INVASIVE SPARTINA First record of Spartina alterniflora in southern Africa indicates adaptive potential of this saline grass Janine Adams . Ernita van Wyk . Taryn Riddin Received: 12 February 2015 / Accepted: 17 August 2015 Ó Springer International Publishing Switzerland 2016 Abstract Spartina alterniflora was recorded in 2004 in the Great Brak Estuary, a system along the southern coast of South Africa that closes to the sea. This is alarming as this is a species with a known history as an aggressive invasive plant which has now been found 8000 km from its nearest known location and further- more it is spreading under atypical conditions of submergence. This first recorded population in Africa indicates the adaptive potential of this invasive grass which survives inundation and non-tidal conditions for months at a time. Spartina alterniflora spread from 2566 m 2 in 2006 to a maximum area covered of 10,221 m 2 in 2011. There was an increase in silt, sediment organic matter and a significant reduction in sediment redox potential at sites invaded by S. alterniflora. When the estuary closes to the sea the water level rises and S. alterniflora is flooded, limiting opportunities for mechanical and chemical control. Application of a glyphosate-based herbicide in 2012 showed that chemical control was more effective in reducing the stands than mechanical removal. The additional use of imazapyr in 2014 significantly reduced stem density and the proportion of live stems. Spread of this invasive plant to the intertidal marshes in adjacent estuaries is a potential biodiversity threat although, fortunately, this population does not seem to produce viable seed. There is also the concern that hybridization with the resident S. maritima may occur. Important research and management questions remain i.e. how quickly will the natural marsh re-establish following eradication and how can we prevent move- ment of the grass to other estuaries? Keywords Sediment characteristics Á Redox potential Á Inundation Á Chemical control Á Salt marsh Introduction Spartina alterniflora Loisel., is a notorious invader of coastal ecosystems in many parts of the world, including estuaries in New Zealand, China, and the Pacific coast of the USA (Ayres et al. 1999; Chung 2006; Strong and Ayres 2013). It forms dense, highly productive monospecific stands by colonizing open intertidal mudflats or by outcompeting and replacing less productive salt marsh plant communities. In doing so it threatens the biodiversity of native salt marsh plants communities and the faunal communities that Guest editors: Alan Gray and Malika Ainouche/Invasive Spartina. J. Adams (&) Á T. Riddin Department of Botany, Nelson Mandela Metropolitan University, PO Box 7700, Port Elizabeth 6031, South Africa e-mail: janine.adams@nmmu.ac.za E. van Wyk Invasive Species Programme, South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont 7735, South Africa 123 Biol Invasions (2016) 18:2153–2158 DOI 10.1007/s10530-015-0957-5