Life cycle of the trematode Echinochasmus spinosus Odhner, 1911 (Echinostomatidae) in the natural conditions of Primorye

Life cycle and developmental stages of the trematode Echinochasmus spinosus Odhner, 1911 are described. As it was established experimentally, in the conditions of Primorsky Krai circulation of the trematode involves first intermediate host, mollusk Parafossarulus spiridonovi, and the second one, freshwater fishes. Adult worms were reared in chicken.     

Summer distribution of the purplegray sculpin <Emphasis Type="Italic">Gymnocanthus detrisus</Emphasis> (Cottidae) in Waters of Primorsky Krai,Sea of Japan

Results of trawl catches show that in the summer period, in the waters of Primorsky Krai, Russia, Sea of Japan, the purplegray sculpin Gymnocanthus detrisus occurs at depths of 20 to 411 m, preferring the range 80–250 m. The temperature of the species’ habitat varies from 0.8 to 8.6 ° C, and the optimal one is 1.2–2.2 °C. G. detrisus occurs at the preferred depths more frequently in the southern area—the Peter the Great Bay, which is more favorable for foraging; in the area of North Primorsky Krai it was found both at greater and lesser depths. The latter is probably determined by the more limited spreading of waters with unsuitable temperatures for the species there. The body size of the purplegray sculpin grows with depth. Juveniles avoid depths over 200 m, where inflow of low-temperature waters is recorded. G. detrisus, which inhabits waters of Primorsky Krai, is represented mainly by females; the proportion of males exceeds that of females only in the 21–27 cm size group. This may be related to the lower growth rate in males after maturation as compared to females.     

Systematic and biogeographical study of Protura (Hexapoda) in Russian Far East: new data on high endemism of the group

Proturan collections from Magadan Oblast, Khabarovsk Krai, Primorsky Krai, and Sakhalin Oblast are reported here. Twenty-five species are found of which 13 species are new records for Russian Far East which enrich the knowledge of Protura known for this area. Three new species Baculentulus krabbensis sp. n., Fjellbergella lazovskiensis sp. n. and Yichunentulus alpatovi sp. n. are illustrated and described. The new materials of Imadateiella sharovi (Martynova, 1977) are studied and described in details. Two new combinations, Yichunentulus borealis (Nakamura, 2004), comb. n. and Fjellbergella jilinensis (Wu & Yin, 2007), comb. n. are proposed as a result of morphological examination. Keys to species of the genera Fjellbergella and Yichunentulus are given. An annotated list of all species of Protura from Russian Far East is provided and discussed. Widely distributed species were not recorded in this area. This may be because of the high sensitivity of Protura to anthropogenic impact and low dispersal ability of the group.     

Communities of metazoan parasites in open water fishes of Cold Lake, Alberta

Communities of metazoan parasites in ten species of fishes from Cold Lake, Alberta are described and compared. Relative abundances in the overall community of parasites in the lake were estimated using data on abundance in each host species, plus estimates of the relative abundances of the species of hosts. Parasites of the numerically dominant salmonid fishes dominated the overall community, with over half of the individual parasites being Metechinorhynchus salmonis . Exchange of parasites between host species was greatest between related and/or abundant host species. Parasite communities in cisco and whitefish, Coregonus spp., were relatively rich in species and diverse (Simpson's index) compared with communities in those species in other lakes in North America; communities in lake trout, Salvelinus spp., and the non-salmonid fishes were poor in species and low in diversity compared with communities in other lakes. Parasite species overlaps (Jaccard index) between related host species in Cold Lake were greater than overlaps within host species between lakes. The same pattern is seen in data from some other lakes. These features support the hypothesis of Wisiewski (1958); that the parasite community within an ecosystem is characterized by parasites of the numerically dominant hosts.     

The parasite faunas of meso- and bathypelagic fishes of Norfolk Submarine Canyon, western North Atlantic

