Seasonal dynamics of the parasite fauna and of the component community structure of parasites of the Minnow phoxinus phoxinus (L.) from the Pechora River

The material represented by 120 specimens of minnow of the age 2(+)-3* was collected according to the standard technique from the Pechora River of the Pechora-Ilechsky reserve in the region of Central homestead during May-September 2006. Three stages of the component parasite community included: the community in the process of formation (May-June), the formed community (June), the destroying community (July and August), the community in the process of formation (August and September).     

Structure of the component community of parasites of Gymnocephalus cernuus (Linnaeus, 1758) in different seasons

In the conditions of middle stream of Vychegda River, the species diversity of parasite community associated with Gymnocephalus cernuus was found to be maximal in March and minimal in September. It is shown, that during a year the parasite community passes through the phases of development in December-March, completion in May-June, and destruction in July-September, which form the annual cycle of the community.     

Fish parasite communities in tropical reservoirs along the Perak River, Malaysia

The parasite communities of fish in three reservoirs (Temengor, Kenering and Cenderuh) along the Perak River, as well as in the lower Perak, are compared. A total of 36 species, 51 species, 61 species and 58 species of metazoan parasites from six types of fishes common in all studied locations, were obtained in Temengor, Kenering, Cenderuh Reservoirs, and downstream Perak River, respectively. The various criteria (prevalence, mean intensity, diversity index, similarity index and evenness) of the parasite community were highest at the Cenderuh Reservoir, followed by the downstream river, Kenering, and Temengor Reservoirs. Monogeneans were the most common parasites in all species of fish examined from all study sites. Fish of the same species showed a high degree of similarity of its parasite fauna regardless of study site, but different hosts had a low similarity of their parasite fauna, even within the same study site. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dependence of the structure of component parasite communities on host age

Dependence of the structure of component parasite communities on host age is studied by the example of parasite communities in minnow and grayling from the North Dvina and Pechora rivers basins. Parasite communities from immature host groups are revealed to be different from those in mature fishes by lesser number of parasite individuals and biomass, number of groups discriminated by the ratio of biomasses, and frequently by lesser number of species. Indices of diversity describing parasite communities from hosts of different ages are nearly always the same in the area examined. This observation needs in verification because values of the indices characterizing parasite communities from fishes of different ages are not equal in the parasite communities from grayling of different age from the Pinega river and minnow from the Chovju river (Dorovskikh, 2002).     

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.     

Community ecology of metazoan parasites of the anchovy Anchoa tricolor (Osteichthyes: Engraulidae) from the coastal zone of the State of Rio de Janeiro, Brazil.

Between October 2001 and March 2002, 103 specimens of A. tricolor from Angra dos Reis (23 degrees 01' S, 44 degrees 19' W), in the coastal zone of the State of Rio de Janeiro, Brazil, were analyzed in order to study their metazoan parasite infracommunities. Ten species of metazoan parasites were collected: 4 digeneans, 1 cestode, 1 acantocephalan, 2 nematodes, 1 copepod, and 1 hirudinean; 77.7% of the fishes were parasitized by one or more metazoan, with a mean of 3.5 +/- 6.2 parasite/fish. Digenean was the most dominant with 4 species that accounted for 53.2% of the total parasites collected; Ergasilus sp. was the most abundant species. Abundance and prevalence of Parahemiurus merus (Linton, 1910) were positively correlated with the total length of host. Relationships between total body length of fish and both total parasite abundance and mean parasite species richness were observed. Mean parasite diversity of species was correlated to host's total length, with significant differences found between male and female fishes. Two pairs of larval species showed significant positive association and covariation. The metazoan parasite infracommunities of A. tricolor presented dominance of larval endoparasites; correlation of parasite abundance, diversity, and species richness with host total length; and low number of parasite interspecific relationships. The parasite community of A. tricolor showed some similarities with the parasite community of another South American Atlantic engraulid.     

