Assessing the extent of establishment of Undaria pinnatifida in Plymouth Sound Special Area of Conservation, UK

Sabrina Heiser,Jason M Hall-Spencer,Keith Hiscock

doi:10.1017/s1755267214000608

Abstract

The north-west Pacific kelp, Undaria pinnatifida, was first discovered in Europe on the Mediterranean coast of France (1971) and introduced to Brittany for aquaculture (1983). In the north-east Atlantic, it occurs in Spain, France, the British Isles, Belgium and Holland. The first UK record was in the Hamble estuary (1994) and it was found off Plymouth in 2003. The UK distribution is presently restricted to the south of England and the northern Irish Sea. We assessed the distribution of U. pinnatifida and native kelps and their allies in Plymouth Sound (at 0 to +1 m relative to Chart Datum). Undaria pinnatifida was widespread along rocky shores, on other hard substrata and grew in the same areas as Saccharina latissima and Saccorhiza polyschides. Undaria pinnatifida was significantly more abundant on vertical substrata than on upward-facing hard substrata. It was almost as common as all of the other kelp species combined on vertical substrata but was outnumbered by native species on upward-facing substrata. Undaria pinnatifida has become the visually dominant macroalga in marinas and has spread to surrounding natural habitats in Plymouth Sound. The extent to which it will outcompete native kelps requires monitoring, especially in conservation areas.

Highlights

Non-native marine and terrestrial species impose high economic costs worldwide (Pimentel et al, 2001)
By summer 2011, Undaria pinnatifida had become well established within Plymouth Sound SAC
Yacht Haven and Queen Anne’s Battery, respectively), which are both visited by boats from all over the world. This indicates that the vector for introduction to Plymouth has been boat traffic, the same suspected vector as at other sites on the south coast of England, like the Hamble estuary where it was first recorded in Britain (Fletcher & Manfredi, 1995)

Summary

Introduction

Non-native marine and terrestrial species impose high economic costs worldwide (Pimentel et al, 2001). For the UK alone, the costs are estimated to be £1.7 billion per year (Williams et al, 2010). Non-native and non-indigenous species are those that have been introduced by humans into an area historically outside their range and they successfully reproduce and maintain a population within the new area (Eno et al, 1997; Reise et al, 2006). Atlantic are often hotspots for marine invasive species (Molnar et al, 2008). Non-native seaweeds pose a threat as they are able to change ecosystem structure and functioning (Schaffelke et al, 2006). Worldwide only 6% of nonnative seaweeds (17 species) have had their ecological effects on ecosystems evaluated (Williams & Smith, 2007). In terrestrial and freshwater ecosystems, non-native species may have devastating consequences for native species. In Britain, examples include the loss of flora from areas due to domination by Rhododendron ponticum L. and Fallopia japonica Houtt

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