A total of 668 specimens representing 18 species of meso- and bathypelagic fishes collected from the western North Atlantic were examined for parasites. Seventeen species and 39.1% of the specimens harboured at least one type of parasite. The highest number of parasite taxa recovered from a single fish species was seven. Host species had overall infection prevalences ranging from 10.0 to 88.9% of the specimens examined. Cestodes were most common (22.8% of all specimens examined), followed by fungi (6.6%), nematodes (6.1%) and digenetic trematodes (4.9%). Mesopelagic fishes showed a greater prevalence of infection (49.1%) than bathypelagic fishes (28.9%). Most parasites recovered were immature; however, based on the presence of adult and postlarval stage parasites, definitive and second intermediate host status is suggested for at least three fish species (Nemichthys scolopaceus, Nessorhamphus ingolfianus and Eurypharynx pelecanoides ). The presence of the cestode Nybelinia and Anisakis-lype nematodes among a number of host species may have been due to predation on the euphausiid Nematoscelis , which was found in the stomachs of all host species infected by these two parasite taxa. Higher overall infection prevalences among host species were found than have been previously reported for mid-water fishes and it is possible that this may be a function of near-bottom presence of the fishes over the continental slope. It is suggested that the low prevalence of parasites within meso- and bathypelagic fishes when compared to benthic and shallow-water species reflects the lower overall energy of, and reduced probability of host-to-host transfer in, the deep-sea pelagic ecosystem.     

Determinants of the parasite community of clariid fishes from Lake Victoria, Tanzania

The factors that determine parasite assemblages among the clariid fishes of Lake Victoria, Tanzania were studied between August 2003 and February 2005. Six hundred and fifty-six fish belonging to seven species were necropsied and examined for parasites, from which 31 species of metazoan parasites were recorded. The community was dominated by the nematodes both in species and numbers. Most species were generalists with only two trematodes, Diplostomum mashonense and Tylodelphys species, being specialists of Clarias gariepinus. Ten species were considered core and predictable. Parasite species richness, number of individuals per host and Shannon-Wiener diversity indices were generally high. At the compound community level, a mean number of 7.8 parasites were shared among different species of fish and the maximum number of parasites species per fish at the infracommunity level was seven. Levels of similarity in parasite species richness at the component community level ranged from 29.6 to 61.5%. The study concludes that parasite communities in clariid fishes of Lake Victoria are structured by ecological factors. At the infracommunity level, host size, diet and vagility promoted a richer parasite community. At the compound level, two factors were crucial, namely the intermixing of the waters in the lake and the predominant and mobile C. gariepinus.     

Life cycles of the trematode species Azygia hwangtsiytii and A. robusta (Azygiidae) in Primorsky Territory

As a result of experimental and faunistic investigations it is established that the development of the trematode species Azygia hwangtsiytii Tsin, 1933 in Primorsky Territory is realized in the first intermediate host, snail Cipangopaludina ussuriensis, and in second hosts, fishes Perccottus glehni and Channa argus warpachowskii, which can serve as transit, as well as final hosts. For Azygia robusta Odhner, 1911 terms of the development in the first intermediate host, snail Anisus centrifugus are established.     

南极鱼类后生动物寄生虫研究进展: 线虫、绦虫与桡足类

极端的环境造就了南极独特的生物群体, 其中鱼类是南大洋生态系统中最具多样性的脊椎动物, 也是许多寄生虫的中间或终末宿主。南极鱼类寄生虫种类丰富, 是南大洋海洋生物多样性的重要组成部分。探究南极鱼类及其寄生虫的营养关系可为阐释南极海洋生态系统功能及其变动提供重要的生态数据。虽然关于南极鱼类寄生虫的研究已有一百多年的历史, 但这些研究主要集中在寄生虫的种类鉴定、区系调查和组织病理等方面。由于南极鱼类寄生虫研究跨度时间长、地域范围广, 相关研究较为零散。文章综述了南极鱼类寄生线虫、绦虫以及桡足类的种类组成、宿主范围和地理分布等方面的研究, 并对今后开展南极鱼类寄生虫研究工作提出了展望。     

Comparison of the parasitic fauna of Aplocheilus panchax and A. melastigma

The metazoan parasite fauna of two species of freshwater fishes Aplocheilus panchax and A. melastigma collected from a stream at Waltair is compared; 17 parasite species were found. Aplocheilus panchax served as a host to 13 parasite species and A. melastigma to 10 parasite species. Of the 17 parasites collected, 12 were larval helminths to which the fishes act as intermediate and paratenic hosts. This has been attributed to the interaction between terrestrial birds, mammals and fishes in determining the parasite fauna in the biocoenosis. The parasite fauna of these fishes is divided into typical and less typical according to their frequencies. Among less typical there are peripheral division parasites which are abundant in other fishes in the stream. Only six parasite species occurred in both A. panchax and A. melastigma and both fish shared most of their parasite fauna with other fishes. Differences in the parasite fauna of these fishes are attributed to the morphological, behavioural or ecological features of these fishes.     