Endoparasites of the blue whiting, Micromesistius poutassou from north-west Spain

The communities of metazoan endoparasites of blue whiting, Micromesistius poutassou, in waters of north-west Spain were analysed and a geographical comparison made with other localities. Four hundred blue whiting collected in July 1999 and September 2000 were examined for parasites, excluding the head and gills. Six species were found: Anisakis simplex s.l. (L3), A. physeteris (L3), Hysterothylacium aduncum (L2 and L3), Stephanostomum lophii (metacercaria), S. pristis (adult), and Prosorhynchus crucibulum (metacercaria). The latter is a new host record, and A. physeteris is reported for the first time in blue whiting from the north-east Atlantic. Host gender was not a significant predictor of abundance of any helminth species, and host length was only weakly and positively related to the abundance of A. simplex. Infracommunities were species-poor, with 56% of fish harbouring only one parasite species, and 92% up to two species. Infracommunities were strongly dominated by A. simplex (389 fish) or S. lophii (6 fish). Fish length or gender, and the year of capture, did not affect species richness nor the degree of dominance. There were no significant pair-wise associations between species. Infracommunities were basically composed of several allogenic parasites with different life histories that converge in the blue whiting through the local food web. The parasite fauna of blue whiting in the study area was poor and distinctive compared with that of other localities in the north-east North Atlantic. These peculiarities might primarily be related to the composition of the local community of definitive hosts, although there might also be some influence of the geographical distribution of parasites.     

Community ecology of the metazoan parasites of pink cusk-eel,Genypterus brasiliensis (Osteichthyes: Ophidiidae), from the coastal zone of the State of Rio de Janeiro,Brazil

Fifty-five specimens of pink cusk-eel, Genypterus brasiliensis Regan, 1903 (Osteichthyes: Ophidiidae) collected from the coastal zone of the State of Rio de Janeiro, Brazil (approx. 21-23 degrees S, 41-45 degrees W), from September 2000 to January 2001, were necropsied to study their parasites. All fish were parasitized by one or more metazoan. Fourteen species of parasites were collected. G. brasiliensis is a new host record for nine parasite species. The larval stages of cestodes and the nematodes were the majority of the parasite specimens collected, with 38.4% and 36.5%, respectively. Cucullanus genypteri was the dominant species with highest prevalence and/or abundance. The parasites of G. brasiliensis showed the typical overdispersed pattern of distribution. Six parasite species showed correlation between the host's total body length and prevalence and abundance. Host sex did not influence prevalence and parasite abundance of any parasite species. The mean diversity in the infracommunities of G. brasiliensis was H= 0.364 +/- 0.103, with correlation with the host's total length and without differences in relation to sex of the host. One pair of adult endoparasites (C. genypteri and A. brasiliensis) showed positive covariations between their abundances. Negative association or covariation was not found. Differences between the qualitative and quantitative aspects of the parasite community of G. brasiliensis from Rio de Janeiro and Argentina suggest the existence of two population stocks of pink cusk-eel in the South America Atlantic Ocean.     

Community ecology of the metazoan parasites of white sea catfish, Netuma barba (Osteichthyes: Ariidae), from the coastal zone of the state of Rio De Janeiro, Brazil.

Between March 2000 and April 2001, 63 specimens of N. barba from Angra dos Reis, coastal zone of the State of Rio de Janeiro (23 degrees 0' S, 44 degrees 19' W), Brazil, were necropsied to study their infracommunities of metazoan parasites. Fifteen species of metazoan parasites were collected: 2 digeneans, 1 monogenean, 2 cestodes, 1 acantocephalan, 2 nematodes, 6 copepods, and 1 hirudinean. Ninety-six percent of the catfishes were parasitized by at least one metazoan parasite species. A total of 646 individual parasites was collected, with mean of 10.3 +/- 16.6 parasites/fish. The copepods were 37.5% of the total parasite specimens collected. Lepeophtheirus monacanthus was the most dominant species and the only species with abundance positively correlated with the host total length. Host sex did not influence parasite prevalence or mean abundance of any species. The mean diversity in the infracommunities of N. barba was H = 0.130 +/- 0.115 with no correlation with host's total length and without differences in relation to sex of the host. One pair of endoparasites (Dinosoma clupeola and Pseudoacanthostomum floridensis) showed positive association and covariation between their abundances and prevalences. The parasite community of N. barba from Rio de Janeiro can be defined as a complex of species with low prevalence and abundance and with scarcity of interspecific associations. However, because of both the presence of assemblages of sympatric ariid species as well as the spawning behavior characteristic of these fishes, additional comparative studies of the parasite component communities of ariids are necessaries to elucidate this pattern.     

