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1.
A review and meta‐analysis of growth and life‐history traits of a declining European freshwater fish,crucian carp Carassius carassius 
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下载免费PDF全文 Ali Serhan Tarkan David Almeida Michael J. Godard Özcan Gaygusuz Mark Rylands Carl D. Sayer Grzegorz Zięba Gordon H. Copp 《水产资源保护:海洋与淡水生态系统》2016,26(1):212-224
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- 1. Crucian carp Carassius carassius, which is native to south‐east England, has received little previous study in Britain but is threatened by introductions of goldfish Carassius auratus through hybridization and by frequent mis‐identification of brown goldfish as crucian carp. The present study provides the first data on back‐calculated growth, morphology and age‐at‐maturity of crucian carp in Britain.
- 2. The youngest mature crucian were female (age 2+), the smallest mature crucian were male (age 3+), with almost all fish mature at age 3+. Sex dimorphism in back‐calculated standard length at age was not observed except at age 2+ (juveniles longest). Shifts in morphological characters often associated with maturation (dorsal and ventral fin length, dorsal and anal fin depth, pre‐dorsal distance, body width) were observed between ages 4+ and 7+, which (in contrast to the relatively abrupt shift in maturity) suggests that age and size at maturation may not reflect the size and age of active (i.e. real) spawning.
- 3. Back‐calculated standard lengths at age for crucian carp were intermediate relative to other European populations, indicating that environmental conditions in England appear to be well suited to the species despite being at the westernmost extent of the species' native European range. The management of ornamental ponds specifically for crucian carp is discussed.
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- 1. It is of vital importance that aquatic conservation is evidence based, and in the field of farmland pond management and restoration evidence was largely lacking until an article published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) in 2012.
- 2. To examine the influence of farmland pond management on aquatic biodiversity conservation, macrophyte and invertebrate diversity in ponds subject to traditional management involving scrub and occasional sediment removal at different time intervals in the past (0–2, 3–5, 6–10 years since management), were compared with a set of neighbouring, highly terrestrialized ponds that had not been managed for many decades.
- 3. With the exception of Mollusca, significantly higher species diversity was found for managed ponds compared with the late‐succession unmanaged ponds, with invertebrate gamma diversity significantly lower for the late‐succession ponds, compared with all the managed pond categories.
- 4. The AQC article was a key component of the Natural England (UK Government's adviser on the natural environment in England) ‘Freshwater and Wetland Conservation Narrative’ and has helped with integrating pond management into recent great crested newt Triturus cristatus mitigation policy as well as bringing it to the fore in past and evolving agri‐environment policy.
- 5. The AQC article provided the evidence and in turn the confidence for the authors and a number of conservation partners to form a Norfolk Ponds Project. Since 2014, the Project has delivered or facilitated more than 100 pond restorations in Norfolk, eastern England, as well as educating conservation practitioners and farmers on the importance of farmland ponds via various events.
- 6. With good underpinning science it has been possible to achieve considerable impact in the field of farmland pond conservation. This study shows the importance of setting aside time and support for academic staff to translate applied research outputs into practical impact.
4.
Ali Serhan Tarkan Gordon H. Copp Grzegorz Zięba Michael J. Godard Julien Cucherousset 《水产资源保护:海洋与淡水生态系统》2009,19(7):797-805
- 1. The crucian carp Carassius carassius is a species of cyprinid fish native to south‐east England, but few studies exist on its growth and reproduction in England, and the species is threatened by introductions of its Asiatic congener, goldfish Carassius auratus. To increase knowledge of the crucian carp as a means of aiding its conservation, the present study assesses the growth (back‐calculated length at age, body condition) and reproduction (fecundity, egg size, length and age at maturity) of crucian carp in small ponds of Epping Forest (north‐east London, England).
- 2. Evaluation of growth and reproduction data with published data for populations from northern Europe (i.e. latitude ?50°) suggest that growth is very variable, even within the same area, and that data on reproductive indices, in particular length and age at maturity, are scarce. In England, the length at age trajectory of crucian carp living in sympatry with feral goldfish Carassius auratus did not differ significantly from allopatric crucian carp populations, but crucian carp body condition and relative fecundity (eggs per body weight) were highest, and mean age and standard length at maturity were lowest in sympatry with goldfish.
- 3. These data suggest that somatic growth and reproductive output may be maximized in crucian carp when confronted by coexistence with feral goldfish. However, the potential impact of goldfish introductions on crucian carp growth and reproduction requires further study, involving a much larger number of crucian carp populations, both in allopatry and sympatry with feral goldfish populations.
