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1.
In this study, a new host record for Dadaytrema oxycephala (Digenea: Cladorchiidae) is described from an important Amazonian ornamental fish. The parasite was identified based in the general morphology and surface ultrastructure of the young and mature trematodes using scanning electron microscopy. The digenetic trematodes were found in the intestine of 15 of 80 specimens (18.7%) of Brochis multiradiatus captured from two floodplain lakes of the Amazonas River, Department of Loreto, Peru and no clinical signs were observed in the parasitized organ. This is the first report of D. oxycephala parasitizing fish of the genus Brochis in the Amazon basin and the first to report this parasite infection in an ornamental fish from Peru. Given that international trade of ornamental fish is a major factor for transboundary spreading of fish parasites and taking account that Peru is the second largest exporter of the Amazonian countries, there is a fundamental need of constant monitoring for diagnosis and timely control of infections by digeneans in order to better prevent introduction in new environments, dissemination and future disease outbreaks.  相似文献   

2.
In the state of São Paulo in southeastern Brazil, a dangerous decree allows the culture of hybrids and non-native extralimital fish species in the Paraná and East Atlantic River basins. We recorded the illegal importation and sale of the non-native striped catfish Pangasianodon hypophthalmus in northeastern, central-western, southeastern, and southern areas of the country. This species is already consumed across Brazil and is cultivated for ornamental purposes. Besides escapes from fish farms and ‘fish and pays’, P. hypophthalmus can reach natural environments through aquarium dumping and ornamental ponds, motivated by its large size that reach after being sold at small size. The species has been introduced in many countries, and if established in Brazil, could put native Brazilian biodiversity and ecosystems at risk. Although importing specimens of P. hypophthalmus is prohibited by law, Decree 62.243/2016 in the state of São Paulo creates a new opportunity for invasion. In fact, once a novel fish species is moved to a new continent, it is irrational to supposed that it will stay static just in the area for which it was intended. In general, the fish disperse in the novel area on their own, by escapes from captivity or deliberate and illicit releases by persons or associations. The unwise attitude of Brazilian decision-makers and lay people in their attempt to develop aquaculture with non-native species goes against the objectives of responsible aquaculture based in native species.  相似文献   

3.
The ornamental fish trade is estimated to handle up to 1·5 billion fishes. Transportation and handling of fishes imposes a range of stressors that can result in mortality at rates of up to 73%. These rates vary hugely, however, and can be as low as 2%, because they are generally estimated rather than based on experimental work. Given the numbers of ornamental fishes traded, any of the estimated mortality rates potentially incur significant financial losses and serious welfare issues. Industry bodies, such as the Ornamental Aquatic Trade Association (OATA), have established standards and codes of best practice for handling fishes, but little scientific research has been conducted to understand the links between stress, health and welfare in ornamental species. In aquaculture, many of the same stressors occur as those in the ornamental trade, including poor water quality, handling, transportation, confinement, poor social and physical environment and disease and in this sector directed research and some resulting interventions have resulted in improved welfare standards. This review considers the concept of welfare in fishes and evaluates reported rates of mortality in the ornamental trade. It assesses how the stress response can be quantified and used as a welfare indicator in fishes. It then analyses whether lessons from aquaculture can be usefully applied to the ornamental fish industry to improve welfare. Finally, this analysis is used to suggest how future research might be directed to help improve welfare in the ornamental trade.  相似文献   

