Distribution, reproductive cycle, and food habits of the herbivorous snail Chlorostoma lischkei oŠ the coast of Suttsu Bay in southwestern Hokkaido, Japan

Abstract

We examined the distribution, reproductive cycle, and food habits of the herbivorous snail Chlorostoma lischkei, which predominates in the intertidal and subtidal zones oŠ the coast of Suttsu Bay in southwestern Hokkaido, Japan, to evaluate the relationship between the activity of C. lischkei and the formation of large algal beds on coralline flats. As revealed by a mark-recapture experiment for 18 months using 1,672 marked snails, the snails released into the intertidal zone in June had moved to the subtidal zone by November and returned to the intertidal zone in May. Histological observation of the gonads indicated that the snail had one spawning season per year, from July to September. Gut content analysis revealed that food consumption of large algae, including fragments, gametophytes and young sporophytes, increased from November to March, while snails fed on benthic diatoms throughout the year. It is known that young sporophytes of annual algae such as Undaria pinnatifida, Desmarestia viridis, Polysiphonia morrowii, and Saccharina spp., invade the subtidal zone from December to January and then grow to macro-sporophytes by April. Therefore, C. lischkei may be interfering with the large algal bed formation in Suttsu Bay through feeding activity.