A preliminary study of parasite diversity in the anadromous Kamchatkan mikizha Parasalmo mykiss mykiss (Osteichthyes: Salmoniformes: Salmonidae)

The study of parasites associated with the anadromous mikizha from several rivers of the Western Kamchatka has revealed 44 parasite species. The majority of parasites (59%) belong to marine and estuarine-marine species. Lecithophyllum bothryophorum, Echinorhynchus leidyi and plerocercoids of the family Litobothriidae were found for the first time in anadromous fish entering into Asian continental watersheds. It has been revealed that only a few specimens of the anadromous mikizha feed in fresh waters. Most of feeding fish consume a minor amount of food, and this feeding is occasional. Young forms of intestinal parasites of the freshwater and estuarine-freshwater groups (Neoechinorhynchus spp., Crepidostomum spp., Cucullanus truttae, Eubothrium salvelinf) come into anadromous fishes mainly before their entering in fresh waters.     

Studies on Ligula intestinalis Some aspects of the pathology in the second intermediate host

A 3 year survey of a lake, in which 120 roach, Rutilus rutilus , were examined revealed the presence of the plerocercoids of Ligula intestinalis in more than 90 % of the fish. The average number of parasites per fish was 4.2 although fish exceeding 32 g were not ligulosed. Gudgeon, Gobio gobio , of all sizes were affected. Implants of the plerocercoids into small roach, gudgeon and goldfish, Carassius auratus , were successful but not in the case of Perca fluviatilis, Esox lucius and Leuciscus cephalus. The pathological effects of the plerocercoids on roach and gudgeon are described.     

The distribution of Poecilancistrium caryophyllum (Trypanorhyncha) plerocercoids in spot, Leiostomus xanthurus Lacèpéde, and spotted seatrout, Cynoscion nebulosus (Cuvier)

Spotted seatrout, Cynoscion nebulosus (Cuvier), and spot, Leiostomus xanthurus Lacèpéde, from two sites along Florida's west coast were collected, weighed, sexed and measured. A systematic search for plerocercoids of the cestode Poecilancistrium caryophyllum yielded infection prevalences of 81.9% for C. nebulosus and 25.0% for L. xanthurus . The maximum infection intensity was 10 (mean = 2.65) plerocercoids per fish in C. nebulosus and six (mean = 1.69) per fish in L. xanthurus . Significant correlations were found between infection prevalence and length in C. nebulosus , and a significant correlation was observed between intensity and length in both species. Condition coefficient ( K ) and intensity were negatively correlated in C. nebulosus but not in L. xanthurus . An iterative computer technique based on the truncated negative binomial distribution indicated no parasite-induced mortality occurred in either species. Sand drum, Umbrina coroides Cuvier, is reported as a new host record for P. caryophyllum .     

Five cases of Diphyllobothrium nihonkaiense infection with discovery of plerocercoids from an infective source, Oncorhynchus masou ishikawae

Five persons from 2 families residing at Miyama Town, Mie Prefecture, Japan, ingested fresh raw fish Oncorhynchus sp. on 9 May 1999 that was caught at Owase district in Mie. They all expelled diphyllobothriid cestodes 11-37 days after ingesting the fish. The parasites were morphologically identical to Diphyllobothrium nihonkaiense Yamane et al., 1986. Five plerocercoids were detected from a portion of the fish. Nucleotide sequence of a region of the cytochrome c oxidase subunit I gene of mitochondrial DNA from an adult worm was identical with that from the plerocercoid. The fish was identified as Oncorhynchus masou ishikawae according to the nucleotide sequence of the nuclear ribosomal second internal transcribed spacer region II gene. This is the first record of D. nihonkaiense plerocercoids from O. m. ishikawae.     

Abundance and distribution of Diphyllobothrium ditremum Creplin (Cestoda: Pseudophyllidea) plerocercoids in benthic whitefish, in northern Finnish Lapland

The prevalence of Diphyllobothrium ditremum plerocercoids in whitefish Coregonus lavaretus ranged between 70 and 100% in Lake Kilpisjärvi and in three other lakes in Northern Lapland, Finland. The mean abundance in Lake Kilpisjärvi (age groups 1+-10+ years), ranged between 103·5± 71·3 in 1992–1993 to 110·9± 80·0 plerocercoids per fish in 1997. The asymptotic value of the infection levelled at 113 plerocercoids per host after age 3. No significant difference in abundance was detected between study years ( P >0·10). Abundances in other lakes ranged between 4·8±9·7 and 91·1±115·1. Two seasonal peaks of plerocercoid recruitment were observed in Lake Kilpisjärvi; between March and April ( P <0·002) and between September and October ( P =0·042). In autumn the numbers of larvae increased particularly in female fish. The invasion rate of the parasite was lower in other lakes studied, and the infection rate in whitefish was closely related to the copepod food eaten.     

