RESUMO
European eel, Anguilla anguilla (Linnaeus) (Elopomorpha: Anguilliformes), is a critically endangered fish of ecological and economic importance, hosting numerous parasites, including myxozoans (Cnidaria). Since its initial discovery in the kidney of European eel, Myxidium giardi Cépède, 1906 has been reported with numerous spore sizes and shapes from various tissues of multiple anguillid species. Morphological variability, wide host and tissue spectrum, and lack of sequence data raised doubts about the conspecificity of reported isolates. Subsequent studies provided 18S rDNA sequences of several isolates from anguillids and other elopiform fish, and demonstrated a split of parasite data into two distinct phylogenetic lineages, one comprising the M. giardi sequence, and the other all species infecting elopiform fishes classified under the recently established genus Paramyxidium Freeman et Kristmundsson, 2018. Myxidium giardi was, however, transferred to this genus as Paramyxidium giardi n. comb. and designated as the type species of the genus. In line with this change, the sequence originally identified as M. giardi was considered to have been incorrectly associated with this species. To shed light on the status of M. giardi originally described by Cépède (1906), we conducted microscopic and molecular examinations of various organs of 24 individuals of European eel, originating from diverse Czech habitats. Through morphometric and molecular analyses, we demonstrated that spore and polar capsule morphology, morphometry and tissue tropism of our European eel kidney parasite isolates matched the features of the original M. giardi description. Our isolates clustered in the lineage encompassing the first published M. giardi sequence. Thus, the originally described M. giardi indeed represents an existing species within the genus Myxidium Bütschli, 1882, which we formally resurrect and redescribe. Due to the morphological and molecular differences between M. giardi and P. giardi of Freeman et Kristmundsson (2018), we additionally rename the latter species as Paramyxidium freemani nom. nov.
Assuntos
Anguilla , Doenças dos Peixes , Rim , Myxozoa , Doenças Parasitárias em Animais , Filogenia , Animais , Myxozoa/classificação , Myxozoa/genética , Myxozoa/fisiologia , Doenças dos Peixes/parasitologia , Doenças Parasitárias em Animais/parasitologia , Rim/parasitologia , Anguilla/parasitologia , RNA Ribossômico 18S/análiseRESUMO
A 30 years long data series on the infection dynamics of European eel (Anguilla anguilla L.) with the non-native invasive nematode Anguillicola crassus Kuwahara, Niimi & Hagaki, 1974 is presented. Parasite burden was evaluated for 30 years in inland and coastal waters in Mecklenburg-Western Pomerania from 1991 to 2020. The total prevalence, mean intensity and damage status of the swim bladders were very high during the first decade (19912000), and significantly decreased in both marine and freshwater eel populations in the following decades (20012010, 20112020). The parasite intensity of eels in coastal waters was significantly lower compared with the freshwater systems (61.3% vs 79.5% in the first decade), indicating the vulnerability of the parasites to brackish water conditions and the fact that the life cycle of A. crassus cannot be completed under high saline conditions. Eel caught in the western part of the Baltic Sea (west of Darss sill) had the lowest mean infection (51.8% in first decade) compared to the eastern part with 63.8%. Thus, besides different infection patterns caused by the environmental conditions, a temporal trend towards a reduced parasite intensity and a more balanced parasitehost relationship developed in the 30 years of interaction after the first invasion. Possible reasons and mechanisms for the observed trends in parasitehost interactions are discussed.
