Triaenophorus Crassus Research Articles

Specific features of parasite communities of Siberian cisco Coregonus sardinella in polytypic water bodies of the polar regions: species richness.

The article dwells upon characteristics of the species richness of parasite communities in least cisco Coregonus sardinella Valenciennes in Polar water bodies: Kureyskoye Reservoir, Lake Kutaramakan, Khatanga River. The communities consist of parasite species common in coregonids. The main species in all the parasite communities in least cisco are Dibothriocephalus ditremus and D. dendriticus. Triaenophorus crassus plerocercoids dominate in the regulated water body (Kureyskoye Reservoir). To analyze the species richness of the component communities (s), coefficients of the power-law equation s = a × nb were applied, where a is the expected species richness in the first host individual examined, and b is the rate of species accumulation in parasite component communities (s). The resulting curves of species accumulation give statistical rigor to the assessment of differences and similarities of the species richness of the component communities of parasites in least cisco of various ages and habitats. The species richness of infra- and component parasite communities in least cisco was found to be significantly lower in the lake and the storage reservoir than in riverine habitats (Khatanga River). At the same time, the species accumulation rate for parasite communities in least cisco from Lake Kutaramakan was higher than in the reservoir due to a higher diversity of parasite infracommunities.

A re-evaluation of conflicting taxonomic structures of EurasianTriaenophorusspp. (Cestoda, Bothriocephalidea: Triaenophoridae) based on partialcox1mtDNA and 28S rRNA gene sequences

Cestodes of the genus Triaenophorus Rudolphi, 1793 are widely distributed parasites of Esocidae, Percidae, Salmonidae, Thimallidae, Cobitidae, Osmeridae, Cyprinidae, Cottiidae, Lotidae, and several others in the Holarctic. The taxonomic arrangements of different authors, based on morphological and ecological–biogeographic characters, suggest the presence of two to five species of this genus in Eurasia. The genetic variation of Eurasian Triaenophorus spp. was evaluated using DNA barcoding ( cox1 and 28S gene sequences). This confirmed the validity of five Triaenophorus species: T. amurensis, T. crassus, T. meridionalis, T. nodulosus, and T. orientalis. We demonstrated systematic concordance between traditional meristic criteria and DNA sequence data. Phylogenetic reconstructions support the monophyletic origin of the group of species with a long basal plate of the scolex hook ( T. crassus, T. meridionalis, and T. orientalis). Triaenophorus crassus is represented by two haplogroups, associated with Siberia and northwestern Russia. Our results show differences between T. nodulosus, T. amurensis, and T. crassus in terms of the haplotype diversity level, which are probably related to the Quaternary history of the development of their ranges, as well as the degree of euryxeny to the second intermediate host.

Features of bacterial diseases of rainbow trout in industrial farms in North-West Russia

Studies of the parasite fauna of rainbow trout have revealed a number of pathogens of parasitic diseases at enterprises that use open water bodies as sources of water supply. Of the parasitic protozoa, the most dangerous is Ichthyophthirius multifiliis. This is due to the presence of a free-living stage in this ciliate, as well as to the possibility of localization under the fish scales. Of the helminthiases that occur in rainbow trout during artificial cultivation on the farms of the North-West region of Russia, the most problematic are monogenes and cestodes, which cause gyrodactylosis and trienophorosis. The plerocercoids of the cestode Triaenophorus crassus, in particular, are localized in the musculature of fish and, with a high degree of invasion, trout loses its commercial value. In the presence of a focus of parasitic diseases in natural reservoirs, wild fish are a reservoir of invasion, aquatic invertebrates (planktonic crustaceans, molluscs) are the most important element of the parasite-host system, and fish-eating birds, being the final host, contribute to the spread of invasions. In cage farms, due to the peculiarities of the cultivation technology, the fight against parasitic protozoa is extremely difficult and requires significant labor costs. In basin farms, on the contrary, the design of fish-breeding tanks and the water supply system allows for the most efficient implementation of therapeutic and prophylactic measures. Nevertheless, outbreaks of parasitic diseases can be observed in violation of the cultivation technology (overcompaction of the planting, violation of the feeding regime, etc.). Control of the epizootic state makes it possible to identify infection and carry out a set of necessary therapeutic and preventive measures.

