Resource partitioning on basis of hydrolytic enzymes in deposit-feeding mud snails (Hydrobiidae) : II. Studies on niche overlap.

Crude extracts of hydrolytic enzymes from the related mud snailsHydrobia ulvae, H. ventrosa andH. neglecta are compared by use of six different methods and 18 natural carbohydrates. Synthetic substrates for linkage specific carbohydrases and trypsin-like activity were studied in addition to lysozyme-like activity.A significant hydrolysis was only observed with the reserve carbohydrates amylose, glycogen and laminaran. Many algal carbohydrates were, however, digested to some extent.The qualitative spectra are almost identical for the three species but significant quantitative differences were found. The findings are discussed in relation to information on the chemical composition of potential food items and it is concluded that the commonly observed coexistence of the snails can in part be explained by selection for microalgae and detritus particularly meeting their enzymatic potentials.