Assuntos
Anguilla , Dracunculoidea , Doenças dos Peixes , Animais , Anguilla/parasitologia , Sacos Aéreos/parasitologia , Estágios do Ciclo de Vida , Alemanha/epidemiologia , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/parasitologiaRESUMO
Being able to systematically detect parasitic infection, even when no visual signs of infection are present, is crucial to the establishment of accurate conservation policies. The nematode Anguillicola crassus infects the swimbladder of anguillid species and is a potential threat for eel populations. In North America, naïve hosts such as the American eel Anguilla rostrata are affected by this infection. The accidental introduction of A. crassus following restocking programs may contribute to the actual decline of the American eel in Canada. We present a quantitative real time PCR-based method to detect A. crassus infection in final and intermediate hosts. We tested two protocols on samples from different geographical origins in Canada: 1) a general detection of A. crassus DNA in pools of young final hosts (glass eels) or crustacean intermediate hosts 2) a detection at the individual scale by analyzing swim bladders from elvers, or from adult yellow and silver eels. The DNA of A. crassus was detected in one pool of zooplankton (intermediate host) from the Richelieu River (Montérégie-Québec), as well as in individual swim bladders of 13 elvers from Grande and Petite Trinité rivers (Côte-Nord-Québec). We suggest that our qPCR approach could be used in a quantitative way to estimate the parasitic burden in individual swim bladders of elvers. Our method, which goes beyond most of previous developed protocols that restricted the diagnosis of A. crassus to the moment when it was fully established in its final host, should help to detect early A. crassus infection in nature.
Assuntos
Anguilla , Dracunculoidea , Doenças dos Peixes , Animais , Doenças dos Peixes/diagnóstico , Doenças dos Peixes/parasitologia , Anguilla/parasitologia , Sacos Aéreos/parasitologia , GeografiaRESUMO
Anguillicoloides crassus is an invasive nematode parasite of the critically endangered European eel, Anguilla anguilla, and possibly one of the primary drivers of eel population collapse, impacting many features of eel physiology and life history. Early detection of the parasite is vital to limit the spread of A. crassus, to assess its potential impact on spawning biomass. However accurate diagnosis of infection could only be achieved via necropsy. To support eel fisheries management we developed a rapid, non-lethal, minimally invasive and in situ DNA-based method to infer the presence of the parasite in the swim bladder. Screening of 131 wild eels was undertaken between 2017 and 2019 in Ireland and UK to validate the procedure. DNA extractions and PCR were conducted using both a Qiagen Stool kit and in situ using Whatman qualitative filter paper No1 and a miniPCR DNA Discovery-System™. Primers were specifically designed to target the cytochrome oxidase mtDNA gene region and in situ extraction and amplification takes approximately 3 h for up to 16 individuals. Our in-situ diagnostic procedure demonstrated positive predictive values at 96% and negative predictive values at 87% by comparison to necropsy data. Our method could be a valuable tool in the hands of fisheries managers to enable infection control and help protect this iconic but critically endangered species.
Assuntos
Anguilla , Dracunculoidea , Doenças dos Peixes , Parasitos , Sacos Aéreos/parasitologia , Anguilla/parasitologia , Animais , Dracunculoidea/fisiologia , Doenças dos Peixes/parasitologia , HumanosRESUMO
Anguillicola (Anguillicoides) crassus is a swimbladder nematode parasite of Anguilla anguilla (Linnaeus, 1758). The present study investigates the morphology and pathogenicity of A. crassus in European eel, as well as, the effects of different aquatic environments on the infection of A. crassus, in Greece. A total of 268 nematodes were collected from four estuarine systems in Greece. In all collected parasites, measurements carried out to define the morphological characteristics of parasites: parasite length and width, oesophagus max length and max width. Τhe mean parasite length was 23.50 mm (95% CI: 22.42-24.58) for females, 12.95 mm (95% CI: 12.25-13.64) for the males and 6.39 mm (95% CI: 5.27-7.50) for the juveniles. The mean parasite width was 1.99 mm (95% CI: 1.88-2.10) for females, 0.93 mm (95% CI: 0.86-1.00) for males and 0.51 mm (95% CI: 0.39-0.64) for juveniles. In total, the mean intensity was found 3.15 (95% CI: 2.53-3.78), while the highest mean intensity per eel was 8.00 (95% CI: 0.00-29.51) in Tholi Lagoon and the lowest was 2.20 (95% CI: 0.36-4.04) in Amvrakikos Gulf. Longitudinal and transverse histological sections of two adults A. crassus and two swimbladders were carried out. Multiple granules were observed, as a tissue reaction of the organism to swath around the 4th stage larvae (L4) that have entered the swimbladder. Molecular analysis was performed on three female adults A. crassus derived from eel specimens coming from the Vistonis estuarine system. The high reproductive capacity of the parasite reveals that A. anguilla has low effective defense mechanisms against the parasite. Also, the morphometric variations of the A. crassus seems to have a plastic feature which is being differently expressed when exposed to various environments.
