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The structure of a natural population of the medicinal leech, Hirudo medicinalis , at Dungeness, Kent
Author(s) -
WILKIN P. J.,
SCOFIELD A. M.
Publication year - 1991
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1991.tb01397.x
Subject(s) - hirudo medicinalis , leech , hatchling , foraging , biology , population , zoology , ecology , fishery , demography , hatching , sociology , world wide web , computer science
SUMMARY 1. A hot branding method was used to mark medicinal leeches ( Hirudo medicinalis L.) from five samples (four in 1984, one in 1985) at agravel pit at Dungeness in Kent. Analysis of capture‐recapture data by the Fisher‐Ford and Jolly methods gave similar results and indicated a population in excess of 10000 (0.112 leeches per m 2 ) in 1984 and 1985. Successive estimates were each higher than the last suggesting a thriving community. 2. The population structure was skewed towards the lower weight classes. This may indicate good recruitment of hatchlings, as also indicated by the presence of cocoons, or the failure to capture heavier satiated or gravid leeches because of their relative unresponsiveness to the sampling method involving water disturbance, or their complete absence from the water during cocoon laying. Gravid leeches were always above 2 g in weight. Recaptured marked leeches revealed that they migrated throughout the site, indicating active foraging for hosts.