Surface deposit feeding versus filter feeding in the amphipod Corophium volutator

Abstract

The previously indicated ability of the amphipod Corophium volutator to switch between deposit feeding and filter feeding was confirmed and studied in more detail in controlled laboratory experiments in which filtration rate measurements were combined with simultaneous video recordings of surface-feeding activity of the amphipod exposed to different known concentrations of algal (Tetraselmis sp.) cells. When algal cells were added to the ambient water, this stimulated C. volutator, buried in natural sediment or transferred to glass tubes, to commence filter feeding, which was maintained as long as the algal concentration was kept above a certain threshold level. However, shortly after the algal concentration was grazed below the threshold level, filter feeding was abandoned and replaced by surface deposit feeding, as evident from a video observed increase in surface scraping frequency. The average frequency of surface scraping was 0.64±0.27 min^–1, with a residence time of 3.7±1.4 s on the sediment surface where the amphipod grabbed material within a semicircle. Such detailed knowledge of filter feeding versus deposit feeding in C. volutator is of importance for a better understanding of the ecological role of this key organism in many shallow-water ecosystems where the feeding conditions are frequently changing.

Keywords:

• Clearance rates
• Corophium volutator
• deposit feeding
• filter feeding
• switching of feeding modes
• video observations

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

HUR was funded by a grant from the Danish Natural Science Research Council (grant no. 21-03-0481). PS was supported by a Leonardo da Vinci grant during his stay at the Marine Biological Research Centre. Thanks are due to two anonymous reviewers for constructive comments on the manuscript.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark