Date: 05 March 2012
Department of Conservation staff have closed a bay within Lake Waikaremoana, Te Urewera National Park, after a dive survey has discovered a small infestation of lagarosiphon (oxygen weed) within Te Raoa Bay off Whareama Penninsula.
Te Urewera Whirinaki Area's acting southern biodiversity manager Mark Lewis said the dive was part of an annual inspection to see if the lake continued to be free of the noxious weed. He said the discovery of live plants was very disappointing.
The discovery has triggered immediate action and DOC staff are currently working on ensuring the erradication of the plants which cover an area of approximately 10 x 20 metres. They advise all boat users to Lake Waikaremoana to be aware of the situation and adhere to the closure of Te Raoa Bay (close to the area commonly called the Narrows).
The last discovery of the weed was in 2010 in the lake and was sucessfully removed from Rosie Bay.
Mr Lewis said it is unknown how the plants got into the bay, but it is most likely that a small piece was transported from another waterway on a boat.
The plant is epidemic in the lakes at Tuai and Kaitawa where it thrives in the shallow water and sheltered conditions to form thick mats.
A piece as small as a $1 coin can be enough to get another plant started, so Mr Lewis says the message is for boaties and other water users to be vigilant when moving their craft or swimming gear from one waterway to another. "Preventing spread is a whole lot easier than cleaning up the problem."
The dive survey continues this week and it is possible that other areas will be discovered.
Mark Lewis, Biodiversity Programme Manager (Southern), Department of Conservation. Phone: +64 6 837 3803