Component Community Research Articles

Decomposing biodiversity data using the Latent Dirichlet Allocation model, a probabilistic multivariate statistical method.

We propose a novel multivariate method to analyse biodiversity data based on the Latent Dirichlet Allocation (LDA) model. LDA, a probabilistic model, reduces assemblages to sets of distinct component communities. It produces easily interpretable results, can represent abrupt and gradual changes in composition, accommodates missing data and allows for coherent estimates of uncertainty. We illustrate our method using tree data for the eastern United States and from a tropical successional chronosequence. The model is able to detect pervasive declines in the oak community in Minnesota and Indiana, potentially due to fire suppression, increased growing season precipitation and herbivory. The chronosequence analysis is able to delineate clear successional trends in species composition, while also revealing that site-specific factors significantly impact these successional trajectories. The proposed method provides a means to decompose and track the dynamics of species assemblages along temporal and spatial gradients, including effects of global change and forest disturbances.

Helminth communities of Xiphophorus malinche (Pisces: Poeciliidae), endemic freshwater fish from the Pánuco River, Hidalgo, Mexico

A total of 141 highland swordtails, Xiphophorus malinche, were collected from 2 localities in the Pánuco river drainage (Chicayotla and Malila) from Hidalgo, México. The parasite community structure of the 2 localities was examined and compared. Five taxa of helminths were recovered: 2 digeneans, adults of Paracreptotrema sp. and metacercariae of Uvulifer sp.; an adult monogenean, Urocleidoides vaginoclastrum; an adult cestode, Bothriocephalus acheilognathi, and an adult nematode, Rhabdochona xiphophori. Among them, Ur. vaginoclastrum was the most frequent and abundant species. The remaining species were rare and found at low mean abundance. Only 2 species of helminth were found at both localities. The observed species richness, individual abundance, and diversity were low at component community and infracommunity levels. Abundance of helminths and fish standard length were correlated. Uvulifer sp. was more abundant in small fish, but Ur. vaginoclastrum showed the opposite pattern, high abundance in larger fish. Differences observed in this study can be attributed to abiotic and biotic environmental factors resulting from the geographic separation of these localities during to the orogeny of the Sierra Madre Oriental that restricted fish to isolated headwaters.

Metazoan parasite communities of catfishes (Teleostei: Siluridae) in Benin (West Africa).

The need for more precise information on the effect of dry season on fish parasite communities in Benin lead us to undergo a focus during this season in one of the major sites of collection fry by fish farmers.Metazoan parasites were then inventoried in 166 specimens of catfishes which constituted of C larias gariepinus, Clarias ebriensis, Synodontis schall, Synodontis nigrita, and Chrysichthys nigrodigitatus (Teleostei: Siluridae). Those fishes were collected from fishermen of Agonlin-Lowé at the side of Oueme River in south Benin from November 2011 to March 2012. In total, 12 parasite species were listed comprising three Monogena (Gyrodactylus sp., Synodontella sp., and Protoancylodiscoides chrysichthes), three Cestoda (Stoeksia pujehuni, Lytocestus sp., and Cestode indeterminate), five Nematoda (Paracamallanus cyathopharynx, Procamallanus laevionchus, Cithariniella petterae, Synodontisia thelastomoides, and nematode indeterminate), and one indeterminated Copepod species. Total infestation rate varied between 83.87 and 100% for the different fish species. This was high but independent of fish sex (χ(2) = 1.669, df = 4, nonsignificant). The highest mean intensity and mean abundance were, respectively, 44 and 13.33. Monogenea and Nematoda have elevated frequency of dominance, and their presence in the host is significantly correlated (r = -0.999; p < 0.05). Clariids were highly infected by Nematoda. Except for P. laevionchus and Proteoancylodiscoides, respectively, in C. gariepinus and in C. nigrodigitatus, the parasites showed clumped distribution. The component community diversity, as measured by the Shannon index (H'), revealed that S. schall had the most parasite diversity.

