Transcript Slide 1

Threats to biological diversity
4: Environmental Factors
Sam Hopkins
Biodiversity and Conservation
Biology
Available at http://planet.uwc.ac.za/nisl/Eco_people/Presentations/
What Are The Environmental Factors
Causing Loss Of Biodiversity?
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Pollution
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Litter
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Oil Spills
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Pesticides
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Fertilizers
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Light
Global Warming
Pesticides
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100s of different pesticides
exist
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Many are worldwide
contaminants as they have
been carried in the air and
water
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Have been seen as agent
of evolutionary change in
some species
Pesticides: Chlorinated hydrocarbon
pesticides (CHs) 1
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These pesticides all have
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Chemical stability
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High mobility
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High solubility
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Toxicity
A well known example of a chlorinated
hydrocarbon pesticide is DDT
Pesticides: DDT 1
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Discovered in 1939
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First used to kill mosquitoes
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Used to control against pests such as the elm
bark beetle
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DDT does not just affect the target species
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DDT is still used in some developing countries
Pesticides: DDT
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Has been seen to bioaccumulate and biomagnify
throughout the trophic levels in the environment
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An example is seen in a study by Boykins (1967) 2
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Worms were absorbing DDT
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The worms kept the DDT 18 months after spraying
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Birds absorbed the DDT from the worms when they ate
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DDT caused bird mortality
Seen in the artic and sub-artic 3
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DDT increased from Ringed and Square flipper seals to
Polar bears
Polar bear milk contained increased levels of DDT
Pesticides: DDT
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This is not just affecting animals and plants
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In Kibaha in Tanzania DDT was found in crops 4
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The crops were eucalyptus, cashew, plums and
casava which are eaten by humans
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In Mato Grosso, Brazil the DDT in the soil is
leaking into the underground water 5
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In Turkey DDT has been found in 12 edible fish 6
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These are concerns for public health
Pesticides: DDT
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Some animals such as a few of the bird species
that showed eggshell thinning are recovering
since DDT was banned 1
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In Grey Seals since the use of DDT has been
stopped the gynaecological problems that the
seal populations had have decreased and
pregnancies have increased 7
Pesticides: Carbamates and
Organophosphates
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These are the alternatives to the CHs 1
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Have been seen to kill herbivorous birds 1
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Affects birds that feed on sprayed insects 1
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Rainbow trout that were exposed to methiocarb
had lemmellar edema and the epidermis became
separated from the lamellae 8
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One of these is called Dioxin which causes
cancer and birth defects in lab animals, this is
still in use 1
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Many of these substances have now been banned
Oil Pollution 1
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The estimate of oil input into
the environment is 3.2 million tons a year
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Most of this is from land waste put into the ocean
or into rivers
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Evaporation and combustion allow petrol
compounds into the air which are then cycled
into the sea
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More noticeable is the large media events of the
ocean oil spills
Oil Pollution 1
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The worst spill was seen in the
Persian gulf
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This was during the war to liberate Kuwait in 1991
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1,700,000 tons of oil was released into the sea
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Not far off was the spill in 1979 from a Mexican
platform
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500,000 to 1,400,000 tons of oil was spilt
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Better publicised are the oil tanker spills such as
the Exxon Valdez in Alaska and Amoco Cadiz in
France
Oil Pollution Case Study:
The Exxon Valdez 1
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Spill occurred on March 24th 1989
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The tanker hit a reef off the coast of Alaska
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41,000 tons of crude oil was spilt
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40-45% of the oil spilled ended up on the coast
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Death Toll
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350,000-500,000 sea birds
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200 bald eagles
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3,500-5,500 sea otters
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350 Harbour seals
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14 killer whales
Oil Pollution Case Study:
The Exxon Valdez 1
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A misguided clean up operation was started
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Activities lasted four years
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Shores were washed with hot water and oil and tar was
collected
