Weed shuts boaties from bay

What should have been an inspection to confirm the continued eradication of an invasive aquatic weed, has instead put Lake Waikaremoana's Rosie Bay off limits to the public.

A routine inspection by a diver last week, discovered three small lagarosiphon (oxygen weed) plants in the bay, adjacent to the end of the boat ramp.

Department of Conservation staff immediately declared the bay off-limits and triggered a response plan.
Te Urewera Whirinaki Area's southern biodiversity manager Matt Hickson said it had been hoped the inspection dive would come up with nothing and the eradication of lagarosiphon from the bay had been successful.

He said the discovery of live plants was very disappointing.
On the bright side, Mr Hickson said the plants were small (approximately 120mm in height) and it is the belief of the survey diver that they have not been in this area particularly long.

"The three offending plants were completely removed by the contractor at the time of discovery and I will be getting a dive team together for a one day survey as soon as possible to hopefully confirm that the three plants found were the only ones in this location," he said. "Once this has been taken place, (assuming no more weeds are found) Rosie Bay will be reopened."

Mr Hickson 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 or boat trailer.

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 Hickson 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."

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