridae) in the Irtysh River valley

The spatial distribution of Elateridae larvae in the Lower Irtysh valley has been analyzed. The larvae analyzed belonged to 19 Elateridae species inhabiting soils of the floodplain and the river terrace. It has been pointed out that the larvae of Paraphotistus nigricornis, Agriotes lineatus, Limonius parallelus, and Aplotarsus incanus are most tolerant to the regular spring flooding. It has been found that the species compositions of floodplains and terrace meadows are significantly different. As a rule, species with a wide tropical spectrum inhabit floodplain soils, including bush and forest habitats. At the same time, the terrace was dominated by species characteristic of open habitats, including the steppe zone. It has been revealed that the values of species diversity vary significantly in the floodplain and terrace plots, but the higher species richness (Menhinick index) was registered in the floodplain.     

Factors influencing the seed source and sink functions of a floodplain nature reserve in the Netherlands

Question: How do species traits and abiotic factors influence the extent of hydrochorous dispersal into and out of a small floodplain area along a free‐flowing river in The Netherlands? Location: The Kappersbult nature reserve (53°07′28″N, 6°37′14″E), which is a floodplain along the Dutch River Drentsche Aa. Methods: Seeds transported by the river were collected in fine mesh nets for 24 consecutive hours once or twice a week for 1 year, upstream and downstream of the studied floodplain. Data on the captured seeds were related to species traits and abiotic factors and species composition in the floodplain. Results: The floodplain functioned both as a seed source and sink. High levels of river water seemed to promote seed transport to or from the floodplain. Seeds of riverbank species occurred significantly more often in the river water than expected. Net source species had significantly higher seed production, taller stature and higher seed buoyancy, but lower site elevation than net sink species. Seed weight was significantly higher for sink species than for other species. Conclusion: Our study found that inundation, and therefore more natural river water management, is a prerequisite for seed transport to and from a floodplain. The restoration of target floodplain vegetation may be successful for common species that produce many seeds and grow in proximity to the river. Consequently, it is expected that the probability of restoring vegetation types that occur further from the river, such as wet grasslands, by hydrochorous dispersal is low.     

Estimation of minimum area requirement of river‐connected lakes for fish diversity conservation in the Yangtze River floodplain

Aim Hydrological disconnection of floodplains from rivers is among the top factors threatening river‐floodplain ecosystems. To keep enough floodplain area is of great importance to biodiversity conservation. In the Yangtze River floodplain, most lakes were disconnected from the mainstream by dams in 1950–1970s. By analysing fish diversity data, we aim at determining the effects of river‐lake disconnection on fish diversity, at estimating the minimum protected area of river‐connected lakes and at proposing a holistic strategy for fish conservation in the mid‐lower reaches of the river. Location The Yangtze River floodplain, China. Methods We collected recorded data of fish diversity of 30 Yangtze floodplain lakes. Species–area relationships were analysed and compared between river‐connected and river‐disconnected lakes. Cumulative species–area models were constructed to estimate the minimum protected area of river‐connected lakes. Results River‐lake disconnection reduced fish diversity of Yangtze lakes by 38.1%, so that the river‐connected lakes play an important role in maintaining the floodplain biodiversity. The minimum protected area of river‐connected lakes was estimated to be 14,400 km². Therefore, we should not only protect the existent connected lakes of 5500 km², but also reconnect disconnected lakes of at least 8900 km² in the Yangtze basin. Main conclusions Species–area relationships are of importance in reserve design. We suggest that cumulative species–area model might be more suitable for ecosystems with high connectivity among regions such as floodplains. As the Yangtze River floodplain is an integrative ecosystem, we suggest establishing a holistic nature reserve in the mid‐lower basin for effective conservation of biodiversity.     

Interactions of the introduced rotan Perccottus glenii Dybowski, 1877 (Osteichthyes, Odontobutidae) with aboriginal fish species: The parasitological aspect

This study was conducted in the water-filled Neverovo sandpit, located in Ruza district of Moscow province. This water body is inhabited by 6 fish species, including the introduced rotan. Twelve species of parasites were recorded in/on the rotan, and most of them circulate using aboriginal fish species. Reliable evidence of the involvement of the rotan in the circulation of a parasite species native to the water body-recipient (Ergasilus sieboldi) was obtained for the first time. Rotan does not play a significant role in the circulation of 11 other parasite species, or, at least, quantity estimations of its role were not yet undertaken.     

Fish in the tributaries of the Novosibirsk reservoir

Data on the species composition of the fish population inhabiting the tributaries of the Novosibirsk reservoir are given in the article. The structure of fish communities and possible environmental factors determining it have been revealed. The relation between the heterogeneity of fish communities and the river depth and length, relief, current velocity, floodplain, and estuarial areas, presence of sand-pebble shallow waters and channel order, has been studied.     

