Similarity and structure of the ectoparasite communities of rockfish species from the southern Chilean coast in a temporal scale

Metazoan parasite communities of two deep-sea elasmobranchs: the southern lanternshark, Etmopterus granulosus, and the largenose catshark, Apristurus nasutus, in the Southeastern Pacific Ocean

Two deep-sea shark species were obtained as by-catch of the local fishery of the Patagonian toothfish, Dissostichus eleginoides, at depths ranging from 1000 to 2200 m off central and northern Chile. A total of 19 parasite taxa were found in 133 specimens of the southern lanternshark, Etmopterus granulosus, (n = 120) and largenose catshark, Apristurus nasutus, (n = 13). Fourteen taxa (four Monogenea, one Digenea, four Cestoda, one Nematoda, two Copepoda, one Annelida and one Thecostraca) were found in E. granulosus, whereas five taxa (one Monogenea, two Cestoda and two Nematoda) were found in A. nasutus. Representatives of Cestoda showed higher values of prevalence and a greater intensity of infection; this pattern is consistent with reports for elasmobranchs, but the monogenean richness was higher than that previously reported for related deep-sea sharks. Regarding E. granulosus, a positive and significant correlation between host length and abundance was found for six (four ectoparasites, one mesoparasite, and one endoparasite) of the 14 taxa recorded, but prevalence was significantly correlated with host length only for the monogenean Asthenocotyle sp. Although the sample size for A. nasutus was limited, we compared richness, abundance, diversity and evenness at the infracommunity and component community levels. All of these variables were higher for E. granulosus, but at the infracommunity level, abundance was higher for A. nasutus. All the parasite taxa (except two) represent new host and geographical records.

Sea lice (Siphonostomatoida: Caligidae) diversity on littoral fishes from the south-eastern Pacific coast determined from morphology and molecular analysis, with description of a new species (Lepeophtheirus confusum)

Parasitic copepods of the family Caligidae are common on marine fish worldwide, and some species are responsible for disease outbreaks in aquaculture. Ten species of Lepeophtheirus have thus far been described in the south-eastern Pacific coast. Seven species have been recorded from littoral fish species. However, the latitudinal distribution and host ranges of these Lepeophtheirus spp. are not known. We evaluated, using morphology and molecular analyses, the taxonomic diversity, geographical distributions and host range of known Lepeophtheirus species. Seventeen fish species were examined for copepods. The collected parasites were identified according to their morphology and genetic sequences, based on rDNA 28S and COI genes. The recognition of Lepeophtheirus chilensis and L. mugiloides was indeed difficult due to the high morphological similarities between them. However, their taxonomic statuses were supported by the COI gene and ABGD analysis, with 6% of genetic distance. Moreover, a new species with a genetic distance of 19-22% with respect to known species was detected and described herein as L. confusum. This new species can be distinguished from other Lepeophtheirus spp. by a combination of characters (maxillary tine length and width; furca shape; the fifth leg position, shape and armature; maxillule tine length and thickness; and maxilliped armature on the myxal area). Lepeophtheirus chilensis, L. mugiloides and L. frecuens co-occurred on several littoral fish species, showing an extensive latitudinal distribution, whereas L. confusum was found only on Eleginops maclovinus from southern latitudes.

Parasite communities of the predatory fish, Acestrorhynchus falcatus and Acestrorhynchus falcirostris, living in sympatry in Brazilian Amazon

Abstract This study investigated the parasite communities of wild Acestrorhynchus falcatus and Acestrorhynchus falcirostris populations living in sympatry in Brazilian Amazon. In these two hosts, a total of 12 parasite species e 1-9 parasite species were found per fish, and 10 of these species are metazoans. Eight species of parasites were common to both host species and four of them exhibited differences in abundance and/or prevalence. Parasite communities of the hosts were taxonomically similar (83%) and composed of both ectoparasites and endoparasites, and characterized by high prevalence and high abundance of endoparasites and an aggregated dispersion pattern. For A. falcirostris, the dominant parasite was Ichthyophthirius multifiliis, and for A. falcatus, it was Piscinoodinium pillulare. Shannon diversity and Berger-Parker dominance were similar for both hosts, while the parasites species richness and evenness showed differences influenced by the ectoparasites species. These two populations of hosts that inhabited the same geographical area had different sizes, but were exposed to the same infective stages, and acquired qualitatively and quantitatively similar endoparasites community, thus indicating that the amounts and types of prey congeneric that they were eating were similar. Therefore, the overlap in the same occurrence area play an important role in the parasite communities to these phylogenetically related hosts.

