Development and population dynamics of Amonardia normani Brady reared on axenic and non-axenic diatoms

Amonardia normani Brady nauplii, harpacticoid copepods, were fed axenic and non-axenic Nitzschia constricta cultures in order to study the dietary imp ortance of heterotrophic bacteria associated with diatom cultures. The conc entration of diatoms used during experiments (0.13 mu g chlorophyll-a ml(-1 )) resulted in maximum ingestion rates. Larval development was delayed but survival was higher in the axenic diatom diet. Female fecundity did not cha nge significantly between diets. The exponential rate of population increas e (r) estimated from Life table analysis was greater in the non-axenic diat om diet. Although A. normani are able to grow on a diatom-only diet, hetero trophic bacteria were important for significantly increased rates of popula tion growth. (C) 1999 Elsevier Science B.V. All rights reserved.