4.
The principal species of marine aquaculture in Europe are Atlantic salmon (Salmo salar), sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus). For Atlantic salmon and sea bass, a substantial part of total genetic variation is partitioned at the geographical population level. In the case of sea bream, gene flow across the Azores/Mediterranean scale appears to be extensive and population structuring is not detected. For Atlantic salmon and sea bass, natural population structure is at risk from genetic interaction with escaped aquaculture conspecifics. The locally adaptive features of populations are at risk from interbreeding with non‐local aquaculture fish. Wild populations, generally, are at risk from interactions with aquaculture fish that have been subject to artificial selection or domestication. Atlantic salmon is the main European aquaculture species and its population genetics and ecology have been well‐studied. A general case regarding genetic interactions can be based on the information available for salmon and extended to cover other species, in the appropriate context. A generalized flow chart for interactions is presented. Salmon escape from aquaculture at all life stages, and some survive to breed among wild salmon. Reproductive fitness in the escaped fish is lower than in native, wild fish because of behavioural deficiencies at spawning. However, as the number of salmon in aquaculture greatly exceeds the number of wild fish, even small fractional rates of escape may result in the local presence of large numbers, and high frequencies, of escaped fish. At present, policy and legislation in relation to minimizing genetic interactions between wild and aquaculture fish is best developed for Atlantic salmon, through the recommendations of the Oslo Agreement developed by the North Atlantic Salmon Conservation Organization and subsequent agreements on their implementation. In future, the potential use of genetically modified fish in aquaculture will make additional policy development necessary. Improved containment is recommended as the key to minimizing the numbers and therefore the effects of escaped fish. Emergency recovery procedures are recommended as a back‐up measure in the case of containment failure. Reproductive sterility is recommended as a future key to eliminating the genetic potential of escaped fish. The maintenance of robust populations of wild fish is recommended as a key to minimizing the effects of escaped fish on wild populations.  相似文献   

5.
Morphological differences between wild and farmed Mediterranean fish   总被引:3,自引:0,他引:3  
Gilthead seabream (Sparus aurata L.) and European seabass (Dicentrarchus labrax L.) are important commercial marine fish species both for aquaculture and fisheries in the Mediterranean. It is known that farmed individuals escape from farm facilities, but the extent of escape events is not easy to report and estimate because of the difficulty to distinguish between wild and farmed individuals. In this study, significant differences provided through morphometry evidence that the cranial and body regions of seabream and seabass are different regarding their farm or wild origin at different scales. Morphological variations have been shown to be a valuable tool for describing changes in shape features. Therefore, the biomass contribution of escapees to local habitats could be determined by identifying escaped individuals from fisheries landings as a first step to assess the potential negative effects of fish farm escapees on the environment, and their influence on wild stocks and local fisheries.  相似文献   

6.
Two fish species reared in aquaculture (pink salmon Oncorhynchus gorbuscha and whitefish Coregonus lavaretus) and ten fish species from natural habitats (whitefish C. lavaretus, tugun Coregonus tugun, broad whitefish Coregonus nasus, least cisco Coregonus sardinella, vendace Coregonus albula, boganid charr Salvelinus boganidae, charr Salvelinus alpinus complex, northern pike Esox lucius, sharp-snouted lenok Brachymystax lenok, and taimen Hucho taimen) have been studied. The content of two long-chain polyunsaturated omega-3 fatty acids (PUFAs), eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA), in the muscle tissue of the fish and in their food (intestine contents) are compared. In the aquacultures of whitefish and pink salmon, the total content of EPA and DHA is significantly higher in feed than in the muscle tissue of the fish, which indicates losses of PUFA in the two-link food chain of the aquaculture during their transfer to the upper trophic level. EPA and DHA losses in aquaculture, which are confirmed by numerous literature data, mean an inefficient usage of the available sources of PUFAs and the aggravation of the global deficit of these biochemicals in the human diet. A study of natural fish populations reveals the accumulation of EPA and DHA in their biomass compared to food in many cases, although opposite phenomena are also observed. An assumption on the presence of an optimal, physiologically adequate species-specific level of PUFA in the fish muscle tissue has been made based on our data and literature data. If the level of PUFAs in the muscles is lower than optimal, their accumulation (bioaccumulation) from food and/or de novo synthesis are observed. When the optimal level is exceeded, the content of EPA and DHA in biomass approaches maximum species-specific values; however, part of these PUFAs entering from food is not digested or is catabolized. According to the obtained data, the species of the order Salmoniformes have an optimal level of 2 to 6 mg/g of wet weight. It has been found that in aquaculture approaching to maximum values of EPA + DHA content was accompanied by their losses (scattering) in the food chains, while in natural ecosystems the maximum values of PUFA content in the fish biomass are achieved by their accumulation from the lower trophic level. Boganid charr S. boganidae had the highest content of EPA + DHA in the muscle tissue among all known fish species (32.78 mg/g of wet weight).  相似文献   

