Food availability and temperature are the main factors influencing copepod reproduction, but their relative importance is still a topic of discussion. Moreover, even less is known about the role of food quality. In this study, we investigated the response of the calanoid copepod Temora longicornis to natural and enriched food. Throughout a seasonal succession we varied food quality and quantity by adding Rhodomonas and Dunaliella to natural seston. Egg production and ingestion were established at in situ temperatures. A preliminary analysis of the data shows that temperature may not play the prominent role that was expected, and that effects of food additions are especially clear in periods of low food availability