Assuntos
Anguilla , Dracunculoidea , Sacos Aéreos/parasitologia , Anguilla/parasitologia , Animais , Feminino , Grécia , Masculino , VirulênciaRESUMO
The European eel Anguilla anguilla is listed as critically endangered by the IUCN. Among many threats, the introduced parasitic nematode Anguillicola crassus is suspected to alter the eels' swim bladder and jeopardize their reproductive oceanic migration. To date, gaining knowledge about the distribution and prevalence of A. crassus requires individual sacrifice (over 50,000 eels were sacrificed for epidemiology studies since 2010). This paper describes a non-lethal molecular protocol for identifying prevalence of A. crassus in A. anguilla, based on searching for A. crassus DNA in the feces of eels. Tests using three DNA microsatellite markers specific to the nematode showed that molecular detection provided similar results to visual examination of the swim bladder in up to 80% of the cases, and allowed for comparison of prevalence among sites. Easy to implement, this non-lethal protocol for detecting A. crassus could be valuable for management plans of this endangered species.
Assuntos
Sacos Aéreos/parasitologia , Anguilla/parasitologia , Dracunculoidea/isolamento & purificação , Doenças dos Peixes/parasitologia , Animais , Dracunculoidea/genética , Fezes/parasitologia , Feminino , Masculino , ReproduçãoRESUMO
The global invasive anguillid gill parasite Pseudodactylogyrus anguillae (Yin and Sproston, 1948) has only recently been documented from eels in South Africa. As there is no known eel trade in South Africa, the source of introduction of this parasite has been debated, and its status as an alien parasite was rendered uncertain. We report on the first infection of Pseudodactylogyrus anguillae from the giant mottled eel Anguilla marmorata from the Phongolo River (South Africa) using classic morphological and molecular methodologies and clarify the introduction status category of this parasite as alien and invasive.
Assuntos
Anguilla/parasitologia , Doenças dos Peixes/parasitologia , Trematódeos/classificação , Infecções por Trematódeos/veterinária , Animais , DNA Intergênico/genética , Feminino , Brânquias/parasitologia , Espécies Introduzidas , Masculino , Filogenia , Rios , África do Sul , Trematódeos/anatomia & histologia , Trematódeos/genética , Trematódeos/isolamento & purificação , Infecções por Trematódeos/parasitologiaRESUMO
Recent occasional examinations of two species of eels (Anguilliformes: Anguillidae) in Japan, the Japanese eel Anguilla japonica Temminck & Schlegel from central Japan and the giant mottled eel Anguilla marmorata Quoy & Gaimard from southern Japan, respectively, revealed the following four species of gastrointestinal parasitic nematodes: Cucullanus filiformis Yamaguti, 1935 (Cucullanidae) from A. japonica; Paraquimperia japonica n. sp. (Quimperiidae) from A. japonica (type-host) and A. marmorata; Heliconema anguillae Yamaguti, 1935 (Physalopteridae) from A. marmorata (new host record); and Spinitectus anguillae n. sp. (Cystidicolidae) from A. japonica (type-host) and A. marmorata. Specimens of all species are described based on light and scanning electron microscopical examinations. Paraquimperia japonica n. sp. is mainly characterised by the presence of a ventral sucker, spicules 210-231 µm long and by narrow cervical alae, whereas S. anguillae n. sp. by the number (29-36) of cuticular spines in the first ring, the length of the left spicule (351 µm) and the structure (without polar caps, filaments or lateral swellings), and the size of eggs (36-42 × 21-27 µm).