Community structure analysis of endoparasitic helminths of Anabas testudineus from unpolluted and polluted sites of a freshwater body of Dhaka

Community structure of metazoan endoparasites of Anabas testudineus collected from an unpolluted and a polluted water body was determined. Out of 100 A. testudineus observed, 78% was parasitized by at least one species of endohelminth parasite. Eight metazoan endoparasites were recorded. Nematode showed higher prevalence than trematode. One species was accounted as satellite species and others as secondary. Larger hosts were more abundantly infected than the smaller ones as positive correlation was observed between the standard length of the hosts and the abundance/ prevalence of all parasites. Maximum parasite species followed a typical overdispersed type of distribution pattern. Parasite species richness was lower in fish from polluted (4) than unpolluted water (6). Per cent similarity of infestation between the sample hosts was high (55.73%). Three common parasite species from both sample hosts showed insignificant difference in intensity of infestation in relation to host habitat. Host sex had influenced infestation at infra?community but not at component community level. Interspecies association between parasites was strong in fish from unpolluted in comparision from polluted water. Host’s habitat quality also played an influential role in building parasite community, diversity and other associated community indices. DOI: http://dx.doi.org/10.3329/dujbs.v23i1.19823 Dhaka Univ. J. Biol. Sci. 23(1): 27-38, 2014

Urbanization breaks up host-parasite interactions: a case study on parasite community ecology of rufous-bellied thrushes (Turdus rufiventris) along a rural-urban gradient.

Urbanization drastically alters natural ecosystems and the structure of their plant and animal communities. Whereas some species cope successfully with these environmental changes, others may go extinct. In the case of parasite communities, the expansion of urban areas has a critical effect by changing the availability of suitable substrates for the eggs or free-larval stages of those species with direct life cycles or for the range of hosts of those species with complex cycles. In this study we investigated the influence of the degree of urbanization and environmental heterogeneity on helminth richness, abundance and community structure of rufous-bellied thrushes (Turdus rufiventris) along a rural-urban gradient in the metropolitan region of Porto Alegre, State of Rio Grande do Sul, Brazil. This common native bird species of southern Brazil hosts 15 endoparasite species at the study region. A total of 144 thrushes were collected with mist nets at 11 sites. The degree of urbanization and environmental heterogeneity were estimated by quantifying five landscape elements: buildings, woodlands, fields, bare lands, and water. Landscape analyses were performed at two spatial scales (10 and 100 ha) taking into account home range size and the potential dispersal distance of thrushes and their prey (intermediate hosts). Mean parasite richness showed an inverse relationship with the degree of urbanization, but a positive relationship with environmental heterogeneity. Changes in the structure of component communities along the rural-urban gradient resulted from responses to the availability of particular landscape elements that are compatible with the parasites' life cycles. We found that the replacement of natural environments with buildings breaks up host-parasite interactions, whereas a higher environmental (substrate) diversity allows the survival of a wider range of intermediate hosts and vectors and their associated parasites.

Size, time, and asynchrony matter: the species-area relationship for parasites of freshwater fishes.

The tendency to attribute species-area relationships to "island biogeography" effectively bypasses the examination of specific mechanisms that act to structure parasite communities. Positive covariation between fish size and infrapopulation richness should not be examined within the typical extinction-based paradigm, but rather should be addressed from the standpoint of differences in colonization potential among individual hosts. Although most mechanisms producing the aforementioned pattern constitute some variation of passive sampling, the deterministic aspects of the accumulation of parasite individuals by fish hosts makes untenable the suggestion that infracommunities of freshwater fishes are stochastic assemblages. At the component community level, application of extinction-dependent mechanisms might be appropriate, given sufficient time for colonization, but these structuring forces likely act indirectly through their effects on the host community to increase the probability of parasite persistence. At all levels, the passive sampling hypothesis is a relevant null model. The tendency for mechanisms that produce species-area relationships to produce nested subset patterns means that for most systems, the passive sampling hypothesis can be addressed through the application of appropriate null models of nested subset structure.