INFECTION OF COREGONIDS OF CHIVYRKUISKY BAY OF LAKE BAIKAL AND TSIPO-TSIPICANSKIYE LAKES BY TRIAENOPHORUS CRASSUS PLEROCERCOIDS

Triaenophorus crassus is the causative agent of muscular trienophorosis in fish, especially pathogenic for juvenile salmonids and coregonids. The purpose of this work was to analyze the infection of coregonids with T. crassus plerocercoids in the Chivyrkuisky Bay of the Lake Baikal and Tsipo-Tsipikanskiye (Bauntovskie) lakes (basin of the Lena River, Transbaikalia). Level of infection with plerocercoids T. crassus in coregonids from 1976 to 2013 in the Chivyrkuisky Bay of the Lake Baikal did not cause concern: the prevalence in the Baikal omul did not exceed 23.6%; intensity was no more than 6 specimens; the prevalence in the Baikal whitefish is up to 5.0%. At the same time, in 1954, in the Chivyrkuisky Bay, a higher level of infection of the Baikal omul was noted (the prevalence was 44.4%; the intensity was 1–9 specimens), which does not allow us to exclude a recurrence of this situation in the future. There was a sharply different situation in terms of infection of coregonids with T. crassus plerocercoids in two lakes of the Tsipo-Tsipikanskaya group: in the lake Bolshoye Kapilyushi, the prevalence of this cestoda is ten times higher than in the lake Baunt. It is likely that such contrasting levels of infection were associated with the difference in the location of the habitats of pike (the definitive host of T. crassus) and coregonids in these lakes: the coincidence in the lake Bolshoye Kapylyushi and divergence in the lake Baunt.

Feeding habits shape infection levels by plerocercoids of the tapeworm Triaenophorus crassus in muscle of a sympatric pair of whitefish in an oligotrophic lake.

Lake Teletskoye (West Siberia, Russia) is inhabited by a sympatric pair of whitefish, with each member of the pair being characterized by different feeding habits. Coregonus lavaretus pidschian (Gmelin, 1789) is a large 'benthivorous' form, while C. l. pravdinellus (Dulkeit, 1949) is a small 'planktivorous' form. Fish were collected from the end of August to the middle of September in 2017 and 2019-2020 in the north part of Lake Teletskoye. For the 'benthivorous' form the prevalence, intensity and abundance of T. crassus ranged from 22.4% to 51.9%, 1.9-2.8 and 0.4-1.3, respectively, whereas the same indices for the 'planktivorous' form ranged from 94.7% to 97.5%, 4.2-4.8 and 4.0-4.7, respectively. The level of prevalence of infection and abundance of T. crassus in muscle was relatively stable among studied years for both forms. The level of prevalence was higher in the years 2019 and 2020 than in 2017 for the 'benthivorous' form, whereas for the 'planktivorous' form this index did not change during the studied years. For the first time, a partial sequencing of the cox1 gene (593 bp) for T. crassus was sequenced. All 15 plerocercoids of T. crassus were represented by four haplotypes.

Monitoring of sanitary and hygienic state of water bodies in the republic of Dagestan for egg contamination of intestinal cestodes Triaenophorus Nodulosus (Pallas, 1781) and Triaenophorus Crassus (Forel, 1868)

Authors monitored the sanitary and hygienic state of the river and pond basin of the Republic of Dagestan for contamination of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868) eggs. The water pollution of 25 rivers and pond water bodies of Dagestan with eggs of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868) was studied in winter, spring, summer and autumn in control sections by researching 2 500 water samples using conventional methods in the laboratory of invasive diseases of animals and birds. For the presence of eggs of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868), using conventional methods in different seasons (winter, spring, summer and autumn), 100-200 samples of water and silt of vegetation of pond reservoirs in natural zones were examined. According to the results of the sanitary and hygienic examination of water and silt of natural and pond water bodies of the Republic of Dagestan for the contamination of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868) eggs, it is possible to state moderate and high levels of water pollution with eggs of these cestodes species. According to the sanitary and hygienic state, natural and pond water bodies of the Republic of Dagestan in all natural and climatic zones are unsuccessful foci of trienophorous fish invasion by eggs of the Triaenophorus nodulosus Triaenophorus (Pallas, 1781) and Triaenophorus crassus. (Forel, 1868).

