The effects of fine-scale substratum roughness on diatom community structure in estuarine biofilms

Abstract

Benthic diatoms are a major component of biofilms that form on surfaces submerged in marine environments. Roughness of the underlying substratum affects the settlement of both diatoms and subsequent macrofouling colonizers. This study reports the effects of roughness on estuarine diatom communities established in situ in the Indian River Lagoon, FL, USA. Natural communities were established on acrylic panels with a range of surface roughnesses. Smoother substrata exhibited higher cell density, species richness, and diversity. Twenty-three of 58 species were found either exclusively or more abundantly on the smooth surfaces compared to one or both roughened treatments. The results suggest a greater ability of benthic diatoms to recruit and colonize smooth surfaces, which is probably explained by a higher degree of contact between the cells and the surface.

Keywords:

• diatoms
• biofilms
• substratum roughness
• attachment
• biofouling

Acknowledgments

The authors would like to thank Dr Geoffrey Swain and members of the Center for Corrosion and Biofouling Control at Florida Institute of Technology for access to their test facility and for assistance with the substratum roughness analysis. Special thanks are extended to Ms Kelli Zargiel and Dr Paul Hargraves for help with diatom identification, and to the members of the Biological Oceanography Laboratory at Florida Tech for laboratory and field support. The authors would also like to thank Dr Valerie Paul and Ms Julie Piraino at the Smithsonian Marine Station, as well as staff of the USDA Horticultural Research Laboratory in Fort Pierce, Florida for their help with the scanning electron microscopy.