Infracommunity Composition Research Articles

Strongylids of Domestic Horses in Eastern Slovakia: Species Diversity and Evaluation of Particular Factors Affecting Strongylid Communities

PurposeThis study aimed to examine the species diversity and structure of the strongylid community in domestic horses in Eastern Slovakia. Also, an analysis of the impact of age, sex, and collection location factors on the strongyid communities was performed.MethodsTwenty-seven horses 1.5–21 years old from two farms in eastern Slovakia with different horse-management conditions were studied. Strongylids were collected after horse treatments with Noromectin (0.2 mg ivermectin); 66,170 specimens were collected and identified. Faecal egg count reduction test (FECRT) was performed following fenbendazole (FBZ) and ivermectin (IVM) treatments.ResultsTwenty-four strongylid species were found; horses were infected with 6 to 16 (average = 11.7) species. Six cyathostomin species (Cylicocyclus nassatus, Cyathostomum catinatum, C. pateratum, Cylicostephanus longibursatus, C. goldi, C. calicatus) were the most prevalent; C. catinatum was the dominant species in both farms (Berger-Parker index 0.34 and 0.42). The structure of the strongylid community was multimodal with dominant, subdominant, background, and rare species. The Mantel test showed that horse age and sex did not significantly affect the nematode infracommunity composition (p > 0.05), while the impact of the collection location (farm) was significant (p = 0.03). Additionally, C. longibursatus was identified as the species contributing significantly to the observed farm differences. Strong resistance to FBZ was documented on both farms (FECRT was 36.4% and 22.7%); IVM resistance was not observed (FECRT = 100%).ConclusionThis study presents the first report on the strongylids parasitizing domestic horses in Eastern Slovakia and gives basic information for further studies of horse parasites and their control in the region.

Temporal variation of metacommunity structure in arthropod ectoparasites harboured by small mammals: the effects of scale and climatic fluctuations.

We applied the elements of metacommunity structure (EMS) approach and studied the temporal dynamics of metacommunity structure in arthropod ectoparasites (fleas, gamasid mites and ixodid ticks) harboured by six small mammalian hosts sampled for three decades in the same locality in Western Siberia at three hierarchical scales (inframetacommunities, component metacommunities and a compound metacommunity). All metacommunities were positively coherent. Inframetacommunity structures varied across sampling periods in all host species. The main structural pattern in an inframetacommunity of the same host varied across sampling times but was mostly characterized by clumped species distributions (Clementsian, Gleasonian and their quasi-versions). Component metacommunities in five of the six host species were characterized by either a Clementsian or a quasi-Clementsian distribution. In four of the six host species, this pattern was driven by mite distribution. The temporal structure of compound metacommunity was characterized by a Clementsian pattern. In contrast to the majority of component metacommunities, this pattern was driven by fleas, whereas the temporal structure of gamasid mite compound metacommunities demonstrated a Gleasonian distribution. The temporal gradient in infracommunity composition was not associated with temporal changes in either air temperature or precipitation, whereas the precipitation gradient was positively correlated with the structure of component (in five host species) and compound metacommunities. In conclusion, the best-fit metacommunity structure of ectoparasites varies temporally due to temporal changes in distribution patterns that can be associated with year-to-year climatic variation, affecting both hosts and parasites.

Gastrointestinal nematodes in two galliform birds from South Africa: patterns associated with host sex and age.

Parasite ecology has recently focused on elucidating patterns and processes that shape helminth communities in avian hosts. However, helminths parasitizing gamebirds are still poorly understood. Here we describe the gastrointestinal nematode fauna of Swainson's spurfowl, Pternistis swainsonii (Phasianidae) and helmeted guineafowl, Numida meleagris (Numididae), collected at three and four localities, respectively, in South Africa and analyze the prevalence, mean abundance and diversity of their helminth communities. Eleven nematode species were collected from spurfowl, which had a mean number of nematode species per host of 3.01 ± 0.18, whereas guineafowl harboured 15 nematode species, with a mean number of nematode species per host of 3.93 ± 0.12. Focusing on the most prevalent species, we also asked if host sex and/or age were associated with infracommunity structure with regard to nematode counts and species richness, as well as the species and taxonomic composition of infracommunities. While pooling data of nematode species masked the influence of host characteristics on helminth communities, analysis of individual nematode species revealed a number of patterns. In particular, adult female bias was seen in Tetrameres swainsonii in spurfowl and in Allodapa dentigera and Gongylonema congolense in guineafowl; Acuaria gruveli reached higher numbers in adult spurfowl than in juveniles, and helminth infracommunities in juvenile male guineafowl were more species rich than those in adult males. Combined, our results suggest that helminth communities of spurfowl and guineafowl are associated with a complex interplay of numerous factors, including host characteristics, parasite traits and environmental conditions.

