Abstract:
In March 2013 the Asian kelp Undaria pinnatifida (Harvey) Suringar, 1873 was discovered in Rangaunu Harbour, northern New Zealand (34°89′05"S, 173°29′54"E), a site where water temperatures typically range between 14 and at least 24°C. This is the first report of Undaria in subtropical parts of New Zealand and demonstrates that Undaria is capable of invading marine environments throughout the country. The presence of healthy juvenile and reproductive sporophytes during late summer (SST >21°C) is of particular concern as juvenile Undaria sporophytes have previously only been recorded during summer in cooler water regions. This discovery indicates a previously unreported deviation from a winter annual lifecycle at subtropical temperatures and an increased risk of invasion impacts for subtropical sites worldwide.
