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1.
- Few conservation studies have examined fish communities in entire drainage basins, especially in developing regions such as Southeast Asia, one of the most diverse biomes globally. The aim of this study was to establish conservation projections for the whole of the Irrawaddy River system, based on fish diversity patterns, human impact, and environmental change.
- The Irrawaddy River is one of the five largest rivers in Southeast Asia. Although it has very high diversity of fish species and species endemism, our understanding of resident fish status remains poor.
- Based on 1,726 field survey and 1,056 database records, 470 fish species and their distribution patterns (i.e. alpha, beta, threatened species, and endemic species diversities) in sub-basins of the Irrawaddy drainage were identified. Canonical correspondence analysis of diversity and environmental patterns indicated that climatic factors had the largest effect on diversity, compatible with the species–energy theory.
- Fish conservation priorities of sub-basins were evaluated based on diversity patterns and human impact. The delta and Manipur basin regions were highlighted as areas of focus for future fish diversity conservation, and the importance of connectivity in the Irrawaddy main stem was demonstrated.
- The results of this study will be valuable for future management of the Irrawaddy basin and as a reference for other river basins when implementing protection strategies for fish diversity. This study also advocates the need for systematic investigations across entire drainage basins and further detailed studies on the ecological conditions of poorly studied river systems.
2.
- River fish diversity is threatened by anthropogenic environmental alteration to landscapes. The early life-history stages of fish play an important role in maintaining diversity and population recruitment and can be heavily influenced by landscape patterns. Information on temporal and spatial distribution patterns of fish eggs and larvae is also important for biodiversity conservation and management of fish resources.
- The Yangtze River possesses a high diversity of fishes, including many commercially important species. The economy along the lower reach of the river is well developed, and most of the area is experiencing high pressure from human impacts. This section of the Yangtze River connects with the largest freshwater lake in China at the upstream end and flows into the estuary at the downstream end. These two landscape features are likely to have a significant impact upon the spatial distributions of fish egg and larval assemblages.
- Environmental variables, fish eggs, and larval assemblages were sampled in three locations, at Hukou, Anqing, and Jingjiang, in the lower reach of the Yangtze River. The results suggest that the higher number of species and greater abundance in upstream sites reflect the critical function of connectivity of Poyang Lake with the river for fish recruitment in the lower Yangtze. The delayed bloom of larval fish, occurrence of estuarine species, and a lower species number and abundance of freshwater fish downstream reflect the influence of tidal intrusion from the estuary.
- This study highlights the value of maintaining natural river–lakes connectivity in the Yangtze River as a conservation measure. The connected river–lake system should be designated as a priority area for fish resource protection in the lower reach of the Yangtze River. We recommend further measures to break down barriers between the river and other lakes and to restore the natural lateral connectivity of the floodplain ecosystem.
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- 1. A basin approximation was used to analyse distribution patterns of different components of biodiversity (taxonomic richness, endemicity, taxonomic singularity, rarity) and conservation status of freshwater fish fauna in 27 Mediterranean Iberian rivers.
- 2. Basin area alone explained more than 80% of variation in native species richness. Larger basins featured not only a higher number of native species, but also more endemic and rare species and fewer diversified genera than smaller basins.
- 3. In contrast, smaller basins scored higher community conservation values, owing to their lower degree of invasion by introduced species.
- 4. The presence of dams was the most important factor determining the conservation status of fish communities, and it was also positively associated with the number of introduced species.
- 5. While the most important components of Iberian freshwater fish biodiversity are located in large basins, small unregulated basins feature better conserved fish communities.
4.
Casey A. Pennock Mark C. McKinstry Charles N. Cathcart Keith B. Gido Travis A. Francis Brian A. Hines Peter D. MacKinnon Skyler C. Hedden Eliza I. Gilbert Christopher A. Cheek David W. Speas Katherine Creighton Darek S. Elverud Benjamin J. Schleicher 《水产资源保护:海洋与淡水生态系统》2020,30(8):1540-1551
- Reservoirs and associated river fragments are novel ecosystems not experienced by fishes in their evolutionary history, yet they are now commonplace across the globe. Understanding how fishes use these novel habitats is vital to conservation efforts in contemporary riverscapes.