Assuntos
Anguilla/parasitologia , Nematoides/classificação , Animais , Japão , Microscopia Eletrônica de Varredura , Nematoides/ultraestrutura , Especificidade da EspécieRESUMO
Gnathostomiasis, an emerging food-borne parasitic zoonosis in Asia, is mainly caused by Gnathostoma spinigerum (Nematoda: Gnathostomatidae). Consumption of raw meat or freshwater fishes in endemic areas is the major risk factor. Throughout Southeast Asia, including Thailand, Lao PDR, Cambodia, and Myanmar, freshwater fish are often consumed raw or undercooked. The risk of this practice for gnathostomiasis infection in Lao PDR, Cambodia, and Myanmar has never been evaluated. Here, we identified larvae of Gnathostoma species contaminating freshwater fishes sold at local markets in these three countries. Public health authorities should advise people living in, or travelling to, these areas to avoid eating raw or undercooked freshwater fishes. Identification of larvae was done using molecular methods: DNA was sequenced from Gnathostoma advanced third-stage larvae recovered from snakehead fishes (Channa striata) and freshwater swamp eels (Monopterus albus). Phylogenetic analysis of a portion of the mitochondrial cytochrome c oxidase subunit I gene showed that the G. spinigerum sequences recovered from southern Lao PDR, Cambodia, and Myanmar samples had high similarity to those of G. spinigerum from China. Sequences of the nuclear ribosomal DNA internal transcribed spacer 2 region closely resembled sequences of G. spinigerum from Thailand, Indonesia, the USA, and central Lao PDR. This is the first molecular evidence of G. spinigerum from freshwater fishes in southern Lao PDR, Cambodia, and Myanmar.
Assuntos
Anguilla/parasitologia , Peixes/parasitologia , Gnathostoma/classificação , Gnatostomíase/veterinária , Smegmamorpha/parasitologia , Animais , Camboja , DNA Intergênico/genética , DNA de Protozoário/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Doenças Transmitidas por Alimentos/parasitologia , Água Doce , Variação Genética , Gnathostoma/genética , Gnathostoma/isolamento & purificação , Gnatostomíase/parasitologia , Indonésia , Laos , Larva , Mianmar , Filogenia , Zoonoses/parasitologiaRESUMO
Biological invasions are frequently studied topics in ecological research. Unfortunately, within invasion ecology parasite-associated aspects such as parasite impacts on new environments and on local host populations are less well-studied. Round gobies migrating from the Ponto-Caspian region into the Rhine River system are heavily infested with the Ponto-Caspian acanthocephalan parasite Pomphorhynchus laevis. As shown by experimental infestations the acanthocephalans occur as pre-adults in host-encapsulated cysts within the internal organs of the migrating gobies, but remain infective for their definitive host chub. Recently, we described the occurrence of larvae of another parasite, the invasive eel swim bladder nematode Anguillicola crassus, in these Pomphorhynchus cysts. In the present study, we could prove the infectivity of the nematode larvae for European eels for the first time. After experimental inoculation of Pomphorhynchus cysts occasionally infested with A. crassus larvae, the nematodes grow to maturity and reproduce whereas all P. laevis were unviable. We therefore postulate that the nematode larvae behave like immunological hitchhikers that follow a "Trojan horse strategy" in order to avoid the paratenic host's immune response. Accordingly, the interaction between both invasive parasites gives first evidence that the invasional meltdown hypothesis may also apply to parasites.
