MEPS 350:79-89 (2007)  -  DOI: https://doi.org/10.3354/meps07095

Coprorhexy, coprophagy, and coprochaly in the copepods Calanus helgolandicus, Pseudocalanus elongatus, and Oithona similis

Morten H. Iversen1,2,*, Louise K. Poulsen1

1Danish Institute for Fisheries Research, Department of Marine Ecology and Aquaculture, Kavalergården 6, 2920 Charlottenlund, Denmark
2Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany

ABSTRACT: Studies of fecal pellet flux show that a large percentage of pellets produced in the upper ocean is degraded within the surface waters. It is therefore important to investigate these degradation mechanisms to understand the role of fecal pellets in the oceanic carbon cycle. Degradation of pellets is mainly thought to be caused by coprophagy (ingestion of fecal pellets) by copepods, and especially by the ubiquitous copepods Oithona spp. We examined fecal pellet ingestion rate and feeding behavior of O. similis and 2 other dominant copepod species from the North Sea (Calanus helgolandicus and Pseudocalanus elongatus). All investigations were done with fecal pellets as the sole food source and with fecal pellets offered together with an alternative suitable food source. The ingestion of fecal pellets by all 3 copepod species was highest when offered together with an alternative food source. No feeding behavior was determined for O. similis due to the lack of pellet capture in those experiments. Fecal pellets offered together with an alternative food source increased the filtration activity by C. helgolandicus and P. elongatus and thereby the number of pellets caught in their feeding current. However, most pellets were rejected immediately after capture and were often fragmented during rejection. Actual ingestion of captured pellets was rare (<37% for C. helgolandicus and <24% for P. elongatus), and only small pellet fragments were ingested unintentionally along with alternative food. We therefore suggest coprorhexy (fragmentation of pellets) to be the main effect of copepods on the vertical flux of fecal pellets. Coprorhexy turns the pellets into smaller, slower-sinking particles that can then be degraded by other organisms such as bacteria and protozooplankton.


KEY WORDS: Fecal pellet · Grazing . Functional response · Visual observation · Video recording


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Cite this article as: Iversen MH, Poulsen LK (2007) Coprorhexy, coprophagy, and coprochaly in the copepods Calanus helgolandicus, Pseudocalanus elongatus, and Oithona similis. Mar Ecol Prog Ser 350:79-89. https://doi.org/10.3354/meps07095

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