Biodiversity Crisis 2010 GB

Semaine Européenne
Écologie & Sociétés
The biodiversity crisis
Franck Courchamp
[email protected]
16 novembre 2010
01: Introduction: definition of the problem
02: Biodiversity: value and quantification
03: Biodiversity crisis
04: Major causes of extinctions
05: Biological Conservation
Slides on http://www.ese.u-psud.fr/epc/conservation/pdf/biocrisis.pdf
1st part
Introduction
When one tugs at a single thing in nature, he finds it attached to the rest of the world
Muir, John Naturalist, Preservationist and Founder of the Sierra Club (1838-1914)
Where does the biodiversity crisis problem come from?
Malthusean growth of the human population
Available resources are not infinite
Tragedy of the commons
Malthusean growth of the human population
The human bomb
Size of the human population in November 2010
> 6,5 billions inhabitants
Size of the human population in November 2010
> 6,5 billions inhabitants
~ 100 years ago : < 1 billion
in ~ 50 years : > 9 billions
The Population Bomb
de Paul R. Ehrlich, 1968
8000 years ago, doubling time: one million years
150 years ago, doubling time: 200 years
Today, doubling time: 35 years
The Population Bomb
de Paul R. Ehrlich, 1968
8000 years ago, doubling time: one million years
150 years ago, doubling time: 200 years
Today, doubling time: 35 years
Even if we stopped the doubling
time decreasing (at 35 years), in
900 years time, we’d be…
The Population Bomb
de Paul R. Ehrlich, 1968
8000 years ago, doubling time: one million years
150 years ago, doubling time: 200 years
Today, doubling time: 35 years
Even if we stopped the doubling
time decreasing (at 35 years), in
900 years time, we’d be…
60 000 000 000 000 000 humans
The Population Bomb
de Paul R. Ehrlich, 1968
8000 years ago, doubling time: one million years
150 years ago, doubling time: 200 years
Today, doubling time: 35 years
Even if we stopped the doubling
time decreasing (at 35 years), in
900 years time, we’d be…
60 000 000 000 000 000 humans
(sixty millions of billions, enough to cover the whole of Earth
with a density of 100 inhabitant/m2)
1
This class started at 2 pm, it should stop at 5 pm
This means there will be over 42 000 more people
on Earth at the end of it…
1
If I just stop to breath…
20 more people…
1
in 4 days, One more million …
1
Human population, in billions
Earth cannot support more than a given population size
2
Available resources are finite
2
Thomas Malthus
“An Essay on the Principle of
Population” (1798) The human population increases geometrically while
resources availability increase arithmetically
If the population is not controlled intentionnally, it will distance
the resources and will lead to unexpected controls which will put
the population back to sustainable levels
Increase 2
Time Threshold where the needs
are higher than the
availability
Human population and availability of
renewable resources
1990
Population (millions)
Fisheries landing (million of tons)
2010
5,290 7,030
Total
Per Capita
Change (%) Change (%)
33
85
102
20
-10
237
277
17
-12
1,444 1,516
5
-21
(million hectares)
3,402 3,540
4
-22
Forests (million hectares)
3,413 3,165
-7
-30
irrigated lands
(million hectares)
arable lands
(million hectares)
Farms and pastures
Ref: Postel, S. "Carrying capacity: Earth's bottom line." State of the World, 1994.
2
Water availability in the world
2
Fresh water global distribution
About 1,1 billion people still
don’t have access to drinkable
water, and 2,4 more need
cleaner water
Human population, in billions
Max number
of human
that can be
fed by Earth
resources
Earth ecosystems cannot support more than a given human population size
2
In conclusion, our needs are quickly going to
exceed our available ressources
The major problem thus lies in
the managment of these
resources
Is this compatible with the
protection of biodiversity?
