Do native subtidal grazers eat the invasive kelp Undaria pinnatifida?
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Key to understanding the impacts of invasive macroalgae on local food webs is determining the extent to which native herbivores consume the invasive macroalga. We used multiple-choice feeding assays to ascertain the relative feeding preferences of four subtidal grazers (the amphipod Aora typica, the isopod Batedotea elongata and the gastropods Cookia sulcata and Haliotis iris) for the invasive macroalga Undaria pinnatifida and six native macroalgae (Macrocystis pyrifera, Durvillaea antarctica, Carpophyllum flexuosum, Cystophora scalaris, Marginariella boryana and Ulva spp.) that are all abundant along the Otago coast of southern New Zealand. Multiple-choice feeding assays were run under laboratory conditions during the austral autumn (April and June) of 2013. The relative abundances of the macroalgae in the field were also determined. All of the grazers ate U. pinnatifida at rates comparable to most of the native macroalgae, except for B. elongata, which barely consumed it. This indicates that U. pinnatifida, which was shown to be more abundant than native macroalgae in subtidal habitats, has the potential to contribute organic matter to the local food web and may be an undesirable food for some group of grazers. We suggest that U. pinnatifida could potentially alter existing trophic relationships.
KeywordsMacroalgae Macroalgal Species Feeding Assay Macrocystis Pyrifera Native Grazer
We thank S. Bell, R. Pooley, P. Jones, P. S. Fernández, M. Desmond and B. Flack for field and laboratory assistance. This study was funded by an Otago University Doctoral Scholarship to RSJ, Performance Based Research (PBRF) funding from the Department of Botany, University of Otago to CLH, a Foundation for Research, Science and Technology (FRST) subcontract to CLH from the National Institute of Water and Atmospheric Research Ltd., Biodiversity and Biosecurity OBI (C01X0502) and a FRST Science and Technology Postdoctoral Fellowship to RJM (UOOX0814).
- Cabin RJ, Mitchell RJ (2000) To Bonferroni or not to Bonferroni: when and how are the questions. Bull Ecol Soc Am 81:246–248Google Scholar
- Conover WJ (1980) Practical nonparametric statistics, 2nd edn. Wiley, New YorkGoogle Scholar
- Edgar GJ, Moore PG (1986) Macro-algae as habitat for motile macrofauna. Monogr Biol 4:255–277Google Scholar
- Lowe S, Browne M, Boudjelas S, De Poorter M (2000) 100 of the World’s worst invasive alien species A selection from the Global Invasive Species Database. The Invasive Species Specialist Group (ISSG) a specialist group of the Species Survival Commission (SSC) of the World Conservation Union (IUCN)Google Scholar
- Peteiro C, Freire O (2012) Observations on fish grazing of the cultured kelps Undaria pinnatifida and Saccharina latissima (Phaeophycea, Laminariales) in Spanish Atlantic waters. AACL Bioflux 5:189–196Google Scholar
- Piriz ML, Casas G (1994) Occurrence of Undaria pinnatifida in Golfo Nuevo, Argentina. Appl Phycol Forum 10:4Google Scholar
- Richards DK (2009) Subtidal rocky reef communities of the East Otago Taiapure: community structure, succession and productivity. Master thesis, University of Otago, DunedinGoogle Scholar
- Suárez RJ (2015) The ecology of the invasive kelp Undaria pinnatifida: functioning at an ecosystem level. Ph.D. thesis, University of Otago, DunedinGoogle Scholar