Feeding of calanoid copepods and analyses of their faecal pellets

• Main Author: Jansen, Sandra
• Other Authors: Smetacek, Victor, Bathmann, Ulrich
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2006
• Subjects: Copepods; Feeding; Phytoplankton; SEM; North Sea; Southern Ocean; 570; 570 Life sciences; biology; ddc:570
• Online Access: https://media.suub.uni-bremen.de/handle/elib/2246; https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000103665

Observations on the feeding behaviour of calanoid copepods, microscopical analysis of their faecal pellets and the possible ecological importance of copepod grazing will be addressed in this thesis. Laboratory as well as field studies were applied to investigate the responses of different copepod species to different food environments, covering the three main phytoplankton groups - Diatoms, Dinoflagellates and Coccolithophores. Since many of the species belonging to these groups are surrounded by mineral skeletons, qualitative observations can be revealed by the use of scanning electron microscopy (SEM).The importance of calcifying algae in the marine carbon and calcium cycles is widely known, but the role of copepods for the coccolith calcite dissolution is vague. Dissolution experiments were performed using the calcifying algae Calcidiscus leptoporus. SEM observations of the morphological changes of the coccoliths were used for content interpretation of freshly produced faecal pellets in feeding experiments with the common North Sea copepods Calanus helgolandicus and Temora longicornis. Coccolith calcite dissolution during copepod gut passage was found to be minor and can therefore not contribute significantly to the generally observed calcite dissolution in the upper ocean.Field experiments conducted during a dinoflagellate bloom in the North Sea clearly showed that some copepod species can feed very efficiently on the dinoflagellate species Dinophysis norvegica. SEM observations showed that faecal pellets produced by C. helgolandicus were almost exclusively filled with intact cells of this toxic dinoflagellate species. Faecal pellets, containing intact toxic phytoplankton species may be an important vehicle and new pathway transferring toxins within the pelagic and to the benthic community. The viability of D. norvegica cells within the faecal pellets was not investigated, but lead to the idea to observe the ability of different phytoplankton species to survive the copepod gut passage. Therefore a new ...