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Unfortunately the hot washing killed many of the shores
invertebrates and pushed the oil onto unaffected beaches
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The coast that had been cleaned was more damaged than
the unclean part
Oil Pollution Case Study:
The Exxon Valdez
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Long term affects
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Fry of the pink salmon were sterile 1
Sockeye salmon could not be harvested, their numbers
increased allowing many fry to starve to death 1
Mussels and clams are still poisoned 9
Sea otters have only managed to regain half of their
numbers 9
People have had to move away from the coastline as
they relied on the fish and seals for food 10
Oil Pollution: Impacts on the wildlife 1
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Differs from habitat to habitat
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In open ocean oil slicks kill plankton and fish and
effect sea mammals and sea birds
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At the coast, sandy beaches can hide oil for months
and rocky coasts become coated with the oil and kills
almost all the organisms, this can last for years
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In estuaries and salt marshes the effect of an oil spill
are felt the hardest, here the oils can affect the
environment for decades as it gets buried in the
anoxic sediments to be exposed again at a later date
Oil Pollution: Impacts on the wildlife 1
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Sea birds suffer the most when oil is spilled into the
ocean
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Many sea birds dive into the ocean to get food, every
time they dive they pass through the oil slick
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This causes their feathers to become oily which in
turn inhibits their flight and buoyancy
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Oil soaked feathers are not good insulators so the
birds get cold
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Trying to remove the oil by preening causes more
problems like toxic effects on the liver, kidneys and
pancreas
Polychlorinated biphenyls
1
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Used as insulators and fire retardant
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Have made way into aquatic systems
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Long lived
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High solubility in lipids
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Food chain magnification
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Impairs reproductive success in birds and seals and
affects polar bears
Polynuclear aromatic hydrocarbons
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Found in petrol and cigarette smoke and given off
after combustion of fossil fuels 1
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Pollute aquatic environment
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PAHs are activated by cytochrome P450 and form
compounds that damage or mutate DNA, RNA or
proteins 11
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Some bond with the DNA, RNA or proteins and can
cause cancer 11
1
Heavy Metals
12
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Heavy metal pollution has been going on for about 8000 years
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Archaeologists have found evidence of copper extraction and
smelting in the Faynan orefield in Jordan 12
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Athenian civilisations managed to pollute the air with 2300 tons of
copper every year, these figures were calculated from the ice
sheets in Greenland 12
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Other examples; mercury, lead and nickel 1
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Many show food chain magnification 1
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Affects fish, marine birds 1
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For example gold mining uses mercury to separate the gold and
the waste is poured into local water 1
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An obscure example is the use of a paint on the hulls of ships that
contains tin, it is toxic to marine organisms and is banned in some
countries 1
Selenium 1
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Naturally occurs in soils
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Where desert regions are farmed selenium leaches
into the local water
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An example of this was seen in California at the
Kesterson National Wildlife Reserve
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Caused reproductive failure in some birds and birds
that did manage to breed hatched deformed chicks
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Also caused death
Radioisotopes 1
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For example, caesium, strontium and
phosphorous
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All show bioconcentration and biomagnification
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A well known example of this kind of pollution
was seen at the disaster of Chernobyl
Radioisotopes – Chernobyl
13
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The Chernobyl disaster occurred
in the Ukraine in 1986
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There had been a nuclear reactor at the site since
1977
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The explosion occurred due to a safety test
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The explosion exposed the core
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Radioactive fission products and debris rose 1 km
into the air
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The pollution was carried north-west on the wind
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The graphite fire lasted 9 days
Radioisotopes – Chernobyl
13
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The soviet government at the time
did not admit that there was
anything wrong
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Only noticed by Swedish workers
who saw the smoke
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A tunnel was dug underneath the
core to place a concrete slab and a cooling system
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The core was placed in a 300,000 ton concrete and
steel box
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Before the box was in place six tonnes of uranium
dioxide and fission products along with xenon,
krypton, iodine, tellurium and caesium were released
into the atmosphere
Radioisotopes – Chernobyl
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The effects of the radiation widespread
