Growth of Moina macrocopa (Straus 1820) (Crustacea, Cladocera): influence of trophic conditions, population density and temperature

摘要

The growth of a strain of Moina macrocopa (Straus 1820) isolated from an experimental stabilization pond in Marrakesh, was examined at seven concentrations of algae (6.25–6.25 × 105 cells ml−1 and at 5 different temperatures (15–30 °C)). Feeding conditions influenced the growth rate as well as the maximum size that reached 1.8 mm at 25 °C and at the highest algal concentration (6.25 × 105 cell ml−1). The life span and number of moltings reached a maximum (17.4 days and 13 moltings) at average nutrient concentrations (6.25 × 105 cell ml−1). Juvenile stages varied from 1 to 3 and adult ones from 6 to 8. In the temperature interval tested, growth rate increased with temperature while longevity decreased. Temperature had less effect on maximal size than nutrient availability. Population density (but not crowding) influenced longevity and survival but had no effect on growth.