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- This article introduces a special issue of Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) whose contributions demonstrate examples of the practical impact of the authors' previous AQC articles on the conservation of aquatic ecosystems.
- The submitting authors of all articles published in AQC since 2009 were invited to express their interest in writing an article for the special issue. The 20 articles selected for publication discuss 33 AQC articles published from 2004 to 2019, spanning a wide range of geographical locations, habitat types, species groups, and impacts on aquatic conservation.
- The two impacts reported most frequently are ‘Undertaking practical management of habitats and species’ and ‘Establishing partnerships’, closely followed by ‘Restoring habitats/reintroducing or translocating species’. Many authors demonstrate the importance of their articles in raising awareness across an extensive range of organizations.
- Some impacts occur soon after publication (e.g. introduction of conservation guidelines), whereas others (e.g. influencing policy) take far longer. Authors report a wide range of methods for disseminating research results appropriate for different audiences, such as technical handbooks, seminars, magazine articles, media broadcasts, and field workshops.
- To assess whether ‘conventional’ measures of impact match authors' perceptions, three metrics were calculated for the 33 AQC articles discussed in this issue: the number of citations, the number of downloads, and the Altmetric Attention Score. These metrics were not significantly higher for the 33 articles than the corresponding median metrics of the articles in the issues in which the 33 were published.
- The goal of AQC is to continue to encourage scientists to recognize and promote the application of their research to practical conservation and management. Given the growing threats to aquatic ecosystems, much remains to be done to make this process even more effective.
6.
Ilaria de Meo Kjartan Østbye Kimmo K. Kahilainen Brian Hayden Marius Magnus Antonio B. S. Poléo 《Ecology of Freshwater Fish》2023,32(1):10-22
Generalist fish species can feed on a wide resource spectrum and across trophic levels depending on resource availability and trophic interactions. Crucian carp (Carassius carassius) represents a good candidate species to investigate variation in the trophic ecology of generalist fish as it can be found in highly variable fish communities and its resource use is well documented. In this study, we explored the trophic ecology of crucian carp at the individual and population levels using stable isotope and gut content analysis. We tested if trophic resource use varied according to lake productivity, predation risk, intra- and interspecific competition, or individual fish size. We found that crucian carp resource preference was highly variable among and within lakes. In predator-free lakes, small crucian carp occurred in high densities, showed increased interindividual specialisation, and relied mainly on pelagic zooplankton. In presence of predators, large crucian carp occurred in low densities and included greater proportions of benthic macroinvertebrates in their diet. This shift in resource use was further favoured in productive, shallow lakes where littoral prey were probably abundant. Resource partitioning was an important factor determining crucian carp niche use, as fish had higher trophic position in absence of other cyprinids. Crucian carp showed highly dynamic resource use and food preferences in response to variable environmental conditions. Overlooking complex diet preferences of generalist fish may lead to an oversimplification of freshwater community dynamics. 相似文献
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Simone Fattorini Barbara Fiasca Tiziana Di Lorenzo Mattia Di Cicco Diana M. P. Galassi 《水产资源保护:海洋与淡水生态系统》2020,30(8):1483-1504
- Species of conservation concern are usually considered important elements in site prioritization for biodiversity conservation. To overcome the lack of information on species conservation status, multidimensional measures of species rarity can be used as proxies of species vulnerability.
- Under this assumption, a two‐step protocol for site prioritization of aquatic groundwater‐dependent ecosystems is proposed using invertebrate vulnerability estimated from species' traits. In the first step, each species occurring in the sites of interest are scored according to their vulnerability. In the second step, sites are prioritized using species' scores.
- Species vulnerability scores are based on five dimensions, for which various traits are scored: (i) geography, (ii) ecology, (iii) biology, (iv) population, and (v) evolutionary history. For each species, the scores of the various traits belonging to the same dimension are multiplied to obtain a synthetic score. These scores are then ranked into four classes and, for each dimension, each species receives a new score that reflects its rank. The sum of these scores represents the species' overall score.
- Site conservation priorities are assessed by combining species scores into three indices: Sum of Species Scores, Biodiversity Conservation Concern (which relates the sum of species scores with the local species richness) and Groundwater Biodiversity Concern (which is the average of the former two). The protocol is illustrated using case studies in Italy and it is fully implemented in the software AQUALIFE which is freely available at: http://app.aqualifeproject.eu by registered users.
