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The Natural Feeding and Resource Partitioning of Erpobdella octoculata L. and Erpobdella testacea SAV. in Lake Esrom, Denmark

1983; Wiley; Volume: 68; Issue: 4 Linguagem: Inglês

10.1002/iroh.19830680404

0020-9309

Peter Dall,

Fish Ecology and Management Studies

Abstract The natural feeding and competitive interactions between populations of Erpobdella ostoculata and Erpobdella testacea were investigated in Lake Esrom, Denmark, during 1979/80. Statistical analysis revealed that the size of the leeches was the main factor involved in resource utilization. Size‐specific feeding included differences in the numerical composition of diets and the size of individual prey. Five weight classes of Erpobdella spp. were distinguished. The number of prey per leech increased from 1.63‐2.84 for the first to the fifth weight class, whereas diversity in feeding averaged 1.71 prey per leech. Quantification of competitive interactions indicated that the temporal differences in weight class composition of the two species were sufficient to explain coexistence, although both species have an annual life cycle, and neither species showed taxonomic food refuges.