Observations on reproductive effort in British erpobdellid and glossiphonid leeches with different life cycles.

Examined Erpobdella octoculata from an annual population, E. octoculata from a presumed biennial population and E. testacea from a presumed annual population; and Glossiphonia heteroclita and Helobdella stagnalis, both annual and predatory, Glossiphonia complanata, presumed perennial and predatory, and Theromyzon tessulatum and Hemiclepsis marginata, both ectoparasitic. The erpobdellids laid cocoons which they deserted; the glossiphoniids brooded their eggs and carried their offspring. Reproductive effort was measured in terms of offspring production per parent. On this basis the annual erpobdellids invested more in reproduction than the biennial populations. After correcting for size differences, Helobdella stagnalis and G. heteroclita carried a larger number of offspring than G. complanata. Differences were less obvious when brood sizes were expressed as live weights. Using laboratory data, reproductive effort was also measured for erpobdellids in terms of the energy investment and the sacrifice of parent biomass to gametes. On those criteria, E. testacea invested more in reproduction than any E. octoculata. Brooding leeches ingested less food per unit time than non-brooding equivalents and this was most marked in short-lived species. Brooding leeches also suffered a larger proportional reduction in weight than non-brooding ones, again most marked in short-lived species. -from Authors