Conspecific migration and environmental setting determine parasite infracommunities of non-migratory individual fish.

Parasite infracommunities tend to be stochastic in nature, although environmental characteristics such as the type of water source in streams and host traits can have an effect on the biotic assemblages and by extension the parasite fauna. We examined the effect of water source and the rate of adult fish migration on the metazoan parasite infracommunities of conspecific juvenile brown trout, Salmo trutta L. among streams flowing into Lake Lucerne (Switzerland). Juvenile (1 to 2-year old) fish harboured higher parasite species richness in groundwater-fed than in surface water-fed streams, whereas the rate of fish migration did not affect infracommunity richness. Heteroxenous species were more common in groundwater-fed streams with high and medium rates of trout migration, whereas infracommunities in surface water-fed streams and streams with low rates of fish migration were dominated by one monoxenous parasite or lacked infections. Similarity in the parasite infracommunity composition of juvenile trout across streams was explained by the interaction between type of water source and adult migration rates. Our conclusions support that similarity in the parasite composition of resident freshwater conspecifics can be predicted by the local environmental settings and host migratory behaviour, whereas parasite richness is mainly influenced by the environmental characteristics.

Spatial and temporal variation of compositional, functional, and phylogenetic diversity in ectoparasite infracommunities harboured by small mammals.

We studied patterns of compositional, functional, and phylogenetic α- and β-diversity in flea and gamasid mite infracommunities of small Siberian mammals, taking into account host-associated (species) and environmental (biome or sampling period) factors. We asked: (a) How do these factors and their interactions affect infracommunity diversity? (b) Does infracommunity composition, in terms of species, traits, and phylogenetic lineages, deviate from random? (c) Are species, traits, and phylogenetic lineages in infracommunities clustered or overdispersed?, and (d) Do patterns of diversity differ between the three diversity facets and/or the two ectoparasite taxa? We found that the α-diversity of infracommunities was strongly affected by host species, biome, and sampling period. The highest proportion of infracommunity diversity in both taxa was associated with the interaction between either host species and biome or host species and sampling period. Infracommunities of both taxa within, as well as between, host species, biomes, and sampling periods were characterized by the clustering of species, traits and lineages. The patterns of the effects of host species, biome, and sampling period on infracommunity diversity were congruent among the three diversity facets in both fleas and mites. We conclude that the assembly patterns in ectoparasite infracommunities mirror those characteristics of component and compound communities.

Parasites as indicators of fish population structure at two different geographical scales in contrasting coastal environments of the south-western Atlantic

Fish parasites are widely used as biological tags of stocks and populations of their hosts at large spatial scales, but less frequently at small geographical scales. The application of this methodology at small scales requires heterogeneity in the availability of infective stages of parasites and hosts with high site fidelity. Here we tested the value of parasite tags at both large and small spatial scales using the Argentine silverside, Odontesthes argentinensis (Valenciennes, 1835) as a model. This is a marine fish that can tolerate a wide range of salinities and has great phenotypic plasticity, which has promoted adaptive divergences at reduced spatial scales across populations, in the absence of geographical barriers isolating them, which could be reflected in their parasite assemblages. A total of 142 specimens were examined for parasites. Samples were collected at two close localities from each of two different biogeographical regions of the south-western Atlantic. The structure and composition of both parasite infracommunities and component communities were analysed through uni and multivariate statistics. All sites were significantly different in their infracommunity structure, even those that were at shorter distances from each other. However, infracommunity composition and component community structure showed higher similarities within each region than between samples from different ones. These results proved that fish parasites are valuable tools to assess fine-scale population structure of their hosts when site fidelity and adaptations to local conditions prevail. The inclusion of parasite indicators as complementary tools in such kind of studies can provide valuable evidence for those resources requiring stock assessments and management at fine-scale, in order to prevent negative impacts over exploited populations.

