We’ve known for at least half a century that plastic debris in the ocean poses risks to wildlife. And now, according to researchers modeling debris exposure, 99% of all seabird species are likely to ingest plastic by 2050. The findings were published in Proceedings of the National Academy of Sciences this week.
"For the first time, we have a global prediction of how wide-reaching plastic impacts may be on marine species," Chris Wilcox from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) said in a statement. "The results are striking." Every year, more than 4.8 million metric tons of plastic waste enters the oceans: bags, balloons, bottle caps and plastic fibers from synthetic clothing wash out into the ocean from urban rivers, sewers and waste deposits. Concentrations reach up to 580,000 pieces in just one square kilometer – and they’re increasing exponentially, according to the study. In 1960, plastic was found in the guts of less than 5% of the individual seabirds studied, but that number jumped to 80% by 2010. Sometimes these bright items are mistaken as food, and birds who swallow them could suffer gut impaction, weight loss and death.
To quantify the risk of these growing concentrations of plastic debris, Wilcox’s team performed a “spatial risk analysis” by analyzing debris distributions and known ranges for 186 species of seabirds, from albatrosses to penguins. Then to adjust their model, they turned to studies of plastic ingestion conducted between 1962 and 2012. In those five decades of research, ingested plastic was found in 80 of the 135 seabird species studied – that’s 59%. Plastic dissected from a dead flesh-footed shearwater is pictured to the right. The items amounted to 8% of the bird’s body weight.
In those historical observations, 29% of individual birds had plastic in their gut on average. If those same studies were conducted today, the team estimates that 90% percent of individual seabirds would be affected. "This is a huge amount and really points to the ubiquity of plastic pollution," Wilcox added. Plastics are expected to have the biggest effect in the Southern Ocean, where the debris gathers in a band around the southern edges of Australia, South Africa, and South America. According to the team's model, the highest area of potential impact for wildlife is the Tasman Sea, between Australia and New Zealand.
Alarmingly, plastics ingestion may affect up to 99% of all seabird species by 2050, although effective waste management could reduce this threat.
A red-footed booby on Christmas Island in the Indian Ocean. Image courtesy of Britta Denise Hardesty.
All images in text courtesy of Britta Denise Hardesty