7.
Aquatic organisms physically interact with the water that surrounds them, and this interaction is fundamental in shaping many aspects of their biology. General characteristics of the hydrodynamic interactions between organisms and the flow around them can be captured by the dimensionless Reynolds number (Re), depicting the ratio between inertial and viscous forces operating on the organism. The characteristic flow regime of larval fish that cruise at slow speeds is a regime of low Re, where viscous forces dominate. In this study, we experimentally test the ‘safe harbour’ hypothesis, which proposes that increasing larval body size facilitates an ‘escape’ from the detrimental effects of low Re. Larval gilthead seabream (Sparus aurata) were reared during early ontogeny under artificially manipulated water viscosities to expose larvae to low Re regimes. Larval survival decreased significantly with increasing water viscosity, and increased with increasing standard length. Surviving larvae exceeded the mean length of mortalities by ~1 mm, on average. Our findings provide direct experimental support for the ‘safe harbour’ hypothesis, indicating that marine larvae incur a fitness cost when operating under low Re conditions. Moreover, the results highlight the need to recognize the hydrodynamic environment when considering the a-biotic characteristics that may influence organismal performance and fitness.  相似文献   

8.
Ornamental palms are an economically important component of international trade yet have recently experienced yield losses in Mexico due to red ring and bud rot diseases, which are spread by Rhynchophorus palmarum L. Considering that massive capture is a common strategy to control this pest and the cost of commercial traps and baits could be inaccessible for small farmers, an inexpensive trap–bait combination is desired. In this study, 16 trap–bait combinations for capturing R. palmarum were assessed in ornamental palm polycultures over the course of 1 year. An expensive yellow bucket trap combined with aggregation pheromone + insecticide + banana was compared with inexpensive, handmade trap–bait combinations. A total of 4712 weevils were collected in all traps, of which 52.7% were male and 47.3% female. The efficacy of the handmade trap made from a colorless polyethylene bottle and baited with banana + pineapple + sugarcane + sugarcane molasses was similar to that of the yellow bucket trap baited with aggregation pheromone + insecticide + banana. These two trap–bait combinations remained effective even when the R. palmarum population significantly decreased during the dry, warm season. The affordable handmade trap baited with food attractants and without insecticides was highly efficient in capturing R. palmarum and therefore represents an effective tool for monitoring weevil populations. As ornamental crops have recently gained greater economic importance in the studied region, the use of a novel and cheap trap–bait combination could offer great benefits to producers and form part of the integrated management of R. palmarum.  相似文献   

9.
As the world increasingly relies on aquaculture operations to meet rising seafood demands, reliable biocontainment measures for farmed fish stocks are desired to minimize ecological impacts arising from interactions of cultured fish with wild populations. One possible biocontainment strategy is to induce a dietary dependence on a vitamin, such as thiamine (vitamin B1), required for survival. Fish expressing thiaminase (an enzyme that degrades thiamine) within a confined aquaculture facility could receive supplemental thiamine to allow survival and normal growth, whereas escapees lacking this dietary rescue would die from thiamine deficiency. To test the concept and efficacy of such a dietary dependency system (for potential future use in larger aquaculture species), we expressed thiaminase in zebrafish as a test model. We drove the expression of thiaminase under the strong ubiquitous and constitutive control of the CMV promoter which resulted in non-viable fish, indicating that the thiaminase sequence kills fish. However, the CMV promoter is too strong to allow conditional survival since the lethality could not be rescued by exogenous thiamine provided as a supplement to typical food. In addition, microinjection of 0.5 pg of thiaminase mRNA in zebrafish embryos at the one-cell stage resulted in 50% larval mortality at 5 days post-fertilization (dpf), which was partially rescued by thiamine supplementation. Evaluating the efficacy of biocontainment strategies helps assess which methods can reliably prevent ecological impacts arising from breaches in physical containment systems that release engineered organisms to nature, and consequently provides critical information for use in regulatory risk assessment processes.  相似文献   

