Mass mussel deaths ‘due to climate change’

There could be more mass die-offs of mussels on the horizon in the face of climate change, an expert warns.

The warning by Dr Andrew Jeffs, a marine scientist with Auckland University, comes after hundreds of thousands of mussels perished at a Northland beach because of ‘‘heat stress’’.

In the face of climate change and the increasing temperatures and disturbed weather cycles it brings, Jeffs said we would ‘‘definitely see’’ more mass dieoffs in the future.

He said it could create problems for the country’s mussel industry, which he said relied heavily on mussels collected in the Far North.

Jeffs said hundreds of thousands of green-lipped mussels had died at Maunganui Bluff Beach in the first week of February thanks to a combination of spring low tides, clear skies and high daytime temperatures.

‘‘It is a bit like spending several days sunbathing under the full sun – you would get serious heat stroke too.’’

Jeffs said a period of high pressure had forced the spring tide out even further, leaving the green-lipped mussels exposed to the sun for longer and when it was at its hottest.

The mussels had basically been cooked by it, he said.

‘‘Over several days, they just cannot handle repeated heating up.’’ Jeffs said the beds of mussels, aged anywhere between two years and five years old, would have died off over a couple of days. Mussels were ‘‘quite clever’’, he said, with ‘‘heat shock proteins’’ capable of repairing tissues damaged by heat. But even the proteins would not have been able to respond to this sustained damage.

Jeffs said mussels had also died at Muriwai two years ago.

Local Brandon Ferguson made the grisly discovery at Maunganui, a video posted to social media showing a sea of dead mussels blanketing the sand near the rocks in the intertidal zone.

‘‘There are no more mussels at the bluff,’’ Ferguson said.