Dynamics of parasite communities in an age series of Baikal omul Coregonus migratorius (Georgi, 1775)

Parasite communities of Baikal omul from Chivyrkuiskii Bay of Lake Baikal have been analyzed at levels of a host individual (infracommunity), a separate age group of a host (set of infracommunities), and a host population (component community). Significant positive correlations of parameters of species richness (number of parasite species, Margalef and Menhinick indices) with the age of Baikal omul were recorded only at the level of parasite infracommunities. The absence of linear positive correlations between the parameters of species richness and the age of Baikal omul at the level of sets of parasite infracommunities were revealed for the first time for fishes of Lake Baikal. The peculiarity of the dynamics of parasite communities of Baikal omul is determined by specific features of the host physiology and ecology, primarily by the age dynamics of the feeding spectrum.

Richness and diversity of helminth species in eels from a hypersaline coastal lagoon, Mar Menor, south-east Spain

The composition and diversity of parasite communities and intestinal components, as well as infra-community structure, were assessed in eels Anguilla anguilla, from Mar Menor, a permanent Mediterranean hypersaline coastal lagoon. Data were used to determine whether this helminth community differs in composition and structure from that of eels in lagoons with lower salinity regimes and higher freshwater inputs. A total prevalence of 93% was detected. Specifically, parasites were identified as Deropristis inflata, Bucephalus anguillae, Contracaecum sp., Anguillicoloides crassus and two plerocercoid larvae belonging to theorder Proteocephalidae, the marine species representing 91% of the isolated helminths. In the total community, digenetic trematodes were the dominant group of helminths, and D. inflata, an eel specialist, dominated both the component community and the infra-community. Richness and diversity were low but similar to those reported in other saline lagoons, and maximum species per eel did not exceed four. At the infra-community level, higher abundance than in other brackish or marine Mediterranean environments was detected. The findings provide further evidence of the similarity in composition and structure of helminth communities in eels from various Mediterranean coastal lagoons. Moreover, salinity-dependent specificities are well supported and reflect the life history of individual eels.

The communities of helminth parasites ofHeterandria bimaculata(Teleostei: Poeciliidae) from the upper Río La Antigua basin, east-central Mexico show a predictable structure

We investigated a basic generalization in parasite community ecology stating that stochastic processes played a major part in determining the composition of helminth communities of freshwater fish, or on the contrary, if these communities are predictable, diverse and structured species assemblages. We determined the species pool of helminth parasites of a tropical freshwater fish Heterandria bimaculata in its heartland, the upper Río La Antigua basin in east-central Mexico. Approaching our data from the metapopulation standpoint we studied the spatial patterns, and examined the variation in composition and richness of the component communities across different locations. We tested the prediction that helminth species may be recognized as common or rare; and also two hypotheses anticipating depauperate communities and decay of similarity between component communities with increasing distance. We found these communities composed by a highly structured and predictable set of specialist autogenic helminth species that are constant and abundant, dominating all components throughout space. The prediction that it is possible to recognize common and rare species was met. Richer than expected communities were found, as well as highly homogeneous component communities, where neighbouring components were more similar than distant ones. We speculated that the processes shaping the development of these component communities include stable, predictable habitats through time, allowing for a slow gradual dispersion process limited by host and parasite species capabilities. Our study suggests that metapopulation theory can assist in the prediction of community composition and in the understanding of spatial and temporal community variability.

The Use of Traditional Microfinance Method as an Innovative Approach to the Development of Obizi Regional Water Supply Scheme in Aguata, Nigeria

The aim of this study was to assess the use of traditional microfinance method as an innovative approach to the development of Obizi Regional Water Supply Scheme in Aguata, Nigeria. Towards achieving the aim, data were generated through the use of questionnaire between January and April 2013 and others from secondary sources. Some of the variables employed are amount of money contributed monthly through microfinance approach for the development and extension of the scheme, the population of water consumers in the area, government assistance, daily water consumption amount, cost of developing water infrastructure etc. Data were analysed by the use of factor scores from the Principal Component Analysis to establish the performance of this innovation in all the component communities that benefited from the water scheme. Principal Component Analysis (PCA) output revealed that the innovation is performing well in some communities but not in some others. Suggestions recommended include persistent mobilization of community members, better method of loan distribution and involvement of women in the microfinance processes etc.

