Dispersal and gene flow in the habitat-forming kelp, Ecklonia radiata: relative degrees of isolation across an east–west coastline
M. A. Coleman A B C , B. M. Gillanders A and S. D. Connell AA Southern Seas Ecology Laboratories, DP418 School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia.
B Present address: Batemans Marine Park, Burrawang St, Narooma, NSW 2546, Australia.
C Corresponding author. Email: melinda.coleman@environment.nsw.gov.au
Marine and Freshwater Research 60(8) 802-809 https://doi.org/10.1071/MF08268
Submitted: 19 September 2008 Accepted: 8 January 2009 Published: 27 August 2009
Abstract
Characterising patterns of dispersal and gene flow in habitat-forming organisms is becoming a focal concern for conservation and management strategies as anthropogenic impacts drive change in coastal ecosystems. Here, we use six microsatellite markers to characterise dispersal and gene flow across the South Australian distribution of the habitat-forming kelp Ecklonia radiata. Populations of E. radiata on subtidal reefs in South Australia were highly genetically structured on large (100s of km, FST = 0.211) and small (10s of km, FST = 0.042) spatial scales with the extent of differentiation positively correlated with geographic distances among populations. Neither the presence of oceanic currents nor intervening rocky reef habitats appeared to facilitate widespread gene flow. There was a trend for island populations to be more genetically differentiated from those on the mainland and to have slightly greater levels of heterozygosity than mainland populations. Our results show relatively low dispersal and gene flow suggesting that recovery following kelp loss may be slow. Such information not only provides insights into relative rates of recovery, but may also identify which populations may be best used for propagation and restoration efforts.
Additional keywords: connectivity, genetic structure, subtidal reef.
Acknowledgements
We thank H. Bartram and Dr B. P. Kelaher for field assistance. We also thank T. Wernberg, J. Waters and an anonymous reviewer for helpful comments on this manuscript. We thank the South Australian Government’s Wildlife Conservation Fund and Department of Environment and Heritage for funding. This research project comprises information assisting research-informed policy (i.e. new SA Water Recycling and the Water Proofing Adelaide: 20-year blueprint initiative) that intends to underpin future restoration efforts. The broader program of research into habitat loss was funded by ARC grants to Coleman, Gillanders and Connell.
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