Reproductive response of Calanus helgolandicus. I. Abnormal embryonic and naupliar development

Abnormal embryonic development is described for the copepod Calanus helgolandicus Anomalies followed ingestion of diatoms by females which led to erroneous synchronization between nuclear division and cytok~nesis, with malformation of the cellular membrane between daughter cells during mitosis. Similar types of cellular anomalies and morphological deformities, reported for the first time in the embryonic and naupliar stages of C. helgolandicus, were observed both in the laboratory and in situ. The ecological Importance of this process as a factor controlling mortality and recruitment of copepods In the ocean IS discussed.