Rubbish from continents, aquaculture and fishing vessels are invading large marine protected areas, conference attendees learned at the 4th International Marine Protected Area Congress.
A network of 30 to 50 schools in Chile are surveying marine litter along the Chilean coast in a special programme.
Martin Thiel of the Department of Marine Biology at the Universidad Catolica del Norte in Chile says the surveys, started in 2008, and repeated in 2012 and 2013 showed a variety of sources of litter.
In northern Chile, the survey found that people were leaving their litter on the beach and rubbish was also being swept down rivers.
In southern Chile, where fewer people live, most litter is in areas where there is aquaculture.
On Easter Island, where the public recently voted in support of a 720,000sqm marine park, litter is coming from the industrial tuna fishery.
Marine litter has also been an issue for Rarotonga, with some residents attempting to burn their rubbish on stream banks and on the beachside, only for it to be washed away during heavy rain and extreme high tides.
However, with education from the National Environment Service and community leaders this problem is less common than previously.
Observations on Suwarrow and other islands in the north, show these islands receive floating litter primarily from the industrial tuna fishery.
Easter Island is situated in the centre of the South Pacific Gyre, part of the Earth’s system of rotating ocean currents, which moves anticlockwise pulling litter to its centre.
Thiel says over time, plastic components among the litter start to become brittle and fragment, resulting in a proliferation of “microplastics”. Thiel says there is so much of it, seabirds are using it to make nests
He says microplastics are a concern because they are so small, they can easily enter the food chain.
“Some species of fish ingest microplastics with their food. Birds obtain them via food or pick them up from the sea surface. We found a storm petrel that had more than 400 pieces of microplastics in its stomach.”
Thiel says in South America, Chile has a particular responsibility for the problems because most of the coast of South America is Chilean coast.
However, he believes the public are ready to do something about it.
“There are many organisations in Chile who are concerned about litter. The indication is people are ready. What is missing is the industry,” he says.
Thiel says a refundable deposit system for bottles would help reduce the problem.
Similar systems have been suggested for the Cook Islands, but have failed to gain traction.