Artificial structures influence fouling on habitat-forming kelps

Abstract

The addition of artificial structures along urbanised shorelines is a global phenomenon. Such modifications of habitats have important consequences to the abundance of fouling organisms on primary substrata, but the influence on fouling of habitat-formers living on these structures is poorly understood. Fouling of habitat-forming kelps Ecklonia radiata on pier-pilings was compared to that on rocky reefs at three locations in Sydney Harbour. Kelps on pilings supported different assemblages of bryozoans from those on reefs. The abundances of bryozoans on kelps, inparticular of the non-indigenous species Membranipora membranacea, were significantly greater on pilings. Differences were consistent in time and space. This indicates that the addition of artificial structures also affects fouling on secondary biogenic substrata, altering biodiversity and potentially facilitating the introduction and dispersal of non-indigenous epibiota. Understanding the processes that cause these patterns is necessary to allow sensible predictions about ecological effects of built structures.

Keywords:

• artificial habitat
• urbanisation
• fouling
• kelp
• epibiota
• bryozoans
• non-indigenous species

Acknowledgements

This work was supported by funds from an International Postgraduate Research Scholarship and an International Postgraduate Award. A.J. Underwood, R.A. Coleman, D.Blockley and M. Mayer-Pinto are thanked for helpful comments on earlier versions of this manuscript. Phil Bock is thanked for helping to identify species of bryozoans.

Additional information

Notes on contributors

Ezequiel M. Marzinelli

Present address: Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.