MARINE DEBRIS - Marine Pollution: What Everyone Needs to Know - page 48

that up to 100,000 marine mammals, including endangered
species, are killed each year by marine debris. Very serious
effects happen when marine animals become entangled in
debris such as fishing line and six-pack rings. Birds get fish-
ing line entangled around their legs, which get injured and
may be lost. Large amounts of plastic debris have been found
in the habitat of endangered Hawaiian monk seals, includ-
ing in areas that serve as nurseries. Entanglement in plastic
debris has led to injury and deaths in endangered Steller sea
lions, with packing bands the most common entangling mate-
rial. Hatchling sea turtles run down the beach to the ocean, a
critical phase in their life cycle. Debris can be a major impedi-
ment if they get entangled in fishing nets or trapped in con-
tainers such as plastic cups and open canisters. Marine debris
is an aspect of habitat quality for nesting sites and may help
explain declines in turtle nest numbers on certain beaches.
Many marine birds such as Northern Gannets use plastics as
nesting material. Gannet nests studied contained an average
of 470 grams of plastic, which translates to an estimated col-
ony total of 18.46 tons. Most of the plastic used was synthetic
rope. About 63 birds were entangled each year at one study
site, totaling 525 individuals over eight years, the majority of
which were nestlings.
Many marine animals consume flotsam by mistake, as it
often looks similar to their natural prey. Sea turtles, for exam-
ple, may mistake plastic bags or balloons for jellyfish, a favor-
ite food. At study of stranded sea turtles in Australia found
that larger individuals had a strong preference for soft, clear
plastic, lending support to the idea that they ingest debris
that resembles jellyfish. Smaller turtles were less selective in
their feeding, though they tended to prefer rubber items such
as balloons. Young sea turtles in the western Atlantic have a
stage described as their “lost year,” when they are thought
to live among the floating seaweed Sargassum. Juveniles col-
lected from Sargassum have been found to ingest plastic debris
that floats along with the seaweed. Plastics in diet samples