Shoreline distribution and parasite infection of black‐striped pipefish Syngnathus abaster Risso, 1827 in the lower River Danube

This study aimed to characterise the shoreline distribution and metazoan parasite community in black‐striped pipefish Syngnathus abaster along the freshwater section of the River Danube (Bulgaria). An extensive survey of the shoreline zone showed the regular presence of S. abaster along the entire stretch from Vetren to Vrav (395–836 river km). The preference of shoreline habitat was analysed using abundance data and the proportion of this species in the fish community within particular habitat types. Highest frequencies of occurrence and density were found in sites with a muddy substrate, as compared to gravel and sand. A subsample of S. abaster from the upper section of the Bulgarian stretch was examined for metazoan parasites. The parasite fauna comprised eight metazoan species, representing half the parasite species richness known from its original range. Only three parasite species previously reported from S. abaster were found in the Danubian range of expansion: the adult trematode Orientocreadium siluri, metacercariae of Diplostomum sp., and an accidental finding of the trematode Nicolla skrjabini. The other five species appear to have been acquired in the new area, although these were recorded at a very low prevalence and/or abundance. Syngnathus abaster, therefore, is not likely to represent an important component in native parasite life cycles. Fish condition was not affected by either total parasite abundance or abundance of core species. Regular occurrence and dominance of Syngnathus abaster indicates that this species now represents a significant component of the Danubian shoreline fish community.     

苏州工业园区湖泊后生浮游动物群落结构及影响因子

苏州工业园区地处长江流域下游,随着城市化进程的不断推进,园区水生态系统结构与功能的稳定面临严峻考验。浮游动物作为水生态系统的重要组成部分,探究其群落结构的形成机制对生物多样性保护及生态系统健康发展具有重要意义。为深入了解苏州工业园区五个主要湖泊后生浮游动物群落结构的动态变化及影响因子,于2018年7月至2019年6月进行4次调查。研究共检出后生浮游动物112种（轮虫65种、枝角类29种、桡足类18种）,其中优势种12种（轮虫10种、枝角类和桡足类各1种）。Jaccard相似性分析表明,湖泊间后生浮游动物物种组成整体处于中等相似水平。后生浮游动物密度呈现出显著的季节和湖泊差异,而生物量、Shannon-Wiener多样性指数、Pielou均匀度指数以及Margalef丰富度指数仅存在显著的季节差异。聚类分析结果表明,夏季和秋季后生浮游动物群落结构最为相似。RDA分析表明,水温、溶解氧和pH是影响园区湖泊后生浮游动物群落结构的主要环境因子。Pearson相关性分析表明,湖泊面积与后生浮游动物群落结构无显著相关关系,样点近岸距离与生物量具有显著的正相关关系。基于水质评价标准和物种多样性指数可知,园区湖泊水质整体处于轻-中度污染水平。研究表明苏州工业园区五大湖泊后生浮游动物群落结构表现出同质化趋势;季节变化、环境因子以及样点近岸距离是调控群落结构形成的主要因素。     

Infracommunity structure of parasites of Hemigymnus melapterus (Pisces: Labridae) from Lizard Island, Australia: the importance of habitat and parasite body size

This study describes the community of all metazoan parasites from 14 individuals of thicklip wrasse, Hemigymnus melapterus, from Lizard Island, Australia. All fish were parasitized, and 4,649 parasite individuals were found. Twenty-six parasite species were identified although only 6 species were abundant and prevalent: gnathiid isopods, the copepod Hatschekia hemigymni, the digenean Callohelmis pichelinae, and 3 morphotypes of tetraphyllidean cestode larvae. We analyzed whether the body size and microhabitat of the parasites and size of the host affected understanding of the structure of the parasite community. We related the abundance, biovolume, and density of parasites with the host body size and analyzed the abundances and volumetric densities of some parasite species within microhabitats. Although the 2 most abundant species comprised 75% of all parasite individuals, 4 species, each in similar proportion, comprised 85% of the total biovolume. Although larger host individuals had higher richness, abundance, and biovolume of parasites than smaller individuals, overall parasite volumetric density actually decreased with the host body size. Moreover, parasites exhibited abundances and densities significantly different among microhabitats; some parasite species depended on the area available, whereas others selected a specific microhabitat. Parasite and habitat size exhibited interesting relationships that should be considered more frequently. Considerations of these parameters improve understanding of parasite community structure and how the parasites use their habitats.     

