04 March 2016

Bay of Plenty Regional Council scientists are working on identifying a blue-green algae that has bloomed near Ōmokoroa in Tauranga Harbour.

The algae, which looks like fine, green cotton wool, is growing amongst sea grass in an area of approximately 20 hectares in the upper reaches of Mangawhai Bay, on the eastern side of the Ōmokoroa Peninsula.

“It’s a type of blue-green algae or cyanobacteria that looks a lot like a species called Lyngbya. We’ve seen it amongst sea grass beds in the harbour before but not on this scale.

We don’t know at this stage if it’s likely to be harmful to people or what’s caused the bloom, so we suggest people avoid contact with it for now as a precautionary measure,” said Regional Council Coastal Scientist Rob Win.

Mr Win said the bloom is likely to have occurred in response to unusually warm water temperatures in the harbour over summer and the high number of swans around Ōmokoroa.

“There’s lots of swan excrement in the water there at the moment that may have fuelled algae growth,” Mr Win said.

Mr Win said that the algae accumulates gas bubbles (from high rates of photosynthesis) around its filaments, causing algae clumps to rise to the surface and form large conspicuous floating mats.

“We’re keeping an eye on it. In the meantime if anyone experiences irritation after contact with the algae, they should seek medical advice,” Mr Win said.