Ref ID : 7503
Frode Thorhauge; Reproduction of Potamothrix hammoniensis (Tubificidae, Oligochaeta) in Lake Esrom, Denmark. A field and laboratory study. Arch.Hydrobiol. 76(4):449-474, 1975
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Production of cocoons, the number of eggs, and the duration of breeding period of P. hammoniensis in relation to temperature and weight of the adult individuals was studied in the laboratory. A relation between the developmental rate of embryos and temperature was found. At 11-20 m depth in Lake Esrom deposition of cocoons occurred in spring and summer, beginning at lower depths at about 5 degrees C due to a larger weight of the specimens here. Usually breeding first creased at lower depths because of higher temperature. In the deepest parts of the lake the breeding period may be shortened by anaerobic conditions. The production of eggs per individual increased with decreasing depth. Deposition of cocoons was accompanied by decrease in weight of the individuals.