- Movement patterns of the endangered razorback sucker (Xyrauchen texanus) synthesized from tagging efforts in the upper Colorado River basin, USA, illustrate the applications of tagging technology and data sharing by multiple agencies to better understand the spatial ecology of large river fishes.
- Tagging studies between 2014 and 2018 in Lake Powell and its two main tributary rivers, the Colorado (unfragmented) and San Juan (waterfall‐fragmented), were used to quantify movement of razorback sucker within this river–reservoir habitat complex. In addition, facilitated translocations of fish upstream of a waterfall barrier in the San Juan River were assessed in 2016–2017.
- Extensive movement of fish occurred within and across river and reservoir habitats. Of 722 fish captured in the Colorado River arm of Lake Powell, 36% of re‐encounters occurred upstream in the Colorado or Green rivers, or fish dispersed through the reservoir and were detected in the San Juan River arm. Fourteen fish moved more than 600 km. In the San Juan arm of the reservoir, 29% and 20% of fish in 2017 and 2018, respectively, had moved ~30–40 km upstream below the waterfall in the San Juan River within a year. In 2016–2017, 303 fish were translocated upstream of the waterfall into the San Juan River, but 80% were re‐encountered downstream of the waterfall within a year.
- Long‐distance movements by razorback sucker were common within and among rivers and reservoirs illustrating how large river fish, in general, might maintain population connectivity in highly altered ecosystems.
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Hui Wei Ratcha Chaichana Lorenzo Vilizzi Punyanuch Daengchana Fei Liu Matura Nimtim Yunjie Zhu Shan Li Yinchang Hu Gordon H. Copp 《水产资源保护:海洋与淡水生态系统》2021,31(8):2041-2057
- Global trade in non-native ornamental species coupled with high connectivity among countries is well known to result in worldwide biological invasions, which pose challenges for the conservation and management of biodiversity.
- There are few studies aimed at implementing management strategies that have examined differences in the potential invasiveness of non-native species between neighbouring political regions within the same ecoregion.
- To compare the potential risk of invasiveness of non-native ornamental fishes with high commercial value in the river basins of two neighbouring regions of East and Southeast Asia, 32 extant and horizon species were screened with the aquatic species invasiveness screening kit (as-isk ) for the lower Pearl River basin (South China) and the Chao Phraya River basin (Thailand). Both regional (i.e. basin level) and combined risk-ranking thresholds were determined by receiver operating characteristic curve analysis.
- Of the 32 species screened, 14 were categorized as posing a high risk and seven were categorized as posing a medium risk of being invasive in both regions, under current and future climate conditions. These species have a history of invasiveness and the climate of their native ranges is similar to that of the two study regions. Pterygoplichthys pardalis received the highest risk score in both regions. The risk ranks of 11 species differed between the two regions, based on either the combined or regional thresholds, and this was partly related to the different risk of invasiveness between the two regions, coupled with cognitive subjectivity among the assessors.
- The results of the present study suggest that the invasion of non-native ornamental fish species could pose similar threats to biodiversity in neighbouring regions. This will serve to inform policy makers of neighbouring countries in the development of coordinated, mutually beneficial regulations and management strategies to enhance the conservation of native species.
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Nicholas T. Simpson Alexander P. Bybel Michael J. Weber Clay L. Pierce Kevin J. Roe 《水产资源保护:海洋与淡水生态系统》2021,31(7):1831-1846
- Many fish species of greatest conservation need (SGCN) in Iowa and Minnesota, USA, have been in decline for decades. A key reason for the decline is the alteration and degradation of naturally flowing streams owing to land use changes resulting from agricultural practices. Populations of several fishes have been adversely affected by widespread stream channelization that has resulted in more homogeneous stream habitats throughout Iowa and Minnesota.
- The goal of this study was to determine the abiotic and fish assemblage characteristics associated with the presence of these rare fishes. Electrofishing and seining were used to sample fish assemblages and 43 abiotic characteristics were measured at 111 sites in the North Raccoon and Boone River basins in central Iowa and the Rock River and Beaver Creek basins in north-west Iowa and south-west Minnesota during 2016 and 2017.
- Six SGCN, including the federally endangered Topeka shiner (Notropis topeka), were included in statistical modelling to determine habitat and fish assemblage characteristics associated with their presence.
