First record of invasion leeches Hellobdella sp (Glossiphonidae) and Cystobranchus respirans (Piscicolidae, Euhirodina), periodic parasites on two native Cyprinids of Zayandeh-rud River in central region of Iran

Objective: In aquatic ecosystem, leeches are important component of food webs, as predators, parasites vectors of parasites and as food of aquatic animals, since some species morphologically adapted for obtaining and digesting food consisting primarily of the blood of fish. Identification and investigation in their parasitic life is important. Pervious work on fresh water leeches in Iran is scarce. The purpose of the present study was identification of leech fauna, and to investigate the prevalence, spatial distribution, and mean intensity of parasites on each host. Method & Materials: Sampling was carried out monthly from March 2007 to April 2008, in central Zayandeh- rud River. A total of 150 specimens of C. damascina and 100 C. aculeata were captured using appropriate gill nets. Specimens were transported live to the laboratory for bio-examination. Age determined by both scale and otolith reading. Positions and populations of leeches on each specimen were also recorded. Thereafter, parasites were anesthetized by 90% ethanol and then preserved in 10% formalin for further examinations. Binocular was used for studying and identification of leeches. Specimen’s identification carried out using identification key. Results & Conclusion: About 90% were infected with both Helobdella sp. and Cystobranchus respirans. The results showed that both parasites have significantly preferred microhabitat, generally aggregating on the base of host fins. Pattern of distribution was as follows: 40% on the base of anal fins, 20% on the pelvic, 20% on the caudal, 12% close to the pectoral fins, and 8% were scattered on body surface. Similar patterns of parasites distribution were found on C. aculeata. Incidence of parasite on the later species was about 80%. Presence of Helobdella sp and C. respirans was observed between April and May, disappearing thereafter. The pathogenic effects of two leech species was not carried out by us but according to Burreson et al (1995) leeches alone are generally not considered important fish pathogen and effects are usually localised and restricted to attachment on feeding sites which cause haemorrhage and even anima resulting in succumb of hosts. But sure both species, Glossiphonidae and Piscicolidae are rectors of infections agents such as bacteria, viruses and haematosis protozoa. In our case, C. respirance is the one which can transmit pathogen. However, such ecological relation need further study.

کلیدواژه ها:

Leech ، Hellobdella ، Cystobranchus respirans ، Zayandeh-rud ، Capoeta damascina and Capoeta aculeata