Assuntos
Anguilla/parasitologia , Espécies Introduzidas , Nematoides/fisiologia , Parasitos/fisiologia , Animais , Trato Gastrointestinal/parasitologia , Esporos/fisiologiaRESUMO
The rate of glucose metabolism has been shown to be correlated to glucose uptake in swimbladder gas gland cells. Therefore, it is assumed that in the European eel silvering, i.e., the preparation of the eel for the spawning migration to the Sargasso Sea, coincides with an enhanced capacity for glucose uptake. To test this hypothesis expression of all known glucose transport proteins has been assessed at the transcript level in yellow and in silver eels, and we also included Anguillicola crassus infected swimbladders. Glucose uptake by rete mirabile endothelial cells could be crucial for the countercurrent exchange capacity of the rete. Therefore, this tissue was also included in our analysis. The results revealed expression of ten different members of the slc2 family of glucose transporters, of four slc5 family members, and of kiaa1919 in gas gland tissue. Glucose transporters of the slc2 family were expressed at very high level, and slc2a1b made up about 80% of all slc2 family members, irrespective of the developmental state or the infection status of the eel. Overall, the slc5 family contributed to only about 8% of all detected glucose transport transcripts in gas gland tissue, and the slc2 family to more than 85%. In rete capillaries, the contribution of sodium-dependent glucose transporters was significantly higher, leaving only 66% for the slc2 family of glucose transporters. Neither silvering nor the infection status had a significant effect on the expression of glucose transporters in swimbladder gas gland tissue, suggesting that glucose metabolism of eel gas gland cells may not be related to transcriptional changes of glucose transport proteins.
Assuntos
Sacos Aéreos/metabolismo , Anguilla/genética , Dracunculoidea/fisiologia , Doenças dos Peixes/genética , Proteínas Facilitadoras de Transporte de Glucose/genética , Infecções por Nematoides/veterinária , Sacos Aéreos/parasitologia , Anguilla/parasitologia , Animais , Doenças dos Peixes/parasitologia , Regulação da Expressão Gênica , Infecções por Nematoides/genética , Infecções por Nematoides/parasitologia , TranscriptomaRESUMO
In a process called silvering, European eels prepare for their long-distance migration from European freshwater systems to the Sargasso Sea for reproduction. During this journey, eels perform extended diel vertical migrations, and the concomitant changes in hydrostatic pressure significantly affect the swimbladder, functioning as a buoyancy organ. As the swimbladder is primarily filled with oxygen, the tissue has to cope with extreme hyperoxic conditions, which typically are accompanied by the generation of reactive oxygen species (ROS) and oxidative stress. In addition, since the introduction of the parasitic nematode Anguillicola crassus in the early 1980s, swimbladder function of most of the European eels is impaired by the infection with this parasite. However, the exact pathways to detoxify ROS and how these pathways are affected by silvering or the infection are still unknown. In swimbladder and muscle tissue from uninfected and infected yellow, and from uninfected and infected silver eels, we measured the level of lipid peroxidation, which increases with ROS stress. To assess the capacity of the ROS defense systems, we analyzed the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione reductase (GR), and determined the concentration of the antioxidant glutathione (GSH + GSSG). In swimbladder tissue, we found increased concentrations of GSH + GSSG as well as higher activities of SOD, GPx and GR, suggesting that SOD and the glutathione cycle are important for ROS detoxification. Comparing swimbladder tissue of uninfected yellow with uninfected silver eels, the concentration of GSH + GSSG and the activity of SOD were higher after silvering, corresponding with lower levels of lipid peroxidation. Whereas in yellow eels the infection with A. crassus had no effect, in silver eels the capacity to cope with ROS was significantly impaired. In muscle tissue, silvering or the infection only affected the activity of SOD but in exactly the same way as in swimbladder tissue.