- Species-specific nonmetric multidimensional scaling ordinations indicated that abiotic characteristics and fish assemblages often differed between sites where SGCN were present and absent. Random forest and logistic regression models suggested that the presence of four of six SGCN were positively associated with species richness, whereas all other 10 important abiotic and fish assemblage variables were unique to only one or two of the six SGCN.
- Topeka shiners were present at 36% of sites and were positively associated with orangespotted sunfish (Lepomis humilis) catch per unit effort while being negatively associated with canopy cover and fantail darter (Etheostoma flabellare) catch per unit effort.
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Guillain Estivals Fabrice Duponchelle Uwe Rmer Carmen García‐Dvila Etienne Airola Margot Delglise Jean‐Franois Renno 《水产资源保护:海洋与淡水生态系统》2020,30(8):1521-1539
- Assessing biodiversity and understanding how it works is a prerequisite for species conservation. The Amazon basin is one of the main biodiversity hotspots where fish are heavily exploited for ornamental purposes.
- The ornamental trade heavily exploits the genus Apistogramma, which is one of the most species‐rich among Neotropical cichlids with 94 formally described species. This number is certainly underestimated owing to the limitations of conventional taxonomy, which is still too often based solely on morphological criteria and sometimes on few individuals.
- Most species of this genus have a high degree of endemism and are highly prized on the ornamental market, which could put them at risk. A few species are supposed to have extensive distributions, and in particular Apistogramma agassizii, present from the Amazon estuary up to the Ucayali and Marañon rivers in Peru.
- This study assessed the taxonomic status of 1,151 specimens of A. agassizii collected from 35 sites around Iquitos in the Peruvian Amazon. On the basis of molecular analyses (nuclear and mitochondrial DNA) and mate choice experiments, at least three biological species within the nominal A. agassizii were evidenced in the sampling area, which is extremely small compared with the known distribution of the species as initially described.
- According to the molecular calibrations, these three species would have diverged during the Plio‐Pleistocene. Two of them seem to be endemic from small sub‐basins, one from the Nanay River and the other from the Apayacu/Ampiyacu systems. A possible scenario that may explain the evolutionary history of these species is proposed.
- The conservation implications of these results on the estimation of the diversity of A. agassizii, of Apistogramma species in general, and of other Amazonian cichlids are discussed.
9.
Maria R.M. Coimbra Hozana L. Dantas Manuela M.S. Luna Maíra A. Lima Mondrian Sales Bruno C.N.R. da Silva Ana P.S. Lima 《水产资源保护:海洋与淡水生态系统》2020,30(6):1063-1073
- Two migratory and endangered freshwater fish species, Salminus franciscanus and Brycon orthotaenia, are endemic to one of the most important basins for hydropower capacity in South America. These two fish are target species of conservation aquaculture programmes along the São Francisco River system.
- In order to implement effective strategies for the conservation of these species, microsatellite markers were developed and used to assess the genetic diversity and structure among wild groups. Fish were collected during the spawning season at four sampling sites, covering more than 1000 km.
- Polymorphism loci were assessed, and a total of 133 and 107 alleles were found for S. franciscanus and B. orthotaenia, respectively. Despite the critical conservation status, B. orthotaenia showed high levels of genetic diversity, comparable with those of other closely related species.
- Salminus franciscanus exhibited half of the genetic diversity of its sister species in terms of allelic diversity, indicating that this species will be more prone to genetic drift and inbreeding in conservation aquaculture programmes.
- The results of an analysis of molecular variance for microsatellite markers in these species (FST = 0.007 for S. franciscanus and FST = 0.003 for B. orthotaenia) and the estimated recent migration rates (>40% among sampling sites) support panmixia in both species, despite the heterogeneities of the riverscape.
- The results of this study and the microsatellites developed will play an important role in assisting agencies in making informed decisions on conservation aquaculture programmes.
10.
- To understand the ecological factors behind the decline of functionally important threatened species with complex life cycles, many different life‐cycle stages need to be investigated. The highly threatened unionoid freshwater mussels, with their complex life cycle, including a parasitic stage on host fish, often have a large influence on biodiversity and ecosystem functioning.
- The overall aim of the present article is to summarize and discuss the impact of two articles published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) on biotic interactions and adaptation of a threatened unionoid mussel (Margaritifera margaritifera) to its host fish (Salmo trutta).
- The two AQC publications described research on the influence of population size and density of mussels and host fish, and host–parasite interactions between mussels and their host fish, on the recruitment of juvenile mussels.
