Abundance Of Parasite Species Research Articles

The hidden threat: Exploring the parasite burden and feeding habits of invasive raccoon dogs (Nyctereutes procyonoides) in central Europe

Originally from Asia, the raccoon dog Nyctereutes procyonoides is an invasive alien species in Europe, listed since 2019 on the List of invasive alien species of Union concern. The raccoon dog is considered to have negative impact on native biodiversity, as well as a crucial role in hosting and transmitting diverse parasites and pathogens of human and veterinary importance. In the present study, stomach content analyses and parasitological examinations were performed on 73 raccoon dogs from Germany. In addition, fecal samples were analyzed. The results of the study confirm the assumption that the examined raccoon dogs were infested with a various ecto- and endoparasite fauna. A total of 9 ecto- and 11 endoparasites were detected, with 6 of the endoparasites having human pathogenic potential. Trichodectes canis (P = 53.42%), Toxocara canis (P = 50.68%) and Uncinaria stenocephala (P = 68.49%) were the most abundant parasite species. The stomach contents consisted of approximately one-third vegetable and two-thirds animal components, composed of various species of amphibians, fish, insects, mammals and birds. Among them were specially protected or endangered species such as the grass frog Rana temporaria. The study shows that the raccoon dog exerts predation pressure on native species due to its omnivorous diet and, as a carrier of various parasites, poses a potential risk of infection to wild, domestic and farm animals and humans.

Seasonal Parasitic Contamination of Vegetables Marketed in Bori Central Market, Khana Local Governemnt Area, Rivers State, Nigeria

Seasonal parasitic contamination of vegetables marketed in Bori central market, Khana Local Government Area, Rivers State, Nigeria was investigated. A total of 80 vegetable samples, (40 samples each during the rainy and dry season respectively) were purchased from the Bori central market. The vegetable samples were examined in the laboratory for the presence of intestinal parasites using sedimentation techniques and microcopy. The results revealed that out of 80 vegetable samples (20 samples of each vegetable type and 40 samples each for rainy and dry seasons) examined, an overall prevalence of 41(51.3%) was recorded. Out of the 40 samples of vegetable each examined during the rainy and dry seasons, 23(57.5%) and18(45.0%) samples were positive for intestinal parasites during the rainy and dry seasons respectively. Across the two seasons, intestinal parasites belonging to four genera were identified. The genera were Ascaris, Giardia, Ancylostoma and Trichuris. A total of 23 intestinal parasites were identified during the rainy season (Ascaris 13/23(56.3%), Giardia 3/23(13.1%), Ancylostoma 4/23(17.4%) and Trichuris 3/23(13.1%) while a total of 18 parasites were extracted from the vegetables during the dry season (Ascaris 9/18(50%), Giardia 1/18(5.5%), Ancylostoma 3/18(16.7%) and Trichuris 5/18(27.8%). Carrot and tomatoes were the most statistically (P>0.05) contaminated vegetables in the rainy and dry seasons respectively. All species of parasites identified have a high relative abundance in the rainy season than in the dry season. Ascaris sp. (56.5%) was the most abundant species of parasite in the rainy season, followed by Ancylostoma sp. (10.0%), Giardia sp. (7.5%) and Trichuris sp. (7.5%). In the dry season, Ascaris sp. had the most relative abundance (50.0%), followed by Trichuris sp. (27.8%), Ancylostoma sp. (7.5%) and Giardia sp. (2.5%). There was a statistically significance difference (P<0.05) in the relative abundance of parasite species in the rainy and dry seasons. The high level of parasitic contamination of vegetables recorded in the study area is a public health concern and demands serious intervention especially in areas of health education on personal hygiene, sanitation and the danger of consumption of improperly washed vegetables, provision of sanitary facilities, mass deworming, open defecation and use of waste water for fertilizer.