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Caesium has a long half life and is absorbed into the
body like potassium so it quickly got into the food
chain 13
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Radiation got in to the ground water 13
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There was a rise in thyroid cancer 13
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More than 20 species show genetic damage
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Radiation reduces antioxidants and immune response
in animals 15
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Has increased levels of partial albinism
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Has affected breeding successes of animals
14
15
Radioisotopes – Chernobyl
14
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Now the concrete and steel box that is
containing the radiation is breaking down
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Work is being carried out to repair the box
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A large arch is being constructed to contain the
radiation and the concrete box
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The three undamaged reactors need to be
decommissioned
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Need to dispose of the radioactive waste that was dug
into the ground in 1986
Plastic
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Plastics pollute the land and sea
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On the Sargaso sea surface there are
about 3500 pieces of plastic making up
290 grams per km2 16
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Animals are known to eat plastics
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Sea turtles are notorious for eating plastic bags assuming they
are jellyfish
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Laysan albatrosses have been seen to feed plastic bags to their
chicks 1
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In a study by Moser and Lee (1992) 1033 birds were collected from
1975-1989 17
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21 of the 38 bird species had plastic in their stomach
The amount of plastic in the birds stomach increased over
time
Some birds selected for particular colours or shapes
The answer
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There is no easy answer
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Man will continue to pollute and the environment will
carry on suffering
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Some governments regulate the use of pesticides
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Oil tankers are now built with a double hull
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An international dumping convention in 1972 agreed
to by 64 countries states that deliberate dumping of
CHs, PCBs, some heavy metals, plastics, petroleum
and radioactive waste must be stopped 1
1
Light Pollution
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This pollution occurs when we switch
lights on outside at night
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Estimates show that two thirds of the population are living
in areas above the accepted light pollution level 18
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Light pollution affects many species in ways we are only
just understanding
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Trees increase their growing season in the presence of
outdoor lighting and are then susceptible to winter frosts 19
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The Hawk moth (Deilephilia elpenor) shows decreased
ability to see colours in artificially lit environments 20
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Artificial light at night increased tumour growth and
decreased survival in female rats 21
Global Climate Change 1
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Large topic much talked about recently
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Estimate that 18% of the species in Central America,
Australia, South Africa and Europe will disappear 22
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Earth warmer now than in the last 40 million years
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Problems:
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23
Change may occur so rapidly that plants and animals
cannot adjust
Compounded by habitat fragmentation and degradation
The new conditions may be more suitable for invasive
species
Has caused distribution shifts in species
Global Climate Change
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Species are moving pole-wards, global meta-analysis
predicts that ranges will move north by 6.1km per decade
and spring will become 2.3 days earlier
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Shown by non-migratory butterfly species, 63% of 35
species have shifted their range northward by between 35240km 24
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Species are adjusting their breading seasons
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Shown by native amphibian species in Britain 25
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Species are moving higher in altitude
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Species are becoming extinct
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Shown by Bufo periglenes 26
Global Climate Change –
Species altering breeding season 25
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Study by Beebee (1995)
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The time that five species entered a
pond was recorded over 17 years
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Bufo calamita and Rana esculenta
spawned earlier each year
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The three newt species arrived 5 weeks earlier in 1994 than
in 1978
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Pond arrival time of T. vulgaris and spawning of R.
esculenta gets 9-10 days earlier every 1 °C increase in
temperature
Global Climate Change –
Species becoming extinct 26
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Study by Pounds et al. (1997)
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The Golden toad (Bufo periglenes)
lived in the Monteverde cloud forest
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It is not conclusive but evidence suggests that the climate
changed in the years preceding the disappearance of the
Golden Toad
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The toad relied on the cool, wet cloud forest and water
bodies for breeding
In conclusion
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This is an enormous topic and not everything is
covered here
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The human population is doing a lot to pollute the
environment
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The effects of this pollution are not fully
understood
References
1.