- The results from these publications filled gaps in knowledge and resulted in recommendations and incentives for conservation. The results and method development have been used in practical conservation work with threatened mussel species and have been implemented and cited in management handbooks. The outcome of the publications has been implemented in large conservation and restoration projects, and in several recent scientific publications.
- Specifically, the results from one publication showed that ecological parameters such as mussel and host fish density and population size influenced recruitment of the threatened freshwater pearl mussel. The results from the second publication showed that understanding host–parasite interactions is important for comparing the suitability of host fish strains, and that host fish strains differ in their suitability for mussel infestations. In combination, the articles show that integrating ecological parameters of threatened mussels and their host fish with host–parasite interaction experiments can be an important influence on conservation recommendations, adaptive management and national management programmes for threatened species.
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- 1. Studies dealing with the fish fauna of coastal streams are scarce in the scientific literature, particularly those from Mediterranean climates. Owing to their small size, these systems suffer extreme seasonal fluctuations, following the typical Mediterranean flood–drought cycle and leading to a high risk of extinction to freshwater fish.
- 2. This work analyses fish distribution in 14 stream stretches belonging to eight basins in the northern sector of the Strait of Gibraltar (southern Spain). Fish–habitat relationships were studied through multivariate ordination techniques at two scales: basin and stretch.
- 3. A principal components analysis clearly discriminated larger and more sinuous basins from smaller and steeper ones. This ordination was related to the non‐migratory freshwater fish species richness and to the total number of fish species present in the middle reaches of each basin.
- 4. The main sources of variation in community composition and habitat characteristics in the different stretches were related to a clear upstream–downstream gradient, along which total species richness increased.
- 5. These small coastal basins are inhabited by two highly endangered species, Andalusian toothcarp (Aphanius baeticus) and Iberian chub (Squalius pyrenaicus), and have similar or higher overall freshwater species richness than larger adjacent basins. The near absences of flow regulation and introduced species make these streams one of the few types of Iberian aquatic system where unaltered fish–habitat relationships can be studied.
13.
- 1. Lake Encantada, in the basin of the Almada River (Bahia State), has an area of 650.5 ha and a perimeter of 13.3 km. In 1993, an area of 11 800 ha around the lake was designated an Environmental Protection Area (Class V category). The main goal of this study was to identify fish species in the lake and to determine possible threats to their conservation.
- 2. Fish samples were obtained with gillnets between May 2002 and February 2004, and used to calculate indices of species diversity Shannon (H′), richness (d) and evenness (J′).
- 3. Eleven fish species comprising nine families were collected during the sampling period. Three introduced species occurred in the lake: Prochilodus argenteus, endemic to the São Francisco river basin, and two African species, Oreochromis niloticus and Clarias gariepinus. In overall ranking, Prochilodus argenteus was first in number of individuals (46%) and weight (59%), followed by Genidens genidens in numbers (31%), and Clarias gariepinus in weight (15%).
- 4. The occurrence and dominance of introduced species is discussed as well as their possible impacts on the trophic structure of this ecosystem.
14.
- 1. Three classes of habitat used by groups of fish species classified as conservation and management priorities were developed for the Gerua River (also known as the Girwa River, Karnali River) in the Ganges river basin. This river is large (mean annual discharge ca 1500 m3 s?1, up to 900 m wide), surrounded by protected lands of India and Nepal, and upstream of major diversions and river alterations.
- 2. Fish and habitat sampling was conducted at 45 sites from 2000 to 2003. Data were analysed for 2172 fish of 14 species. Species and life stages found occupying a statistically distinct subset of the river habitats were grouped to identify classes of river habitat for conservation.
- 3. Most species and life‐stage groups specialized on specific habitat conditions revealed by multivariate analyses of variance and a principal component analysis. The most numerous and diverse group (six species, 15 life stages) was associated with deep depositional habitats with sandy substrate. Two species covering three life stages were primarily oriented to erosional habitat marked by fast current velocity with pebble and cobble substrate. A third group of three species of adults and juveniles were intermediate in habitat use.
- 4. River conservation for fish faunas should maintain both erosional and depositional channel habitats with depths, substrates, and current velocity inclusive of the ranges reported. The erosional and depositional nature of the key habitats requires that rivers be maintained with flows capable of channel‐forming functions.
