PPT - Human Impact on the Oceans

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Transcript PPT - Human Impact on the Oceans

Human Impact on The
The Ocean
 One
of the most valuable and untapped
 Yet, seriously threatened by what humans
have done to it.
 The problem of controlling human impacts
on the ocean boils down to short term
 These short term costs ($$$) often prevent
effective controls.
Problem #1: Habitat Alteration
Dredging –
 Removing sediment from the bottom of the
ocean with mechanical force to dislodge
and excavate material.
 Dredging is used to clear obstructions so
larger ships can enter ports.
 Used to keep harbors, rivers and other
waterways from silting up.
Dredging is also a method used to
collect scallops.
Dredging dramatically
affects marine ecosystems,
causing severe seabed
habitat destruction.
Sea creatures living on the bottom
are crushed, buried or exposed to
predators, and clouds of sediments
rise, altering seabed biochemistry.
Natural healthy undisturbed
cobble-shell bottom, habitat
for scallops.
After just one pass of a
scallop dredge this is
the result!
 By
leveling the ocean floor, the food chain
is disturbed, the hiding places have been
removed and conditions favorable to faster
growing species take over.
 Seafloor recovery could take centuries.
 Some species of sponges can reach 50
years old.
 Some clams can live for more than 200
 Some individual corals have been
estimated to live 500 years or more.
Problem #2: Offshore Drilling (Oil)
Problems with it:
Noise from Seismic Testing
 Water and air pollution
 Visual impacts
 Coastal Development
Sonic blasts damage the
brain and ears of marine
mammals and other
species, disorienting them
and causing them to beach
Problem # 3: By Catch
This refers to fish and other marine
life caught "incidentally" while
harvesting another species.
These are fish that are the wrong
type, size, sex, or quality as well as
marine mammals, sea turtles, and
Facts about Bycatch
 Commercial
fishing worldwide wastes
approximately 44 billion pounds of ocean
life annually.
 Roughly 25 percent of the entire global
 In the United States, all sea turtles are
listed as endangered or threatened under
the Endangered Species Act, as a result of
fishing bycatch.
Whale Entanglement
More whales, dolphins and
porpoises die every year by
getting entangled in fishing gear
than from any other cause.
Problem #4 Toxic Ocean
Our waste, even in small quantities, have
huge effects on ocean communities and
 Toxic pollutants in the ocean ecosystem have
massive impacts on the plants and animals.
Some major types of pollutants:
 garbage
 sewage
 chemicals
 radioactive
 eutrophication
 heavy metals
 oil
Oil Spills (1)
The effects of an oil spill of
marine life depend on a number
of physical and biological factors.
The distribution of the oil spill will
be affected by currents and wind
In addition, the amount of oil
spilled will determine the
eventual geographic boundaries
of the impact area.
The physical and chemical
properties of the oil will
determine the behaviour of the
slick, in terms of its thickness
and rate of spreading.
Oil Spills (2)
Environmental conditions such as salinity, water
temperature, and type and slope of shoreline will
determine habitat effects and clean-up
 Some example habitats include sandy beach,
mud, cliffs, estuaries and open water. In terms of
difficulty of clean-up and relative vulnerability, a
salt marsh ranks the highest, followed by
eelgrass, mud, mixed-fine sediment, mixedcoarse sediment, rock, sand, algae (kelp) and
open water.
Oil Spills (3)
characteristics of the
organisms affected
will determine the
severity of impact.
 These characteristics
include the type of
species, life stage
(larval, juvenile or
adult) and size.
Cleaning-up oil spills:
1. Dispersants: Oil can be broken down more quickly by
spraying dispersants (chemicals) on the oil slick from
boats or planes. This method only works on fresh, small
oil spills.
2. Booms: A boom has a floating skirt suspended down
in the water and a sail holding it above the water line.
The floating skirt stops the oil from passing. These are
used to prevent oil from entering delicate and protected
3. Slick-lickers: This method uses a belt of oil absorbing
material that sucks up the oil from the ocean water. The
oil is then squeezed out of the absorbing material into a
collecting bin.