Are similar the parasite communities structure ofTrachelyopterus coriaceus and Trachelyopterus galeatus (Siluriformes: Auchenipteridae) in the Amazon basin?

Abstract The aim of this study was to compare the parasite communities in two sympatric host populations, Trachelyopterus coriaceus andTrachelyopterus galeatus, which were caught in tributary of the Amazon River in Brazil. All the specimens of T. galeatusand T. coriaceus were infected by one or more parasites, such as Ichthyophthirius multifiliis, Tripartiella tetramerii, Trichodina nobilis,Cosmetocleithrum striatuli, Contracaecumsp., Cystidicoloides sp., Dadaytremoides parauchenipteri and Gorytocephalus spectabilis. Seven species were common to both host fish, and there were 1-5 parasite species per host. In both hosts, trichodinids were dominant. Aggregate dispersion of ectoparasites and endoparasites was observed, with greater aggregation among endoparasites. Only the ectoparasites species showed differences in intensity and/or abundance. However, the parasite communities of the two hosts were taxonomically similar (99%) and characterized by high prevalence and high abundance of ectoparasites, but with low diversity, prevalence and abundance of endoparasites. Trachelyopterus galeatus, the host with the larger body size, presented greater variation of Brillouin diversity and evenness, while T. coriaceus had higher Berger-Parker dominance values and total numbers of parasites. This first study on these parasites ofT. galeatus and T. coriaceus showed that the life mode, size of the hosts and the availability of infective forms of the parasites were the main factors that influenced the parasite communities structure.

Species spectrum, diversity profile and infection indices of helminth parasite fauna of Chirruh snowtrout, Schizothorax esocinus (Heckel) in lake ecosystems of Kashmir Himalayas-Do similarity and host-parasite associations arise?

In order to assess the species richness and diversity profile of helminth parasite fauna in an endemic fish, an investigation was carried out in two urban and two rural lakes of Kashmir. Overall nine species of helminth parasites were observed in four lakes. Of these three were autogenic and six were allogenic. Heteroxenous parasite species were more in number than monoxenous species. Results showed significant differences in heteroxenous / monoxenous ratio between different lakes. Core species (Prevalence > 20) were only found in hypertrophic lake (Anchar Lake). Overall, majority of helminth species were either secondary or satellite species. Prevalence of some helminth parasites showed significant differences in different lakes. In addition mean intensity showed significant differences between autogenic and allogenic parasites (P < 0.05). Principle Component Analysis based on prevalence showed that Anchar Lake was strongly associated with most of helminth parasites. Diversity indices showed significant variation between different lakes. Maximum helminth species per host was in Anchar Lake. Finally we concluded that helminth parasite fauna showed significant differences in species richness and infection indices between different lakes. Diversity profile was higher in Anchar Lake in comparison to other three lakes. The results clearly show that environmental features of lake ecosystems have got an impact on distribution pattern of helminth parasites in S. esocinus. We suggest comparative parasitological study should be taken between different species of fish in order to have a clear picture regarding the species composition of helminth species in this region. Also we need to characterize the species spectrum of parasitic worms in fish of freshwater bodies of this region as well as other similar type of climatic zones because parasite fauna is an integral part of the inventory of biodiversity and as possible regulators of host populations in aquatic ecosystems.

