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The Life Cycle and Production of the Leech Erpobdella octoculata (L.) (Hirudinea: Erpobdellidae) in a Lake District Stream

J. M. Elliott
Journal of Animal Ecology
Vol. 42, No. 2 (Jun., 1973), pp. 435-448
DOI: 10.2307/3296
Stable URL: http://www.jstor.org/stable/3296
Page Count: 14
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Life Cycle and Production of the Leech Erpobdella octoculata (L.) (Hirudinea: Erpobdellidae) in a Lake District Stream
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Abstract

(1) The life cycle of Erpobdella octoculata took 2 years in the Wilfin Beck, a small, stony stream in the English Lake District. The leeches bred and died at the end of their second year. Exponential rates of mortality and growth varied throughout the life cycle, but were constant in each year-class for the same period in the life cycle. In most months, there was a negative correlation between rates of mortality and growth. (2) Production was highest in the first year of the life cycle and occurred chiefly in the period of rapid growth (March to July). Although estimates of production and standing crop varied considerably between years and between year-classes, ratios of production to mean standing crop were very similar in each year (mean annual value of P/B ratio = 1.5).

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