Population dynamics of Gyrodactylus sp. (Monogenea) infecting the sand goby in the Oslo Fjord, Norway

Prevalence and abundance of Gyrodactylus sp. on the 1993 year-class of sand gobies Pomatoschistus minutus in the Oslo Fjord, Norway, decreased slightly during the cold months, increased as temperature increased in spring, reaching a peak in June, then decreased significantly, corresponding with a decline in the number of hosts from August. Abundance and, especially, prevalence increased again in September, and decreased in late autumn. Death of the most heavily infected hosts, and/or host resistance might be responsible for the decline in parasite numbers on post-spawners in summer. The young of the year (1994 year-class) were probably infected shortly after they commenced benthic life in July, and prevalence and abundance increased significantly throughout late summer and autumn. Parasite abundance on males was significantly higher than on females at the height of the breeding season in June, but significantly lower at the end of the breeding season in July. Two-thirds of the parasites infected the gills, oral cavity and pharynx. The proportion of parasites on the body, head and fins increased on both sexes, but significantly more so on males, during the breeding season of the host, when parasite intensity was highest. Possible routes of transmission of the parasite are discussed.     

Component parasite communities in the minnow Phoxinus phoxinus (L.) from ecologically safe and polluted reservoirs

A comparative analysis of the structure of component parasite communities in the minnow from ecologically safe or polluted to variable extent reservoirs was made. The analysis showed that the increase of the reservoir pollution by everyday drains, washings of fertilizers from the fields around and the dacha sections causes the change of dominant parasite species in the minnow, alteration of the sum of errors in the regression equation characterizing the spread of values of biomasses of the species forming the parasite community, and change of the "graphic" structure of the community. It is proved, that the high concentration of biogens has a destructive effect on natural systems, and at the same time causes the process of self-organizing, leading to the alteration of the community structure. As soon as even a small part of biogens is stopped to come into the reservoir, and the quality of environment is restored, the community restores its structure.     

Metazoan parasite species in cultured mussel Mytilus galloprovincialis in the Thermaikos Gulf (North Aegean Sea, Greece)

This is the first study on parasites of cultured Mytilus galloprovincialis L. in Greek waters, and is based on samples collected every 2 to 3 mo between September 2000 and November 2001 at 3 stations in the Thermaikos Gulf. Each sample comprised 40 mussels. We found 4 metazoan parasite species: hydroid Eugymnanthea inquilina, gill turbellarian Urastoma cyprinae, trematode Proctoces maculatus and gut copepod Mytilicola intestinalis. Of 840 mussels examined, 406 (48.3%) mussels were harbouring hydroids of E. inquilina, 278 (33.1%) were infested with U. cyprinae, 94 (11.2%) were infested with M. intestinalis, and only 7 (0.8%) were infested with P. maculatus. The prevalence and intensity of these parasites were related to temperature and pollution. Mussels infested with these parasites had significantly lower condition indices than non-infested mussels; larger mussels were more often infested than smaller ones.     

Community ecology of the metazoan parasites of namorado sandperches, Pseudopercis numida Miranda-Ribeiro, 1903 and P. semifasciata Cuvier, 1829 (Perciformes: Pinguipedidae), from the coastal zone of the State of Rio de Janeiro, Brazil