Aquatic carbon fluxes dampen the overall variation of net ecosystem productivity in the Amazon basin: An analysis of the interannual variability in the boundless carbon cycle

The river–floodplain network plays an important role in the carbon (C) cycle of the Amazon basin, as it transports and processes a significant fraction of the C fixed by terrestrial vegetation, most of which evades as CO₂ from rivers and floodplains back to the atmosphere. There is empirical evidence that exceptionally dry or wet years have an impact on the net C balance in the Amazon. While seasonal and interannual variations in hydrology have a direct impact on the amounts of C transferred through the river–floodplain system, it is not known how far the variation of these fluxes affects the overall Amazon C balance. Here, we introduce a new wetland forcing file for the ORCHILEAK model, which improves the representation of floodplain dynamics and allows us to closely reproduce data‐driven estimates of net C exports through the river–floodplain network. Based on this new wetland forcing and two climate forcing datasets, we show that across the Amazon, the percentage of net primary productivity lost to the river–floodplain system is highly variable at the interannual timescale, and wet years fuel aquatic CO₂ evasion. However, at the same time overall net ecosystem productivity (NEP) and C sequestration are highest during wet years, partly due to reduced decomposition rates in water‐logged floodplain soils. It is years with the lowest discharge and floodplain inundation, often associated with El Nino events, that have the lowest NEP and the highest total (terrestrial plus aquatic) CO₂ emissions back to atmosphere. Furthermore, we find that aquatic C fluxes display greater variation than terrestrial C fluxes, and that this variation significantly dampens the interannual variability in NEP of the Amazon basin. These results call for a more integrative view of the C fluxes through the vegetation‐soil‐river‐floodplain continuum, which directly places aquatic C fluxes into the overall C budget of the Amazon basin.     

Consistent trophic patterns among fishes in lagoon and channel habitats of a tropical floodplain river: Evidence from stable isotopes

The relationship between food web dynamics and hydrological connectivity in rivers should be strongly influenced by annual flood pulses that affect primary production dynamics and movement of organic matter and consumer taxa. We sampled basal production sources and fishes from connected lagoons and the main channel of a low-gradient, floodplain river within the Orinoco River Basin in Venezuela. Stable isotope analysis was used to model the contribution of four basal production sources to fishes, and to examine patterns of mean trophic position during the falling-water period of the annual flood cycle. IsoSource, a multi-source mixing model, indicated that proportional contributions from production sources to fish assemblages were similar in lagoons and the main channel. Although distributions differed, the means for trophic positions of fish assemblages as well as individual species were similar between the two habitats. These findings contradict recent food web studies conducted in temperate floodplain rivers that described significant differences in trophic positions of fishes from slackwater and floodplain versus main channel habitats. Low between-habitat trophic variation in this tropical river probably results from an extended annual flood pulse (ca. 5 mo.) that allows mixing of sestonic and allochthonous basal production sources and extensive lateral movements of fishes throughout the riverscape.     

The main radionuclides and dose formation in fish of the Chernobyl NPP exclusion zone

The results of the researches of spices-specificity, accumulation dynamics and distribution of 90Sr, of 137Cs and of transuranic elements in fish of the Chernobyl NPP exclusion zone are analysed. The data of estimations of absorbed doze rate from incorporated radionuclides for pray fish and predatory species are given. For the fish from the lake of the left-bank floodplain of the Pripyat River the increase of 90Sr specific activity is registered which is presumably connected with the dynamics of the physical-chemical forms of the radionuclide in soils and their wash out in water bodies from the catchment basin. Now about 90% of internal dose rate of fish from closed aquatic ecosystems within the Chernobyl NPP exclusion zone is caused by 90Sr incorporation.     

Landscape variables affecting fishery yield in lake systems of the Central Amazon region, Brazil

According to fisheries data, lakes are important systems for fish production in the Amazon basin. However, there is no information about the relationship between landscape variables and fishing yield that allows foresight into potential resource exploitation in this environment. The present study aims to evaluate this relationship with the hypothesis: lakes of different shapes give the same fishery yield in the Amazon, after considering the effects of lake size, distance to the river, fishing effort, fuel and ice used. Fishery data from 1994 to 1996 were analyzed with regard to 3228 trips on 50 lakes of the main white water tributaries of the Amazon basin. Analysis of covariance was applied to test this hypothesis. With variables such as fishing grounds access, fishing effort and lake shape the model explained a significant 72% of variabilities in the fisheries yield. Fishing yields among lake systems were different, thus the null hypothesis was rejected (P < 0.05). Results indicate that dendritic lakes far distant from the main river have greater productivity than floodplain lakes because there are more habitats of fish refuge for reproduction and feed available to the fish; there are also more limitations to access by predators.     