The Role of the Oldest Mariculture Farm in Restoration of Stock of the Japanese Scallop Mizuhopecten yessoensis (Jay, 1856) in Posyet Bay, Sea of Japan

The pilot mariculture facility for rearing commercial invertebrates has existed in Minonosok Bay of Posyet Bay, Sea of Japan, since 1971. This bay is one of the few in Primorsky Krai where the risk of destruction of mariculture plantations from the effect of storms is a minimum. The total annually yield of spat of the Japanese scallop varied from 6 to 10 million individuals. Two-thirds of this amount was placed in cages for further rearing, and the rest was seeded on the bottom or passed to other enterprises. From 1972 to 2002 there were 104 million individuals of fitted juveniles (yearlings) and 24 million young-of-the-year seeded on the bottom in coastal water areas of the Primorsky Krai from Minonosok Bay. Thanks to the activity of the mariculture farm (two farms since 1994) in Posyet Bay, the stock of the Japanese scallop, which had been depleted by over-fishing in 1934–1935, was completely restored, and, according to our assumption, the total stock of the Japanese scallop was increased two times in Peter the Great Bay.Original Russian Text Copyright © 2005 by Biologiya Morya, Vyshkvartsev, Regulev, Reguleva, Grigorjev, Lebedev.     

Patterns of interactions of a large fish-parasite network in a tropical floodplain

1.?Describing and explaining the structure of species interaction networks is of paramount importance for community ecology. Yet much has to be learned about the mechanisms responsible for major patterns, such as nestedness and modularity in different kinds of systems, of which large and diverse networks are a still underrepresented and scarcely studied fraction. 2.?We assembled information on fishes and their parasites living in a large floodplain of key ecological importance for freshwater ecosystems in the Paraná River basin in South America. The resulting fish-parasite network containing 72 and 324 species of fishes and parasites, respectively, was analysed to investigate the patterns of nestedness and modularity as related to fish and parasite features. 3.?Nestedness was found in the entire network and among endoparasites, multiple-host life cycle parasites and native hosts, but not in networks of ectoparasites, single-host life cycle parasites and non-native fishes. All networks were significantly modular. Taxonomy was the major host's attribute influencing both nestedness and modularity: more closely related host species tended to be associated with more nested parasite compositions and had greater chance of belonging to the same network module. Nevertheless, host abundance had a positive relationship with nestedness when only native host species pairs of the same network module were considered for analysis. 4.?These results highlight the importance of evolutionary history of hosts in linking patterns of nestedness and formation of modules in the network. They also show that functional attributes of parasites (i.e. parasitism mode and life cycle) and origin of host populations (i.e. natives versus non-natives) are crucial to define the relative contribution of these two network properties and their dependence on other ecological factors (e.g. host abundance), with potential implications for community dynamics and stability.     

Determinants of tapeworm species richness in elasmobranch fishes: untangling environmental and phylogenetic influences

Parasite species richness is a fundamental characteristic of host species and varies substantially among host communities. Hypotheses aiming to explain observed patterns of richness are numerous, and none is universal. In this study, we use tapeworm parasites of elasmobranch fishes to examine the phylogenetic and environmental influences on the variation in species richness for this specific system. Tapeworms are the most diverse group of helminths to infect elasmobranchs. Elasmobranchs are cosmopolitan in distribution and their tapeworm parasites are remarkably host specific; therefore, making this an ideal system in which to examine global patterns in species diversity. Here, we 1) quantify the tapeworm richness in elasmobranch fishes, 2) identify the host features correlated with tapeworm richness, and 3) determine whether tapeworm richness follows a latitudinal gradient. The individual and combined effects of host size, factors associated with water temperatures (influenced by latitude and depth), host habitat, and type of elasmobranch (shark or batoid) on measures of species diversity were assessed using general linear models. These analyses included tapeworm host records for 317 different elasmobranch species (124 species were included in our analyses) and were conducted with and without taking into account phylogenetic relationships between host species. Since sharks and batoids differ substantially in body form, analyses were repeated for each host subset. On average, batoids harboured significantly more tapeworm species than shark hosts. Tapeworm richness in sharks was influenced by median depth, whereas no predictor variable included in our models could adequately account for interspecific variation in tapeworm richness in batoid hosts. The taxonomic diversity of tapeworm assemblages of sharks and batoids was influenced by median depth and median latitude, respectively. When the influence of host phylogeny is accounted for, larger hosts harbour a greater tapeworm richness, whereas hosts exploiting wider latitudinal ranges harbour more taxonomically distinct tapeworm assemblages. Species richness and taxonomic diversity of tapeworm assemblages in elasmobranch fishes are influenced by different evolutionary pressures, including host phylogenetic relationships, space constraints and geographical area. Our results suggest that ca 3600 tapeworm species have yet to be described from elasmobranch fishes.     