Ecology and seasonal variation of parasites in wild Aequidens tetramerus, a Cichlidae from the Amazon

This study is the first investigation on seasonal dynamics of parasites component community of the Aequidens tetramerus from an Amazon River tributary, in Northern Brazil. A total of 239,2407 parasites were recovered from 92 hosts examined from February to October 2011. Such parasites included Ichthyophthirius multifiliis, Tripartiella tetramerii and Trichodina nobilis (Protozoa), Dolops longicauda (Argulidae), Gussevia alioides, Gussevia disparoides (Monogenoidea), Digenea metacercarie, Pseudoproleptus larvae, Anisakidae larvae (Nematoda), Proteocephalidea plerocercoid (Eucestoda) and Gorytocephalus spectabilis (Acanthocephala). Ciliates were the most dominant and abundant taxon, while cestodes were the least prevalent. The parasites showed seasonal variation in their infection dynamics associated with environmental changes during the Amazonian drainage season, except the infection with I. multifiliis. The parasites community in A. tetramerus was also characterized by higher diversity, species richness and uniformity during the drainage season when compared to Amazon flood season. With the exception of T. tetramerii, these parasite species are new records for A. tetramerus.

&lt;b&gt;Parasites in &lt;i&gt;Curimata cyprinoides&lt;/i&gt; (Characiformes: Curimatidae) from eastern Amazon, Brazil&lt;/b&gt; - doi: 10.4025/actascibiolsci.v35i4.19649

This work is the first study on parasitic fauna of Curimata cyprinoides Linnaeus, 1766 (Curimatidae) and the host-parasite relationship. The total of 154,740 parasites such as Ichthyophthirius multifiliis (Ciliophora), trophozoite of Spironucleus sp. (Hexamitidae), Urocleidoides sp. (Monogenoidea), Digenea gen. sp. and Polymorphus sp. (Polymorphidae) were collected. The component community showed low diversity (HB = 0.004 ± 0.020) and parasite species richness (1.4 ± 0.6). However, I. multifiliis and Urocleidoides sp. were prevalent and with higher intensity on the host population and also aggregated the distribution pattern. The occurrence of these ectoparasites in C. cyprinoides may be a consequence of its alimentary diet. Positive correlation between the abundance and size of I. multifiliis and the relative condition factor of the host were observed and discussed. These data represent increased knowledge of the biology of these parasites. Furthermore, this study expanded the geographic distribution of some parasite species for this new host from Brazil.

Extrinsic- and intrinsic-dependent variation in component communities and patterns of aggregations in helminth parasites of great cormorant (Phalacrocorax carbo) from N.E. Poland

In the present study, we investigate the effect extrinsic (habitat and season) and intrinsic (host’s age and sex) factors on the richness, diversity, and structure of parasite component communities and aggregation patterns in the helminth fauna of the great cormorant Phalacrocorax carbo from northeastern Poland. The helminth fauna of cormorants from the brackish water habitat was far richer (30 species) than in those from freshwater lakes (18 species) and strongly depend on season and age of the host. The values of diversity index strongly varied in relation to habitat and host age with clear seasonal differences in the value of diversity index, i.e., its value increased over time in adults from the brackish water habitat and decreased in those from the freshwater lakes. The number of helminths in adult and immature birds varied, depending on the season and habitat: in the brackish water habitat, the overall percentage of helminths was higher in spring than in summer, while in the freshwater habitat a higher proportion of helminths was recorded in summer. During spring, in the brackish water habitat, we observed a higher level of aggregation (for all groups of helminths) than in autumn. The opposite pattern was found in the freshwater habitat. However, this regularity was typical of adult birds only. In immature hosts, the level of aggregation was not predictable and varied among the higher taxa. Our study clearly showed that processes determinate diversity, structure, richness, and patterns of aggregation in helminth assemblages of avian hosts are multi-origin and highly complex.Electronic supplementary materialThe online version of this article (doi:10.1007/s00436-013-3714-7) contains supplementary material, which is available to authorized users.