One hundred and twenty-eight specimens of namorado sandperches, 62 P. numida and 66 P. semifasciata, collected between October 2002 and June 2003 off the Cabo Frio, Rio de Janeiro, Brazil (Lat 23 degrees S and Long 42 degrees W), were examined to study their metazoan parasites. Parasite communities of these fish were composed basically of endoparasites, mainly digenean and cestodes species, with low prevalence and abundance but having high parasite species richness values (at the component community level). Among these values, that found for P. numida is the highest so far recorded for marine fishes from the Neotropical Region. Thirty-nine species of metazoan parasites were collected: 36 from P. numida and 28 from P. semifasciata. Twenty-five parasite species were common to both species of namorado sandperches. Pseudopercis numida and P. semifasciata are new host records for all parasite species collected, with the exception of Microcotyle pseudopercis. Choanodera sp., Leurodera decora, Neolebouria georgenascimentoi, and Proctoeces sp. which were recorded for the first time in the South American Atlantic Ocean. Gnathia sp. from P. numida and Scolex pleuronectis from P. semifasciata were the species having the greatest dominance frequency. Parasite abundance in P. numida and P. semifasciata were positively correlated with the host total length. Only in P. numida was parasite species richness correlated positively with the host total length. No significant differences between endoparasite infracommunities of P. numida and P. semifasciata were detected. The ectoparasites of P. numida had higher values for parasite abundance, parasite richness, Brillouin index, evenness index, and Berger-Parker index than those of the ectoparasites of P. semifasciata. Comparisons among all ecto- and endoparasites showed the ectoparasites of P. numida as the most heterogeneous group. Low similarity values were observed among the three types of parasite infracommunities of the two hosts.     

Parasite communities of Adriatic cage-reared fish

From June 2001 to March 2002, 7 semi-offshore facilities in the Adriatic Sea rearing sea bass Dicentrarchus labrax, sea bream Sparus aurata, sharpsnout bream Diplodus puntazzo and red sea bream Pagellus bogaraveo aged 1+, were monitored for the presence of protozoan and metazoan parasites. Obtained data sets of abundance and prevalence were used to evaluate the structure and dynamic of infra- and component parasite communities. In all hosts, except the red sea bream, dominant parasites were monogenean specialists, showing clear seasonality. Average infracommunity richness was very low, ranging from 1 to 3 parasites per fish, while at component community level, values ranged from 3 to 8, depending on host species. Based on low diversity indices and a moderate to high similarity coefficient between different facilities, it can be concluded that the parasitofauna of Adriatic cage-reared fish is a stable and impoverished stochastic assemblage, with monogeneans as the predominant parasitic group.     

Seasonal dynamics of the population structure of Sphaerostomum globiporum (Trematoda: Opecoelidae) maritae in Ladoga Lake

Data on the seasonal dynamics of population structure is obtained for the first time for the Trematode species Sphaerostomum globiporum from roach Rutilus rutilus (L) in Ladoga Lake, which situates in the northern limit of the distribution range of this species. The parasites infest the host in October and leave it from the end of July to the beginning of August. The maximum of the magnitude of the Trematode population falls on spring, and the minimum is observed in summer. In August and September roach is free of the parasites. It is established that the period of maturing occupies 10 months for S. globiporum from roach in Ladoga Lake. The prereproductive period takes 5 months and comes to the end in February. The reproductive period occupies 5 months too. Although these two periods of the parasite's life cycle do not separated from each other clearly, an overlapping of two generations was not observed, unlike the case of more southern water bodies.     

The occurrence of tumors in the minnow Phoxinus phoxinus (L.), their influence upon the parasite fauna, component community of parasites, and organism of the host

The occurrence of tumors, their influence upon the organism of Phoxinus phoxinus (L.), its parasite fauna, and parasite component community were investigated in the upstream of the Pechora River. According to the data obtained, tumors could occur in the fishes of every age group, but one-year (0+) or two-year (1+) old minnow is affected by tumors more frequently. The tumors lesion extensiveness ranges from 0.02 to 3 %. From 1 to 3 tumors were recorded on one fish specimen. The investigated tumors were in progressive stage (Georgiev, 2000), since the vascular ingrowth and dissemination (in few cases) of the tumors were observed. Tumors are colored in intensive-black and taupe. The taupe tumors usually have a compact capsule at its peripheries, which isolates affected tissue from muscle fibers. In the intensive-black tumors the invasion of tumor cells to the adjacent transversal striated musculature is observed. Distinct symptoms of necrosis are revealed in all slides of the new growths. Blood vessels are formed in most tumors, and the blood flow is recorded before the completion of the vessels forming, that apparently supplies the tumors feeding. Metastases in different organs revealed in several minnow specimens. Tumor affected individuals of the minnow has parasite species complex practically identical (by species list and quantity) with the same of the even-aged unaffected fishes. However, the parasite component communities of the affected individuals are characterized by 4 groups of species, while the parasite component communities of the intact individuals--by 3 groups. The parasite communities of affected and unaffected one-year fishes are similar by the number of the groups of species, but differ in the number of species.