Vertical positioning and swimming performance of lobster larvae (Homarus gammarus) in an artificial water column at Helgoland, North Sea

Abstract

The vertical distribution and swimming ability of the three larval stages (Zoea I, II, and III) of Homarus gammarus were determined in laboratory experiments. In an artificial water column, newly hatched larvae were positively phototactic to white light at intensities near 0.6 µmol m⁻² s⁻¹. The positive phototactic behaviour decreased with increasing larval age and stage. Accordingly, older larvae were mostly distributed away from the light source in deeper layers and near the bottom. The measured vertical swimming speed of newly hatched larvae was 4.6±0.5 cm s⁻¹. Lobster larvae were positively rheotactic and thus able to swim against the current direction. The horizontal swimming ability of the larvae increased with stage from 0.7±1.0 cm s⁻¹ (Zoea I) to about 1.5±0.9 cm s⁻¹ (Zoea II) and 2.2±0.7 cm s⁻¹ (Zoea III). Implications for the persistence of the small, isolated lobster population around the island of Helgoland are discussed.

Keywords:

• Homarus gammarus
• larvae
• North Sea
• phototaxis
• rheotaxis

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

This work is part of the PhD thesis of I.S. This study was supported financially by the Ministry of Fisheries and Agriculture of the State of Schleswig-Holstein, Germany, project no.: 1317-11-68511005. Thanks are due to the local fishermen for providing berried females and to Michael Janke for technical support and help in rearing and keeping of the female lobsters. We want to thank Professor Heinz-Dieter Franke for his helpful comments on the study and the manuscript. We also thank the two anonymous reviewers for their valuable comments and suggestions.

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