A Study of Predation Rates of Leeches on Tubificid Worms Under Laboratory Conditions

Abstract

The objective of this study was to establish the rate at which predatory leeches consume tubificid worms, at worm population densities simulating those of Cleveland Harbor. Two common species of leeches from Lake Erie were studied, Helobdella stagnalis and Erpobdella punctata. A mixed population of tubificids, mostly Limnodrilus hojfmeisteri, Limnodrilus cervix and Peloscolex multisetosus were used for prey. The mean consumption rate for Helobdella stagnalis was 0.57 tubificids/leech/day. The mean consumption rate of Erpobdella punctata was 1.78 tubificids/leech/day. Previous studies of the benthos of the Cleveland Harbor reported 11 Helobdella stagnalis per square meter of bottom area. Using this number, specimens of Helobdella stagnalis were estimated to consume 6.27 tubificids per square meter of bottom area per day at 23.5° C.