Seasonal and depth related variation of parasite communities of Notacanthus bonaparte Risso, 1840 (Notacanthiformes: Notacanthidae) over the northwest Mediterranean slope

In the last decades fishing activities have spread from coastal to deeper waters with serious effects on the deep-sea ecosystems and its fauna, which are considered to be highly susceptible to these impacts. The implementation of protection measures is necessary, but the knowledge on this biome is scant, and often limited to species of commercial value. To the best of our knowledge, this study is the first survey to describe and analyse parasite infracommunities of the deep-sea fish Notacanthus bonaparte sampled from three bathymetric strata between the upper and lower slope in the western Mediterranean Sea (Balearic Sea, Spain). The aim of this work was to assess the effect of host specific parameters as well as environmental conditions and spatial and temporal variation on the composition and structure of the parasite communities. We have found poor parasite infracommunities, usually described rather for bathypelagic fishes than observed in fishes with benthic feeding habits such as N. bonaparte, in which two out of five species are considered as accidental infections. The infracommunity composition is determined by the factors, depth and maturity status (size). The dominating taxon, cucullanid larvae, seem to be accumulated throughout the life of the host showing higher abundances in larger fish in deeper waters on the middle and lower slope. The prevalence and abundance of this parasite could be linked to increased water turbidity and it is supposed that these larvae are free-living in the sediment being ingested by N. bonaparte when feeding on benthic organisms. The results suggest that N. bonaparte acts as important intermediate host for this taxon though, the final host is still unknown. The single monogenean species Tinrovia mamaevi was mainly recorded in the upper slope and its higher prevalence in this depth range could be related to higher host densities observed in these depths. The prevalence and abundance of this parasite species could be linked to temperature and salinity, and although measured variations for these parameters were marginal it is supposed that these and probably further additional abiotic factors may influence its distribution pattern. Considering previously published diet data this study indicates potential pathways other than those expected for parasites transmitted via the food web using N. bonaparte as intermediate and definitive host.

Temporal changes and between-host variation in the intestinal parasite community of Arctic charr in a subarctic lake

The occurrence of trophically transmitted intestinal parasites in Arctic charr was analyzed from data material collected over two decades from Lake Takvatn, northern Norway. The main objectives were to investigate (i) between-year variation in parasite infracommunity composition, (ii) between-host variation in infracommunity composition, and (iii) possible interspecific interaction between parasites. The trematode Crepidostomum spp. and the cestode Eubothrium salvelini were most prevalent and had the highest mean intensities whereas the cestodes Proteocephalus sp. and Cyathocephalus truncatus were uncommon taxa. No clear indication of interspecific parasite interactions was evident. By far the most frequent infracommunity composition was E. salvelini co-existing with only Crepidostomum spp. Despite some indications of individual dietary specialization in Arctic charr, this strong species co-occurrence suggests that the majority of fish had been preying on the very different intermediate hosts of both parasites. Overall, even though some sporadic between-year variation was present, no long-term or cyclical variation in infracommunity composition and mean intensity was revealed, suggesting that the host–parasite system is in a steady state. Minor between-year variation was likely the result of changes in habitat and dietary utilization by Arctic charr, possibly linked to documented changes in the fish community structure of the lake.

Community structure of Diplostomum spp. (Digenea: Diplostomidae) in eyes of fish: Main determinants and potential interspecific interactions

Parasite communities in freshwater fish vary annually and seasonally and can be influenced by the length, age, sex and phylogeny of hosts, and by associations among parasite species. We assessed the influence of these factors in species of Diplostomum in the eyes of 828 fish in 20 different species collected in a single lake in early summer or autumn over a 5year interval. Strong negative associations were found between five pairs of Diplostomum spp. and associations were strongest among abundant species. Most interspecific associations occurred among species inhabiting the lens, suggesting competitive interactions. However, the strongest association occurred between two Diplostomum spp. that inhabit different tissues (i.e., the vitreous humour and lens), indicating processes other than direct competition. Seasonal variation was small compared with inter-annual variation. Infection intensities were high in 2006 and decreased dramatically in 2010 and 2011. Infracommunity composition and structure showed no clear correspondence to the ecology or phylogeny of host species. Host length and age, but not sex, had significant effects on the structure of Diplostomum infracommunities in lenses. However, a significant amount of variance in lens infracommunities could not be explained, indicating the potential importance of other factors such as resistance or exposure in determining infracommunity structure.

Spatial Structure of Helminth Communities in the Golden Grey Mullet, Liza aurata (Actinopterygii: Mugilidae), from the Western Mediterranean