Comparative analysis of the helminth fauna of Myotis brandtii and Myotis mystacinus (Сhiroptera, Vespertilionidae) in the Samarskaya Luka National Park (Russia)

The article presents the comparative analysis of the helminth fauna of the sympatric bat species, Myotis mystacinus and M. brandtii (Chiroptera, Vespertilionidae), in the Samarskaya Luka National Park (Russia). Twelve species of parasites were recorded in both bat species in 2005–2007, including nine species of Trematoda, one species of Cestoda, and two species of Nematoda. All of these 12 species were noted in M. brandtii. The helminth fauna of M. mystacinus included a slightly depleted parasite fauna of M. brandtii being represented by seven species of parasites found in M. mystacinus, including six species of Trematoda and one species of Cestoda. The helminth fauna of both bat species has a moderate level of the fauna similarity. Differences in the infection level of the two bat species are found in both number of helminth species and quantitative rates of the helminth fauna. Helminth infection of M. brandtii is significantly higher than of M. mystacinus. The helminth fauna of M. mystacinus and M. brandtii is driven by the bat lifestyle and diet. Both bat species are being infected by helminths through food items. The broader diet composition of M. brandtii and its feeding on a wider number of insect groups increases the infection probability of this bat species by rare and accidental parasites, and it also increases the infection rates by obligate species of trematodes. Therefore, M. brandtii has a more diverse helminth fauna and a higher number of abundant parasite species as well. The diet of M. mystacinus contains a limited number of food items. This reduces the probability of its infection by several helminth species and, on the other hand, it causes a relatively high infection rates for some trematode species. The similarity of helminth faunas of M. brandtii and M. mystacinus is caused by the use of the same feeding habitats and the similarity of their diet. The obtained data confirm the partial overlap of spatial and trophic niches of the two studied bat species.

Parasitological Records of Eight Rockfish Species (Scorpaeniformes: Scorpaenidae) from Pacific Baja California, Mexico

This study reports parasitological records of eight species of marine rockfishes (Sebastes auriculatus, S. chlorostictus, S. umbrosus, S. miniatus, S. atrovirens, S. constellatus, S. serranoides, and Scorpaena guttata) collected from Todos Santos bay and San Quintin coast, Baja California, Mexico. The vermilion rockfish, S. miniatus, showed the highest parasite species richness (two species of monogeneans, two species of digeneans, three species of nematodes and one species of copepods), while the lowest richness was found in S. atrovirens and S. umbrosus (one species of copepod and one species of nematode, respectively). The species S. auriculatus, S. chlorostictus, S. constellatus, S. serranoides, and S. guttata showed a richness of up to four parasite species. Seven of the eight fish species (except S. atrovirens) presented larval stages of nematodes Anisakis sp., Pseudoterranova sp. and Hysterothylacium sp. (prevalences ranging from 8.3 to 100%), which were found in the fish mesentery (guts). The parasite species with the highest prevalence values (>80%) were found in S. miniatus (Anisakis sp.), S. guttata (Anisakis sp. and Hysterothylacium sp.), S. umbrosus (Anisakis sp.), S. auriculatus (Anisakis sp.), and S. constellatus (Anisakis sp.). The most abundant parasite species (>4 ind./host) were recorded in S. guttata (Anisakis sp. and Hysterothylacium sp.), S. umbrosus (Anisakis sp.), S. constellatus (Parabothriocephalus sagitticeps), and S. miniatus (Anisakis sp.). The parasite species with the highest intensity of infection values (>5 ind./host) were found in S. constellatus (P. sagitticeps), followed by S. guttata (Anisakis sp., Hysterothylacium sp.), S. umbrosus (Anisakis sp.), and S. serranoides (Microcotyle sebastis). The present study, in addition to listing the helminths and parasitic copepod species (and providing quantitative data on them) of eight commercially important scorpaenid fish species in the northwestern Mexico, can also serve as a baseline for future parasitological studies on these fish species.