- Sensitivity analyses showed that the protocol is robust against the lack of information on species biology or sampling limitations. However, trait scoring rests with the user, who must be familiar with the study group.
- This approach can be applied at any spatial scale and to different types of aquatic groundwater‐dependent ecosystems.
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- 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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Jack A. Greenhalgh Harold J. R. Stone Tom Fisher Carl D. Sayer 《水产资源保护:海洋与淡水生态系统》2021,31(8):2017-2028
- Ecoacoustics is increasingly being used to monitor species populations and to estimate biodiversity in marine ecosystems, but the underwater soundscapes of freshwater environments remain largely unexplored in this respect. Few studies exist concerning the acoustic diversity of ponds, but because aquatic plants and many arthropods such as Coleoptera and Hemiptera are known to produce sound, there is potential to use ecoacoustic techniques to monitor changes in biodiversity and conservation value.
- This pilot study compares the underwater soundscapes of recently restored open-canopy ponds and unmanaged highly terrestrialized ponds situated in an arable agricultural landscape of North Norfolk, UK, in order to assess the benefits of farmland pond restoration.
- Daytime sound recordings were made for 10 min in each pond and analysed primarily for arthropod stridulations. In addition, six commonly used acoustic indices were calculated to assess the soundscape biodiversity between the unmanaged and the restored ponds. The stridulations of three diving beetle species (Dytiscidae) were recorded in tank studies to assess the potential for individual species recognition from underwater sound capture.
- Sound-type richness and abundance, as estimated by visually and aurally identifying arthropod stridulation from spectrograms, were significantly higher in the restored open-canopy ponds compared with the unmanaged terrestrialized ponds. In addition, the acoustic indices ‘acoustic complexity’ and ‘biodiversity index’ were significantly higher in restored open-canopy ponds than in unmanaged terrestrialized ponds.
- The three dytiscid water beetle species recorded in a tank were found to produce distinctive and recognizable sounds, indicating potential to create an audio reference library that could be used for automatic acoustic monitoring of freshwater arthropods.
- Pond soundscapes are rich in biological information and this study suggests that, with further development, automated passive ecoacoustic monitoring could be an effective non-invasive technique for assessing pond conservation value and pond restoration and management success.
10.
- The mahseer (Tor spp.) fishes of South and Southeast Asia are iconic megafaunal species that are highly valued by recreational anglers. Knowledge on their populations is limited owing to the challenges associated with sampling these large‐bodied fishes (>50 kg) in remote monsoonal rivers.
- Despite its global iconic status among recreational anglers, the hump‐backed mahseer of the Cauvery River (South India) lacked a valid scientific name and was on a trajectory towards extinction until its rapidly declining population status was established by analyses of angler catch records.
- Angling records from 1998 to 2012 showed that mahseer catch rates had increased in this period. The resulting publication in Aquatic Conservation (AQC) highlighted the positive role of catch‐and‐release angling in providing information on data‐poor species. However, further analyses showed that these catches comprised not one but two distinct phenotypes.
- Before 1993, all mahseer captured were hump‐backed; since then, a blue‐fin phenotype appeared in catches and subsequently dominated them. These results triggered further studies indicating that the hump‐backed mahseer was the endemic Tor remadevii and that the blue‐fin was the invasive Tor khudree, introduced in 1976 and then stocked periodically from hatcheries.
- The initial AQC publication successfully demonstrated the high value of organized angling as a monitoring tool for data‐poor fishes and its application to assessing the temporal population patterns of large‐bodied fishes in monsoonal rivers. It was also the catalyst for initiating subsequent studies on T. remadevii that, together, enabled its recent assessment as ‘Critically Endangered’ on the International Union for Conservation of Nature (IUCN) Red List. In the absence of the AQC paper, and the subsequent studies that it triggered, it is highly probable that the species would have remained on a trajectory towards rapid extinction. Instead, the first major steps to safeguarding its future have been taken.