The First Data on Parasites of Monkey Goby Neogobius fluviatilis (Perciformes, Gobiidae) in the Saratov Reservoir

The parasite fauna of the monkey goby Neogobius fluviatilis has been studied from the lower part of the Saratov Reservoir. Six species of parasites are recorded, for one of which (the goby-specific plerocercoid Triaenophorus crassus) the monkey goby is recorded as an additional host for the first time. The 100% invasion of the goby by the alien fluke Nicolla skrjabini makes it possible to attribute it to the main definitive hosts of the parasite in the water body.

How to contain a tapeworm epidemic-testing the efficiency of different catch methods to reduce the translocated final hostEsox luciusin an alpine lake

Half a century after introducing the final host Northern pike (Esox lucius L. 1758) into Lake Grundlsee in Austria, a sudden massive infection with the pike tapeworm Triaenophorus crassus Forel 1868 was noticed in the population of the intermediate host Arctic charr (Salvelinus umbla (L. 1758)) and led to the closure of this famous fishery. In an effort to contain the epidemic, a total of 1163 pike were removed over a period of three years (2008–2010). The efficiencies of gill and fyke netting as well as electro and spear fishing were assessed. All four methods were costly with EUR 37–371 to catch a single fish. During intensive fishing, catch per unit effort and fish lengths of pike declined. Fyke netting coupled with electro fishing turned out to be the most practicable strategy to reduce the pike stock. After another three years, prevalence of T. crassus in Arctic charr could be reduced by 40% in 2013. However, it will be impossible to completely eradicate pike and its parasite in the lake.

Infection levels of plerocercoids of the tapeworm Triaenophorus crassus and feeding strategy in two fish species from the ultra-oligotrophic Lake Achensee, Austria.

Thus far, high burdens of Triaenophorus crassus plerocercoids have been reported only in old age groups of coregonid and salmonid fishes. Here we show heavy infection with T. crassus in young whitefish Coregonus lavaretus in the ultra-oligotrophic and regulated Achensee in Tyrol, Austria. Prevalence of T. crassus on C. lavaretus was 100% in all age groups and abundance significantly increased with fish age. The mean annual accumulation of T. crassus was 5.2 parasites in 0- to 7-year-old C. lavaretus, and 2-year-old specimens already harboured a mean of 19.4 plerocercoids. In Arctic charr Salvelinus umbla, however, the prevalence of T. crassus was less than 16% and the majority of infected fish contained only one or two plerocercoids. Triaenophorus nodulosus was present neither in C. lavaretus nor in S. umbla. We assume that the heavy T. crassus infection in C. lavaretus is largely related to their zooplankton-dominated diet and to the characteristics of Achensee, while habitat choice and feeding strategy of the S. umbla population are seen to be the main reasons for their low burdens of T. crassus.

Occurrence and intensity of parasites in Wels catfish, Silurus glanis L. 1758 from Amirkelayeh wetland, southwest of the Caspian Sea.

Amirkelayeh international wetland with a surface area of 1,230hectares and fifteen fish species is an important water resource in the southern part of the Caspian Sea. There is few reports on fish parasites of this area. In the present study, a total of 80 Wels catfish, Silurus glanis, were collected from April through July 2011. After recording biometric characteristics, common necropsy and parasitology methods were used. In the present study, a total of 441 individuals of seven parasite species consisting of one nematode: Raphidascaroides sp., one cestode: Triaenophorus crassus, two digenean trematodes: Aphanurus stossichi and Diplostomum spathaceum, two monogenean trematodes: Silurodiscoides vistulensis and Silurodiscoides siluri, and one crustacean: copepodid stage of Lernaea cyprinacea was found in the catfish. The occurrence of copepodid stage of L. cyprinacea, Raphidascaroides sp. and T. crassus are reported for the first time from S. glanis in Iran.

Infestation of zooplankton with Triaenophorus and Proteocephalus procercoids (Cestoda) in a deep oligotrophic lake