Isozyme genetics and the phytogeny of Italian freshwater gobies (Teleostei: Gobioidei)

Although predominantly a marine group in the Atlantic/Mediterranean fish fauna, three species of exclusively freshwater gobies (Teleostei: Gobiidae) occur in Italy. These are Padogobius marltmsii of north Italy and parts of Croatia, P. nigricans from the Tyrrhenian catchment area of Tuscany and Lazio, and Knipowitschia punctatissima from north-eastern Italy. Using horizontal starch-gel electrophoresis, isozyme polymorphism in 12 enzymes encoded at 18 loci was investigated in these species and related euryhaline forms. Genetic distance, and morphological cladistic analysis, indicates that the Italian freshwater gobies do not form a monophyletic group, with the Padogobius species well separated from other taxa, and K. punctalissima closest to its morphological congener, the lagoonal K. panizzae . No close correlation was found between genetic variation and environmental heterogeneity.     

Studies on lesions caused by plerocercoids of Triaenophorus nodulosmin some fish of an alpine lake, the Königssee

Lesions caused by plerocercoids of Triaenophorus nodulosus in the second intermediate hosts were studied in fish of an alpine lake, the Königssee. Four species (Arctic charr, Salvelinus alpinus; minnow, Phoxinus phoxinus; burbot, Lota lota: perch, Percafluviatilis) could be shown to be affected, whereas seven other fish species did not have macroscopical or histological signs of invasion. The capsules of T. nodulosus plerocercoids were usually located in liver tissue. Whereas only living parasites were found in charr and minnow, dead and destroyed plerocercoids could be demonstrated additionally in burbot and perch.
The histological picture is characterized by capsules surrounded by connective tissue and by fresh or older migration routes in charr and minnow. Furthermore, larvae migrating through the biliary ductules were found regularly in charr. In burbot and perch, different stages of destruction of the parasitic larvae took place. The ability to reject the parasite by immunological reactions seems to depend on the species of host. Even if heavy changes in the liver tissue could be demonstrated, no negative influences on condition and growth of affected fish could be established.     

Host switch and infestation by Ligula intestinalis L. in a silver bream (Blicca bjoerkna L.) population

Sampling of the fish community was carried out for 20 years in the Mirgenbach reservoir, in North-Eastern France. The prevalence and the mean intensity of Ligula intestinalis (Cestoda) were analysed in roach (Rutilus rutilus) and silver bream (Blicca bjoerkna) populations, the main two infected species. The aim of this study was to investigate the host switch from roach to silver bream and the consequences of L. intestinalis infestation in silver bream, which is an unusual host for this parasite as Ligula parasitism in silver bream appears to be rare. We analysed in detail the relationships between parasitism index (PI), gonadosomatic index (GSI), perivisceral fat abundance (PFA) and condition index (CI) in the silver bream population. In 1998, prevalence of L. intestinalis highlighted a clear host switch from roach to silver bream. In the silver bream population, young fish were the most severely infected and the impact of plerocercoids appeared to be different depending on the host sex. In male silver bream, plerocercoids drew energy from fat reserves even if GSI was also slightly impacted. On the contrary, in females energy was diverted from gonad maturation rather than from perivisceral fat reserves. No significant difference was observed in terms of CI in either sex.     

The ecological interaction between arctic charr, Salvelinus alpinus (L.), and the plerocercoid stage of Diphyllobothrium ditremum

Six hundred and two arctic charr, Salvelinus alpinus , from a small lake (30 ha) were examined for infection with plerocercoids of Diphyllobothrium ditremum the only species of this genus present; 466 (77.4%) harboured the parasite in an overdispersed infection. The prevalence of infection increased with age and reached 100% at 7+ years for males and 8+ years for females. The rate of infection appeared to be related to the feeding biology of the charr which did not change within the age span studied. The rate of increase in density of infection (plerocercoids per fish) decreased with age as did the degree of overdispersion. It is concluded that the infection probably induces mortality in the fish population, and that such mortality is dependent on parasite density.     

