Epidemiological Study on Frequency of Myxosporidian Diseases in Freshwater Fish Stemming from Aquatic Habitats Pertaining to the Danubian Delta Biosphere Reservation

Abstract

In the study we aimed at estimating prevalence of two Myxosporidian diseases (Henneguyosis and Myxoboliosis), in order to measure their frequencies and distributions within populations of Esox lucius, Sander lucioperca (Henneguyosis) and Perca fluviatilis (Myxoboliosis) originating from Sontea-Fortuna (S.F.) and Gorgova-Uzlina (G.U.) aquatic habitats, within the Biosphere Reservation of Danubian Delta, Romania.
The biologic material was selected without prior knowledge of the disease status. Prevalence was determined by classifying fishes as either diseased/infected or not, at one moment in time (Point prevalence). The prevalence was determined as the proportion of diseased/infected individuals within the studied fish species.
The research started in 2003 and finished in 2008. In Esox lucius maximum prevalences were found during the years 2005 (10.26% in S.F. aquatic habitats) and 2008 (11.43% in G.U. aquatic habitats); in Sander lucioperca maximum prevalences were found during the years 2004 (15.91% in G.U aquatic habitats) and 2006 (16.67% in S.F. aquatic habitats); in Perca fluviatilis maximum prevalences were found during the years 2003 (8.97% in S.F. aquatic habitats) and 2004 (15.93% in G.U. aquatic habitats).
Overall, during the research period, an over-dispersed distribution of the parasites was noticed within both aquatic habitats.