Parasite infection reflects host genetic diversity among non-native populations of pumpkinseed sunfish in Europe

Species introductions often coincide with loss of genetic diversity and natural enemies. Anthropogenic translocation of the North-American pumpkinseed Lepomis gibbosus (L., 1758) (Centrarchidae) and its further spread have resulted in recent species establishment in most European countries. This study determines genetic differentiation of non-native European pumpkinseed populations and identifies how their genetic structure relates to the distribution and abundance of parasite species. Microsatellite analysis indicated presence of three genetic lineages, which were well supported by discriminant analysis based on parasite abundance data. The first lineage clustered pumpkinseed populations from northern and southern France and showed high allelic richness, heterozygosity and parasite richness. The second included populations along the “Southern invasion corridor” connecting the rivers Rhine, Main and Danube. The fish exhibited low to high genetic and parasite diversity and generally high parasite abundance. The third lineage clustered populations with low genetic and parasite diversity, located in Portuguese reservoirs and water bodies along the upper Elbe. Parasite species richness was significantly associated with host microsatellite heterozygosity and allelic richness, a trend partially affected by richness of North-American parasites. Furthermore, our results indicate that parasite community composition may serve as a useful biological tool to discriminate non-native fish populations and their inter-relationships.

Diversity of Parasites from Xenopus Laevis (Amphibia: Pipidae) and their Seasonal Rate of Infection in Selected Habitats in the Limpopo Province, South Africa.

SummaryThis study determined the diversity and seasonality of parasites species of the African clawed frog, Xenopus laevis (Daudin, 1802), from three localities, namely Modjadjikloof, Mokopane and University of Limpopo, Limpopo Province, South Africa. A total of seven parasite species were collected and identified. They included two nematodes, Camallanus kaapstaadi Southwell & Kirshner, 1937 and Batrachocamallanus slomei (Southwell & Kirshner, 1937), a monogenean, Protopolystoma xenopodis (Price, 1943), a cestode, Cephalochlamys namaquensis (Cohn, 1906), a protozoan, Trichodina xenopodos Fantham, 1924, two digeneans, Progonimodiscus doyeri Ortlepp, 1926 and Dollfuschella rodhaini Vercammen-Grandjean, 1960. The most common and abundant parasite species by far were Cm. kaapstaadi, B. slomei and Cp. namaquensis, with Cm. kaapstaadi, B. slomei present in all localities. Trichodina xenopodos was a rare species, only present in host populations from Modjadjiskloof. Modjadjiskloof had the highest species richness (all seven parasite species) followed by Mokopane (five parasite species) and University of Limpopo (3 parasite species). There were also higher infection levels (prevalence and mean intensity) of Cm. kaapstaadi, B. slomei, Cp. namaquensis and Pt. xenopodis in hosts from Modjadjiskloof while Pd. doyeri and D. rodhaini infection levels were greater in Mokopane. The variability between localities shows that parasites with heteroxenous life cycles are more strongly associated with more pristine habitats. The variability in calculated indices (prevalence and mean intensity) also suggests that the occurrence of some of the parasites is affected by season, favouring higher infection rates during summer. This suggests that temperature has a direct role in the reproductive and developmental processes of these parasites. Neither length nor sex had an influence on the prevalence or intensity of parasites.

Parasite communities of striped bonito Sarda orientalis (Pisces: Scombridae) on the Pacific coast of Mexico

ABSTRACT The parasite communities of marine fish in the tropical Pacific remain poorly studied. We did an initial study of the metazoan parasite communities of striped bonito Sarda orientalis from the Pacific coast of Mexico. Two hundred thirty individuals from two locations were collected between April 2017 and March 2018. Twenty-two metazoan parasite taxa (20 helminths and two Crustacea) were identified: one species of Monogenea, twelve of Digenea, one of Acanthocephala, two of Cestoda, four of Nematoda, one of Copepoda, and one of Isopoda. Didymozoid digeneans (six species) were the most frequent and abundant parasite species at both sampling locations. Parasite species richness at the component community level was similar in both locations (16–17 species). However, parasite community structure and species composition varied between them. Local fluctuations in some biotic (e.g. host feeding behaviour and body size) and abiotic environmental factors were probably responsible for these variations.