Ecological investigations regarding the parasite fauna of grey mullets are scarce. The present study provides a detailed description of the helminth communities of Liza aurata in the Spanish western Mediterranean and analyzes the role of spatial, temporal, and host variables in shaping the infracommunities. In total, 204 fish were collected in 2 localities, situated ca. 290 km apart, in spring and fall of 2004 and 2005. A non-metric multidimensional scaling (NMDS) was used to visualize an ordination of the infracommunities according to their relative similarities in parasite abundances. The relationship between infracommunity composition and explanatory variables (host size, locality, year, and season of harvest) was examined by permutational analysis of variance (PERMANOVA) applied to species abundances. Permutational tests for homogeneity of multivariate dispersion were used to test the null hypothesis of no differences in dispersion among groups formed by the factors whose effects were significant in PERMANOVA. A total of 33,241 helminth parasites, belonging to 18 species, was collected, i.e., 12 species of adult digeneans (23% of the parasite specimens), 3 digeneans as metacercariae (68%), 1 acanthocephalan (2.1%), and 2 monogeneans (6.5%). An important part of this helminth fauna is specialized to grey mullets, with a sizable portion of the component community restricted to the Mediterranean and northeast Atlantic. The NMDS ordination indicated high heterogeneity among infrapopulations. However, most differences at both the component and infracommunity level were related to geographic locality. In fact, the PERMANOVA showed that, among the explanatory variables considered, sampling locality accounted for the largest share of variation. The geographical differences observed may be related to local environmental characteristics or to the limited spatial dispersal of the species forming the component community. The latter was supported by the significant portion of variation explained by a 3-way interaction term. Thus, the spatial structure of our helminth infracommunities seems to be determined by a combination of differences in local environmental conditions and the transmission ability of each species at small local and time scales.

Seasonal variation in parasite occurrence and microhabitat distribution of monogenean parasites of gudgeon Gobio gobio (L.)

Abstract Seasonal changes in occurrence, infracommunity composition and microhabitat distribution of the monogenean parasites of gudgeon Gobio gobio (L.) were studied during two years in the River Haná (Czech Republic). Altogether 212 specimens of gudgeon were examined and a total of 6456 specimens of eight monogenean species were recorded: Dactylogyrus cryptomeres, Gyrodactylus gobiensis, Gyrodactylus gobii, Gyrodactylus gasterostei, Gyrodactylus vimbi, Gyrodactylus markakulensis, Gyrodactylus sedelnikowi and Paradiplozoon homoion. The occurrence of monogeneans correlated with seasonal changes of water temperature. In 2001, gyrodactylids peaked in March and D. cryptomeres in May, whereas in 2002, gyrodactylids peaked in May and D. cryptomeres in July. The majority of specimens of all Gyrodactylus species were found on the fins; the remaining specimens of Gyrodactylus were located on the body surface and gills, and all Dactylogyrus and Paradiplozoon specimens were located on the gills. The microhabitat distribution of the monogeneans changed in relation to changing water temperature and intensity of infection.

Patterns of infracommunity species richness in eels, Anguilla anguilla.

Between October 1999 and October 2001, a total of 510 European eels Anguilla anguilla were captured in 13 different samples from the rivers Thames (five locations) and Test (one location) in southern England. The relationship between parasite component community species richness (CCR) and maximum infracommunity species richness (ICRmax) compared with that previously observed in bird and mammal hosts. Specifically, the maximum number of parasite species occurring in infracommunities equalled or exceeded half the number of parasite species in the component community at that time, across a wide range of CCR values (2-9 parasite species). Furthermore, the frequency distribution of infracommunity richness (ICR) suggested that the species composition of infracommunities is probably random. These findings suggest that intestinal macroparasite infracommunities in eels are unsaturated and potentially species rich assemblages and, in these respects, share a fundamental similarity with the infracommunities of birds and mammals.

Colonization and seasonality of goby (Gobiidae, Teleostei) parasites from the southwestern Baltic Sea

A comparative parasitology study of gobiid fishes from two sites on the western Baltic Sea was done to get information on the quality of the respective environments. The parameters used were the infracommunity, the species numbers and abundance with respect to the size classes of the hosts, and the abundance with respect to the seasons. The hosts, Gobius niger, Gobiusculus flavescens, Pomatoschistus minutus, and P. pictus, were caught at Blank Eck (Kiel Bight) and Dahmeshöved (Lübeck Bight) during 1992 and 1993. The infracommunities of Dahmeshöved attained higher rates of prevalence of helminth parasites than did those of Blank Eck, as was valid in all host specimens harboring one or two parasite species. The group bearing three parasite species was present in Dahmeshöved but absent in Blank Eck. Parasite species numbers, which were similar in the two sites, increased from the smallest to the largest hosts but changed with growth. With one exception, this result is also valid for the abundance, which clearly differed between the hosts and between the sites. Whereas species numbers as well as abundance rates were low in spring, they increased in summer. The results reveal that the composition of infracommunities depends on the local parasite fauna and on the strength of general host defense mechanisms, whereas that of the component community is dependent on the susceptibility of hosts to single parasite species and on the density of intermediate parasite stages. This is also the reason for the stronger infestation of hosts from Dahmeshöved as opposed to those from Blank Eck, where the degree of eutrophication is lower and, therefore, fewer herbivorous intermediate hosts can exist.