How Does Marine Debris Impact Marine Wildlife?

 Marine debris can have serious impacts on both
marine wildlife and humans.
 Debris can entangle, maim, and even drown many
wildlife species.
 Animals can also mistake some debris for food; once
ingested, these materials can cause starvation and/or
 Although almost any species can be harmed by marine
debris, certain species – including seals, sea lions,
seabirds and sea turtles – are more susceptible to its
dangers than others.
TWO Main Threats to Marine
 The two primary threats that marine debris poses to
marine wildlife are entanglement and ingestion.
 Some entanglement occurs when the animal is
attracted to the debris as part of its normal behavior or
out of curiosity.
 Entanglement is harmful to wildlife for several
 It can cause wounds that can lead to infections or loss of
 It may cause strangulation, choking, or suffocation.
 It can impair an animal’s ability to swim, which may
lead to drowning, or make it difficult for the animal to
move, find food, and escape from predators.
Entangled manatee
 Ingestion occurs when an animal swallows marine
 Ingestion sometimes happens accidentally, but
generally animals ingest debris because it looks like
 Ingestion can lead to choking, starvation or
malnutrition if the ingested items block the intestinal
tract and prevent digestion, or accumulate in the
digestive tract and make the animal feel “full”
Endangered and Threatened
 Endangered species: A species of animal or plant that
is in immediate danger of becoming extinct.
 Threatened species: A species whose numbers are low
or declining. A threatened species is not in immediate
danger of extinction, but is likely to become
endangered if it is not protected.
Marine debris can pose
significant threats to
threatened and endangered
Affected Animals
 Marine mammals, sea turtles, birds, fish, and
crustaceans all have been affected by marine debris
through entanglement or ingestion.
 Unfortunately, many of
the species most vulnerable
to the impacts of marine
debris are endangered or
Of the different types
of marine mammals,
seals and sea lions are
the most affected
(primarily by incidents
of entanglement)
because of their
natural curiosity and
tendency investigate
unusual objects in the
Fishing nets, fishing line,
ropes, plastic sheeting and
packing straps can be
major problems for these
Sea Turtles and Debris
 All six species of sea turtles found in the United States have
been found entangled in different types of marine debris,
such as fishing line, rope and fishing nets.
 however, ingestion of debris is an even greater problem for
these species, as they are indiscriminate feeders.
 Sea turtles have swallowed plastic bags because they look
like jellyfish, one of their favorite foods.
 Cases of turtles swallowing balloons, tar balls, and other
debris that has become encrusted with algae and other
marine forms have also been reported
Seabirds and Debris
 Thousands of seabirds are thought to die from
entanglement or ingestion each year. Since many
seabirds feed on fish, they are often attracted to fish
that have been caught or entangled in nets and fishing
 Unfortunately, when birds prey upon entangled fish,
they can become entangled themselves.
 Entanglement in fishing line has been a particular
problem for the brown pelican, which has been listed
as an endangered species.
Fish, Crustaceans and Debris
 Fish and crustaceans (such as lobsters and crabs) are
frequently caught in lost or discarded fishing nets and
fishing line (also referred to as derelict fishing gear).
This phenomenon is known as ghost fishing
Here are some animals
that could be harmed
by marine debris
Giant Squids
Architeuthis dux
• Largest invertebrate ever known to exist
• Average 3-9 meters long
• Largest eyes out of any animal
• Eat deep sea fishes and other squid species
• Sperm whales and sleeper sharks are two known predators
Moon Jellyfishes
Aurelia aurita
• Range from 5-40cm in diameter
• Swim horizontally
• Found near the coast in warm and
tropical waters
• Occur in large numbers
• Feed on zooplankton
Tiger Shark
Galeocerdo cuvier
• One of the largest sharks in the
• Gray with tiger-stripe markings
• Found worldwide in temperate
and tropical seas
• Widest variety in their diet out
of all shark species
• Can be curious and aggressive
Saltwater Crocodiles
Largest living reptiles
Jaws contain between 64-68 teeth
Communicate with barks
Found on coasts of northern
• Feed on cabs, turtles, snakes,
buffalo, wild boar, and monkeys
• Females lay between 4o-60 eggs
• Harvested for their skin
• Populations in some countries are
Crocodylus porosus
Blue-ringed Octopuses
Hapalochlaena maculosa
• Bright blue rings appear when
• 5-10cm long (size of golf ball)
• Deadliest of all cephalopods
• Venom is 10,000 times more
toxic than syonide
• Powerful beak-like mouth
• Found in coral reefs and tide pools in
Southern Australia
Atlantic Bluefin Tuna Thunnus thynnus
 One of the largest bony fishes
 Dark blue and black with silver
 Live in subtropical and
temperate waters of the Atlantic
Ocean, the Mediterranean, and
Black Seas
 Feed on smaller fish
 Victim of overfishing
Loggerhead Sea Turtles
 Named after large heads
 Dive for 4 to 5 minutes
 Breath holding ability affected by
 Can sleep underwater for hours, but
need air every few minutes under
 Found in Atlantic Ocean
 Feed on jellyfish, mollusks, egg
clusters, squids, and flying fishes
 Live to be over 50 years old
Coral Reefs
 Shelter marine life, used in
medicines, create recreation for
humans, create sand for beaches,
and serve as buffer for shoreline
 Built by coral polyps (small
animals similar to jellyfish)
 Hard corals, soft corals, sea fans,
tropical coral reefs
 Extremely sensitive to
environmental changes
Spinner Dolphins Stenella Longirostris
 Perform playful stunts
 Different shades of gray
 Inhabit waters off the west coast
of central America
 Feed at night on small fish and
 Predators include sharks and
killer whales
 Often caught in fishing nets
Harp Seals
Pagophilus groenlandicus
 Latin name translates to “ice
loving seal of Greenland”
Baby seals have yellow coats
Live in waters of the Arctic and
Northern Atlantic Oceans
Diet of fish and crustaceans
Predators are polar bears, killer
whales, and sharks
Hunted for their coats
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