Helminth metacommunity of small mammals in a Brazilian reserve: the contribution of environmental variables, host attributes and spatial variables in parasite species abundance

The role of environmental factors and landscape heterogeneity on species distribution on different spatial scales is one of the most important questions in community ecology. Variations in the environmental gradient characteristics, host attributes and spatial scales may influence the parasites distribution. The helminth metacommunity of 12 small mammal species was investigated in an Atlantic Forest reserve located in the State of Rio de Janeiro, southeast Brazil. We evaluated the influence of environmental variables, host attributes and spatial factors on the helminth metacommunity of small mammals, considering infracommunity and component community levels. Twenty-nine helminth morphospecies were recovered. The host attributes and spatial variables influenced the abundance of helminth species in the metacommunities for rodents and marsupials together, and for rodents alone at the infracommunity level. Host body mass, host diet and spatial variables at broad spatial scale (among localities) were the most important variables to explain the variation in helminth abundance. Parasite species richness influenced this variation only for the marsupial helminth metacommunity at the infracommunity level. The metacommunity showed larger turnover (parasite replacement) than nestedness (parasite loss) for their helminth species at both infracommunity and component community levels, which is associated with a high host specificity, and low helminth sharing among hosts for most species, resulting in a structured metacommunity.

Helminth fauna of Passer domesticus (Passeriformes: Passeridae) in the southern extreme of Brazil

The objective of this study was to report helminth parasite species of Passer domesticus (Linnaeus, 1758) (sparrow) and to analyze infection rates in relation to total length, body mass and sexual gender of hosts. Each of the 100 sparrows caught in the urban area of Pelotas, Rio Grande do Sul, Brazil, was weighed, measured, submitted to euthanasia and necropsied for collection of helminths. The helminths and their respective prevalence were: Synhimantus (Dispharynx) nasuta (2%), Aproctella sp. (1%) (Nematoda), Prosthogonimus ovatus (8%), Eumegacetes sp. (2%), Tanaisia zarudnyi (4%) (Digenea), Choanotaenia passerina (26%) (Cestoda), and Mediorhynchus sp. (2%) (Acanthocephala). The prevalence and mean intensity of infection of the C. passerina between male and female hosts did not present significant differences, and there was no correlation between the abundance of parasite species, body mass and total length of the sparrows. The helminth fauna of P. domesticus has remained the same throughout the propagation of this bird for new geographical areas and ecosystems, with the exception of the nematode Aproctella sp., found for the first time parasitizing this host.

Biological drivers of individual-based anuran-parasite networks under contrasting environmental conditions.

Understanding the mechanisms driving host-parasite interactions has important ecological and epidemiological implications. Traditionally, most studies dealing with host-parasite interaction networks have focused on species relationship patterns, and intra-population variation in such networks has been widely overlooked. In this study, we tested whether the composition of parasite communities of five anuran species (Leptodactylus chaquensis, Leptodactylus fuscus, Leptodactylus podicipinus, Pseudis paradoxa and Pithecopus azureus) vary across a pasture pond and a natural reserve site in south-eastern Pantanal, Brazil. We analysed the structure of individual-based networks of these five anuran species, assessed the species roles in the networks and the contribution of host species and body size to interaction strength in the networks, and tested if network ecological attributes varied between the two sites. We observed a total of 17 parasite morphospecies in 151 individual anurans and found that the abundance of parasite species tends to vary, with host species being the main filter driving parasite community structure. The composition of core parasite species remained similar between study sites, and network structure (i.e. parasite richness, interaction diversity, specialization, nestedness and modularity) did not change between pasture and natural reserve. Individual traits of hosts influenced network descriptors since larger hosts presented greater interaction strength independent of the study site. In short, we found that the occurrence of highly connected parasite taxa in both the pasture and the reserve sites may have promoted similarity in network structures, and host body size was the best predictor of associations with parasites in both study sites.

