Effects of Bucephalus sp (Trematoda : bucephalidae) on Perna perna mussels from a culture station in ratones Grande Island, Brazil

This study reports the prevalence of Bucephalus sp. in Perna perna populations from a Culture station Of Southern Brazil and its effect on the mussel reproductive tissue and immune system. The prevalence of Bucephalus sp. in P. perna (n = 1871) was considered low (3.1%) and did not seasonally vary. Histological sections of the mantle of infected mussels revealed a marked (80'%) reduction of the reproductive tissue that was severe even in mussels exhibiting a moderate infection degree. The total (THC) and differential (DHC) hemocyte counts were lower in infected mussels (3.9 x 10(6) hem/ml granular hemocytes = 33%) as compared with noninfected animals (5.5 x 10(6) hem/ml; granular hemocytes = 40%). The plasma protein concentration did not vary upon infection. Hemocyte infiltration was significantly higher only in mussels with a very heavy infection degree. The parasite sporocysts were never seen encapsulated by the host hemocytes. Our results indicate that Bucephalus sp. promotes a severe castration in its host and apparently evades the mussel immune system. (C) 2002 Elsevier Science (USA), All rights reserved.