3
Tragedy of the Commons (Hardin, 1968)
To explain the tradedy of the commons, Hardin imagined a common pasture. Each
farmer has interest to increase his herd without limit, while no one has incentive to
take care of the pasture, invest in it or increase its productivity, which inevitably
leads to the pasture destruction.
In many ways, we are
currently living the
tragedy of the commons
For forests,
For fisheries,
For soils,
For living species,
For fresh water,
For air quality, temperature,
…
Hence a threat on biodiversity
3
Easter Island
Originally, there were dense forests, with a rich plant and animal biodiversity.
Colonised by man 400 years ago. Forests were cut down and burned, marine and
terrestrial birds hunted down, fish schools and dolphins overexploited, domestic
animals and cultivated plants introduced. The human population increased up to
10 000, which is probably more than this closed and naïve ecosystem could
support. There are now no forests left, and no animal larger than insects. In 1877,
there were only 111 inhabitants. And 200 stone statues.
3
Average temperature variation on the planet
since 1861
3
Carbon in the
atmosphere
3
Temperature increase
3
Sea level increase
75% of humanity will live on
costs in 2025
Climatic changes:
Average temperature increase
- not uniform on the planet
Increase from 2 to 6°C within the next century
--> increase of 5 to 10 °C in some regions in
Canada
- not uniform during the year
Climatic changes:
- Changes in the wind and rain
patterns
- Increase of frequency and
magnitude of extreme
meteorological events
Saint-Louis, Août 2005
Conclusion
 Human demography explosion
 Limitation of resources
 Tragedy of the commons
+
+
The problem of biodiversity loss we currently face comes
from the fact that these three points occur simultaneously.
Each would not have the same impact if it occured alone.
2nd part
Biodiversity
The most striking feature of Earth is the existence of life, and
the most striking feature of life is its diversity.
David Tilman, Nature, 2000
Definition of biodiversity
Origin of biodiversity
Levels of biodiversity
Quantification of biodiversity
Value of biodiversity
4rth part
Loss of biodiversity
Definition of biodiversity It’s a contraction of biological diversity. It refers to the
variation of the living world, the declination of all living
forms on the planet in all its level of wealth, from genes
to ecosystems 2
Origin of biodiversity
2
Humans: 30,000 years
2
Evolution can be seen as a slowly increased of life, with an
explosion at the Cambrian, and an important richness of
life since then
There has already been hundreds of millions
of species on Earth
Over 99% of these species are now gone
2
Andrewsarchus
Yes, but the natural fate of most species has been to
evolve into new species
Propalaeotherium
Three levels of Biodiversity
 genetic
 specific
 of ecosystems
3
All these levels are linked together, but are distinct enough so tht
each can be studied separately
Most studies focus at the specific level, as it is the easiest, both
conceptually and practically
4
Quantification of biodiversity
4
4 000
400 000
99 % 4 000
1 000 000
99 % 40 000
400 000
90 % 270 000
320 000
15 % 40 000
200 000
80 % 90 000
750 000
88 % 100 000 200 000 50 % 950 000 8 000 000 88 % 23 2500 25 0000 7 % 5 000 6 000 17 % 7 400 8 000 8 % 9 900 10 000 1 % 4 600 5 000 8 % Without knowing it, we live in
a world of insects and fungi…
4
1,5 millions species described
270 000 plant species
1 230 000 animal species
A recent study of the
entomofauna in the canopy
of 19 trees in Panama
showed that over the 950
coleopter species found, 80%
were unknown!
Estimates of the total number of species on
Earth vary between 5 and 100 millions
Procaryots: 1 to 10 billions « species » !!!
By far the largest part of biodiversity
animals
Procaryots: 1 to 10 billions « species » !!!
By far the largest part of biodiversity
For biodiversity, we know only the
tip of the iceberg!
The Mindoro stripe-faced fruit bat (Styloctenium mindorensis), nicknamed the "flying fox" or the
platupus for its foxlike face is a species of large Philippine fruit bat.