Interannual variation in the metazoan parasite communities of bigeye trevally Caranx sexfasciatus (Pisces, Carangidae).

Parasite communities in Caranx sexfasciatus were characterized and analyzed to determine any interannual variations in structure and/or species composition. In total, 422 C. sexfasciatus were collected from Acapulco Bay, Mexico, between May 2016 and March 2019. Thirty-two taxa of metazoan parasites were identified: five Monogenea, thirteen Digenea, one Acanthocephala, one Cestoda, three Nematoda, seven Copepoda, and two Isopoda. Monogeneans were the most frequent and abundant parasite species in all sampling years. Parasite species richness at the component community level varied significantly from 8 (May 2016) to 25 (March 2019) and was similar to previous reports for other species of Carangidae. The component communities and infracommunities in C. sexfasciatus were characterized by low parasite species numbers, low diversity, and dominance of a single species (the monogenean Neomicrocotyle pacifica). Parasite community structure and species composition varied between sampling years and climatic seasons. Seasonal or local fluctuations in some biotic and abiotic environmental factors probably explain these variations.

Trematode parasites associated with amphibians from a rice field in the northeastern Argentina

In altered environments, such as agricultural lands, studies of amphibian parasites can provide helpful information about the food web structure, parasite species abundance and composition, and environmental stress. Here, we investigate the parasitic digeneans in three amphibian families (Leptodactylidae, Bufonidae and Hylidae) in a rice field (30 ha) from Corrientes Province, Argentina. A total of 171 amphibian specimens were collected between March 2017 and February 2018. Amphibian trematode parasites in this area included 18 species, with dominance of common species. The trematode fauna was characterized by only one species (Choledocystus vitellinophillum) with high prevalence (>50%). The dominant adult species corresponded to Catadiscus propinquus for most of the hosts (80%), and when only larval trematodes were analyzed, the dominant metacercariae in most hosts (60%) were strigeids larvae. Of the total trematode individuals (n = 278), 57% corresponded to metacercariae that complete their life cycles mainly in birds. The amphibians Leptodactylus chaquensis and Lysapsus limellus presented high species richness. This is related to the microhabitats occupied by these hosts as well as with the biology of their parasites. Infection of all the trematode taxa for which larvae and adults were examined occurs through a sequence of trophic relationships. Finally, the results expand the knowledge of the biodiversity and ecology of parasite helminths in amphibians from agricultural landscapes; furthermore, this information is a fundamental baseline to quantify the loss of biodiversity and assess the health of the ecosystem.

Linking community assembly and structure across scales in a wild mouse parasite community.

Understanding what processes drive community structure is fundamental to ecology. Many wild animals are simultaneously infected by multiple parasite species, so host–parasite communities can be valuable tools for investigating connections between community structures at multiple scales, as each host can be considered a replicate parasite community. Like free‐living communities, within‐host–parasite communities are hierarchical; ecological interactions between hosts and parasites can occur at multiple scales (e.g., host community, host population, parasite community within the host), therefore, both extrinsic and intrinsic processes can determine parasite community structure. We combine analyses of community structure and assembly at both the host population and individual scales using extensive datasets on wild wood mice (Apodemus sylvaticus) and their parasite community. An analysis of parasite community nestedness at the host population scale provided predictions about the order of infection at the individual scale, which were then tested using parasite community assembly data from individual hosts from the same populations. Nestedness analyses revealed parasite communities were significantly more structured than random. However, observed nestedness did not differ from null models in which parasite species abundance was kept constant. We did not find consistency between observed community structure at the host population scale and within‐host order of infection. Multi‐state Markov models of parasite community assembly showed that a host's likelihood of infection with one parasite did not consistently follow previous infection by a different parasite species, suggesting there is not a deterministic order of infection among the species we investigated in wild wood mice. Our results demonstrate that patterns at one scale (i.e., host population) do not reliably predict processes at another scale (i.e., individual host), and that neutral or stochastic processes may be driving the patterns of nestedness observed in these communities. We suggest that experimental approaches that manipulate parasite communities are needed to better link processes at multiple ecological scales.