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Anastasios Bounas Maria Keroglidou Elisavet‐Aspasia Toli Ieremias Chousidis Dimitris Tsaparis Ioannis Leonardos Konstantinos Sotiropoulos 《水产资源保护:海洋与淡水生态系统》2020,30(5):1037-1049
- Freshwater communities and especially pond‐breeding amphibians are extremely vulnerable to land‐use change, alien species introductions and the use of pesticides or other toxic chemicals, as reflected in their worldwide decline. Effective conservation and management of ponds requires a better understanding of the biotic and abiotic factors that shape diversity patterns and species distribution, especially in cases of habitat loss
- The present study aimed to reveal and classify which pond and landscape characteristics are the most important determinants for the occurrence patterns of amphibian species as well as for the overall amphibian species richness in an urban pond network. To achieve this aim, 17 biotic and abiotic variables were measured for 61 ponds and the dataset was analysed by means of a machine‐learning approach, suitability indices and co‐occurrence modelling
- The highest probability of Triturus macedonicus occurrence was found at fishless artificial and semi‐natural ponds. The persistence of Lissotriton graecus in ponds was predicted by high pond connectivity and the absence of fish reflecting the species dispersive potential. Pelophylax kurtmuelleri showed a higher probability of occurrence with increased pond connectivity and macrophyte cover.
- Amphibian species richness was higher in fishless ponds with well‐oxygenated waters located in sites with a low to intermediate road density network. Ponds categorized as ‘average’ in terms of newt suitability were more frequently inhabited by fish than Triturus macedonicus. Alien fish species showed negative associations with both newt species, while both newt species showed a positive association between them.
- The results support the view that conserving a greater number of water bodies with increased landscape connectivity and without any fish presence could provide amphibian species with alternative habitat choices, especially in sites with human pressure where pond stability is at stake owing to continuous landscape changes.
12.
- Translating scientific evidence into practical actions is a primary goal of scientists working to inform evidence‐based policy and decision‐making, but how can authors best facilitate new conservation interventions following publication of their research?
- This case study used two articles in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) to examine the mechanisms and barriers to translating published aquatic science into social, ecological and policy interventions for the conservation of threatened Murray crayfish (Euastacus armatus).
- These articles revealed how steep declines in Murray crayfish abundance arose from the loss of in‐stream and riparian habitats preferred by crayfish, and demonstrated the social reasons for conserving Murray crayfish to protect the wellbeing of a diversity of people (e.g. Traditional Owners, landholders, ecotourism operators).
- Following publication of these articles in AQC the authors used multi‐modal communication (e.g. written briefs, personal discussions, seminars, magazine articles, media broadcasts) to translate their findings to stakeholders and the general public.
- Analysis of relevant documents (e.g. management plans, public information leaflets) and stakeholder interviews uncovered a range of interventions arising from the two AQC articles. Social interventions (e.g. new public signage, ecotourism briefings) were the quickest to occur after publication (1–2 years). Although some changes in management were apparent (e.g. revised Murray crayfish action plans, monitoring programmes), systemic barriers (e.g. policy/funding timeframes) have prevented some ecological and policy interventions from being realized.
- Diverse communication strategies can help rapidly translate published science into new conservation actions by giving stakeholders the right evidence in the right way to inform their particular practice. Open‐access summaries that explain findings within readily shareable media (e.g. graphical/video abstracts) can be particularly effective in raising early awareness. Some types of intervention, however, may require a long‐term perspective and assistance from boundary‐spanning knowledge brokers with an aptitude for evidence‐based policy development.
13.
Sarah M. Larocque Colin Lake Jonathan D. Midwood Vivian M. Nguyen Gabriel Blouin‐Demers Steven J. Cooke 《水产资源保护:海洋与淡水生态系统》2020,30(9):1783-1790
- Although it is sometimes difficult for researchers to ensure that their work is used by resource managers to make informed decisions, an example where this knowledge–action gap has been breached is in research published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) – among other journals – that has assisted fisheries managers in identifying strategies for reducing freshwater turtle bycatch in commercial hoop net fisheries in Ontario, Canada.
- Research published in AQC has provided evidence towards a simple and effective method for preventing turtle bycatch mortality in hoop nets, which could be adopted by the fishers. Other research published in AQC evaluated the effect of bycatch mortality on the probability of persistence of turtle populations with population viability analyses, and outlined the need to minimize bycatch mortality to prevent local extirpation. Nine other papers have been published on freshwater turtle bycatch in Ontario, furthering our knowledge on this issue including seasonality and temperature effects on catches, other net modifications, post‐release effects and assisted recovery, and the perspectives of fishers.
- The research results were presented to local resource managers with further discussions involving industry and stakeholders to minimize turtle bycatch mortality. Over several years, researchers have provided information to resource managers; however, when an incident of high turtle mortality caught the public eye, the research was readily available and changes in regulations were quick to occur.