The Effect of Low Temperatures on the Motility of Diphyllobothrium Latum Plerocercoids

The effect of low temperature exposure on the motility of Diphyl-lobothrium latum plerocercoids was studied, with the particular aim of finding the exposure that immobilizes all the larvae in fish freezing. Both isolated larvae immersed in normal horse serum and larvae enclosed in pieces of muscle tissue of the size of 1 cm3 were tested. The pieces of tissue containing a larva were placed in the middle of a plastic beaker filled with densely packed minced fish flesh. In the central part of this phantom, where the plerocercoids were situated, the temperature decline was considered to take place in the same way as in the interior of a whole fish. A total of 200 isolated larvae were tested, and a temperature of −14° G was found to have a fully immobilizing effect on them. The number of plerocercoids frozen enclosed in muscular tissue was 453, and −10° G was found to immobilize them. The observed difference seems to be mainly due to the cryoprotective properties of serum.     

Studies on Ligula intestinalis (L.) effects on a roach population in a gravel pit

The effects of the plerocercoids of Ligula intestinalis were studied on a population of roach, Rutilus rutilus in a gravel pit. The incidence of the cestode fell from 92% in 0+ roach in April to 25 % in January of the succeeding year. The fall in the number of parasitized fish was due to predation, mainly by pike, Esox lucius. Observations indicated most of the parasitized fish failed to become sexually mature although the actual growth rate of the fish was not markedly reduced. The plerocercoids of L. intestinalis grew more rapidly during the summer. The author recommends roach of less than 9 months of age should not be introduced into confined water such as a gravel pit, since after this period they appear to be much less likely to be parasitized.     

Changes in numbers and growth of Ligula intestinalis in the spottail shiner (Notropis hudsonius), and their roles in transmission

Eighteen species of fishes were collected during the open water (1985-1987) and winter seasons (1985-1986) from Dauphin Lake, Manitoba, Canada (51 degrees 17'N, 99 degrees 48'W) and examined for plerocercoids of Ligula intestinalis (L.). Plerocercoids were most prevalent (5.3%) in spottail shiners (Notropis hudsonius), the major fish host for Ligula in Dauphin Lake. Detailed analysis of the spottail shiner-Ligula host-parasite system revealed that the number of plerocercoids differed between years and among habitats but there was no statistically significant seasonal pattern; recruitment of new worms was highest in young fish and decreased with age, and infected spottails had reduced gonad development. Analysis of host and parasite growth revealed that the soma of male spottails infected with Ligula weighed more but had a reduced growth rate. Growth rate of females was unaffected by Ligula but somatic weight was slightly increased. This appears to be related to the greater metabolic stress on infected males. Based on increased mean somatic weight and skewness of the weight distribution for infected fish, we propose that infected spottails are subjected to size-selective mortality. Some of the contradictions in the literature may be attributed to underestimated prevalence due to increased numbers of spawning fish in the spring, mixed age-classes of Ligula in separate age-classes of fish, and differential effects on growth due to infection in male versus female hosts.     

Phenotypic modification of roach (Rutilus rutilus L.) infected with Ligula intestinalis L. (Cestoda: Pseudophyllidea).

In European freshwater, cyprinid fish may be heavily infected by plerocercoids of the pseudophyllidea cestode Ligula intestinalis (L.). During their development, these parasites grow rapidly to a large size in the fish's body cavity, characteristically distending the abdomen. In this study, the influence of this tapeworm on roach (Rutilus rutilus L.) morphology was analyzed. Forty-five infected and 45 uninfected roach were collected from the Lavernose-Lacasse gravel pit in Toulouse, south western France and examined for 40 morphological measurements to study phenotypic modification of the body and 14 bilateral characters for an analysis of asymmetry. Results indicate that the degree of bilateral asymmetry does not change between infected and uninfected roach, despite the strong host-morphological modifications such as deformation of the abdomen, fin displacements at the level of the tail, and sagging of the vertebral column. The intensity of abdominal distension and fish morphology changes depends on the total parasite biomass present. Differences were observed in morphology at different levels of infection, which relate to established effects of L. intestinalis on the physiology and behavior of intermediate hosts. These morphological changes induced by the parasite could increase trophic transmission to the definitive avian hosts.     

