[Kinetics of zooplankton in an aquatic continuum: from the Marne River and reservoir to the Seine estuary].

A study was carried out within a 700-km river sector, including three types of ecosystems (a reservoir, a river and its estuary) to characterise the major features of zooplankton communities in the Seine Basin. In rivers, zooplankton biomass becomes significant only when the growth rate of the organisms is higher than the dilution rate (4-5th orders rivers, according to River Continuum Concept). Upstream, short residence times favour the development of small species (Rotifers) with low individual body weight and biomass.

[Influence of photoperiod length on the mictic-female production rate in Notommata copeus Ehr. (Rotifera)].

In short-day conditions, the reproduction of N. copeus is parthenogenetic (no mictic females). The mictic females appear when the day-length exceeds 14 hrs (LD=14/10).