Assuntos
Sacos Aéreos/metabolismo , Anguilla/parasitologia , Dracunculoidea/patogenicidade , Doenças dos Peixes/parasitologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Antioxidantes/metabolismo , Catalase/metabolismo , Doenças dos Peixes/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/parasitologia , Estresse Oxidativo , Infecções por Spirurida/metabolismo , Infecções por Spirurida/veterinária , Superóxido Dismutase/metabolismoRESUMO
The present study is based on infection experiments of two different swim bladder parasite species, Anguillicola crassus Kuwahara et al., 1974 and Anguillicola novaezelandiae Moravec and Taraschewski, 1988, which were experimentally transferred to the two eel species Anguilla anguilla Linnaeus, 1758 and Anguilla japonica Temmink and Schlegel, 1846, respectively. The host-parasite groups were selected due to their different grades of mutual adaptation. The main aim of this study was to analyze the stress responses within the parasites, which were confronted with different hosts, i.e. with different stressors related to the respective host. For this purpose, mean intensities, recovery rates, larvae output, and levels of synthesized heat shock proteins (Hsp70) were determined in nematodes of each infection group. Increased stress responses were detected in the endemic system of A. crassus parasitizing A. japonica and A. crassus in its recently acquired host A. anguilla, which seems to be associated with the immune response of the particular host species and the expenditure of energy on producing larvae. A. novaezelandiae showed overall weak activities in its unknown host species A. japonica, with the lowest recovery rate of all examined groups neither featuring elevated Hsp responses, nor a high mean intensity, nor any reproductive output. On the contrary, in A. anguilla, the parasite reached higher recovery rates, mean intensities, and reproductive output, but no increased Hsp70 levels could be detected. The four considered factors proved partially interdependent, whereas few results did not follow a clear pattern.
Assuntos
Anguilla/parasitologia , Dracunculoidea/fisiologia , Doenças dos Peixes/parasitologia , Proteínas de Choque Térmico HSP70/metabolismo , Sacos Aéreos/parasitologia , Animais , Proteínas de Choque Térmico HSP70/genética , Especificidade de Hospedeiro , Larva , Reprodução , Estresse FisiológicoRESUMO
We investigated the spatial distribution and measured the hard parts of the attachment apparatuses and reproductive organs of the 2 eel-specific monogenean species Pseudodactylogyrus anguillae and Pseudodactylogyrus bini. Comparative analysis focused on parasite microhabitats within the gill apparatus. Additionally, we compared the morphometric characteristics of the monogeneans based on geographical locality and seasonality. The attachment apparatus and reproductive organ characteristics of the monogeneans were similar in all gill apparatus microhabitats. However, measurements differed significantly between localities and between seasons, with the results suggesting that abiotic factors play a larger role in determining parasite morphology than do the gill microhabitats.
Assuntos
Anguilla/parasitologia , Doenças dos Peixes/parasitologia , Brânquias/parasitologia , Trematódeos/anatomia & histologia , Infecções por Trematódeos/veterinária , Animais , Ecossistema , Água Doce , Letônia , Estações do Ano , Trematódeos/isolamento & purificação , Infecções por Trematódeos/parasitologiaRESUMO
Anguillicola crassus is a non-native parasite of the American eel, Anguilla rostrata. Since being introduced into North America, the nematode has spread rapidly across the range of A. rostrata, but paratenic hosts, which may facilitate parasite dispersion, have yet to be identified in the region. We investigated infection of larval A. crassus in 261 fish specimens belonging to 23 species and 12 orders collected from estuarine habitats in South Carolina (salinities 0-9 ppt) and Nova Scotia (10-18 ppt). A total of 35 fish belonging to 5 species and 3 orders were infected with the third-stage larvae (L3) of A. crassus, providing the first record of paratenic hosts for the parasite in North America. In South Carolina, high prevalence and abundance of the worm were found in spot (Leiostomus xanthurus), silver perch (Bairdiella chrysoura), and highfin goby (Gobionellus oceanicus), and a high prevalence but lower abundance was found in mummichog (Fundulus heteroclitus). In Nova Scotia, 2 nematodes were found in a single specimen of tomcod (Microgadus tomcod). All of the infected species are associated with a benthic lifestyle, and some of them are known to move between estuaries along the coastline. Lower infection rates in Nova Scotia may be associated with lower water temperatures and/or higher salinity of the sampling site. Most of the L3 were found encapsulated in mesenteric tissue around the intestine and stomach. No L4 or pre-adult worms were found. Mean body length of the L3 was smaller than L3 stages found in American eels from Cape Breton. This suggests that development of A. crassus is arrested at the L3 in the 5 fish species reported here, supporting their status as paratenic hosts.