In spring 2004, a massive infestation of the whitefish population in the Austrian Lake Achensee with Triaenophorus crassus was observed. Procercoids, the larval stage of parasitic cestodes, infest copepods as their first intermediate host. Therefore, in spring 2011, zooplankton samples were taken weekly at two sampling sites and depth ranges to determine the abundances of crustaceans as well as percentages of infected copepods and temporal occurrence of parasites. In addition, whitefish (Coregonus lavaretus) stomach contents were analysed for food spectrum and parasite infestation. From the end of June to mid-August, procercoids of Triaenophorus spp. were detected in Cyclops abyssorum, the only first intermediate host for this parasite in Lake Achensee. Highest percentages of infected copepods were reached in mid-July (prevalence: 0.38%). Furthermore, an infestation of Proteocephalus sp. was observed in this copepod species, which occurred earlier until the end of the sampling period (prevalence: 1.34%). Besides C. abyssorum, also Eudiaptomus gracilis was occasionally infected with Proteocephalus (prevalence: 0.05%). The procercoids were found in both depth ranges, with no clear vertical infestation preference. More female C. abyssorum were Triaenophorus-infected than males, while the opposite was observed for Proteocephalus infection. The whitefish stomachs contained large numbers of Proteocephalus and Triaenophorus procercoids, coinciding with the occurrence of these parasites in the copepods.

TranslocatedEsox luciusL. (PISCES) trigger aTriaenophorus crassusForel (CESTODA) epidemic in a population ofSalvelinus umbla(L.) (PISCES)

In 2005, an epidemic of the pike tapeworm Triaenophorus crassus Forel, 1868 broke out in the Arctic charr (Salvelinus umbla (L. 1758)) stock of Lake Grundlsee, Austria. Besides the definitive host Northern pike (Esox lucius L. 1758), which was introduced into the lake in the 1960s, the cestode requires copepods as first and salmonid fish as second intermediate hosts. Within 2 years, the prevalence of the cestode in medium sized Arctic charr increased to almost 100% and the abundance reached a maximum of 55 cysts per fish, leading to the closure of the fishery. Such a massive infection of Arctic charr has never been reported. High pike abundance and the occurrence of a suitable copepod host facilitated the outbreak. The only first intermediate host Cyclops abyssorum praealpinus Kiefer, 1933 predominated the zooplankton community during May, when cestode coracidia hatch from eggs. Only during this infectious period, C. abyssorum praealpinus was eaten by Arctic charr (2–50% of prey organisms). Low fishing pressure on pike enabled the development of a large population that served as reservoir for T. crassus with up to 687 cestodes per fish. To contain the epidemic, 1671 pike were removed between 2008 and 2013. Infection of Arctic charr decreased to 60% and a maximum number of 16 cysts in 2013.

An assessment of parasite infestation rates of juvenile sockeye salmon after 50 years of climate warming in southwest Alaska

Climate change has produced disproportionate levels of warming in high latitude ecosystems. A critical challenge is to understand how changes in temperature will mediate ecological processes, such as disease. Several authors have suggested that warming will increase prevalence of diseases at high latitudes, yet long-term studies are lacking. We evaluated how parasite abundance and prevalence in an ecologically and economically important species (juvenile sockeye salmon Oncorhynchus nerka) has changed in an Alaskan watershed that has experienced substantial climatic change over the past half-century. We hypothesized that the average increase in summer water temperature of 1.9°C over the past 46 years in our study system would have resulted in a corresponding increase in fish metabolism, and thus potential consumption rates, that would increase infestation rates of the tapeworm Triaenophorus crassus. However, our comparison of data from 1948–1960 to 2008–2009 provided no evidence that the parasite load in juvenile sockeye salmon has significantly changed and that there is no significant relationship between summer temperature and average infestation rates. Climatic projections for southwest Alaska forecast a continuation of the current warming trend, which could potentially have effects on our studied parasite-host interaction, but thus far we found no change in infestation rates over the last 60 years.

Differential diagnosis of Triaenophorus crassus and T. nodulosus experimental infection in Cyclops abyssorum praealpinus (Copepoda) from the Alpine Lake Grundlsee (Austria) using PCR–RFLP

In 2005, an epidemic of the cestode Triaenophorus crassus in Arctic charr, Salvelinus umbla from Lake Grundlsee (Austria) was reported, resulting in the closure of the local fisheries. The parasite uses a copepod and a salmonid fish as intermediate hosts, and the European pike (Esox lucius) as definitive host. In Lake Grundlsee procercoids of T. crassus, T. nodulosus and Eubothrium salvelini use the copepod Cyclops abyssorum praealpinus as their first intermediate host. We report on the development of a PCR-RFLP assay for the specific differentiation between the procercoids of the three cestode species. Ban I restriction sites within a 207-bp 18S rRNA-amplified fragment yielded two and three species-specific products to unequivocally distinguish between T. crassus and T. nodulosus, respectively. The assay is sufficiently sensitive to characterise a single procercoid of both Triaenophorus species in their copepod host, enabling a direct measure of infection. This assay will be useful in monitoring the progress of the control methods currently in place.

