Invasion
Invasion Description
1st record: Wellington, North Island/New Zealand/Wellington Harbor (1987, Hay and Luckens 1987: Nelson 1999)
Geographic Extent
North Island/New Zealand/Waitemata Harbor (2004, Russell et al. 2008); North Island/New Zealand/Tauranga Harbor (2005, Russell et al. 2008); Wellington, North Island/New Zealand/Wellington Harbor (1987, Hay and Luckens 1987; Nelson 1999); Port Tauranaki, North Island/New Zealand/Tasman Sea (2005, Russell et al. 2008); Napier, North Island/New Zealand/Napier Harbor (Hawke Bay) (Nelson 1999); Picton, South Island/New Zealand/Picton Sound (Nelson 1999); Lyttleton, South Island/New Zealand/Pegasus Bay Nelson 1999; Schiel et al. 2012); Timaru, South Island/New Zealand/Pacific Ocean (Nelson 1999); Oamaru, South Island/New Zealand/Pacific Ocean (Nelson 1999); Coromandel Peninsula, South Island/New Zealalnd/Cook Strait (James and Shears 2016); Great barrier Island/New Zealalnd/Cook Strait (James and Shears 2016)
Vectors
| Level | Vector |
|---|---|
| Alternate | Hull Fouling |
| Alternate | Ballast Water |
Regional Impacts
| Ecological Impact | Habitat Change | |
| In Wellington Harbor, the invasion of U. pinnatifida altered invertebrate communities and increased sediment deposition (Battershill et al. 1998, cited by Schaffelke and Hewitt 2007). However, impacts of U. pinnatifida on seaweed diversity or benthic invertebrate assemblages were not detected in a rigorously designed survey (BACI, before-after-control-impact) in Lyttleton Harbor, New Zealand, possibly because canopy-forming species, providing similar structure were already present (Forrest et al. 2002). | ||
| Economic Impact | Fisheries | |
| Undaria pinnatifida has proliferated on Greenshell Mussel (Perna canaliculata) aquaculture farms, with subsequent spread to adjacent reefs (James and Shears 2016). | ||
| Economic Impact | Shipping/Boating | |
| A risk-assessment panel concluded that U. pinnatifida had moderate impacts on moorings and boating in New Zealand as a result of fouling (Campbell and Hewitt 2013). | ||
| Ecological Impact | Competition | |
Undaria pinnatifida showed greater photsynthesis (quantum yield) than native New Zealand Kelps at high temperatures (20 and 25 C, 6 and 12 PSU) (Bollen et al. 2016). Removal experiments indicated that when light and nutrients are not limiting, U. pinnatifida invaded undisturbed and cleared plots at about equal rates. The introduced kelp does not appear to be impeded by naitve algae, at least at this site near Wellingotn, New Zealand (Morelissen et al. 2016). After a marine heatwave, U. pinnatifida largely replaced dominant native kelps of the genus Durvillea. Undaria initially colonized a wide range of the intertidal zone, but died out in the upper intertidal, and was replaced by smaller brown seaweeds, and persisted only in the lower intertidal zone (Monite and Thomsen 2023) | ||