Short-term reproductive responses of Capitella sp. I (Annelida: Polychaeta) fed on different diets

We measured short-term reproductive responses (15 days) of Capitella sp. I (Annelida: Polychaeta) at 20 °C for six daily ration levels (0.13–1.30 mg of organic N per cup) of four food sources (diatoms, Ulva, Tetramen fish food and Gerber's mixed cereals). Both food ration and food type influenced the size of the females and their reproductive characteristics (number of fertile segments, fecundity, number of eggs per fertile segment, and reproductive output). Daily food rations also affected the proportion of brooding females. The amount and the source of the food available affected both the periodicity and the intensity of reproduction. We used simple linear regression models to describe the relationships between reproductive characteristics (fecundity and reproductive output) and daily (N, C, and calories) rations. We ran an experiment allowing us to account for differential losses of hydrosoluble molecules by leaching from the different food types. This correction increased the correlation coefficients. In all cases, N ration best described both fecundities and reproductive outputs.