Cellulase Activity in Gastropods: Should It Be Used in Niche Separation?

The hypothesis tested was that snail species with different diet preferences should exhibit different CMCase (carboxymethylcellulase) activities. CMCase activities of three species in a tempory pond, and two species in a permanent lake, in Indiana were determined. While the three temporary pond species have significantly different diet preferences (Brown 1982), a one-way ANOVA of CMCase activities yielded no significant difference (P>0.05), suggesting that cellulolytic enzymes were not being used in niche separation when the snails were collected. Reducing sugars were formed when homogenates of Aplexa, Lymnaea, Physa, and Goniobasis were incubated with microcrystalline cellulose, demonstrating that these species can degrade native cellulose for possible nutritive value. CMCase activities of different parts of the digestive system of Pseudosuccinea columella were determined in snails from two locations in Rhode Island. A two-way ANOVA indicated a possible pond effect (P=0.079), strengthening the conclusion of no CMCase activity differences among the Indiana woodland species. Activity in the stomach was significantly (P<0.05) greater than that observed in the digestive gland in both freshly collected and starved individuals. Starvation did not significantly reduce CMCase activity.