Tuatua shellfish. Photo / Michael Cunningham
A study that found "alarming" levels of microplastics in Bay of Plenty shellfish has sparked health concerns for kaimoana-lovers and the wider marine ecosystem.
Te Rangapu Mana Whenua o Tauranga Moana chairwoman Matire Duncan said microplastics in shellfish was "detrimental to all the sea life and shellfish".
"It definitely won't be good for eating," she said.
"We live off the ocean - we live off the Tangaroa and his children which are the shellfish and the seafood. And if they're not healthy, then the people won't be healthy.
"In the future, we may need to look at what we use to wash our clothing and material stuff we buy," Duncan said.
"That's a huge conversation we need to have in changing those habits to make things better for the ocean and for future kaimoana."
Master of science student Anita Lewis presented findings of her research at the New Zealand Marine Sciences Society Conference held at the university's Tauranga campus this week.
Tiny plastic particles were found in every sediment sample she took from across the Bay of Plenty, between Tauranga Harbour and along the eastern coast to Maketū and Ōpōtiki.
There was not one area sampled where microplastics were not present and particularly high levels were found in shellfish, including tuatua, cockles, and wedge shells.
Lewis said her research findings were alarming, illustrating the impact plastics were having not only on the marine environment but potentially human health.
"Kaimoana (seafood) gathering in New Zealand is common practice and this research is showing microplastics and nano-plastics are now bioaccumulating in our food chain."
She said banning single-use plastics was an important step, but more research was needed to understand the problem.
The highest density of microplastic particles (up to 11087.9 per sq m) was observed at sites that were close to municipal outfalls and populated areas.
She said many microplastics entered the marine environment via treated wastewater.
"While filtering large pieces of plastic, the membranes in the treatment plants also act like abrasives on small microplastics, making them even smaller and turning them into nano-plastics as they go through the system," Lewis said.
Along with banning single-use plastics, she said more work could be done including investigating the use of different filters in household washing machines and investigating different types of membranes for use in wastewater treatment plants.
Tauranga marine conservationist Nathan Pettigrew said he was "not surprised" that microplastics had been found in high levels in the Bay of Plenty.
"With the amount of plastic and rubbish that's around, a portion of it is going to end up in the waterways."
Pettigrew said microplastics in shellfish caused "a chain reaction" when it came to marine life.
"Eagle rays and stingrays will feed on crabs that possibly feed on shellfish. They are then preyed upon by orca, so it kind of just goes right through the food chain.
"At the end of the day, marine life is not geared up for this … Nothing has evolved quick enough to handle it."
Pettigrew said "for the most part", a lot of people and the Government were doing what they could to minimise plastic use, but he wanted to encourage people to think more about it.
"Any plastic you do get if you have to take it in the first place, try to be really vigilant about it."
Pettigrew commended Lewis for bringing awareness to the issue.
"I'm sure it will wake some people up as to what we need to do."
Bay of Plenty Regional Council compliance manager Stephen Mellor said there were numerous agencies the council worked with to improve and protect the Bay's marine environment.
"Pollution prevention and compliance are core to Toi Moana's work."
On microplastics, the most frequent complaint from the pollution hotline was plastic beads sometimes found on the Papamoa Beach coastline, Mellor said.
Mellor encouraged anyone who found microplastics along the coast to call the 24/7 pollution hotline on 0800 884 883 and the council could send a regulatory compliance officer to investigate.