ECOLOGICAL AND BIOLOGICAL IMPLICATIONS OF AFRODIPLOZOON POLYCOTYLEUS (PAPERNA, 1973) INFESTING CYPRINUS CARPIO IN ABBASSA

Ramadan, R. A. M

Fish Diseases Department, Central Laboratory For Aquaculture Research, Agricultural Research Center, Ministry Of Agriculture, Egypt.

Received 2/ 1/ 2012 Accepted 24/ 1/ 2012

Abstract

This study quantized the prevalence and intensity of Afrodiplozoon polycotyleus
on Cyprinus carpio from Abbassa research fish ponds. Begin from June 2009 to August 2010, the ecological interactions between a gill parasite, A.polycotyleus and its host, C.carpio were studied. A total of 630 C.carpio were collected over the study period with length (between 44 and 50 cm) Weight (250-500g).Oxygen levels were low in the ponds over the 12-month study, averaging only 2.5mg \ liter (monthly range 1.2-4.3mg \litre). However, parasite prevalence was high (47.2%), suggesting high tolerance to low oxygen in A.polycotyleus. The prevalence of parasites varied with host body size, with the highest frequency of occurrence in the middle size classes. Prevalence also varied over the year; seasonal peaks of water level coincided with a lower frequency of A. polycotyleus. Of the hosts infected, 37.1% infested by one parasite, and 62.9% infested by two parasites. No fish were infested with more than two diplozoons. There was evidence for strong site specificity within hosts; 77.7% of the parasites were located on the filaments of the second gill arch, which may relate to increased oxygen availability. In addition, only one of 178 infested fish had more than one parasite on one side of the branchial filaments. Although A.polycotyleus is undoubtedly parasitic, we found no evidence of a negative parasitic effect on the condition or reproductive status of Cyprinus carpio.