Port Chalmers, South Island/New Zealand/Pacific Ocean (Nelson 1999); Stewart Island, South Island, New Zealand/Pacific Ocean (Nelson 1999); Moeraki Beach, South Island/New Zealand/Pacific Ocean, Schiel et al. 2012, South et al. 2015, 45 21' 35.07"S, 170 50' 59.81' E).
|Undaria pinnatifida has been spreading in seaweed beds in southern New Zealand. It was consumed by 3 of 4 species of native grazers (an amphipod and 2 gastropods), at rates comparable to native seaweeds, but not by an isopod (Batedotea elongata). It is considered to have the potential to alter local foodwebs (Jimenez et al. 2015). In a community study, U. pinnatifida had only transient effects on community composition, but resulted in an overall doubling of biomass and primary production during its peak abundance (South et al. 2015).|
|A risk-assessment panel concluded that U. pinnatifida had major aesthetic impacts on diving in protected marine areas in New Zealand. One of the areas targeted was Bluff Harbour, a departure point for ships going to Fjordland, Stewart Island, other Sub-Antarctic Island (Hewitt et al. 2005). The control program included removal of sporophytes from vessel hulls, pilings, and other artificial structures, and wrapping pilings to kill the plants by shading and anoxia. After 2009, the program was abandoned because of coast and the continued spread of the seaweed (Forrest and Hopkins 2013).|
|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).|