Impact of habitat fragmentation on genetic population structure of roach, Rutilus rutilus, in a riparian ecosystem

During the last 200 years, the riparianecosystem along major rivers has been reducedto a few scattered remnants. Important elementsof the riparian ecosystem are water bodieswhich were originally connected to the mainriver channel by annual floodings. Due to riverregulations many of these remnants are nowvirtually isolated. In an allozyme analysisusing roach, Rutilus rutilus, as a studyspecies we demonstrate that the geneticdiversity (number of alleles per locus,expected heterozygosity) of populations livingwithin floodplain water bodies is not severelyimpoverished compared to the genetic diversitywithin the main river channel. However, wefound slight differences in the allelefrequencies of flood plain water bodies and themain river channel. Nevertheless, fishpopulations in floodplain water bodies mayserve as reservoirs of autochthonous geneticmaterial for restoration of fish populations inthe main river channel after populationextinction due to catastrophic accidents (e.g.industrial pollution).     

Length‐weight relationships of 10 fish species from two tributaries of Indus River Basin in Jammu and Kashmir,India

Length‐weight relationships (LWRs) are described for 10 fish species belonging to three families from the Jhelum and Poonch River, tributaries of the Indus river basin in India. LWRs for these species were unknown to FishBase and new maximum lengths are recorded for three species. These results will be useful for fishery research, management and conservation in these tributaries of Jammu and Kashmir.     

Fish larvae-environment networks: co-occurrence patterns,nestedness and robustness of reproductive guilds

Hydrobiologia - We assessed the importance of different types of riverine environments (river channels, tributaries, and floodplain lagoons) for the early development of fish larvae from different...     

A checklist of parasites of non-native populations of the fish rotan Perccottus glenii (Odontobutidae): Communication II

The fish rotan, Perccottus glenii Dybowski, 1877 (Odontobutidae) is one of the most successful fish invaders during 20th and beginning of 21st century in European and Asian fresh waters. The diversity of its parasites within its invaded range was first reviewed by Sokolov, Reshetnikov, et al. (2014). The current paper analyzes new data from 2013 to 2019 on protistan and metazoan parasites of the non-native populations of this fish. We used information from peer-reviewed journals, difficult to access grey literature and our own recently obtained original data. 45 literature sources were included in the analysis. The newly-available data originate from 95 water bodies of 13 river basins, isolated lakes in West Siberia, and Gulf of Finland, spanning a total of eight countries. A total of 132 recently detected parasite species/taxa are listed in this paper. Each species is presented with its location in/on the host, geographical localities, countries, and according literature sources. When available, number of examined fish as well as prevalence and range of intensity of infection are cited from the original source. This review enlarges contemporary knowledge on parasites of non-native populations of the studied fish species up to 167 species/taxa. We highlight perspectives for further parasitological investigations of this invasive fish.     

Fish larvae, growth and biomass relationships in an Australian arid zone river: links between floodplains and waterholes

1. Floodplain inundation provides many benefits to fish assemblages of floodplain river systems, particularly those with a predictable annual flood pulse that drives yearly peaks in fish production. In arid‐zone rivers, hydrological patterns are highly variable and the influence of irregular floods on fish production and floodplain energy subsidies may be less clear‐cut. To investigate the importance of floodplain inundation to a dryland river fish assemblage, we sampled fish life stages on the floodplain of Cooper Creek, an Australian arid‐zone river. Sampling was focused around Windorah during a major flood in January 2004 and in isolated waterholes in March 2004 following flood drawdown. 2. Of the 12 native species known to occur in this region, 11 were present on the floodplain, and all were represented by at least two of three life‐stages – larvae, juveniles or adult fish. Late stage larvae of six fish species were found on the floodplain. There were site‐specific differences in larval species assemblages, individual species abundances and larval distribution patterns among floodplain sites. 3. Significant growth was evident on the floodplain, particularly by larval and juvenile fish, reflecting the combination of high water temperatures and shallow, food rich habitats provided by the relatively flat floodplain. 4. Low variation in biomass, species richness and presence/absence of juvenile and adult fish across four floodplain sites indicates consistently high fish productivity across an extensive area. 5. Similarities and differences in fish biomass between the floodplain and isolated post‐flood waterholes suggest high rates of biomass transfer (involving the most abundant species) into local waterholes and, potentially, biomass transfer by some species to other waterholes in the catchment during floodplain inundation and after floods recede. 6. The high concentration of fish on this shallow floodplain suggests it could be a key area of high fish production that drives a significant proportion of waterhole productivity in the vicinity. The Windorah floodplain provides favourable conditions necessary for the spawning of some species and juvenile recruitment of the majority of species. It is also appears to be a significant conduit for the movements of fish that underpin high genetic similarity, hence population mixing, of many species throughout the Cooper Creek catchment. The high floodplain fish production in turn provides a significant energy subsidy to waterholes after floodwaters recede. 7. The identification of key sites of high fish production, such as the Windorah floodplain, may be important from a conservation perspective. Key management principles should be: maintenance of the natural flooding regime; identification of the most productive floodplain areas; and maintenance of their connectivity to anastomosing river channels and the remnant aquatic habitats that ultimately sustain this fish assemblage through long‐term dry/drought and flood cycles.