Seasonal variation in the antifouling defence of the temperate brown alga Fucus vesiculosus

Abstract

The important role of marine epibiotic biofilms in the interactions of the host with its environment has been acknowledged recently. Previous studies with the temperate brown macroalga Fucus vesiculosus have identified polar and non-polar compounds recovered from the algal surface that have the potential to control such biofilms. Furthermore, both the fouling pressure and the composition of the epibiotic bacterial communities on this macroalga varied seasonally. The extent to which this reflects a seasonal fluctuation of the fouling control mechanisms of the host is, however, unexplored in an ecological context. The present study investigated seasonal variation in the anti-settlement activity of surface extracts of F. vesiculosus against eight biofilm-forming bacteria isolated from rockweed-dominated habitats, including replication of two populations from two geographically distant sites. The anti-settlement activity at both sites was found to vary temporally, reaching a peak in summer/autumn. Anti-settlement activity also showed a consistent and strong difference between sites throughout the year. This study is the first to report temporal variation of antifouling defence originating from ecologically relevant surface-associated compounds.

Keywords:

• Fucus
• anti-settlement
• chemical defence
• seasonal variation
• antifouling

Acknowledgements

This study was supported by a PhD scholarship (A077 1469) to M. Saha from the German academic exchange service (DAAD). G. Bock, K. Maczassek and S. Stratil are acknowledged for algal collection, F. Symanowski and Andreas Lehmann for providing the bacterial strains, and the data for salinity and temperature, respectively. N. Stärck is acknowledged for help with algal extraction. The authors are grateful to H.G. Hoppe and R. Koppe for providing the data on bacterial density.