Prevalence of Two Monogenean Parasites on Different Length Groups of Crucian carp ( Carassius carassius Linneus , 1758 )

Dactylogyrus anchoratus Dujardin, 1857 and Gyrodactylus katharineri Malmberg, 1964 were identified on crucian carp, Carassius carassius L., 1758 in the present study, which was carried out between February 1999 and January 2000. A total of 117 fish specimens were examined. The infestation prevalence and mean intensity levels for G. katharineri was 37.61%, respectivly 27.75±2.203 and for D. anchoratus was 24.78%, 4.69±1.730 per fish, respectively. The infestation prevalence and mean intensity levels were higher during spring and sumer, for the both parasites. No statistically significant preference for either sex of the fish was determined. In this study, we examined a total of 117 fish, out of which 44 (38%) were infested by 1221 G. katharineri, and 29 (25%) infested by a total of 136 D. anchoratus.


Introduction
The importance of fish parasites is directly related to the importance of the fish that they affect (Hoffman, 1967).Metazoan parasites, especially trematodes, can cause gill infestations and inhibite oxygen exchange across gill lamella (Mitchum, 1995).Considering these aspects, fish parasites under favorable conditions, cause economic loss by affecting the health of fishes and causing high mortality (Tripathi, 1959).
Monogenean parasites are still widespread in freshwater wildlife, on farm fishes and marine habitats.The genus Gyrodactylus is represented by a great variety of fish parasites, inhabiting both freshwater and sea water environments (Bykhovskaya-Pavlovskaya et al., 1962;Harris, 1985).Gyrodactylus members are viviparous, most mature specimens exhibit a well-formed embryo, complete with a full complement of attaching armament, within the uterus.It is often possible to observe a smaller embryo within the uterus of the first embryo and more rarely a third within the uterus of the second one (Price, 1967).Gyrodactylus are seen especially in teleost fish, frog larvae and adult amphibians, while they infect and live ectoparasitically on the skin, fins and gills of fish.The gill Monogeneans, due to their microscopic size and technical difficulties, were uncounted in their collection and study, and remained little known until the twentieth century.Monogenetic trematodes of freshwater fishes have been studied by Gussev (1967) and Kulkarni (1969).The majority of Dactylogyrids have strictly hosts, as they appear as specific parasites ( Jalali, 1992).
The first relevant study about this subject has been done by Nordmann in 1832 on Gyrodactylus elegans, after which several studies have been carried on all over the world.High infestation rates of Gyrodactylus species on natural population have also been studied by several authors (Hanzelova and Zitnan, 1964;Jansen and Bakke, 1957;Kirby, 1981;Mo, 1957;Rawson and Rogers, 1964).
In this investigation, G. katharineri and D. anchoratus in crucian carp from Enne Dam Lake (Kütahya) were studied during the year of 1999-2000.Here we report the ectoparasitic infestations of G. katharineri as a monogenetic parasite as being noticed for the first time in Turkey.

Materials and methods
A total of 117 fishes collected on a monthly basis were examined with a stereo microscope to determine their ectoparasite community.The fishes were separated according to their sex and were measured for the total length.The first microscopic examinations were done for observing ectoparasites and identifying any cysts, ulceration and scars.Skin, gills and fins were examined and the parasites were counted separately for each body part of the host fish.Then the gill filaments were dissected out of the branchial cavity and placed in a petridish containing saline solution (0.75% NaCl).Parasites were collected and preserved, and identification was performed according to the characteristics described by , Malmberg (1962) and Harris (1982).All of the collected parasites were kept in tap water, fixed in 10% formaldehyde and transferred to 5% glycerol in 70% fishes were infested with D. anchoratus, and its prevalence was 24.78% and mean intensity levels 4.69±1.730per infested fish (Tab.1).
The prevalence and intensity of parasitic infestation in different length groups of female and male crucian carps are given in Tab. 2. These parasite species were found on all sizes of the host fishes.The parasites attained the maximum level on the largest fish specimens (146-184).In addition, total parts and haptor of the recorded parasites were photographed (Fig. 1 and Fig. 2).

Discussion
Out of 117 fishes, 60 were found infested by two nonnative C. carassius parasites.The prevalence of ectoparasite ethanol after 1 week.In addition, at least 10 specimens of Gyrodactylus and Dactylogyrus were placed on glass microscope slides with a drop of 1/4000 formalin while the cover slip was placed over the parasite.They were fixed in glycerin alcohol (90 parts of 70% ethyl alcohol and 10 parts of glycerol), stained in Borax carmine and finally mounted in glycerin jelly.Descriptive terminology fallows, with length and width hard parts (Malmberg, 1970).
All measurements are given in millimeters.The terms infestation prevalence (%) and mean intensity are used in accordance with the definitions established.The prevalence (%) was calculated as the percentage of the total number of fishes infested out of the total number of fishes examined (Bush, 1997).The mean intensity was calculated as the average number of parasites on the total number of infected fishes.

Results
Out of the 117 fish specimens examined, 44 were infested with G. katharineri, resulting a prevalence of 37.61% and mean intensity levels 27.75±2.203., while 29  group (Tab.1).Among the gill inhabiting parasites, G. katharineri has been reported for the first time by Malmberg (1962).Harris (1985) reported about Gyrodactylus species in different places of the fish body and that they are widespread throughout freshwater and marine habitats.The present work states for the first time that G. katharineri parasites were noticed on C. carassius fishes in Turkey.Monogenetic trematodes have been studied by Leuckart (1827), Mamaev (1981) and Hargis (1955).As hosts, the female fishes were more infected than the male ones.Thomas (1964), Bibbly (1972), Watson and Dick (1980) concluded that due to lower physiological resistance, the female sex of the fishes is responsible for a higher infestation rather than ecological conditions.The present study recorded a significant relationship between the host length and the intensity of parasites in C. carassius.
The study revealed that the fishes of the 2 nd intermediate (146-184 mm) and the ones of 102-124 mm length were more heavily infested than the smallest and the 1 st intermediate length groups.These results are in accordance with those of Stromberg and Crites (1975), who reported that the prevalence and intensity of infestation generally increased with the host's size, up to a certain point and then declined.

Conclusions
The aim of this study was to determine the distribution of parasites, according to the fish size and gender.As seen in Tab. 1 and Tab. 2, showing differences in parasite prevalence, the density was close to each other in all cases.Similar studies confirm the data recorded in Turkey (Altunel, 1981;Kartal and Ozturk, 2009;Ozturk, 2000;Ozer et al., 2004).