Metazoan parasite fauna of two peacock-bass cichlid fish in Brazil

A parasitological study of two freshwater cichlid fish of the genus Cichla (C. kelberi and C. piquiti) from six different aquatic ecosystems in Brazil was performed. Based on the survey, a checklist of the component community of the metazoan parasites of each of the two peacock-bass fish species was produced. Fish were collected from May 2009 to April 2011 in six Brazilian aquatic ecosystems using gillnets of different mesh sizes or angling using standardized effort. In total, six groups of parasites were collected: Monogenea, Digenea, Cestoda, Nematoda, Copepoda and Branchiura. Among the groups of parasites found, nematodes presented the greatest number of species, with seven. The study lists new records of parasites in C. kelberi and C. piquiti, and new biogeography records of parasites in six different aquatic ecosystems in Brazil. The present paper collaborates with the study of conservation biology by adding new records of parasite species.

Helminth communities in the burrowing toad, Rhinella fernandezae, from Northeastern Argentina

The main goals of this study were to determine the richness and diversity of helminth parasites of Rhinella fernandezae at the component and infracommunity levels and determine the ecological implications of different biotic and abiotic factors. Specimens were collected near the city of Corrientes, Corrientes Province, Argentina. Prevalence of infection was 94% in the specimens examined (n = 65). The helminth component community in R. fernandezae in this area was comprised a total of 22 species. Of all helminth species, only three (Catadiscus inopinatus, Cosmocerca podicipinus and C. parva) were dominant (importance value: I > 1.0) in the community. The most abundant species were B. tetracotyloides (d = 0.43) among the larvae and C. podicipinus (d = 0.09) among adult worms. At the infracommunity level, the mean individual species richness (2.28 ± 1.48) (mean ± SD) was no more than 3 helminth species per infected host; the diversity and equitability of helminths were 0.23 ± 0.21 and 0.48 ± 0.38, respectively. The host body size was the main factor in determining the parasite abundance. Species richness was significantly and positively correlated with host body size. The parasite helminth species predominantly showed an overdispersed pattern of distribution. Helminth species showed two negative and significant pairs of covariation and one significant pair of association (P < 0.05). R. fernandezae has a wide variety of parasites relating to the host microhabitat, mobility and feeding habits.

Temporal and spatial changes in the composition and structure of helminth component communities in European eels Anguilla anguilla in an Adriatic coastal lagoon and some freshwaters in Italy

The composition and diversity of the helminth component communities in eels Anguilla anguilla were determined in three separate localities in Italy: an Adriatic coastal lagoon, Comacchio and two freshwater localities, the River Po and the Lake Piediluco. Data from Comacchio lagoon were analysed over 15 years to determine whether community composition and diversity changed significantly overtime. The community was species rich (nine species, all marine except Proteocephalus macrocephalus) and was dominated by a suite of digeneans: Deropristis inflata, Helicometra fasciata, Lecithochirium musculus and Bucephalus anguillae. The community showed little change in composition over the period, but the relative abundance and dominance of the species did alter. By contrast, the component communities in the freshwater localities were species poor and the dominant species were freshwater acanthocephalans, Pomphorhyncus laevis in River Po and Acanthocephalus rhinensis in Lake Piediluco. The helminth community of Lake Piediluco with five species was richer than that of the River Po with only three species, but was poorer than that of Comacchio lagoons. Similarity indices between samples from Comacchio were high; between the lagoon and the freshwater localities and between the two freshwater localities, similarity indices were very low. Helminth component community structure in coastal lagoons was comparable across Europe. The helminth community in the River Po was similar to those in the River Tiber and other European rivers whilst that in Lake Piediluco was similar to that in other European lakes. Levels of the pathogenic Anguillicoloides crassus in swim bladders were consistently lower in prevalence and abundance in the coastal lagoons than in freshwater localities. This suggests that this parasite may have little impact on migrating eels if they are indeed primarily of marine origin and so it may be of little importance in the recent decline of eel populations throughout Europe.

Gill arch occupation models of parasite communities of Barbus martorelli (Teleostean: Cyprinidae)

Changes in Barbus martorelli gill arch occupation models by its parasite component community were investigated for nine months. The work revealed three different categories of models. The first category follows the combined action of the respiratory water current and the colonized surface of each gill arch. The second category based on the mode of infestation of Monopisthocotylean larvae while the third category is established as a result of perturbations. Thus, the occupation models of B. martorelli gill arches by its microfauna are constantly changing. Key words: Barbus martorelli, gill parasites, arch occupation models, perturbations month.