The risk of parasite transfer to juvenile fishes by live copepod food with the example Triaenophorus crassus and Triaenophorus nodulosus

Natural zooplankton is a potential food resource for juvenile fish in fish farms as it is a good source of fats, carbohydrates, and protein. However, it is also a potential source of parasites and pathogens. The present study was conducted (1) to estimate the risk of parasite transfer by live copepod food under intensive farming conditions using the parasites Triaenophorus crassus and Triaenophorus nodulosus as example and (2) to look for strategies to avoid parasite infestation of juvenile fish.An easy and routinely applicable aniline blue staining method was developed to check the infestation levels of copepods with procercoids during the on-growing season of juvenile fish. From the copepod species occurring in zooplankton Cyclops spp. was infested frequently (9.4±12.0%, maximum 38.7%), Diaptomus spp. infrequently (1.5±1.6%, maximum 3.2%), Daphnia spp. never. Juvenile grayling, Thymallus thymallus, and corgonids, Coregonus sp., which had been fed with natural zooplankton revealed infestations rates with T. crassus of circa 5%, with T. nodulosus of circa 10%. As the occurrence of procercoids in the zooplankton was temporary limited, Triaenophorus infestation can be avoided by using artificial food instead of live copepods during the risky season.To prevent parasite infestation of juvenile fish methods were investigated to eradicate procercoids from copepods by chemical treatment (sodium chloride, hydrogen peroxide, citric acid treatment) and by freeze-thawing methods. Chemical methods failed to remove procercoids. In fish, which had been fed with frozen thawed zooplankton, no Triaenophorus spp. infestation was observed. Their survival rates were similar as in the control fed with live zooplankton, however the weight of the fish was significantly lower.

‘Global worming’: first record of an epidemic of Triaenophorus crassus in a population of Arctic charr Salvelinus umbla

In May 2005, an epidemic of the cestode Triaenophorus crassus occurred in the Salvelinus umbla population of Lake Grundlsee, an oligotrophic Austrian Alpine Lake. Based on catches with a standardized multi-mesh gillnet survey 53% of S. umbla were infected with up to 17 cysts of T. crassus per fish. This is the first documented record of an epidemic of this tapeworm in S. umbla.

The influence of food competition and host specificity on the transmission of Triaenophorus crassus (Cestoda) and Cystidicola farionis (Nematoda) to Coregonus lavaretus and Coregonus albula (Pisces:Coregonidae) in Finland

As a superior competitor for planktonic food, vendace ( Coregonus albula), when abundant, is expected to displace whitefish ( Coregonus lavaretus) from feeding on plankton and to force it to rely more on benthic food. The predicted result would be a reduced abundance of the copepod-transmitted cestode Triaenophorus crassus in whitefish, but an increase in the abundance of the nematode Cystidicola farionis transmitted via benthic amphipods. We studied the occurrence of both parasites in whitefish during 1991–1996 in three interconnected areas at Lake Saimaa, Finland, where the densities of the vendace stocks varied due to natural fluctuation in year-class strengths. In accordance with our hypothesis, some indication of the effect of the density of the vendace population on abundance of C. farionis infection in whitefish was found, but not in the case of T. crassus. Only 0.2% of vendace were infected with T. crassus, while up to 100% of the whitefish in the yearly samples harboured the parasite. In further experiments we clarified which copepod species in Lake Saimaa act as first intermediate hosts of T. crassus, and verified from stomach samples the exposure of both whitefish and vendace to those species. Experimental infections indicated that the infectivity of T. crassus is lower for vendace than for whitefish. We suggest that the reason why vendace stock density does not affect T. crassus infection in whitefish is that T. crassus is transmitted in littoral areas during a short period in spring. At that time of the year copepods are abundant and available to both whitefish and vendace, but since the parasite is less infective to vendace, they do not become infected. At other times of the year, dense vendace stocks may force whitefish to shift to benthic food, which includes amphipods transmitting C. farionis. During vendace stock decline, whitefish may, however, continue to feed on plankton and avoid exposure to C. farionis.

