MEDIA RELEASE

Another growth visible in Lake Rotorua

For immediate release: 25 June, 2010 DRAFT

A dense green algal scum showing up in large amounts along Lake Rotorua’s shoreline should be avoided by people walking dogs or picnicking along the lake shore.

Environment Bay of Plenty has taken samples and has found that the unusual lumps of scum are made up of large numbers of the blue-green algae Microcystis Wesenbergii, which is not toxic itself but the scum could contain other toxic or irritating algae.

The thick scum is drifting onto the shore over a wide area from Ngongotaha to the city lakefront.

Environmental scientist Matt Bloxham said it was unusual to get such sizeable scums appearing along the lakeshore so late in the season, as most were more likely to proliferate over the warmer summer months. This scum was much more visible and much more buoyant than in previous years, and it was being carried to the shore in large amounts.

“This algae is unusually dense, and has a consistency rather like cottage cheese. It’s more dense than we have ever seen before, and has an iridescent ooze coming out of it.

“We haven’t seen this particular growth accumulating in such large amounts before. Another species, called Gloeotrichia, which is a known toxin producer, has also been found and recorded for the first time around Gisborne Point.”

Environment Bay of Plenty has tested the blue-green algae, and while it is not toxic, scientists cannot be completely sure that other elements are not being carried to shore with it.

“Our advice is that while we don’t believe it is toxic, we would not advise people to touch it or allow animals to eat it. It could easily irritate skin and because it is right on the shore people can come into contact with it.”

Last week another species – a winter proliferating, foam-producing algae – was distributing large amounts of harmless white foam along the Lake Rotorua shoreline. The foam has since shown up at Lake Rotoehu and is still visible in some areas.

ENDS

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