Structure of the parasite communities of a coral reef fish assemblage (Labridae): testing ecological and phylogenetic host factors

The role of ecological and phylogenetic processes is fundamental to understanding how parasite communities are structured. However, for coral reef fishes, such information is almost nonexistent. In this study, we analyzed the structure of the parasite communities based on composition, richness, abundance, and biovolume of ecto- and endoparasites of 14 wrasse species (Labridae) from Lizard Island, Great Barrier Reef, Australia. We determine whether the structure of the parasite communities from these fishes was related to ecological characteristics (body size, abundance, swimming ability, and diet) and/or the phylogenetic relatedness of the hosts. We examined 264 fishes from which almost 37,000 individual parasites and 98 parasite categories (types and species) were recorded. Gnathiid and cestode larvae were the most prevalent and abundant parasites in most fishes. Mean richness, abundance, and biovolume of ectoparasites per fish species were positively correlated with host body size only after controlling for the host phylogeny, whereas no such correlation was found for endoparasites with any host variable. Because most ectoparasites have direct transmission, one possible explanation for this pattern is that increased space (host body size) may increase the colonization and recruitment of ectoparasites. However, endoparasites generally have indirect transmission that can be affected by many other variables, such as number of prey infected and rate of parasite transmission.     

Host-specialization and species diversity in fish parasites: phylogenetic conservatism?

The pattern of parasite species diversification and specialization, appreciated by host range, is investigated in fish parasites. We test whether host range is linked with phylogeny at a high taxonomic level, and if there is a relationship between host range and host species diversification. For this purpose we used two sets of data, one on macro-parasites of marine fishes of the Mediterranean Sea and the other on macro-parasites of marine and freshwater fishes of Canada. Similar patterns of host range among parasitic groups were found. Our findings suggest that habitat (marine vs freshwater) and geographic localization (Canada vs Mediterranean region) play little role in determining the observed patterns of host range. We highlight the potential influence of phylogeny (high-taxonomic level) on the level host range in parasites. We find that parasites with free-swimming larval stages and with direct life cycles have a narrower range of host species than do parasites with indirect life cycle, even if we cannot control for phylogenetic effects because of the lack of variation of life cycles within each parasitic group. Finally, a positive relationship was found between the number of known hosts and parasite species diversity in the case of Mediterranean parasite species. The relationship between host range and species diversification should be related to the mechanism of cospeciation.     

The taxonomic diversity of the parasites of agnathans and fishes in the Volga basin. I. Parasitic protozoa (Protozoa)

A checklist of protozoa parasitizing fishes in the Volga basin is given. The checklist includes host species names for the each parasite and data on the occurrence of parasites in different parts of the Volga basin. The data on parasitic protozoa from 52 fish species are presented. The list containes 224 species and 10 subspecies names of the parasites. 9 species (Trypanosoma gracilis, Eimeria cheni, E. sinensis, Zschokkella striata, Chloromyxum cyprini, Myxobolus amurensis, M. driagini, M. pavlovskii, and Balantidium ctenopharyngodoni) were introduced into the Volga basin from the Amur basin along with acclimatizated fishes.     

Parasitic fauna of the cherry salmon in the Maritime Territory

23 species of fresh water parasites were recorded from cherry salmon of which 11 species were first recorded from this host and 14 species from the Maritime Territory. The monogeneans Tetraonchus awakurai and T. oncorhynchus are specific for this host. Most strongly it is infected with parasites the intermediate hosts of which are benthic organisms. Oligochaetes, larvae of amphibiotic insects and amphipods play a considerable role in the feeding of cherry salmon in fresh water. Differences in the parasitic fauna of this fish from southern and northern parts of the Maritime Territory were found out. In the north the food ration of this species is more limited with predominance of oligochaetes in it. Diversity of the aquatic fauna, the abundance of invertebrates and fishes in it, the history of fauna formation define the peculiarities of parasitic fauna of the cherry salmon.     

Ecosystem consequences of fish parasites*

In most aquatic ecosystems, fishes are hosts to parasites and, sometimes, these parasites can affect fish biology. Some of the most dramatic cases occur when fishes are intermediate hosts for larval parasites. For example, fishes in southern California estuaries are host to many parasites. The most common of these parasites, Euhaplorchis californiensis, infects the brain of the killifish Fundulus parvipinnis and alters its behaviour, making the fish 10–30 times more susceptible to predation by the birds that serve as its definitive host. Parasites like E. californiensis are embedded in food webs because they require trophic transmission. In the Carpinteria Salt Marsh estuarine food web, parasites dominate the links and comprise substantial amount of biomass. Adding parasites to food webs alters important network statistics such as connectance and nestedness. Furthermore, some free‐living stages of parasites are food items for free‐living species. For instance, fishes feed on trematode cercariae. Being embedded in food webs makes parasites sensitive to changes in the environment. In particular, fishing and environmental disturbance, by reducing fish populations, may reduce parasite populations. Indirect evidence suggests a decrease in parasites in commercially fished species over the past three decades. In addition, environmental degradation can affect fish parasites. For these reasons, parasites in fishes may serve as indicators of environmental impacts.     