Accumulation of plerocercoids of Triaenophorus crassus in the second intermediate host Coregonus lavaretus and their effect on growth of the host

Patterns of accumulation of Triaenophorus crassus in its second intermediate host whitefish Coregonus lavaretus s.l. were studied between 1991 and 1996 from two host populations in two separate areas of Lake Saimaa, Finland. Whitefish were infected commonly with several T. crassus plerocercoids and the parasites were aggregated into the oldest hosts. In one host population the annual parasite accumulation was 0·9 parasites in all host age groups between 3 and 8 years. In the other host population the annual accumulation was 1·6 parasites in 3–5‐year‐old fish, but increased up to 3 to 4 parasites per year in fish over 5 years old. The increase did not coincide with the period of maturation or any increase in whitefish growth, both of which could alter the food intake of the fish. The sharp increase in the annual accumulation suggests a threshold intensity above which the probability of acquiring further parasites increases. In spite of a heavy aggregation of parasites there was no evidence of parasite‐induced host mortality. The annual increase in mean abundance was not correlated with the mean annual weight increase in 2–4‐year‐old fish within cohorts. However, evidence of a negative effect of parasites on whitefish growth was revealed by back‐calculation of lengths of uninfected and infected whitefish and correlations between length or weight of fish and intensity of infection with fish age. Both analyses suggested that larger young fish harboured more parasites than the smaller ones while in older fish the reverse was true, a pattern that has not been shown earlier for parasitized fish.

The occurrence of cestode larvae in brown trout after stocking in a large regulated lake in northern Finland

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 31:55-63 (1997) - doi:10.3354/dao031055 Occurrence of cestode larvae in brown trout after stocking in a large regulated lake in northern Finland R. Rahkonen1,*, P. Koski2 1Finnish Game and Fisheries Research Institute, PO Box 4, FIN-00721 Helsinki, Finland2National Veterinary and Food Research Institute, Oulu Regional Laboratory, PO Box 517, FIN-90101 Oulu, Finland *E-mail: riitta.rahkonen@rktl.fi The aim of this study was to obtain relevant information on larval cestode infection of brown trout Salmo trutta m. lacustris, for fish stock management purposes in the large, regulated Lake Inari in northern Finland. Compensatory stockings of brown trout have been carried out annually since the mid-1970s. A total of 209 brown trout, which were stocked at the age of 3 yr, were studied for larval cestodes in 1994 and 1995. Diphyllobothrium dendriticum was clearly dominant among the 4 cestode larval species found. The other species were D. ditremum, Triaenophorus crassus and T. nodulosus. After 1 summer in the lake the prevalence of D. dendriticum infection was 75% (abundance 5.3) and 46% (abundance 0.9) in 1994 and 1995, respectively. After 3 or more years in the lake (>=6+) every brown trout was infected with a mean number of about 130 larvae for both years. All organs in the body cavity were found to be infected. In addition, capsules containing D. dendriticum were found in muscles after the second summer in the lake and the prevalence of muscle infection was 73% (abundance 3.2) and 95% (abundance 7.1) in the oldest age group (>=6+) in 1994 and 1995, respectively. This has decreased the commercial value of the brown trout. A slight positive correlation between the number of D. dendriticum and the condition index (Fulton) of fish was found in each age group, although histological studies of heavily infected fish revealed severe chronic granulomatous peritonitis. Indications of elimination of individuals most heavily parasitized with D. dendriticum were not obtained for the present material. D. dendriticum was not found in the potential prey fishes of the brown trout studied in Lake Inari: vendace Coregonus albula, whitefish Coregonus sp. and nine-spined stickleback Pungitius pungitius. Salmo trutta m. lacustris · Brown trout · Diphyllobothrium dendriticum · Diphyllobothrium ditremum · Triaenophorus crassus · Triaenophorus nodulosus · Regulated lake · Stocking Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 31, No. 1. Publication date: October 28, 1997 Print ISSN:0177-5103; Online ISSN:1616-1580 Copyright © 1997 Inter-Research.

Diapause of copepods as an element for stabilizing the parasite system of some fish helminths

The analysis of infection dynamics of copepods, which are the intermediate hosts of three helminth species of freshwater fishes (Triaenophorus crassus, Proteocephalus exiguus and P. percae), has shown that diapause in the life cycle of the copepods is favourable for preserving the infection in the waterbody until physiological prerequisites for successful infection of the final host are acquired. The peculiarity of a copepod's life cycle may determine the strategy of a parasite in its preimaginal phase as a waiting stage, and the duration of the residence of helminth larvae in copepods that have an obligatory diapause, is one of the elements the provide stability in parasite systems.