Validation of ITS-2 rDNA nemabiome sequencing for ovine gastrointestinal nematodes and its application to a large scale survey of UK sheep farms

We have validated ITS-2 rDNA nemabiome next-generation amplicon sequencing to determine relative species abundance of gastrointestinal nematode species in ovine fecal samples. In order to determine species representation biases, ITS-2 rDNA amplicon sequencing was applied to mock communities or field populations with known proportions of L3 for eight of the major ovine gastrointestinal nematode species: Teladorsagia circumcincta, Trichostrongylus vitrinus, Haemonchus contortus, Cooperia curticei, Trichostrongylus axei, Trichostrongylus colubriformis, Chabertia ovina and Oesophagostumum venulosum. Correction factors, calculated from this data, were shown to reduce species representation biases when applied to an independent set of field samples of known composition. We compared ITS-2 rDNA amplicon sequencing data that was generated from harvested eggs, freshly hatched L1 or L3 larvae following fecal culture and no statistically significant differences were found for the more abundant parasite species. We then applied the validated ITS-2 rDNA nemabiome amplicon sequencing assay to a set of archived L1 gastrointestinal nematode populations, collected in 2008 from fecal samples from 93 groups of 20 ewes and 61 groups of 20 lambs derived from 99 UK sheep farms. The presence of the major gastrointestinal nematode species had previously been determined on this large sample set by species-specific PCR. We show how the ITS-2rDNA amplicon sequencing data provided much more detailed information on species abundance than the previous species-specific PCR. This new data represents the most comprehensive overview of the relative abundance of the major gastrointestinal nematode species across UK sheep farms to date. Substantial variance in the relative abundance of both T. circumcincta and T. vitrinus between farms was revealed with the former species being of statistically significantly higher abundance in all three regions sampled (England, Scotland and Wales). The data also revealed that the relative abundance of T. circumcinta was statistically significantly higher in ewes than in lambs with the opposite pattern being the case for T. vitrinus. The nemabiome sequencing data also clearly illustrated the sporadic nature and skewed distribution of H. controtus across UK sheep farms as well as a higher relative abundance on farms from England compared to Wales and Scotland. The nemabiome survey also provides the first widescale data on the relative abundance of the two major large intestinal nematodes C. ovina and O. venulosum. This work validates ITS-2 rDNA nemabiome sequencing for use in sheep and illustrates the power of the approach for large scale surveillance of ovine gastrointestinal nematodes.

Metazoan parasite communities of the Pacific jack Caranx caninus (Pisces: Carangidae): exploring the variability of their parasite communities

ABSTRACTAn initial study was done of the metazoan parasite communities of Caranx caninus from the Pacific coast of Mexico. Parasite communities were characterised and analyses were done to determine if these experience spatial or temporal variations in structure and/or species composition. Four hundred ninety-two C. caninus were collected between April 2014 and December 2018 from four locations. Thirty-five metazoan parasite species were identified: 6 species of Monogenea, 12 Digenea, 1 Acanthocephala, 4 Nematoda, 10 Copepoda and 2 Isopoda. Monogeneans were the most frequent and abundant parasite species at all locations and in all years. Parasite species richness at the component community level varied significantly from 7 (San Blas 2017) to 22 (Acapulco 2018a). The component communities and infracommunities of C. caninus exhibited similar patterns: low species numbers, low diversity, and dominance by a single species (the monogenean Protomicrocotyle manteri). Parasite community structure and species composition varied between locations and/or sampling years. Seasonal or local fluctuations in biotic and abiotic environmental factors were probably responsible for these variations.

