Polystyrene from damaged Christchurch City Council pontoons in Lyttelton has been breaking down and polluting the environment for nearly 20 years.
The council has no idea how much polystyrene has escaped into the environment, and says it only recently discovered the large pile of damaged pontoons was shedding debris.
A big storm in October 2000 destroyed the floating marina in Magazine Bay, sinking more than 30 boats as the area was lashed by sustained 130kmh winds. The marina's pontoons were made of large amounts of polystyrene encased in concrete.
The wreckage, now the responsibility of the council after original owner Lyttelton Marina Limited was liquidated, was hauled out of the water soon after and left to the elements on the reclaimed land of Naval Point, near the Sea Scout den.
Polystyrene is one of the most common plastic polluters found in the ocean and breaks down into microplastics over time.
Lyttelton resident Mimi van Houten noticed chunks of polystyrene in the water and at the high tide line while walking her son's dog at Naval Point. She later found the damaged pontoons, and assumed it was the source of the polystyrene.
"I know polystyrene and plastics are all destroying a marine environment and eventually break down to microplastics, and it just ends up in the food chain."
Van Houten contacted the council, the Lyttelton Port Company (LPC) and regional council Environment Canterbury (ECan), which is responsible for looking after the region's water.
"Eventually some tarpaulins arrived on the blocks of polystyrene … but they haven't lasted. Within about a week or two in a big southerly, they've all blown off again, and all this polystyrene is just going into the water and destroying our marine environment."
Council-owned company LPC does not own the wreckage but has been helping the council manage it.
LPC strategic engagement manager Phil de Joux said port staff covered the pontoons with tarps and "attempted to collect some of the polystyrene" when they became aware they were breaking down late last year. LPC also contacted the council.
De Joux said the council was working on a way to make sure the pontoons did not break down any further and spread any more polystyrene before it could dispose of them altogether.
LPC's environmental staff and council staff will meet later this week to discuss options.
"LPC is taking this issue seriously and working on a solution with the Christchurch City Council to ensure these pontoons do not break down any further before they can be disposed of," de Joux said.
Council acting parks unit manager Al Hardy said the council only recently found out some of the pontoons had been shedding debris, which prompted work to find a permanent solution as part of plans to redevelop Naval Point.
It was not known how much polystyrene had broken down and escaped into the environment, he said.
The council has set aside $10.6 million to redevelop Naval Point over the next nine years, and is working up a plan for what will be done.
ECan Banks Peninsula zone lead Gillian Jenkins said ECan was called twice about polystyrene getting into the water late last year. ECan investigated both times and issued one warning, leading to the area being cleaned up and tarpaulins added.
Microplastics are a threat to birds and aquatic species who mistake them as a food source.
University of Canterbury distinguished professor of marine sciences David Schiel said polystyrene breaks down easily, floats, and "stays around forever".
A 2019 study found the amount of ocean microplastics could double by 2050. Another study found the average person could be eating up to a credit card's worth of plastic each week.
For the original article, please visit stuff.co.nz