Discovered in 2007
oxyuranus temporalis, from
Australia, possibly one of the
most venomous snake on
earth
Tiger Huntsman, from Australia
New predatory ant species
found in Suriname
Brachylophus bulabula, New Iguana Species Found in Fiji
Discovered in 2008
Tanzanian grey-faced elephant shrew, the size of a
small dog and a long snout like an elephant
New toad species from Suriname
Phobaeticus chani,
The longest insect in the world
(~60 cm)
Desmoxytes purpurosea,
the dragon centipede,
filled with cyanide
Discovered in 2009
Hippocampus satomiae, or pygmy pony, the
smallest sea horse in the world (<14mm)
Tube-nosed fruit bat nyctimene from
Papoua New-Guinea
Tyrannobdella rex: or tyrant leech king, found
living exclusively in the nostrils of its hosts,
including humans
Brachiopsilus dianthus, hand-fin fish, walking at
the bottom of oceans
Discovered in 2010
Ibycus rachelae: the ninja slug, who projects a
hormon loaded dart to its potential mates
The « glass-frog », so
transparent one can
see all its organs
3
Rediscovery of once thought extinct species
Madagascar Dwarf Lemur
Lost in 1964
Re-found in 1989
Coelacanthe « living fossil »: 1938
2008, in Ecuador, herpetologists found the “extinct” species of
harlequin frog (Atelopus palmatus). Not recorded since 1937
this vibrant frog was thought to have succumbed to habitat and
disease long ago.
3
Even entire orders are still discovered
Mantophasmatodea: 2002
Ref: http://www.museums.org.za/bio/insects/mantophasmatodea/
3
Even entire phyla…
The 36th animal
phylum: Cycliophora,
discovered in 1995
3
… and entire ecosysems
In the 70s, new marine ecosystems are
discovered at about 2000 deep
3
A new external energy source (not
light) and many new species
Rate of new species description
10 000 species newly
described each year
Several millions species
still unknown
We would need, at this
pace, 1 000 years to
name all the species
We therefore know only a small part of the
specific biodiversity of our planet
The inversed pyramide of biodiversity
As we see it
Microbs
Invertebrates
Plants Fish Amphibians Reptiles
Mammals Birds
Humans
The inversed pyramide of biodiversity
Microbs
Invertebrates
Plants Fish Amphibians Reptiles
Mammals Birds Humans
As it really is
3rd part
Biodiversity crisis
«We do not inherit the Earth from our Ancestors,
we borrow it from our Children»
Antoine de Saint Exupéry
Value of biodiversity
Loss of biodiversity
1
Value of biodiversity
Anthropocentric value : value as a mean to
reach a goal (e.g., economics benefits)
Intrinsic value : value regardless of its
value to humans
1
Anthropocentric value: goods
e.g. : food
1
Anthropocentric value : goods
e.g., materials
1
Anthropocentric value: goods
e.g., medicine
1
Anthropocentric value : goods
e.g. unknown
The future potential of « yet to be
discovered goods » is often called the
insurance against the future
1
Anthropocentric value : services
e.g., purification of
water and air
1
Anthropocentric value : services
e.g., adequate
concentration of
atmospheric CO2
and O2
1
Anthropocentric value : services
e.g., soil
preservation and
erosion protection
1
Anthropocentric value : services
e.g., reduction of the
severity of droughts
and floods
1
Anthropocentric value : services
e.g., moderation of
extreme climatic
events
1
Anthropocentric value : services
e.g., recycling of
nutrients
1
Anthropocentric value : services
e.g., detoxification and
decomposition of
wastes
1
Anthropocentric value : services
e.g., generation and
conservation of
fertile soils
1
Anthropocentric value : services
e.g., pollination
1
Anthropocentric value : services
e.g., seeds dispersal
1
Anthropocentric value : services
e.g., pest insect
control by their
natural ennemies
1
Anthropocentric value : services
e.g., functions
yet to be
discovered
It is often when the ecosystems have been damages that
we undertand their role and importance, a posteriori
1
Anthropocentric value :
genetic information
Scientific and
socioeconomic value:
artificial selection of
domesticated plants and
animal
1
Anthropocentric value :
genetic information
Scientific and socioeconomic value :
genetically modified organisms
maïs
1
Anthropocentric value : services : esthétique et récréationnelle
Value for recreation and
personnal satisfaction
(tourism)
1
Anthropocentric value : culture
For several societies, biodiversity is a n
important part of the cultural canevas.
