More than half the world's turtles and two-thirds of some bird species along Australia's east coast are being found to have ingested plastics as the toll from pollution mounts, a leading CSIRO researcher said.
With plastic production almost doubling each decade, the world's oceans are receiving a proportional increase in plastic waste.
On current projections, by mid-century, some 95 per cent of all sea birds will be found with plastic inside them, said Denise Hardesty, a senior CSIRO research scientist, said.
"Birds are top predators and a really good indication of the eco-system health of our oceans," Dr Hardesty told Fairfax Media. "Humans are increasingly reliant on our oceans for our food and livelihood."
The threat of rising marine pollution will this week be discussed at a workshop of the G20 group of nations for the first time. "It's clearly an issue that's gaining increased global attention," she said.
While Australia contributes a relatively small share of the world's marine plastic pollution, waters near the continent are among the areas where wildlife is suffering disproportionately.
According to a research paper Dr Hardesty co-wrote in 2015, the impacts on sea birdlife are expected to be concentrated in regions such as the southern Tasman Sea and the south-west Indian Ocean. These areas deserve particular attention because they are currently relatively rich in biodiversity and face multiple threats.
"Many seabird species in this region also suffer from other sources of mortality, including ongoing bycatch in fisheries and predation by invasive species on breeding colonies, and achieving effective management in these remote and often international regions is a significant challenge," the paper noted.
While the findings were "a bit of wake-up call", the CSIRO is leading the response such as by developing techniques to detect plastics within birds. These include swabs that can identify plasticising chemicals found in the preening oil birds produce naturally to waterproof their wings, Dr Hardesty said.
The research agency's modelling has also been used by US agencies and will soon be made available to about 20 nations from India to South Africa and Thailand to China to help them model and managed plastic waste ending up in their coastal waters.
"It's a tractable, solvable problem," Dr Hardesty said. "Most of what ends up in the oceans was in somebody's hand at some point."
Since sea birds are often near the top of the food chain, their health can also be indicator of the condition of other marine life - much of which is also ingesting plastics.
"Do I want plastics on my dinner plate?" Dr Hardesty said, noting that while consumers would be unlikely to eat the digestive tracts of fish, many of the toxins and chemicals contained in plastic are absorbed in the tissue of fish.
The physical effects on sea birds that consume plastic include gut obstruction and death. Those that survive typically experience reduced available stomach volume that may lead to lower weight.
The poor condition of fledglings is also likely to lead to increased mortality among juveniles. In addition, high plastic loads are correlated with increased organic pollutants, straining bird populations further, the paper noted.