Grazing impact of Oikopleura dioica and copepods on an autumn plankton community

Kajsa Tonnesson, Marie Maar, Cristian Vargas, Eva Friis Moller, Suree Satapoomin, Sultana Zervoudaki, Epaminondas Christou, Antonia Giannakourou, Anne Sell, Jens Kjerulf Petersen, Torkel Gissel Nielsen, Peter Tiselius

Research output: Contribution to journalJournal articleResearchpeer-review


Copepods and appendicularians are major grazers in the pelagic environment. They have different retention efficiencies for prey and may therefore exert a variable grazing pressure on the spectrum of pico- to micro-plankton. We determined clearance rates of both groups at one station during 24 h in the Gullmar fjord, west Sweden, in autumn 1999. Total potential prey biomass ranged from 75 mu g C l(-1) at the surface to 14 mu g C l(-1) at 30 m with a dominance of larger dinoflagellates (10-25 mu m athecate species and Gymnodinium /Gyrodinium sp.) and the pennate diatom Pseudo -nitzschia sp. Grazer biomass was dominated by copepods (Acartia clausi, Paracalanus parvus) and appendicularians (Oikopleura dioica). O. dioica showed non-selective clearance rates of 0.7-1.8 ml mu g C-1 h(-1) on most diatoms, flagellates and ciliates, whereas Pseudo -nitzschia sp. and dinoflagellates and ciliates > 25 mu m were not removed by O. dioica. Appendicularian grazing impact was 0.06% d(-1) on the phytoplankton and 0.4% d(-1) on bacterial biomass. Despite a seven-fold higher biomass, the grazing impact of copepods on phytoplankton biomass was only 0.28% d(-1) indicating that O. dioica had a proportionally greater impact and, in contrast to copepods, also utilised bacteria. The low observed grazing impact was due to a low grazer biomass and a prey community largely unavailable to the investigated grazers.
Original languageEnglish
JournalMarine Biology Research
Issue number5
Pages (from-to)365-373
Publication statusPublished - 2005
Externally publishedYes


  • Gullmar fjord Sweden, Europe Palearctic region
  • Algae Plantae (Algae, Microorganisms, Nonvascular Plants, Plants) - Pyrrophyta [14500] dinoflagellate common Gymnodinium genus Gyrodinium genus
  • Crustacea Arthropoda Invertebrata Animalia (Animals, Arthropods, Crustaceans, Invertebrates) - Copepoda [75110] copepod common
  • Organisms (Organisms) - Organisms [00500] plankton common
  • Protochordata Chordata Animalia (Animals, Chordates, Invertebrates, Protochordates) - Urochordata [85104] Oikopleura dioica species
  • Protozoa Invertebrata Animalia (Animals, Invertebrates, Microorganisms, Protozoans) - Ciliata [35100] ciliate common
  • 07506, Ecology: environmental biology - Plant
  • 07508, Ecology: environmental biology - Animal
  • 07512, Ecology: environmental biology - Oceanography
  • 64002, Invertebrata: comparative, experimental morphology, physiology and pathology - Protozoa
  • 64054, Invertebrata:comparative, experimental morphology, physiology and pathology - Arthropoda: crustacea
  • Ecology, Environmental Sciences
  • Marine Ecology


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