Its loss might lead to the loss of
tradition and ancestral values
1
Intrinsic value
Religion
Species have a value
because they were
created by a divinity
92
1
Intrinsic value
Holistic rationalism
Value because it forms a complex and elegant system,
with desirable properties, even if not necessarily useful
1
Intrinsic value
Respect of life
because life is sacred to many
1
Intrinsic value
Bio-empathy
Because we are emotionaly attracted, even if they
are not directly useful
Biodiversity is important
for our well being, for
our survival, for our
future and for itselft
Need a break?
4th part
Biodiversity decline
"Only when the last tree is cut; only when the last river is polluted; only
when the last fish is caught; only then will they realize that you cannot
eat money."
Proverbe Indien (Cree)
Extinction rate
Normal: ~ 12 per year
Smilodon, éteint il y a 10 000 ans
Extinction rate
Normal: ~ 12 per year
1600  1950: ~ 100 per year
Thylacine, éteint il y a 70 ans
Extinction rate
Normal: ~ 12 per year
1600  1950: ~ 100 per year
Today: ~ 1 000 per year
Tigre de Chine, éteint à l’état sauvage
Extinction rate
Normal: ~ 12 per year
1600  1950: ~ 100 per year
Today: ~ 1 000 per year
In a few decades : ~ 10 000 per year
Lion, bientôt éteint?
Extinction rate
Normal: ~ 12 per year
1600  1950: ~ 100 per year
Today: ~ 1 000 per year
In a few decades : ~ 10 000 per year
It is 100 to 1000 times more than the normal rate
As the rate of speciation does not increase, it is a loss
We are currently living what has been called the 6th mass extinction This term is used because of the increase of
the rate of extinction
Unlike the previous
ones, this mass
extinction is our making:
- we will suffer its effects
- we are morally responsible
- we can do something
Losses
One third of world natural ressources consumed
in only a quarter of century (1970 et 1995)
Extinction rate of several species per hour
We have already loss over one million species
We are likely to lose several more millions
in the coming decades
Description rate of new species
- 10 000 newly described species every year
- Several millions still unknown
- At this pace, we would need 1 000 years to
name all species
However, up to 2/3
could be loss within the
next 100 years
Most species will disappear
without even having been
named, let alone described
or studied, and of course
without discovering their
potential benefits for
humanity
Most species will disappear
without even having been
named, let alone described
or studied, and of course
without discovering their
potential benefits for
humanity
We thus still know only a
small part of the
biodiversity of our planet
and we will eventually
never know more than a
small part
What are the causes?
Extinctions causes
Habitat
Overexploitation
Biological
invasions
Pollution
destruction
Which is the worst?
Pollution?
Overrexploitation?
Habitat
destruction?
Biological invasions?