Assuntos
Sacos Aéreos/parasitologia , Anguilla/parasitologia , Dracunculoidea/fisiologia , Doenças dos Peixes/parasitologia , Infecções por Spirurida/veterinária , Animais , Doenças dos Peixes/transmissão , Peixes , América do Norte , Rios , Infecções por Spirurida/parasitologia , Infecções por Spirurida/transmissãoRESUMO
The present study deals with morphological differences between two closely related parasitic nematode species (Anguillicola crassus Kuwahara et al., 1974 and Anguillicola novaezelandiae Moravec & Taraschewski, 1988) in two different experimentally infected eel species (Anguilla anguilla Linnaeus, 1758 and Anguilla japonica Temminck & Schlegel, 1847). Furthermore, it considers the question whether size differences between those two species are ontogenetically determined or host species-dependent. In order to analyse these questions, experimental infections with the four possible host-parasite systems have been performed, followed by precise morphometric measurements related to body size and head structures of all resulting nematodes 120 days post infection. Body size measurements (length and width) of A. crassus generally exceeded those of A. novaezelandiae, while both Anguillicola species turned out to be smaller in Japanese eels than in European eels. Comparative measurements of neck width, maximum oesophagus width, and posterior head end width were found to be highly significant with regard to the different host-parasite systems. Shape and width of neck have been identified as reliable discriminating factors for species distinction. Generally, the relation of anterior head end width and neck width proved to be distinctly species-specific and can thus serve as a decisive and easily measureable distinguishing feature.
Assuntos
Anguilla/parasitologia , Dracunculoidea/anatomia & histologia , Doenças dos Peixes/parasitologia , Infecções por Spirurida/veterinária , Animais , Feminino , Masculino , Especificidade da Espécie , Infecções por Spirurida/parasitologiaRESUMO
The effect of Anguillicola crassus, Pseudodactylogyrus bini and Pseudodactylogyrus anguillae infection on the behaviour of downstream migrating adult European eels Anguilla anguilla as they encountered accelerating water velocity, common at engineered structures where flow is constricted (e.g. weirs and bypass systems), was evaluated in an experimental flume. The probability of reacting to, and rejecting, the velocity gradient was positively related to A. crassus larval, adult and total abundance. High abundance of Pseudodactylogyrus spp. reduced this effect, but A. crassus was the strongest parasitic factor associated with fish behaviour, and abundance was positively related to delay in downstream passage. Delayed downstream migration at hydraulic gradients associated with riverine anthropogenic structures could result in additional energetic expenditure for migrating A. anguilla already challenged by A. crassus infection.
Assuntos
Anguilla/fisiologia , Anguilla/parasitologia , Doenças dos Peixes/parasitologia , Natação , Migração Animal , Animais , Comportamento Animal , Dracunculoidea , Larva , TrematódeosRESUMO
Most animals are concurrently infected with multiple parasites, and interactions among them may influence both disease dynamics and host fitness. However, the sublethal costs of parasite infections are difficult to measure and the effects of concomitant infections with multiple parasite species on individual physiology and fitness are poorly described for wild hosts. To understand the costs of co-infection, we investigated the relationships among 189 European eel (Anguilla anguilla) from Mar Menor, parasites (richness and intensity) and eel's 'health status' (fluctuant asymmetry, splenic somatic index and the scaled mass index) by partial least squares regression. We found a positive relationship with 44% of the health status variance explained by parasites. Contracaecum sp. (Nematoda: Anisakidae) was the strongest predictor variable (44·72%) followed by Bucephalus anguillae (Platyhelminthes: Bucephalidae), (29·26%), considered the two most relevant parasites in the analysis. Subsequently, 15·67 and 12·01% of the response variables block were explained by parasite richness and Deropristis inflata (Platyhelminthes: Deropristiidae), respectively. Thus, the presence of multiple parasitic exposures with little effect on condition, strongly suggests that eels from Mar Menor tolerate multiparasitism.
