There is an abundance of microplastics in marine sponges in Wellington harbour, new research has found. It's raising concern other sea life will have the same in their bodies with microplastics entering the food chain.
Wellington researchers collected 45 marine sponges at three sites in the capital's harbour and found microplastics in every single one. In some cases, an individual sponge had thousands of microplastics in it.
Marine sponges filter on small particles and have accidentally eaten the microplastics and accumulated. But what's worrying is other sealife do the same, potentially being contaminated as well.
"While the sponges are filtering out the water and filtering out these small food particles, there are also all these microplastic particles floating in the water as well. It appears that they are, as well as sucking in the food, sucking in and accumulating these plastics too," Victoria University marine ecologist Professor James Bell told AM.
While the impact of microplastics on sponges and in humans who eat seafood is unknown, Bell said they do know microplastics leak toxins.
The Victoria University study found sponges in Evans Bay had the highest concentrations of microplastics compared with Shark Bay and Mahanga Bay. It said this is likely due to its close proximity to high-density urban areas.
But it's not just Wellington that should be concerned about plastic floating in the ocean.
"It's something that we should be concerned about nationwide. Microplastics are an issue all around New Zealand," Prof Bell said.
"It's probably, particularly likely to be the case in enclosed areas like harbours or bays where there is limited water exchange and lots of water flowing from rivers and off the land because that's where most of our microplastics are coming from."
He said the main contributor to plastics is synthetic fibres from our clothing.
"So, when we wash our clothes fibres are released that go into the wastewater system. Some of that gets filtered out but a lot of those plastics get broken into smaller pieces along the way and then the wastewater from those plants end up in our waterways," Prof Bell said.
While there are filters for washing machines that can help stop microplastics from entering our waterways, plastics are in our lives everyday, making it harder to get rid of this problem.
"People need to be aware of the microplastics, particularly from clothing," Prof Bell said.
"Just being super careful of what you do with your plastic waste. Make sure it doesn't end up on the road and end up in stormwater drains and places like Wellington Harbour."
