Effects of trematode infection on metabolism and activity in a freshwater snail, Semisulcospira libertina

Changes in the metabolism and activity of the freshwater snail Semisulcospi ra libertina infected with larval trematodes were studied experimentally. I n snails up to 11 mm in shell width, crawling distance, feeding frequency, and the proportion of individuals located on vertical walls did not differ among snails infected with mature or immature cercariae, or uninfected snai ls (p > 0.05). In snails larger than 11 mm, individuals infected with matur e cercariae tended to feed more frequently during the light period (p = 0.0 081), but the distance they crawled and the proportion of individuals locat ed on vertical walls did not differ, regardless of infection (p > 0.05). In fection with mature cercariae significantly increased the oxygen consumptio n rate (p = 0.016), which was measured only in the large size.