10.
This study evaluates the fruiting phenology, fruit traits, and seed dispersal in two Pilosocereus (Cactaceae) species that are widely distributed in Caatinga vegetation. We monitored the fruiting phenology of Pilosocereus gounellei and Pilosocereus chrysostele on a monthly basis for a period of 4 years (45 months from March 2009 to November 2012), including 30 individuals of each species. We also carried out focal observations, captured dispersers, and conducted germination tests, to identify the effective seed dispersers of these species. Both species exhibited sub-annual fruiting patterns and high fruiting synchrony index (O jk 0.62), with peaks occurring from February to May for P. gounellei and February to April for P. chrysostele. In all, 248 visits by seven bird and two lizard species were recorded for P. gounellei, and 104 visits by five bird species were recorded for P. chrysostele. The two species shared five seed dispersers. The finch Lanio pileatus was the most frequently visiting bird species. The number of visits to the fruits of P. gounellei was higher than to the fruits of P. chrysostele. Passage of seeds through the digestive tracts of all bird species significantly increased the germination rate for P. chrysostele, whereas for P. gounellei, the birds Forpus xanthopterygius and L. pileatus decreased germination rates. Sub-annual fruiting patterns, similar fruit morphology, and high synchronous fruiting are factors that favor resource sharing among the dispersers of Pilosocereus in the Caatinga.  相似文献   

11.
Aquaculture ponds represent ecologically relevant environments to study the community composition and diversity of methanogenic assemblages, as well as their interactions with cultivated species and chemical indicators. In this study, aquaculture ponds with crab (Eriocheir sinensis), oriental river prawn (Macrobrachium nipponense), perch (Micropterus salmonides) and Wuchang fish (Parabramis pekinensis) were sampled, and Illumina high-throughput sequencing was used to investigate the methanogenic communities. The results revealed that the abundant methanogenic orders in surface sediment were Methanomicrobiales, Methanosarcinales and Methanocellales. The relative abundance of Methanocellales was higher in crab and prawn ponds as compared to other ponds. Methanogenic 16S rRNA gene abundance and beta diversity of the community was affected by the cultivated species. Methanogenic communities in aquaculture ponds with higher contents of total nitrogen and organic matter had decreased species richness, while those with higher contents of ammonia and nitrite had an overall decreased abundance of methanogens and their respective diversities. Overall, in addition to the differences in cultivated species, the consequent differences in farming practices including the types and amounts of feeds used, the contents of total nitrogen, organic matter, ammonia and nitrite could all influence the methanogenic community in surface sediment of aquaculture ponds.  相似文献   

12.
Despite the major importance of sex determination in aquaculture, no master sex-determining gene has been identified so far in teleost fish. In the platyfish Xiphophorus maculatus, this master gene is flanked by two receptor tyrosine kinase genes, the Xmrk oncogene responsible for melanoma formation in some Xiphophorus interspecific hybrids, and its proto-oncogenic counterpart. Both Xmrk genes, which have already been characterised at the molecular level, delimit a region of about 1 Mb that contains other gene loci involved in sexual maturity, pigmentation and melanoma formation. We have constructed a genomic bacterial artificial chromosome (BAC) library of X. maculatus with a tenfold coverage of the haploid genome and walked on both X and Y sex chromosomes starting from both Xmrk genes. This led to the assembly of BAC contigs from the sex-determining region covering approximately 950 kb of the X and 750 kb of the Y chromosome. To our knowledge, these are the largest contigs reported so far for sex chromosomes in fish. Molecular analysis suggests that the sex-determining region of X. maculatus frequently undergoes retrotranspositions and other kinds of rearrangements. This genomic plasticity might be related to the high genetic variability observed in Xiphophorus for sex determination, sexual maturity, pigmentation and melanoma formation, which are encoded by gene loci located in the sex-determining region.  相似文献   