Biogeography of helminth parasites of freshwater fishes in Mexico: the search for patterns and processes

Aim To uncover and describe patterns of biogeography of helminth parasites in freshwater fishes of Mexico, and to understand processes that determine them. Three predictions about host‐specificity, faunal exchange in transitional areas, and the biogeographical ‘core’ fauna, are evaluated, all of which follow from a fundamental hypothesis: that parasites show characteristic associations with particular host clades. The parasite fauna of the southern Mexican cichlids and of the fishes of the Mesa Central are examined as case studies that reflect Neotropical and Nearctic historical influences. Location The region covered in this study includes most of Mexico, with emphasis on six biogeographical areas: the Yucatán Peninsula (area 1), the Grijalva‐Usumacinta drainage (area 2), the Papaloapan and Pánuco drainages (area 3), the Balsas drainage (area 4), the Lerma‐Santiago drainage (area 5), and the Bravo drainage (area 6). Methods A parasite data base containing all the records of helminth parasites of freshwater fishes of Mexico was filtered to extract records of adult helminth parasites in freshwater fishes from the six biogeographical areas designated in this study. Jaccard's similarity coefficients and cluster analyses (using upgma ) were used to analyse the extent of faunal similarity between the designated biogeographical areas and between host (fish) families. Taxonomic composition of parasite assemblages in different host groups was also qualitatively compared from summary data. These data were used to test the three main predictions. Results To date, 184 species of helminths (120 as adults) have been recorded from 127 freshwater fishes in Mexico (almost 33% of the total fish diversity of Mexico). Of these parasite species, 69 are digenetic flukes, 51 are nematodes, 33 are monogeneans, 25 are tapeworms, and only six are acanthocephalans. The data and analyses from the six biogeographical areas corroborate the predictions that: (1) the adult parasite fauna is largely circumscribed by higher levels of monophyletic host taxa (families, orders, etc.), and that this pattern is independent of areas; (2) areas within a certain biogeographical region, and consequently with similar fish composition (e.g. areas 1, 2 and 3) have more similar parasite faunas compared to areas with less similar fish faunal composition; and (3) ‘core’ parasite faunas persist to some extent in transitional areas with limited host‐sharing. Main conclusions Helminth biodiversity in Mexican freshwater fishes is determined by the historical and contemporary biogeography of their hosts. Host lineage specificity, mainly at the level of the host family, appears to be an important factor in the distribution of the parasites. Most fish families (Characidae, Cichlidae, Pimelodidae, Ictaluridae, Catsotomidae, Goodeidae, Atherinidae) possess their own characteristic ‘core’ helminth fauna, with limited host‐sharing in transitional areas (e.g. areas 3 and 4). A re‐evaluation of the helminth fauna of Mexican cichlids questions the hypothesis that cichlids lost parasites during the colonization of Mexico from South America. The evidence supports the idea that they acquired new parasites by host switching, possibly from marine or brackish‐water percomorphs. In contrast, the parasite fauna of the Mesa Central remains enigmatic and reflects the region's history of endemicity with historical marine and Nearctic connections.     

Parasites of native and exotic freshwater fishes in south‐western Australia

In this study, 1429 fishes of 18 different species (12 native and six exotic) were sampled from 29 localities to compare the levels of parasitism between native and exotic fish species and to examine the relationship between environmental degradation and parasite diversity. Forty‐four putative species of parasites were found and most of these appear to be native parasites, which have not previously been described. Two parasite species, Lernaea cyprinacea and Ligula intestinalis, are probably introduced. Both were found on or in a range of native fish species, where they may cause severe disease. Levels of parasitism and parasite diversity were significantly greater in native fishes than in exotic species, and this may contribute to an enhanced demographic performance and competitive ability in invading exotics. Levels of parasitism and parasite diversity in native fishes were negatively related to habitat disturbance, in particular to a suite of factors that indicate increased human use of the river and surrounding environment. This was due principally to the absence in more disturbed habitats of a number of species of endoparasites with complex life cycles, involving transmission between different host species.