ROLE OF WATER TEMPERATURE ON THE SIZE, MIGRATION ACTIVITY AND PATHOGENITY OF DIPHYLLOBOTHRIUM-DENDRITICUM (CESTODA) PLEROCERCOIDS IN BROWN TROUT SALMO-TRUTTA M. LACUSTRIS (L.)

The size, migration activity and pathogenity of Diphyllobothrium dendr iticum (Cestoda) plerocercoids in the intermediate host were studied e xperimentally in age 1+ brown trout Salmo trutta m. lacustris (L.). In the first experiment (A) which lasted 12 weeks, two water temperature s were used: heated water at about 15 degrees C and non-heated at abou t 10 degrees C. In the second experiment (B) which lasted 7 weeks, the water temperature was raised gradually to 24-26 degrees C. Increased water temperature did not promote D. dendriticum-induced mortality in either of the experimental conditions. Experiment A revealed, however, that the worms were longer and migrated more actively outside the bod y cavity of fish in heated aquaria.