What about climate change? Until recently never accounted for in global studies
Interact with the other four causes
Many studies:
- very variable results
- probably significant biodiversity loss
Cause n°1
Habitat destruction :
loss and fragmentation
Habitat fragmentation in Alberta, Canada
Causes of fragmentation:
deforestation
Forest biodiversity losses
45 % of forest covers since the last 8000 years, especially during the last century
Loss over 200 millions hectares since 1990
(>West Europe)
According to the FAO, a yearly loss of 9.4 million hectares since
1990, most of which concerns tropical forests
(>Portugal or Hungary)
Ref: http://www.unep.org/GoverningBodies/GC22/Document/K0263740.F.doc
Zones de forêts et
Zone de Déforestation
Sur les 8 000 dernières années
If deforestation continues at the present rate, Thaïland won’t have any
forests left in 25 years, Philippins in less than 20 years
In most places, deforestation rates actually increase
Biodiversity in 10 km2 of
tropical forest in Brazil
Group
Number of species
Tree
Flowering plants
Mammals
Birds
Reptiles
Amphibians
750
15000
125
400
100
60
Deforestation in China
• Human population increased x2.5
these last 50 years, x5 in forest zones
• Wood exploitation increased from 20
millions m3/year in the 50s to three
times that in the 90s
• Natural forests now represent only
30% of forest zones
Déforestation (Orange) dans un site de la
province de Jilin, 1984-1997
Madagascar
4th island in size in
the world
10 000 endemic plant
flower species
Most forest zones already
destroyed
75% of its flowering plants
97% of its butterflies,
90% of its primates, reptiles and
amphibians
live nowhere else
Cause n°2
Biological invasions
Species that are suddenly introduced into a new
environment often die out, but a few of them survive,
establish and become invasive
Caulerpe
Caulerpa taxifolia
Why is this a problem?
For dozens of millions of years, species unable to
disperse on long distances have diverged behing
« geographical barriers »
Human transports (migrations, tourism
and commerce), recently accelerated the
introcution of species into new
environments, eliminating this isolation
Hence, the number of species colonizing new habitats increased by
several order of magnitude these two last centuries
Kudzu, Japanese ivy
The annual cost of invasive plants is over 6
billions dollar in the US. It reaches 137 billions
(production loss + control) with all introduced
species in the US
4 examples
plant
herbivorous
omnivorous
carnivorous
Example of an introduced plant
Miconia
Introduite comme plante
ornementale sur Tahiti en 1937
Aujourd’hui plus de la moitié de
l’île est lourdement envahie Son système d’enracinement
superficiel et tentaculaire favorise les
glissements de terrain, sa canopée
hermétique élimine les autres plantes
Plusieurs espèces endémiques de
Tahiti sont menacées d’extinction à
cause de Miconia
Miconia a été également introduite
dans plusieurs autres îles, ycompris à Hawaii, où on la trouve
à de nombreux endroits de cet
archipel. Elle est toujours vendue comme
plante ornementale dans les
tropiques
Example of an introduced herbivorous species
The rabbit
En Australie, ils sont une triste illustration du potentiel
néfaste des espèces introduites
Introduit sur plus de 800 îles, ils s’adaptent à des
conditions difficiles, ont un régime alimentaire très
flexible et se reproduisent exceptionnellement bien.
Impact jusqu’à totale disparition d’espèces :
Sur l’île de Laysan, Hawaii, les lapins introduits sont
responsables de l’élimination de 26 espèces de plantes entre
1903 et 1923, soit un taux excédant une espèce par an.
Par la destruction de l’habitat et des ressources, ils sont aussi
responsables de la disparition de 3 espèces d’oiseaux. Une
4ème, le canard de Laysan, ne comptait plus que 7 individus
lorsque les lapins ont été éliminés.
Introduced goats
Dégâts occasionnés par des chèvres
introduites aux Galapagos
Example of an introduced omnivorous species:
Rats
Les omnivores posent un problème particulier car ayant deux types
de sources de nourriture, ils peuvent alterner et subsister en l’absence de l’une d’elles
(hivers pour la végétation, ou migration des oiseaux)
Example of an introduced carnivorous species
The brown tree snake
• Accidentel introduction
in Guam by US Army
during WWII
• Now reaches densities
higher than 31 000/km2
Sole responsible for the extinction of:
• 12 out of the 14 endemic
bird species • Two out of the three
endemic bat species
• 9 out of the 12 endemic
lizard species
Still no clue as to how to remove it from the island
Conflicts of interests: the example of
the Nile perch
• Intentionally
introduced in Victoria
Lake
• Caused a major change
in fish community
structures
• Yet, represents a major
food sources for local
human populations
Victoria Lake
• 2nd largest freshwater
lake in the world
• Major protein source for
3 countries:
– Ouganda
– Kenya
– Tanzania
• Yound lake : 12 000 ans
• Cichlidae diversified
there : 500 sp
This actually constitute the most massive extinction
known in modern time for vertebrates
(disparition of over 200 fish species within a few decades).
