A serological study of the diet of British,lake-dwelling Glossiphonia complanata (L.) (Hirudinea: Glossiphoniidae)

Summary

Monthly or two-monthly samples of G. complanata were taken from the stony littoral of five unproductive lakes in N. Wales and seven productive lakes in Cheshire and Shropshire, England, over two years. Satisfactory antisera were produced against ten potential prey groups, viz. Tricladida, Oligochaeta, Mollusca, Cladocera, Asellus, Amphipoda, Chironomidae, Ephemeroptera, Plecoptera and Trichoptera. These were used in the precipitin test to identify the gut contents of the field-collected leeches.

In productive lakes Mollusca were fed on extensively followed by Oligochaeta and Chironomidae, whereas in unproductive lakes the last two prey groups were most heavily utilized. The lesser utilization of Mollusca in unproductive sites reflects lower availability. Together, these prey groups constituted 91% and 85% of the overall diet in productive and unproductive sites respectively. The other prey groups formed only small proportions of the diet with Tricladida and Cladocera being least favoured.

Dietary composition did not vary much over the course of a year. Feeding activity is low in the reproductive period and in the winter months when low temperatures prevail. There were no significant differences in resource utilization between three weight classes, viz. small, medium and large leeches.