Metacommunity structure of the helminths of the black-eared opossum Didelphis aurita in peri-urban, sylvatic and rural environments in south-eastern Brazil.

Among the Brazilian marsupials, the species of the genus Didelphis are the most parasitized by helminths. This study aimed to describe the species composition and to analyse the helminth communities of the Atlantic Forest common opossum Didelphis aurita at infracommunity and component community levels using the Elements of Metacommunity Structure Analysis, considering peri-urban, sylvatic and rural environments in the state of Rio de Janeiro, Brazil. Seventy-three specimens of D. aurita were captured during the study. Fourteen species of helminths were collected: nine of the phylum Nematoda (Trichuris minuta, Trichuris didelphis, Globocephalus marsupialis, Heterostrongylus heterostrongylus, Travassostrongylus orloffi, Viannaia hamata, Aspidodera raillieti, Cruzia tentaculata and Turgida turgida); four of the phylum Platyhelminthes (three species of Trematoda, Duboisiella proloba, Brachylaima advena and Rhopalias coronatus, and one species of the class Cestoda); and one species of the phylum Acanthocephala (Oligacanthorhynchus microcephalus). More than 95% of the animals were infected with parasites. The most abundant parasite species were V. hamata, T. turgida, C. tentaculata and T. orloffi. The nematodes T. turgida, C. tentaculata and A. raillieti were the most dominant species in the three environments. The analysis of the metacommunity structure indicated a structured pattern as a function of the environmental gradient, but only when all localities were considered together. At the infracommunity and component community levels, quasi-nested and nested structures with stochastic species loss were observed, respectively. The results indicate that the settlement of helminth species in the opossums can be attributed to the heterogeneity among individual hosts in relation to their exposure to parasites and to extrinsic factors, which vary among habitats, considering a regional scale. On a local scale, the characteristics of this host species may promote homogenization among individual hosts in terms of their exposure to the helminths. This study constitutes a new host record for the species G. marsupialis and T. didelphis and represents a pioneering investigation of the helminth metacommunity of a Neotropical marsupial.

Structure of parasites community in Chaetobranchopsis orbicularis (Cichlidae), a host from the Amazon River system in northern Brazil.

The aim of this paper was to investigate the component communities of parasites in Chaetobranchopsis orbicularis from a tributary of the Amazon River system, in Northern Brazil. In 32 fish examined, 902,551 parasites were collected, including Ichthyophthirius multifiliis, Piscinoodinium pillulare, Sciadicleithrum geophagi, Posthodiplostomum sp., Clinostomum marginatum, Echinorhynchus paranensis, Neoechinorhynchus pterodoridis, and Dolops longicauda. I. multifiliis was the dominant and abundant parasite species. The ectoparasites presented aggregate dispersion, but the endoparasites showed random dispersion pattern. Mean species richness was 4.0±1.5 parasites, mean Brillouin diversity (HB) was 0.33±0.28, mean evenness was 0.15±0.13, and Berger-Parker dominance (d) was 0.85±0.17. The species richness of parasites and HB were positively correlated with the length of hosts. There was positive correlation between the abundance of P. pillulare and length and weight, between the abundance of I. multifiliis and weight, as well as between the abundance of E. paranensis and N. pterodoridis and the length of hosts. Body condition of the hosts was not affected by moderate parasitism. The low diversity of endoparasites indicates that C. orbicularis is a host with low position in the food web. This is the first record of all these parasites for C. orbicularis.