- Reasonably good communication among researchers, resource managers, industry, stakeholders, and the broader public allowed the rapid implementation of regulations to mitigate freshwater turtle bycatch mortality and bridged the knowledge–action gap between researchers and resource managers.
- Both articles published in AQC had practical conservation impacts and were influential in providing local resource managers with feasible solutions, and the impetus to change regulations. These impacts extended to other jurisdictions and their monitoring programmes, where methods to reduce turtle bycatch mortality were also implemented.
14.
A. Wheeler 《Fisheries Management and Ecology》2000,7(4):315-322
The crucian carp, Carassius carassius (L.), is a small fish of restricted distribution in the UK, which is probably only native to central and eastern England. The crucian carp is endemic to northern Europe. It has been widely confused with the introduced and congeneric goldfish, Carassius auratus (L.), and forms hybrids with that species and the introduced Cyprinus carpio L. The status of this fish has become confused with the presence of the congener and its hybrids, and it is now thought to be less frequent in occurrence than formerly. 相似文献
15.
Cynthia A. Awruch Justin D. Bell Jayson M. Semmens Jeremy M. Lyle 《水产资源保护:海洋与淡水生态系统》2021,31(8):2178-2192
- The Maugean skate, Zearaja maugeana, is endemic to two isolated western Tasmanian (Australia) estuaries. The species' persistence in one of these estuaries (Bathurst Harbour) is uncertain, while the other estuary (Macquarie Harbour), potentially the remaining stronghold for the species, is an anthropogenically impacted system.
- Key life-history parameters were studied to inform conservation actions for this species. Reproductive information was obtained using non-lethal methodologies, circulating concentrations of sex steroids and ultrasonography. Growth and age parameters were estimated based on vertebral sections from a small sample of individuals.
- Females and males reached 870 and 760 mm total length, respectively. The species reached a maximum age of at least 10 years. Females and males attained 50% sexual maturity at 665 and 633 mm total length, respectively, probably maturing somewhere between four and six years of age. Females displayed an asynchronous, discontinuous reproductive cycle, being able to reproduce throughout the year, with a probable decline in reproductive activity during summer. No egg cases were observed in-utero. Males produce sperm all year round, with a peak in testosterone production during spring–autumn.
- Conservation strategies for Z. maugeana will need to focus on reducing anthropogenic impacts on the environmental health, the primary impacts being altered river flows associated with the production of hydroelectricity and increased nutrient load associated with salmonid aquaculture. There is a need to better understand how reproductive success, egg survival and recruitment are affected by these environmental challenges if the future well-being of this species is to be secured.
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Lea T. Mamo Melinda A. Coleman Patrick G. Dwyer Brendan P. Kelaher 《水产资源保护:海洋与淡水生态系统》2020,30(3):611-616
- Species listing and subsequent conservation efforts are dependent on a number of political, social, and scientific factors, often to the disadvantage of uncharismatic taxa, such as small, cryptic, and rare species, and those that lack commercial value.
- This case study examined the listing, impact assessment and conservation process of the critically endangered marine seaweed Nereia lophocladia (Nereia hereafter), which is a small and sporadically occurring species.
- Nereia was initially listed as vulnerable, and upgraded to critically endangered, following the precautionary principle. Despite the elevation of its listing and the existence of a recovery plan, little conservation effort was devoted to Nereia.
- A major upgrade to a large breakwater adjacent to Nereia's only known location triggered legislation and targeted searches for the species. Once found at the site, adaptive management actions, including modifications to the breakwater and some of the first targeted scientific surveys for this species took place.
- The targeted surveys quickly revealed a far greater population of Nereia with a broader distribution than was previously realized. Given this, the breakwater upgrade probably caused less extinction risk to Nereia than predicted and a costly redesign may not have been necessary to secure the species' survival.
- The case study argues for a proactive, evidentiary approach to species conservation, where conservation actions should be initiated as soon as species are listed and not when an immediate risk of extinction arises. Such approaches would improve conservation efforts and may also reduce the overall costs of saving species
18.
D.T. Bilton L.C. McAbendroth P. Nicolet A. Bedford S.D. Rundle A. Foggo P.M. Ramsay 《水产资源保护:海洋与淡水生态系统》2009,19(2):134-146
- 1. A high proportion of ponds are temporary in nature, although the biodiversity value of such sites is still poorly recognized. This work explores the plant and macroinvertebrate communities of 76 temporary and fluctuating water bodies in two regions of southern England (Lizard Peninsula, Cornwall and New Forest, Hampshire) that have retained high pond densities. The ecology and conservation status of sites is examined, and comparisons made with ponds elsewhere in England and Wales.
