Species interactions within a fouling diatom community: roles of nutrients, initial inoculum and competitive strategies

Abstract

Diatoms constitute an important component of the fouling community. Although a lot of work has dealt with the fouling diatom community structure, work on the species interactions within the community is still meagre. In this regard, a study was carried out by transferring natural diatom biofilms into controlled conditions in order to understand the roles of nutrients, initial cell inoculum and seasonal variation in species composition in structuring the fouling diatom community. This community exhibited seasonal variation during the monsoon, post-monsoon and pre-monsoon periods. During each of these seasons, diatom species interactions varied depending upon the species composition. It was observed that excess nutrients favoured those species with comparatively higher growth rates, thereby suppressing the growth of other co-existing species. This competitive trait was found to be effective at an appropriate cell density ratio of the competitive and target species. Understanding such pathways will be useful for modelling the interactions between diatom species in various habitats under different resource conditions.

Keywords:

• Fouling diatoms
• nutrients
• initial inoculum
• competitive strategies

Acknowledgements

The authors are grateful to the Director of National Institute of Oceanography for his support and encouragement. The authors gratefully acknowledge the help given by Mr K. Venkat. The reviewers' valuable comments improved the manuscript and the authors wish to acknowledge the advice received. The first author acknowledges CSIR for providing the Senior Research Fellowship. This work has been supported by funding from the ONR Grant No: N000114-94-1-0423 and is a NIO contribution (4218).