Divergence and parallelism of parasite infections in Arctic charr morphs from deep and shallow lake habitats

Parasite communities can show large differences in species composition between sympatric host species. Here, we assessed how divergent resource use of polymorphic populations of Arctic charr from two environmentally similar sub-arctic lakes was related to parasite community composition. Large similarities in parasite infections were found for both the reproductively isolated littoral-spawning omnivore LO-morph and the profundal-spawning benthivore PB-morph, reflecting cross-lake similarities in resource use. Furthermore, whereas the PB-morph had the lowest richness and abundance of parasite species in both lakes, a third morph, the profundal-spawning piscivorous PP-morph (one lake only), had the highest parasite richness and accumulated parasites by preying upon fish. These results highlight that host ecology and abiotic factors are important for structuring parasite communities. The dissimilarities in the local parasite species pool between the lakes suggest that stochastic events as well as transmission abilities are involved in structuring the parasite communities. The parallel divergent parasite infections between morphs may form an arena for parasite-mediated selection promoting the incipient speciation process in concert with other factors. The deep-water PB-morphs may avoid parasites by specialising in parasite-poor but low-productive habitats, while the piscivorous PP-morph aggregates infections of detrimental parasites through specialising on energetically rich but generally more heavily parasitised prey.

Larval Helminth Parasites of Fishes and Shellfishes from Santa Gilla Lagoon (Sardinia, Western Mediterranean), and Their Use as Bioecological Indicators

Qualitative and quantitative data of the larval stages of 30 helminth species infecting fish and shellfish in the Santa Gilla lagoon (southern Sardinia, western Mediterranean Sea) were collected and analysed to determine their usefulness as biological and ecological indicators. Parasitological data were collected from 2001 to 2011 from 12 fish species, from the families Anguillidae, Atherinidae, Cyprinodontidae, Gobiidae, Moronidae, Mugilidae, Soleidae and Sparidae and from bivalve molluscs of the families Cardiidae, Mytilidae and Veneridae. Digenean metacercariae dominated the larval parasitofauna; nevertheless, the most abundant parasite species was a nematode, i.e. the third-stage larvae of the anisakid Contracaecum rudolphii. Based on their life cycle, the species detected were divided into autogenic or allogenic parasites, which have fishes and birds/mammals as their definitive hosts, respectively. Data on the prevalence, intensity and abundance of infections and the parasitic diversity in each host species were combined with previous knowledge on the life history of the parasites detected, to build a model food web based on the different trophic relations, especially predator–prey interactions between hosts marked by the transmission of parasites. The results will contribute to the knowledge of species diversity and to the evaluation of general environmental changes occurring in brackish Mediterranean ecosystems. In combination with other analytic tools in a multidisciplinary approach, this will enable us to better understand the functioning of other Mediterranean brackish waters that are comparable to the Santa Gilla lagoon.

Geographical Patterns of Parasite Infracommunities in the Rough Scad, Trachurus lathami Nichols, in the Southwestern Atlantic Ocean

We assessed temporal variability in parasite infections of rough scad (Trachurus lathami) in 3 samples from Miramar (MI) in 2008, separated by periods of 1 mo, and 2 samples from Villa Gesell (VG), 1 each in 2008 and 2009 (Buenos Aires Province, Argentina), respectively. A sample was also obtained from Cabo Frio (CF) (Brazil) in 2009 to compare differences in parasite communities between fish from this locality and each Argentinean locality. All rough scad were parasitized by at least 1 of 27 parasite species. Similarity-based multivariate analysis revealed significant differences between localities, but temporal homogeneity in each Argentinean locality. Overall, prevalence and abundance of parasite species were most similar between samples from MI and VG, while the greatest differences occurred between samples from MI and CF. A canonical analysis of principal coordinates showed significant differences among samples. Grillotia carvajalregorum was the most important species in determining the position of Argentinean samples, especially those from MI, while Ectenurus virgulus , Raphidascaris sp., and Hysterothylacium sp. were the most important species related to fish from CF. The parasite assemblage of T. lathami showed a notable temporal persistence within the same locality and a high variability at the spatial scale, suggesting the existence of 3 independent stocks of T. lathami in South Atlantic waters.