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Community ecology of parasites of chub fry (Leuciscus cephalus L.)
Dávidová, M. ; Jurajda, Pavel ; Gelnar, M.
The formation and development of metazoan parasite community of chub fry (Leuciscus cephalus L.) was followed in the period from July 2000 to May 2001. Chub fry (N=190) were sampled monthly from the River Morava. Altogether 27 parasite species have been recorded. The most common parasites in the investigated locality were representatives of the class Monogenea, especially viviparous gyrodactylids. First, juvenile fish 29 mm in size were found to be infected with ectoparasites and metacercariae. On the opposite, host fish larger then 50 mm were colonised with intestinal parasites.
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The effect of posthodiplostomosis on the cyprinid fish fry
Ondračková, Markéta ; Dyková, Iva ; Gelnar, M. ; Jurajda, Pavel
Posthodiplostomosis, called also black-spot disease, is caused by metacercariae of Posthodiplostomum cuticola (Trematoda, Diplostomatidae). These parasites were studied on the cyprinid fish in floodplain area of the River Dyje in South Moravia. Twelve species from 16 totally explored Cyprinids were infected by metacercariae of P. cuticola during 1998, 1999 and 2001. Roach (Rutilus rutilus), rudd (S. erythrophthalmus), silver bream (B. bjoerkna), common bream (A. brama), bitterling (R. sericeus) and Prussian carp (C. auratus gibelio) were infected in all followed seasons. These species were histologicaly examined. During the cyst development the progressive maturation of connective tissue in outer layer of the cyst and infiltration of pigment cells were observed. Production of black pigment around the parasite cyst was chacteristic host reaction. Mainly melanocytes and in a small measure iridocytes took part in the pigmentation. The metacercariae of P. cuticola caused in the juvenile fish spine and body deformation. By high invasion the tissue dystrophy was observed.
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Species determination of coregonid stocks
Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan ; Kubišta, O. ; Melichar, M. ; Špinar, M.
On the basis of results in reproduction biology, early ontogenesis and morphometrics of Coregonus maraena, C. peled and their reciprocal hybrids, the characterization of artificial reproduction development and morphometrical parameter changes in the parental species due to artificial hybridization is represented here from 1970 up to the present. On the example of populations of both aquacultured coregonid species, reared in the region of the Českomoravská vrchovina Highland, the determinative characterization of eggs, eleuterembryos and juvenile specimens are presented. To be the most important determinative characters, considered are: egg size, number of myotomes, size of hatching embryos, number of gill rackers, mouth position, body depth, number of rays and anal fin size. The actual population of C. maraena does not differ morphometrically from its state before 1970, the population of C. peled differs morphometrically from the state after introduction in 1970.
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