Napier's Red Sea probably harmless algae bloom

The red 'stripe' of algae was clearly visible off Napier. Photo / Ian Cooper

A reddish-brown drift across the ocean off Napier has been confirmed as an algal bloom unlikely to be a risk to human health.

The results of testing this week were revealed by the Hawke's Bay Regional Council soon after 5pm on Wednesday.

Team leader Marine and Coast Anna Madarasz-Smith said samples had been tested by the Cawthron Institute, with the "most dominant species" confirmed to be lingulodinium, which causes red tides.

She said it's a naturally occurring species that on occasion blooms in favourable conditions.

"We've spoken to MPI who have said there's no evidence that there's any impact on human health," she said.

On Tuesday, Food Regulation, New Zealand Food Safety director Paul Dansted told Hawke's Bay Today it was not unusual to see algal blooms in the ocean.

"Most of them are harmless."

The formation was first reported to Hawke's Bay Today by coast watchers several weeks ago as possible bilge from a ship, while members of the public had since wondered if it was linked to dredging off the Port of Napier.

But the formation had spread across Hawke's Bay and was particularly noticeable on calmer seas at the weekend.