Some aspects of the biology of the plerocercoid of Gilquinia squali Fabricius 1794 (Cestoda: Trypanorhyncha)

The eyes of more than 24 000 northern North Sea whiting were examined for infection with Gilquinia squali plerocercoids. Infection, which is apparently non-seasonal, begins when the fish are aged 1 +, builds up to a peak at 2+ to 4+, and decreases thereafter. The intensity of infection ranged from 1–18 plerocercoids per fish. Evidence is presented of the development of immunity in whiting to G. squali , and observations on the parasite's eggs suggests that they are not randomly distributed but tend to aggregate. One or both of these features could give rise to the negative binomial type of frequency distribution observed. The frequency of left eye infection was consistently greater than that of right eye.     

The effects of a change in the growth rate of roach, Rutilus rutilus (L.), on the biology of the fish tapeworm Ligula intestinalis (L.)

Investigations into the biology of the roach and the pathogenic tapeworm Ligula intestinalis (L.) populations at Slapton Ley, Devon were carried out between October 1982 and December 1984. Data collected from the lake since 1977 have also been re-analysed to determine how the dramatic improvement in the individual growth rate of the roach over this period may have affected the growth, maturation and life-cycle of Ligula. Only the very young roach at this site become infected, so it was possible to follow cohorts of plerocercoids of similar age through each roach year class. Results for the 1978 and 1983 year classes are presented in detail. The roach grew extremely rapidly from May to August in each year, resulting in a pronounced cyclical pattern of changes in the condition of the roach, with the lowest condition occurring in late winter and spring. The yearly increase in the roach growth rate was accompanied by an increase in plerocercoid growth rate in the 0 + roach, but not in the 1 + roach. The growth rate of the plerocercoids was very high compared to that at other sites. It is usual for the parasite index (PI) of Ligula-infected fish to be high and to increase throughout their first few years of life. At Slapton, however, a lack of multiple infections has prevented high PIs from occurring, and in recent years the growth rate of the roach has been so high that the plerocercoids were unable to maintain a high weight relative to the fish, and the highest PIs occurred in the 0 + roach throughout late winter and spring. In recent year classes, therefore, the maximum PIs and highest pathogenicities coincided with the period of lowest condition in the 0+ roach. Observations of both caged and natural populations of 0+ roach over winter showed that a significant loss of roach containing the larger plerocercoids occurred from the population. In vitro cultivation of Ligula plerocercoids showed that they were capable of maturation at weights of 0.5 g, and only 6 months after having infected the roach. The increase of the growth rate of the plerocercoids in the 0+ roach has therefore resulted in a greater proportion of these plerocercoids being capable of infecting the definitive host. As a result of the increase in individual growth rate of the roach at Slapton, the potential for Ligula transmission, as measured in terms of both their pathogenicity and maturity, has shifted from the 1 + to the 0+ roach.     

Differences in adult egg output of Schistocephalus solidus from singly- and multiply-infected sticklebacks

In this study, we recovered Schistocephalus solidus plerocercoids from singly and multiply infected three-spine sticklebacks, Gasterosteus aculeatus, transferred them individually to in vitro culture conditions, and quantified their lifetime egg output. We found a significant difference in the relationships between plerocercoid mass and lifetime egg output for parasites recovered from singly and multiply infected sticklebacks. Although egg output was strongly and positively related to plerocercoid mass amongst worms from singly infected fish, for those recovered from multiply infected sticklebacks the relationship was marginally nonsignificant and negative, with small worms achieving high levels of egg production. We suggest 2 hypotheses that may explain differences in the egg production of plerocercoids from singly and multiply infected fish. One possibility is that smaller plerocercoids in asymmetric multiple infections develop precocially, in response to host manipulation strategies of larger worms that decrease survival prospects of the host. Alternatively, small worms in singly infected sticklebacks may be prevented from becoming sexually mature because they face energetic constraints associated with having to overcome the host's immune response alone. We discuss our results in terms of recent studies examining strategic egg production in helminths.     

