A floating dock which broke free from a privately owned island during Cyclone Lusi is posing a serious threat to marine life along Northland's east coast.
A group of kayakers who spent Easter exploring the normally pristine Cavalli Islands, about 3km off Matauri Bay, were horrified by what they said was the worst polystyrene pollution they had seen.
Chunks of polystyrene, which can be fatal to marine life such as seabirds and dolphins, were scattered across the Cavallis after the dock was smashed to pieces on rocks. In the worst-affected bays, vast numbers of polystyrene balls are piled up like snowdrifts.
Richard Saysell said he had been kayaking for 15 years but the polystyrene pollution he witnessed yesterday was the worst he had encountered.
"Someone must know that this thing has broken away and allowed it to pollute the coast," he said.
Only a few weeks earlier a speaker had told his North Shore-based kayak club about polystyrene pollution and "the horrible things that can happen to sealife when they ingest this stuff".
"It looks like food to them so they eat it and feel full, but die of starvation," he said.
Fellow kayaker Peter Beadle said he was upset on Sunday when he saw polystyrene scattered across the southern end of Motukawanui, the biggest island in the Cavallis. That turned to outrage yesterday, when he saw the mass of polystyrene on Kahangaro Island, about 1.5km further south.
Mr Saysell said the largest chunks of polystyrene were about 1m thick, with remnants of concrete and green paint around the outside. It was breaking up into innumerable polystyrene balls which were forming snow-like drifts on the water and up the hillsides.
He said the mess needed to be cleaned up as soon as possible, before the next storm spread it further. Whoever allowed the pontoon to break up needed to be held accountable.
It was impossible to bring the polystyrene back in their kayaks. A clean-up would need a team of people and industrial-sized vacuum sucker pumps.
DoC's Bay of Islands area manager, Rolien Elliot, said she had been made aware just last week that a polystyrene-filled pontoon had torn free from Motukawaiti Island during Cyclone Lusi and broken up.
The Northland Regional Council, responsible for coastal structures and marine pollution, had been in contact with the island's Chinese owners. DoC and council staff were planning to head out to the islands to come up with a clean-up plan. It was a lot bigger than a few individuals could manage, she said.
DoC's concerns were for marine life such as the bottlenose dolphin which could mistake the floating polystyrene for food, blocking the digestive tract. A researcher in the Bay of Islands was watching for adverse effects on dolphins.