Reproduction and mortality of Tubificidae in lakes

With increasing depth the indices of daily egg production decreased, while the breeding periods elongated. Consequently, the fecundity of groupings did not show any clear relationship to depth. The rate of elimination during embryonic development and immediately after hatching attained 59-72% of the total number of eggs laid. In the study environments tubificid cocoons were found in the sediment layer 0-> 5 cm deep. In laboratory experiments, with no predators present, the highest mortality of embryos was recorded for the surface sediments and the lowest for the depth of 2-5 cm. The mortality of newly hatched individuals depended on the depth at which the cocoons were incubated in the sediments, the greater the depth the higher the mortality. For development of eggs of Tubificidae derived from the profundal the optimum temperature was about 12°C.

Pages 463-479 : illustrations ; 24 cm

Strony 463-479 : ilustracja ; 24 cm

Bibliographical references (pages 478-479)

Streszczenie w języku polskim

Bibliografia na stronach 478-479

Abstract in Polish