parasitic worms and their histopathological effects in four sturgeon species from the southwest shores of the caspian sea

this study conducted to provide the status of parasite communities of four sturgeon species viz. acipenser stellatus , a. gueldenstaedtii , a. nudiventris , and huso huso in the southwest of the caspian sea and their histopathological effects on the examined fishes. for this purpose a total of 93 individuals of four sturgeon species were caught in two fisheries regions from the southwest of the caspian sea (guilan province, iran) from march 2010 to may 2011. the histological slides of the infested tissues of the examined fishes were prepared for study of the histopathological effects of the parasites. classical epidemiological variables, including mean intensity, prevalence, abundance and dominance were calculated for overall samples, grouped by season, geographical region, and sex. five worm species, including two nematodes ( cucullanus   sphaerocephalus and eustrongylides excisus larvae), one cestode ( bothrimonus fallax ), one acanthocephalans ( leptorhynchoide plagicephalus ) and one digenean trematode ( skrjabinopsolus   semiarmatus ) were found in examined sturgeons and their histopathological effects on the fish tissues were assessed. based on the results, the diversity of the parasites (including freshwater ones) in the southern part of the caspian sea have decreased since the time of the first study in 1972. this may be related to unfavorable conditions in freshwater ecosystems.