Gastrointestinal Helminths of Two Species of Mouse Opossums (Marmosa demeraraeandMarmosa murina) from French Guiana

The woolly mouse opossum Marmosa demerarae and the murine opossum, Marmosa murina, occur in sympatry across most of their range; however, they are not syntopic in that M. demerarae is more abundant in the canopy of primary and secondary forest, while M. murina is scansorial and appears to be more abundant in lower forest strata. We herein present a survey and comparison of the helminths occurring in these 2 species in French Guiana based on examinations of 18 individuals of M. murina and 21 individuals of M. demerarae. At the level of the component community, species richness was established at 12 for M. demerarae and 14 for M. murina; the nematodes Pterygodermatites (Paucipectines) elegans and Aspidodera raillieti were established as the most abundant and prevalent species in M. demerarae and M. murina, respectively. Infracommunities in both species had an average species richness of 3.7 and 3.8, respectively. Both species share 12 species of parasites, yet Phaneropsolus philanderi, Pterygodermatites (Paucipectines) elegans, Travassostrongylus paraquintus, Trichuris reesali, and Spirura trinitatis were significantly more frequent in M. demerarae. Infections also included Mathevotaenia bivittata, an unidentified anoplocephalid, and Viannaia venezuelensis, all 3 species of which were more frequent in M. murina.

Assessing Helminth Community Structure and Patterns in Gizzard Helminths of Blue-Winged Teal (Anas Discors)

Helminth community structure (prevalence and abundance) and patterns (associations and distributions) of gizzard worms were examined in blue-winged teal (Anas discors) migrating through south Texas to their wintering grounds (n = 50) and as they migrated back to their breeding grounds (n = 50). Three species of nematodes (Amidostomum acutum, Epomidiostomum uncinatum, and Streptocara crassicauda) and 1 species of cestode (Gastrotaenia cygni) were recovered, representing 1,164 helminth individuals. Amidostomum acutum was the most prevalent (92%) and abundant (817 individuals; 70% of total worms), while G. cygni was the least prevalent (16%) and abundant (23 individuals; 2%). Ninety-eight blue-winged teal were infected with 1 to 4 species. Amidostomum acutum and E. uncinatum were the most frequently (45%) observed association of 2 or more species, followed by A. acutum, E. uncinatum, and S. crassicauda (19%), and A. acutum and S. crassicauda (14%). Significant positive correlations were mainly between A. acutum and E. uncinatum, whereas negative correlations were found between each of these 2 species and S. crassicauda. Prevalence and abundance of A. acutum and S. crassicauda were not influenced by season, host age, or host sex. However, E. uncinatum varied by season and host age. The percent similarity index indicated a relatively consistent component community pattern of high similarity irrespective of season, host age, and sex. The same helminth species were found in both fall and spring, indicating that other helminth species were not being acquired on the wintering grounds.

Effects of Host Species and Life Stage on the Helminth Communities of Sympatric Northern Leopard Frogs (Lithobates pipiens) and Wood Frogs (Lithobates sylvaticus) in the Sheyenne National Grasslands, North Dakota

We studied helminth communities in sympatric populations of leopard frogs (Lithobates pipiens) and wood frogs (Lithobates sylvaticus) and assessed the effects of host species and life stage on helminth community composition and helminth species richness. We examined 328 amphibians including 218 northern leopard frogs and 110 wood frogs collected between April and August of 2009 and 2010 in the Sheyenne National Grasslands of southeastern North Dakota. Echinostomatid metacercariae were the most common helminths found, with the highest prevalence in metamorphic wood frogs. Host species significantly influenced helminth community composition, and host life stage significantly influenced the component community composition of leopard frogs. In these sympatric populations, leopard frogs were common hosts for adult trematodes whereas wood frogs exhibited a higher prevalence of nematodes with direct life cycles. Metamorphic frogs were commonly infected with echinostomatid metacercariae and other larval trematodes whereas juvenile and adult frogs were most-frequently infected with directly transmitted nematodes and trophically transmitted trematodes. Accordingly, helminth species richness increased with the developmental life stage of the host.