Diseases of Aquatic Organisms · 1999 · 41 citations · 0 references
The impact of Maritrema subdolum Jagerskiijld, 1908 on Corophjum volutator Pallas, 1766 was examined under laboratory conditions. Adult specimens of C. volutator were placed in petri d s h e s and exposed to different numbers (3, 10, 30, 50, 100, 150, 200) of recently emerged cercariae of the microphallid trematode M. subdolum. Addition of the same number of cercariae to the dishes was repeated every second day until the crustaceans died. The experiments revealed a strong negative correlation between the density of cercariae in the dlsh and the average survival times of C. volutator. Amphipods exposed to cercariae densities of 200 cercanae per 9.6 cm2 d ~e d after 1.6 d (10.5 SD) whereas specimens exposed to cercariae densties of 30 cercariae per 9.6 cm2 died after 35.8 d (17.1 SD). All dead C. volutator were inspected for larval M. subdolum. Highest infestation intensities of approxinlately 80 larval M. subdolum were found In the test group to whlch 50 cercariae were added every second day. In other test groups, where C volutator was exposed to elther higher or lower cercanae densities, the specinlens harboured fewer larval trematodes when they died. Not yet encysted metacercariae seemed to affect C. volutator in a more detrimental manner than encysted metacercariae. Changes in the behaviour of the infested crustaceans were observed during the experiments. Heavily infested specimens had problems with swimming and crawling m the normal way. All results are discussed in relation to field data. Mass mortality of C. volutator as a result of M. subdolum infestation seems to be an exceptional but conceivable occurrence in shallow water areas of the Baltic Sea.