- 2. Lizard and New Forest ponds supported 119 plant and 165 macroinvertebrate species respectively. Patterns of community similarity for plants and macroinvertebrates were highly concordant, taxa being related in a similar manner to measured environmental variables including pond area, depth, pH and water chemistry.
- 3. Patterns of pond occupancy revealed that most species were locally rare, over half occurring in less than 10% of ponds, and less than 10% being recorded from more than 50% of sites. More than 50% of ponds supported at least one nationally rare plant and almost 75% at least one nationally rare macroinvertebrate. These taxa occupied a wide range of pond types in each region, and did not have predictably different ecologies from common species.
- 4. Comparisons with ponds elsewhere in England and Wales revealed that Lizard and New Forest communities are nationally distinct, being most similar to ponds in areas of low intensity agriculture elsewhere in western Britain. Individual ponds in both regions supported more nationally rare taxa, on average, than ponds sampled in the national survey.
- 5. Ponds in the two areas have high conservation value, both regionally and nationally, supporting almost 75% of the global species richness of temporary ponds sampled across England and Wales. Within each region, many taxa are found in relatively few sites, and effective conservation of pond biodiversity will require a regional management approach.
19.
Xiongjun Liu Xue Yang David T. Zanatta Manuel Lopes‐Lima Arthur E. Bogan Alexandra Zieritz Shan Ouyang Xiaoping Wu 《水产资源保护:海洋与淡水生态系统》2020,30(5):1000-1011
- The freshwater mussel (Unionida) fauna of the Yangtze River is among the most diverse on Earth. In recent decades, human activities have caused habitat degradation in the river, and previous studies estimated that up to 80% of the mussel species in the Yangtze River are Threatened or Near Threatened with extinction. However, a comprehensive and systematic evaluation of the conservation status of this fauna has yet to be completed.
- This study evaluated the conservation status of the 69 recognized freshwater mussel species in the middle and lower reaches of the Yangtze River, using the criteria published by the International Union for Conservation of Nature (IUCN). A new method for prioritizing species for conservation was then developed and applied termed Quantitative Assessment of Species for Conservation Prioritization (QASCP), which prioritizes species according to quantifiable data on their distribution and population status, life history, and recovery importance and potential.
- IUCN assessments showed that 35 (51%) species in the study region are Threatened or Near Threatened (11 Endangered, 20 Vulnerable, 4 Near Threatened). In addition, 16 species (23%) could not be assessed owing to data deficiency. Key threats to the freshwater mussel biodiversity of the Yangtze River include pollution, habitat loss and fragmentation, loss of access to host fish, and overharvesting of mussels and their host fish. The genera Aculamprotula, Gibbosula, Lamprotula, Pseudodon, Ptychorhynchus, and Solenaia were identified as particularly threatened.
- Data availability allowed QASCP assessment of 44 species. Only Solenaia carinata, regionally Endangered under IUCN criteria, achieved the highest QASCP rank, i.e. First Priority. The five species assessed as Second Priority were considered either regionally Endangered (one), Vulnerable (three), or Data Deficient (one) under IUCN criteria. The 23 Third Priority species were assessed as regionally Endangered (two), Vulnerable (15), Near Threatened (two), or Least Concern (four).
20.
The crucian carp (Carassius carassius, L.) is a cyprinid freshwater species, whose wild‐living populations have decreased in recent years due to an increasing competition of invasive species. Several initiatives were launched, attempting to reintroduce this fish back into its native open waters, which requires the use of crucian carp fry grown under controlled conditions. However, the use of popular commercial diets results in severe developmental abnormalities. The aim of this study was to analyse the impact of feeding natural feed (Chironomidae sp. larvae) or two popular commercial diets on the skeletal development of crucian carp juveniles. Whole‐mount staining and histological methods were used in the study. Skeletal tissues of fish fed both commercial diets were demineralized and displayed a variety of deformities, such as abnormal vertebral spines and vertebral fusion, as well as a new type of deformation, which involved the action of dorsal fin pterygiophores upon the spine. Finally, a novel analytical method was proposed, which utilizes LA‐ICP‐MS for the estimation of bone mineralization. The study proved that basic commercial diets are inadequate for the rearing of crucian carp juveniles. 相似文献