Not just seabirds: An entangled Hawaiian monk seal. Credit: NOAA. |
Laysan albatross chicks have been found dead with their
bellies stuffed with bits of plastic,
and a new study shows that Kaua`i-based Newell’s and wedge-tailed shearwaters
face similar threats.
Worse, the amount of plastic found in the seabirds is increasing
over time.
“On Kaua‘i…50.0 % of Newell’s…and 76.9 % of wedge-tailed
shearwater … fledglings necropsied during 2007–2014 contained plastic items in
their digestive tract, while 42.1 % of adult wedge-tailed shearwaters had
ingested plastic'
That is one conclusion of the paper, “Plastic ingestion by
Newell’s (Puffinus newelli) and
wedge-tailed shearwaters (Ardenna
pacifica) in Hawaii.” It was published in the journal Environmental Science
and Pollution Research by Elizabeth C.
Kain, Jennifer L. Lavers, Carl J. Berg, Alexander L. Bond and André F.
Raine.
The researchers also found that “For both species, the
frequency of plastic ingestion has increased since the 1980s with some evidence
that the mass and the number of items ingested per bird have also increased.”
In fact, hundreds of marine species are threatened by
plastic, which can mimic natural food sources, or be mistaken for food by
seabirds, turtles, squids, fish, oysters, seals and others.
The researchers in this paper looked at the stomach contents of seabirds
killed by predators or collisions in the 2013-2014 nesting season. The results
were compared with a study done in the 1987 season on Kauai, when 11 percent of
the birds were found to have eaten plastics. For Newell’s shearwaters, that
represents nearly a five-fold increase over
a quarter century.
In both the Newell’s, a mountain-nesting bird, and the
wedge-tailed shearwaters, which nest near the shore, the predominant color of
ingested plastic was white.
Both adults and fledglings had plastic in their guts. Since
fledglings receive all their food regurgitated by their parents, the parents
are presumed to have been delivering plastic-laced meals to their young.
“Plastic ingested by seabirds has been shown to block and
take up space in the digestive tract, contributing to dehydration and in some
cases starvation,” the authors wrote.
There is also suggestion in the scientific literature that
the plastic can release chemical pollutants into the bodies of the birds, they
said.
“The amount of plastic in the oceans is increasing and poses
an increased risk of entanglement, ingestion, and thus morbidity and mortality
for marine life,” the authors wrote.
National Geographic last year had a story that suggested
that every seabird on the planet has or shortly will have a plastic ingestion issue.
That story references this study, which makes the point that
“this threat is geographically widespread, pervasive, and rapidly increasing.”
© Jan TenBruggencate 2016