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Basin‐scale distribution and haplotype partitioning in different genetic lineages of the Neotropical migratory fish Salminus brasiliensis 
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下载免费PDF全文 Eva C. Rueda Sebastián Sanchez María Cecilia Bruno Jorge Casciotta Gastón Aguilera Adriana E. Almirón Federico J. Ruiz Díaz Delia Fabiana Cancino Baltazar Bugeau Ezequiel Mabragaña Mariano González‐Castro Matías Delpiani Juan Martín Díaz de Astarloa 《水产资源保护:海洋与淡水生态系统》2018,28(2):444-456
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17.
Theodore W. Hermann Fabrice Duponchelle Leandro Castello Karin E. Limburg Luciana A. Pereira Marília Hauser 《水产资源保护:海洋与淡水生态系统》2021,31(12):1206-1220
- Freshwater environments host roughly half of the world’s fish diversity, much of which is concentrated in large, tropical river systems such as the Amazon. Fishes are critical to ecosystem functioning in the Amazon River basin but face increasing human threats. The basic biology of these species, and particularly migratory behaviour, remains poorly studied, in part owing to the difficulty associated with conducting tagging studies in remote tropical regions.
- Otolith microchemistry can circumvent logistical issues and is an increasingly important tool for studying fish life histories. However, this approach is still new in the Amazon, and its potential and limitations to inform fish conservation strategies remain unclear.
- Here, otolith microchemistry studies in the Amazon are reviewed, highlighting current possibilities, and several key factors that limit its use as a conservation tool in the Amazon are discussed. These include the dearth of spatiotemporal elemental data, poor understanding of environment–fish–otolith pathways, and insufficient funding, facilities, and equipment.
- A research initiative is proposed to harness the potential of this technique to support conservation in the Amazon. Key aspects of the proposal include recommendations for internal and external funding, which are critical to acquiring and maintaining technical staff, cutting-edge equipment, and facilities, as well as fostering regular scientific meetings and working groups. Meetings can facilitate a systematic approach to investigating environment–otolith pathways, broadening the chemical baseline for most Amazonian tributaries, and exploring potential valuable elements.
- These outcomes are urgently needed to conserve biodiversity and ecosystem functioning in the Amazon, especially given threats such as widespread hydroelectric damming. The initiative proposed here could make otolith microchemistry an important, cost-effective tool to inform and foster conservation in the Amazon, and act as a template for other imperilled tropical river basins, such as the Mekong and the Congo.
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Ana Rita Dias Amílcar Teixeira Manuel Lopes‐Lima Simone Varandas Ronaldo Sousa 《水产资源保护:海洋与淡水生态系统》2020,30(5):988-999
- Coextinction is the simplest form of secondary extinction and freshwater mussels (Bivalvia, Unionida) may be particularly prone to this phenomenon as their life cycle includes an obligatory parasitic larval stage on fish hosts.
- The main aims of this study were to determine the possible ecological fish hosts of Anodonta anatina (Linnaeus, 1758) in several rivers of the Douro basin in northern Portugal and to assess possible spatial and temporal differences in glochidial (larval) loads. In order to achieve this, electrofishing was conducted from December to April, the fish fauna was characterized, and levels of infestation with A. anatina glochidia were determined.
- Native cyprinid species, mainly Luciobarbus bocagei (Iberian barbel) and Squalius carolitertii (northern Iberian chub), together with the non‐native Lepomis gibbosus (pumpkinseed sunfish) and Alburnus alburnus (common bleak), were found to have the highest glochidial loads. Clear differences in infestation between rivers and throughout time were detected, with an infestation period from January to March, and with the Tâmega River having the highest prevalence.
- Anodonta anatina is able to infest a variety of fish species, and this together with earlier studies showed that the metamorphosis into juveniles occurs mainly in native cyprinid species, although non‐native species like common bleak can also be considered suitable hosts. However, the larvae infesting other non‐native species, such as the pumpkinseed sunfish, do not metamorphose and can be considered ‘dead ends’.
- Overall, the results reported here are important for the conservation of A. anatina (and other unionoid species) because several Iberian rivers (and worldwide) have been subjected to the extirpation of native fish species and the introduction of non‐native fish species. Therefore, careful assessments of fish communities should be conducted to assess possible negative interactions with freshwater mussels.