The contents of adenine nucleotides and glycolytic and tricarboxylic acid cycle intermediates in activated and non-activated plerocercoids of Schistocephalus solidus (Cestoda: Pseudophyllidea)

The steady state content of adenine nucleotides, inorganic phosphate and glycolytic and tricarboxylic acid cycle intermediates were measured in freeze clamped plerocereoids of S. solidus taken from the body cavity of infected fish (non-activated plerocercoids) and the results compared with the metabolite levels in plerocercoids which had been cultured in vitro for 12 h (activated plerocercoids). Of the glycolytic intermediates, the levels of fructose-6-phosphate, fructose-1, 6-diphosphate, 3-phosphoglycerate, phosphoenolpyruvate and lactate all decreased on activation, the remainder of the glycolytic intermediates did not alter significantly. In contrast, the levels of the tricarboxylic acid cycle intermediates all increased 2–3 fold on activation, whilst the adenine nucleotides remained virtually unchanged. The differences in the steady state content in intermediary metabolites in activated and non-activated plerocereoids are discussed in relation to possible mechanisms of metabolic control.     

Cadmium,chromium, and lead accumulation in aquatic plants and animals near a municipal landfill

This research was conducted to assess the contamination of heavy metals in the water, sediment, aquatic plants and animals around a municipal landfill. The heavy metals were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). The concentrations of cadmium (Cd), chromium (Cr), and lead (Pb) in water and sediment were Not detected (ND), 0.05 ± 0.98, and 0.02 ± 0.01 mg/L; and 0.47 ± 0.23, 18.65 ± 11.39, and 5.36 ± 2.08 mg/kg, respectively. A total of 24 aquatic plants from 4 species were collected from the municipal landfill. Cd concentrations in all plant species were within the standard, while Cr and Pb exceeded the standard. Forty-four fish from 4 species, 29 freshwater snails from 3 species, 10 freshwater prawns from 1 species, and 9 freshwater crabs from 1 species were collected. Cd and Cr concentrations in 2 species of fish samples exceeded the standard and Pb concentration in all fish species exceeded the standard. Cd and Pb concentrations in all freshwater snails were within the standard, except Cr. Meanwhile, Cd and Pb in freshwater prawns and snails were within the standard, except Cr. Five species of frogs were collected. Cd and Cr concentrations in 2 species exceeded the standard. Pb concentrations in all frog species exceeded the standard. The pattern of metal accumulation was fish > frogs > freshwater snails > freshwater prawns = freshwater crab (Cd), freshwater prawn > frogs > freshwater crab = freshwater snail > fish (Cr), and freshwater prawn > fish > frogs > freshwater snail > freshwater crab (Pb).     

Phylogeography of the Italian vairone (<Emphasis Type="Italic">Telestes muticellus</Emphasis>, Bonaparte 1837) inferred by microsatellite markers: evolutionary history of a freshwater fish species with a restricted and fragmented distribution

Background  

Owing to its independence from the main Central European drainage systems, the Italian freshwater fauna is characterized by a high degree of endemicity. Three main ichthyogeographic districts have been proposed in Italy. Yet, the validity of these regions has not been confirmed by phylogenetic and population genetic analyses and a phylogeographic scenario for Italy's primary freshwater fish fauna is still lacking. Here, we investigate the phylogeography of the Italian vairone (Telestes muticellus).     

The distribution and growth of coarse fish in gravel-pit lakes in south-east England

SUMMARY. Age and growth rates of the coarse fish of thirty-nine gravel-pit lakes in south-east England are compared. Species composition was very variable, the commonest species being roach ( Rutilus rutilus ), bream ( Abramis brama ), tench ( Tinca tinca ), perch ( Perca fluviatilis ) and pike ( Esox lucius ). Two main kinds of fish community were identifiable from the survey: (1) those consisting of a mixture of cyprinids, usually roach and bream; and (2) those in which cyprinids were rare or absent and the fish community was composed of perch and pike. The majority of the lakes fell into the first category. Comparison of growth curves derived by back-calculation showed that, in all species, variation occurred from lake to lake and from year to year. The majority of gravel-pit lake fishes had 'medium' growth rates when compared with published data by other workers on different waters. Seasonal growth of roach infected with plerocercoids of Ligula intestinalis was observed at monthly intervals. Annulus formation on the scales of these fish occurred at the onset of growth in May. The heavy Ligula burden in 89% of these fish had not caused the formation of any additional or false rings.