Patterns of variation in parasite component communities and infracommunities of a littoral fish species from the northern coast of Chile

The structure and similarity of the parasite communities of fish can be evaluated at the component community (CC) and infracommunity (IC) levels. Both hierarchical levels have been used to assess parasite variations in fish at large (biogeographic) scales. However, studies evaluating the consistency between these two hierarchical levels at smaller geographical scales are scarce. In this study, the parasite assemblages of 124 Paralabrax humeralis collected by local fishermen by spear fishing at four sites (El Fierro, EF; P. Angamos, PA; Santa María, ISM; San Jorge, BSJ) in northern Chile were compared to assess the variability (or similarity) of their CCs and ICs at a limited geographical scale using multivariate analysis. At the IC level, discriminant analyses showed that P. humeralis parasite communities varied significantly among sites; 70% of ectoparasite ICs were correctly assigned to each site, but only 55% of helminth parasite ICs were correctly classified. At the CC level, the composition of parasite communities as assessed by correspondence analyses varied significantly between sites. Tagia sp., Neobenedenia sp. and Philometra sp. were associated with BSJ, ISM and PA, respectively; Corynosoma sp. and most digeneans were associated with both ISM and EF. Analysis of similarities (ANOSIM) showed significant variations in the degree of similarity between P. humeralis CCs from different sites, but not between ICs. Variations between CCs from different sites reflect fish population processes (e.g., population age, reproductive segregation) and the particular conditions of their respective habitats, whereas ICs reflect individual host movements. This study demonstrated that, when examined at a limited geographical scale, IC is better than CC at capturing the local pool of parasite assemblages when host populations are spatially segregated. Therefore, in this study, it is demonstrated that at a small geographic scale, CC variations are not reflected by IC, when host population is spatially segregated.

Metazoan parasite communities of rock cod Eleginops maclovinus along southern Chilean coast and their use as biological tags at a local spatial scale

The composition of the metazoan parasite fauna of the rock cod Eleginops maclovinus from three locations in southern Chile was compared to assess the local spatial variation of the community component of their parasitic faunas. A total of 13 108 metazoan parasites (5267 endoparasites and 7841 ectoparasites) belonging to 34 taxa were collected from 268 specimens of E. maclovinus between October 2008 and March 2009. The populations and community quantitative descriptors were estimated. Altogether, 97.4% of the fish were infected with at least one parasite taxon. The most prevalent species were Hypoechinorhynchus magellanicus (Acanthocephala), Caligus rogercresseyi, Lepeophtheirus mugiloides, Clavella adunca (Copepoda) and Similascarophis sp. (Nematoda). Five species are new records for this host: Argulus araucanus, Hirudinea gen. sp1., Hirudinea gen. sp2., Benedenia sp. and Camallanidae gen. sp. A linear discriminant analysis (LDA) showed that the metazoan parasite fauna of E. maclovinus varied qualitatively and quantitatively among three locations, with 89.7% of fish being correctly assigned to their respective locations. This suggested that parasites could be a reliable tool to discriminate individual fish from geographically close locations. There was a weak relationship between the parasite fauna and fish size and there were no accumulations of parasites in the host over time, which could be associated with ontogenetic changes of diet associated with habitat use.

Endoparasite fauna of five Gadiformes fish species from the coast of Chile: host ecology versus phylogeny

The aims of the present study were to compare, using multivariate analyses, the degree of similarity of the endoparasite fauna of five fish species belonging to the order Gadiformes: Merluccius gayi, Merluccius australis, Macruronus magellanicus (Gadoidei) and Micromesistius australis and Nezumia pulchella (Macrouroidei), from the southern and central Chilean coast, and to evaluate whether the composition of the endoparasite fauna was determined by phylogenetic or ecological relationships. We employed our database of Merluccius australis, M. magellanicus and Micromesistius australis, which was complemented with published information for M. magellanicus, Merluccius australis, Micromesistius australis, M. gayi and N. pulchella. A higher number of endoparasite species was recorded for Merluccius australis, Micromesistius australis and M. magellanicus, namely Anisakis sp. and Hepatoxylon trichiuri, which is the most prevalent parasite among these hosts. Aporocotyle wilhelmi and Hysterothylacium sp. were detected only in M. gayi, whereas Lepidapedon sp. was found exclusively in N. pulchella. These results suggest that fish ecology rather than host phylogeny was the most important factor for the determination of similarity in parasite composition. This result could be explained by the similar trophic patterns of hosts and by the predominance of generalist larval species among these fish parasite communities.

