The influence of substrate type on sexual reproduction of the bryozoan Cribrilina annulata (Gymnolaemata, Cheilostomata): A case study from Arctic seas

Abstract

This study compared the fecundity of the colonies of the cheilostome bryozoan Cribrilina annulata (Fabricius, 1870) collected from two differing substrates – shingles and the algae Odonthalia dentata (Linnaeus) Lyngbye, 1819 – in the White and the Barents Seas. Almost all colonies growing on algae had brood chambers (ovicells), and their numbers per colony were high. In contrast, colonies with ovicells were rare on shingles, having fewer brood chambers. Colonies growing on O. dentata started reproduction at a smaller size (having fewer zooids per colony) than those on the shingles. These data contradict the generally accepted opinion that stable substrates are favourable for bryozoan sexual reproduction. We also found that ancestrulae are larger in the colonies growing on shingles, which suggests that the larval pool might be subdivided into two ‘subpopulations’. Conditions for such subdivision are discussed.

Keywords:

• Bryozoa
• Cribrilina
• ovicells
• reproduction
• substrate

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

We are greatly indebted to Professor Dr A.I. Granovich, St Petersburg State University, for very useful discussions and advice. Thanks are given to Dr P. Strelkov, M. Makarov and A. Poloskin, St Petersburg State University, who helped to organize trips to the Barents Sea. We also thank M. Feduk, Y. Samysko and M. Fokin, Zoological Institute of the Russian Academy of Sciences, for their help with collecting. Dr S. Hageman, Appalachian State University, USA, kindly reviewed the early draft of the manuscript and gave useful comments. We also thank Dr B. Berning, Oberösterreichisches Landesmuseum, Austria, and two anonymous reviewers for constructive criticism and suggestions for improving the text. The research was supported by the Russian Foundation for Basic Research (RFBR, grants No. 07-04-00928-a, 07-04-10046-κ, and 07-04-10075-κ), and the Austrian Science Foundation (FWF, grant P19337-B17).

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