13.
We propose a simple and sensitive bioassay for analyzing zooplankton escape behavior and present results of its testing on four Daphnia species under varying temperature, and in either the presence or absence of chemical cues of fish predation. In the assay, the animals are blindly transferred with a pipette through subsequent containers and their final distributions are compared. For testing the effects of a single factor, comparing distributions of the animals is a sensitive tool to detect differences in escape ability. We propose single-value measures to be used in larger experiments with multigroup comparisons in order to enable studying global effects and reduce the loss of statistical significance due to correction for multiple testing. Our results show that if escape ability is considered an important fitness component, among the tested species, which were D. longispina, D. lumholtzi, D. magna, and D. pulicaria, the last may be the most vulnerable to increased fish predation associated with increased lake water temperatures.  相似文献   

14.
To explain current ornamental plant invasions, or predict future ones, it is necessary to determine which factors increase the probability of an alien species becoming invasive. Here, we focused on the early phases of ornamental plant invasion in order to identify which plant features and cultivation practices may favor the escape of ornamental plants from domestic gardens to abandoned agricultural land sites in the Mediterranean Region. We used an original approach which consisted in visiting 120 private gardens in an urbanizing rural area of the French Mediterranean backcountry, and then visited surrounding old fields to determine which planted species had escaped out of the gardens. We built a database of 407 perennial ornamental alien species (most of which were animal-dispersed), and determined nineteen features that depicted the strength of species’ propagule pressure within gardens, the match between species requirements and local physical environment, and each species’ reproductive characteristics. Using standard and phylogenetic logistic regression, we found that ornamental alien plants were more likely to have escaped if they were planted in gardens’ margins, if they had a preference for dry soil, were tolerant to high-pH or pH-indifferent, and if they showed a capacity for clonal growth. Focusing only on animal-dispersed plants, we found that alien plants were more likely to have escaped if they were abundant in gardens and showed preference for dry soil. This suggests that gardening practices have a primary impact on the probability of a species to escape from cultivation, along with species pre-adaptation to local soil conditions, and capacity of asexual reproduction. Our results may have important implications for the implementation of management practices and awareness campaigns in order to limit ornamental plants to becoming invasive species in Mediterranean landscapes.  相似文献   

15.
“观赏渔业”课程教学的实践与探索   总被引:1,自引:0,他引:1  
赵朝阳  邴旭文  徐跑  方秀珍 《生物学杂志》2011,28(6):102-103,108
《观赏渔业》是新兴"水族科学与技术"本科专业学生的专业核心课程,也是水产养殖学专业课程体系中的重要组成。结合作者多年在《观赏渔业》课程教学中的实践和探索,以培养学生对观赏水族的兴趣为本,通过对教学方法的创新、实践教学的注重,极大地激发了学生对该课程的兴趣,充分调动了学生学习和实践的积极性与主动性,增强该课程实践功能促进了教学效果的提高。同时,这对培养水族专业人才,满足中国现代水族产业发展对高素质人才的需要亦具有重要的作用。  相似文献   

16.
Tissue-specific promoters can drive genes specifically expressed in the target organs and have been widely used in plant molecular breeding. In this study, a 1.2-kb promoter region of an anther-specific gene PhLRR from Petunia hybrida “Fantasy” was isolated and fused to the β-glucuronidase (GUS) gene. The pPhLRR::GUS vector was heterogeneously transformed into tobacco in which the GUS staining was only detected in the early development stage of anthers and no GUS expression in any other three floral whirls or vegetative organs was observed. It is very different from other well-studied anther-specific promoters which drive genes specifically expressed in the later development stage of anthers or only in the pollens. Furthermore, the pPhLRR::Barnase was introduced into petunia and induced complete male sterility without influencing the ornamental characteristics or the female fertility in transformed plants. These results indicate that PhLRR promoter is a new kind of petunia anther-specific promoter and could be taken as a valuable tool in ornamental plant breeding.  相似文献   