Cox, G. W. (1997) Conservation Biology (2nd ed) concepts and applications. Pp 223-232
2.
Boykins (1967) The effects of DDT contaminated earthworms in the diet of birds. Bioscience 17:37-39
3.
Bowes, G. W. and Jonkel, C. J. (1975). Presence and distribution of polychlorinated biphenols in artic and
sub-artic marine food chains. Journal of Fish Research Board, Canada 32: 2111-2123
4.
Marco, J. A. M. and Kishimba, M. A. (2006). Pesticides and metabolites in cassava, eucalyptus, plum and
cashew leaves and roots in relation to a point source in Kibaha, Tanzania. Chemosphere 64: 542-548
5.
Villa, R. D. et al. (2006). Dissipation of DDT in a heavily contaminated soil in Mato Gosso, Brazil.
Chemosphere 64: 549-554
6.
Coelhan et al. (2006). Organochlorine levels in edible fish from the Marmara sea, Turkey. Environmental
International 32: 275-280
7.
Bergman, A. (1999). Health condition of the Baltic grey seal (Halichoenis grypus) during two decades.
APMIS 107: 270-282
8.
Altinok, I. et al. (2006). Effects of water quality and fish size on toxicity of methocarb, a carbamate pesticide,
to rainbow trout. Environmental Toxicology and Pharmacology 22: 20-26
9.
BBC news at News.bbc.co.uk/1/hi/world/americas/3333369.stm (accessed July 2006)
10.
BBC news at News.bbc.co.uk/1/hi/ programmes/from_our_own_correspondent/301097.stm (accessed July
2006)
11.
Oh, E. et al. (2006). Comparison of immunological and genotoxilogical parameters in automobile emission
inspectors exposed to PAHs. Environmental Toxicology and Pharmacology 21:108-117
12.
Grattan et al. (2006). The local and global dimensions of metalliferous pollution derived from a
reconstruction of an eight thousand year record of copper smelting and mining at a desert mountain frontier
in Southern Jordan. Journal of Archaeological Science (in press)
References
13.
BBC news at Bbc.co.uk/dna/h2g2/A2922103 (accessed July 2006)
14.
BBC news at News.bbc.co.uk/1/hi/in_depth/europe/2006/chernobyl/default.stm (accessed July 2006)
15.
Moller, A. P. and Mousseau, T. A. (2006). Biological consequences of Chernobyl: 20 years on. Trends in
Ecology and Evolution 21: 200-207
16.
Carpenter, E. and Smith, K. L. (1972). Plastics on the Sargasso sea surface. Science 175: 1240-1241
17.
Moser and Lee. (1992). A fourteen year survey of plastic ingestion by Western North Atlantic sea birds.
Colonial Waterbirds 15: 83-94
18.
Cinzano, P. et al. (2001). The first world atlas of the artificial night sky brightness. Monthly Notices of the
Royal Astronomical Society 328:689-707
19.
International dark sky association at www.darksky.org (accessed July 2006)
20.
Johnsen et al. (2006). Crepuscular and nocturnal illumination and its affects on colour perception by the
nocturnal hawk moth, Deilephilia elpenor. Journal of Experimental Biology 209: 789-800
21.
Cos, et al. (2006) Exposure to light-at-night increases the growth of DMBA-induced mammary
adenocarcinomas in rats. Cancer Letters 235: 266-271
22.
Thomas, C. D. et al. (2004). Extinction risk from climate change. Nature 427: 145-148
23.
Easterling, D. R. et al. (1997). Maximum and minimum temperature trends for the globe. Science 277: 364367
24.
Parmesan, et al. (1999). Poleward shifts in geographical ranges of butterfly species associated with
regional warming. Nature 399: 579-583
25.
Beebee, T. J. C. (1995) Amphibian breeding and climate. Nature 374: 219-220
26.
Pounds, J. et al. (1999) Biological response to climate change on a tropical mountain. Nature 398: 611-614