Metazoan parasite infracommunities of the toadfish Aphos porosus (Pisces: Batrachoidiformes) in central Chile: how variable are they over time?

The present study examines variation in parasite community characteristics of the toadfish Aphos porosus across sampling years. We analyzed and compared the species composition and numeric descriptors of the parasite infrapopulations and infracommunities in 101 fish collected during the springs of 1999, 2006, and 2007 from rocky intertidal ponds in El Tabo, central Chile. Parasites were found in 94.1% of specimens necropsied. In total 5,532 parasites were collected, representing 12 taxa, of which 7 were found in the 3 annual samples. The most prevalent and abundant parasites in the 3 sampling years were larval tetraphyllidean cestodes, followed by anisakid nematodes. The community descriptors of average richness and abundance varied significantly across the 3 yr, with the exception of parasite dominance. The parasite species composition and relative abundance showed low variability among years. A few parasite taxa (Anisakis sp., Pseudoterranova sp., tetraphyllideans, and Clestobothrium crassiceps) dominated the infracommunities of the toadfish; however, tetraphyllideans were the parasites that greatly varied over time. Consequently the parasite infracommunities of the toadfish were variable among years, with a low variation in parasite composition, but large differences in the aggregate descriptors.

Is the nestedness of metazoan parasite assemblages of marine fishes from the southeastern Pacific coast a pattern associated with the geographical distributional range of the host?

Nested structure is a pattern originally described in island biogeography to characterize how a set of species is distributed among a set of islands. In parasite communities, nestedness has been intensively studied among individual fish from a locality. However, nested patterns among parasite assemblages from different host populations (localities) have scarcely been investigated. We recorded the occurrence of parasites in 9 fish species widely distributed along the southeastern Pacific coast to determine whether the ecto- and endoparasite assemblages of marine fishes show a nested structure associated with host distributional range. Nestedness was tested using Brualdi-Sanderson index of discrepancy (BR); and 5 null models incorporated in a‘Nestedness’programme (Ulrich, 2006). The ecto- and endoparasite richness do not show similar patterns of latitudinal gradients among fish hosts, with 33–66% of analysed ectoparasite assemblages, and 25–75% of endoparasite assemblages showing nested structures through the host distributional range. For ectoparasites, species richness gradients and nested structure (when present) might be associated with decreased host densities or could reflect negative environmental conditions in the distributional border of the host species, whereas for endoparasites might be caused by geographical breaks of prey or changes in prey availability (intermediate hosts). The sampled extension of the distributional range of the host species, as well as the lack of specificity of some parasites, could influence the detection of nestedness.

Linking species abundance distributions and body size in monogenean communities

Parasite communities are characterised by one or a few numerically dominant species and many rare species. Although this pattern is well recognised, its underlying causes remain unknown. In this study, we tested whether variation in abundance among species within parasite communities can be explained by interspecific variation in body size. We used data on nine fish species (families Serranidae and Lethrinidae) from New Caledonia, each harbouring strictly host-specific diplectanid monogenean species with very uneven abundances. On each fish species, the most abundant monogenean species accounted for between one half and two thirds of all individuals recovered from the community, and its abundance was between 2 and 114 times greater than that of the second-most abundant species. However, there was no convincing evidence that the ratio of abundance values between the two most abundant species in a community co-varied with the ratio in their body sizes; thus, size differences cannot explain these differences in abundances between common species. It is surprising to note that in two of the three communities with enough species for an analysis to be performed, body size tended to correlate positively with abundance among all species of diplectanid monogeneans. Thus, although body size variation on its own cannot account for the pronounced differences in abundance among monogenean species within the same community, body size remains an important determinant of abundance as it relates to life-history traits underpinning reproductive rates and population growth in these unsaturated communities.