17.
Habitat selection is an important phenomenon that may greatly affect individual fitness. Using an artificial stream, we examined the relationship between the percentage of prey captured, reactive distance, dominance, and water velocity for juvenile Chinook Salmon (Oncorhynchus tshawytscha) from the Chena River, Alaska, and tested the fitness-based microhabitat selection model of Grossman et al. (Ecol Freshw Fish 11:2–10, 2002). Recent declines in the abundance of Chinook accentuate our need for habitat selection studies on this species. We conducted three experiments: two with single fish (1st N?=?27, fish SL 58–84 mm, 2nd N?=?14, fish SL 49–56 mm) and one with pairs of dominant and subordinate fish (N?=?10 pairs, 64–96 mm, mean difference in SL?=?7 mm). We placed individual or pairs of fish in an artificial flume and recorded reactive distance and the percent prey capture with individual dead brine shrimp (Artemia spp.) as prey. Prey were presented at 10 cm/s velocity intervals ranging from 10 to 60 cm/s; velocities found in the natural habitat. Mean reactive distance in single fish experiments (henceforth SFE) averaged 33 and 29 cm respectively, and was not related to velocity. We detected a negative, curvilinear relationship between velocity and percent prey capture. Holding velocities for juvenile Chinook were significantly lower than prey capture velocities. The Grossman et al. (Ecol Freshw Fish 11:2–10, 2002) model yielded an optimal focal-point velocity prediction of 35 cm/s for juvenile Chinook, however focal-point velocities occupied by juveniles in the Chena River averaged 12 cm/s. Predicted optimal velocities were present in the Chena River; hence, this discrepancy suggests that other factors such as distraction from drifting debris or predation risk influenced habitat selection. There were no differences in reactive distances or holding velocity/capture velocity relationships for dominant and subordinate fish; however, dominants captured significantly more prey than subordinates. Being subordinate resulted in a decrease of 61% in mean percent prey capture (the difference between what was captured by the fish alone versus the difference with a dominant), whereas the mean cost to fish with dominant rank was a 21% decline between the percentage captured alone versus that with a subordinate.  相似文献   

18.
Materials of preliminary investigations of the life strategy of mykiss Parasalmo mykiss and trout Salmo trutta introduced to water bodies of Chili are considered. Analysis of the structure of scales demonstrated that, in mykiss and trout, the estuarine and riverine-estuarine types of life strategy prevail. This seems to be related to good feeding conditions in fjords. The hypothesis is suggested that, in the area of Chilean fjords, the successful introduction to rivers and artificial rearing in cages in brackish water resulted in the formation of a peculiar and highly dynamic population system. Elements of this system are from both fish of natural self-reproducing populations and fish grown in cages. There is a continuous exchange with genetic information between them as the fish that have escaped from cages attain maturity, arrive to rivers for spawning, and reproduce together with wild fish.  相似文献   

19.
The perennial grass genus Miscanthus has great promise as biomass feedstock, but there are concerns about potential invasion outside production fields. While the sterile hybrid Miscanthus × giganteus is currently one of the leading feedstock options due to its low invasive potential, fertile varieties are being developed to reduce establishment costs, and their invasive risks need to be further assessed. We performed seed addition experiments in Ohio and Iowa, USA to examine the establishment, flowering, persistence, and shoot biomass per plot of a fertile M. × giganteus biotype (‘PowerCane’) and two Miscanthus sinensis biotypes, one feral, and one ornamental. Seeds were added to small, replicated plots in each of the 2 years under two seeding densities and two competition treatments, and plots were monitored for 2–3 years. The ‘PowerCane’ biotype established better, survived better, and produced greater amounts of biomass per plot than both M. sinensis biotypes. All three biotypes flowered by the second or third year after establishment, with inflorescences more numerous in ‘PowerCane’ and the Ornamental M. sinensis biotypes. Effects of seeding density and competition on these patterns were minor in most cases. Our research suggests that ‘PowerCane’ exhibits many traits shared by both biomass crops and invasive species: multi-year persistence, high biomass potential, and fertility. We suggest that the benefits of a seeded M. × giganteus should be carefully weighed against its increased invasive risk prior to deployment across the landscape.  相似文献   

20.
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