Assuntos
Anguilla/parasitologia , Doenças dos Peixes/epidemiologia , Interações Hospedeiro-Parasita , Infecções por Nematoides/veterinária , Infecções por Trematódeos/veterinária , Animais , Coinfecção , Doenças dos Peixes/parasitologia , Doenças dos Peixes/patologia , Análise dos Mínimos Quadrados , Nematoides/isolamento & purificação , Nematoides/fisiologia , Infecções por Nematoides/epidemiologia , Infecções por Nematoides/parasitologia , Infecções por Nematoides/patologia , Platelmintos/isolamento & purificação , Platelmintos/fisiologia , Espanha/epidemiologia , Infecções por Trematódeos/epidemiologia , Infecções por Trematódeos/parasitologia , Infecções por Trematódeos/patologiaRESUMO
The nematodes Anguillicola novaezelandiae and Anguillicola crassus are both alien parasites of the European eel with severe adverse effects on their new host. Both species differ in terms of their invasiveness and their severity of harmful effects on the European eel. The purpose of this study was to determine under laboratory conditions whether stages of A. novaezelandiae induce stress in European eels (Anguilla anguilla) and if these levels differ from stress levels induced by A. crassus. We analysed levels of plasma cortisol and hepatic hsp70 of eels experimentally infected with A. novaezelandiae and compared them to uninfected eels as well as to eels experimentally infected with A. crassus. Larval stages of A. novaezelandiae induced higher levels of plasma cortisol compared to uninfected controls, while adult parasites increased the levels of hepatic hsp70 above those of uninfected controls. The eels' cortisol response is induced by larval stages of A. novaezelandiae, while adult stages elevate levels of hepatic hsp70. Levels of stress induced by A. novaezelandiae are comparable to those induced by A. crassus.
Assuntos
Anguilla/parasitologia , Dracunculoidea/fisiologia , Doenças dos Peixes/parasitologia , Proteínas de Choque Térmico HSP70/sangue , Hidrocortisona/sangue , Infecções por Spirurida/veterinária , Anguilla/metabolismo , Animais , Dracunculoidea/crescimento & desenvolvimento , Doenças dos Peixes/metabolismo , Proteínas de Peixes/metabolismo , Larva , Fígado/metabolismo , Infecções por Spirurida/metabolismo , Infecções por Spirurida/parasitologia , Estresse FisiológicoRESUMO
A total of 80 specimens of the European eel Anguilla anguilla were collected during the period from February 2013 to March 2014 at the coast of the Gulf of Suez (Red Sea, Egypt). A new species of parasitic nematodes was recovered and described as Cucullanus egyptae. It was found in the eel's intestine with a prevalence of 68.7%. The morphology of the recovered parasite was studied by light and scanning electron microscopy. The adult worms had a wide cephalic extremity with a slit-like oral aperture being surrounded by a cuticular ring and delimited internally by a row of small teeth in addition to four sub-median cephalic papillae and one pair of lateral amphids. Body measurements showed that the male worms were smaller than females measuring 7.5-8.9 mm (8.3 ± 0.2) in length and 1.6-1.9 mm (1.8 ± 0.1) in width. Females measured 12.9-13.5 mm (13.1 ± 0.2) in length and 2.9-3.2 mm (3.1 ± 0.1) in width. The posterior end of the males is provided with ten pairs of caudal papillae and two long spicules which are slightly sclerotized, equal in size measuring 0.59-0.65 mm (0.62 ± 0.01) in length. Comparing the present worms with other species of the genus Cucullanus, several similarities were observed. However, peculiar new characteristics such as the precloacal sucker (especially the spicula length), the arrangement and the distribution of the post-cloacal papillae, and the position of the excretory pore make it reasonable to describe a new species. The sequence data of the small subunit (SSU) ribosomal DNA (rDNA) obtained from the present nematode supported its taxonomic position within the genus Cucullanus. The new species is closely related to the first clade of Spirurina and even more closely related to Cucullanus dodsworthi as a sister taxon with a high percentage of identity. The sequence of the recorded SSU rDNA of this parasite is deposited in the GenBank with the accession no. KF681520. It is proposed to name the new species C. egyptae as the first representative of Cucullanidae in Egypt with a new host record.