Cichlidae
• Small fish
• Varied diet, mostly
herbivores and
detritivores
• Little value for fishing
• A formidable example
of evolutive radiation
IUCN list of the
« 100 of the worst invaders »…
Ref: http://www.issg.org/
2
Characteristics of invasive species
• High r and high dispersal rate
• Vegetative or clonal reproduction (plants)
• Habitat generalist
• Diet generalist (polyphagous/omnivorous)
• Naturally large geographic distribution
144
2
Characteristics of invaded communities
• Low diversity
• Lack of natural ennemies • Lack of ecological equivalent in native species
• Anthropogenic perturbations (degraded habitats)
• Simple trophic webs
145
3
Overexploitation
3
Exploitation of plants or animals at a rate exceeding their
capacity to naturally regenerate
All species can be concerned, but the most
sensitive are large species with low reproduction
rates (large trees, large mammals, species on
isolated islands, …)
• Exploitation accidentelle
d’organismes reliée à des activités
humaines
• Ex: oiseaux migrateurs et gratteciel, routes, lamantins et moteurs à
hélice
Accidental
exploitation
4 à 10 millions / an
Oiseaux migrateurs
Une étude du US Fish and Wildlife service de 2000 rapporte une fourchette de mortalité
de 4 à 10 millions d’oiseaux par an pour les seuls États-Unis
Roadkills
Données très éparses, par pays ou régions
The British Columbia Ministry of Transportation
statistics show that the total of wild animals
killed in the ten year period from 1992 to 2002
could be as high as 128,846 or more.
- At least 3.9 million miles of public
roads crisscross the United States
- State Farm estimates that 1.5 million
vehicles collide with deer every year
- Millions of vertebrates - birds, reptiles,
mammals, and amphibians - are killed
every year by vehicles
Indirect exploitation
• Exploitation d’une espèce par
un effet indirect de
l’exploitation d’une autre
• Ex: tortues marines et
mammifères marins affectés
par la pêche commerciale
1990: 55 000 noyées par an dans les filets à crevettes
des flottes Américaines.
200 000 loggerheads and 50 000 leatherbacks were
likely taken as pelagic longline bycatch in 2000.
Given 80–95% declines for Pacific loggerhead and
leatherback populations over the last 20 years, this
bycatch level is not sustainable.
Ecology Letters, (2004) 7: 221–231
En 1991, une étude sur 1/4 des filets maillants
utilisés au Japon, montre la mortalité suivante:
• • • • • • • 26,000 mammifères marins
406 tortues marines
270,000 oiseaux marins
700,000 requins bleus
25,000 calamars non ciblés
141,000 saumons
39 millions d’autres poissons
3
Subsistance exploitation
• Récolte de ressources naturelles
pour subvenir à ses besoins:
nourriture, vêtements,
combustible, logement
• intensité d’exploitation dépend
de la population et de son
niveau de consommation
• risques de surexploitation
généralement peu élevés
Mais problème si la population augmente
(gibier en Afrique)…
3
Recreational
exploitation
• Récolte de ressources naturelles
comme activité récréative:
chasse et pêche sportive,
collections (insectes, plantes,
papillons)
3
Les NACs
Tous les ans, plus de 8 millions d’oiseaux prélevès pour
le marché des Nouveaux Animaux de Companie
Le Ara hyacinthe, en 20 ans est passé de
plus de 100 000 à moins de 3 000
3
Les NACs
Ce marché est responsable du déclin de 40
espèces dans le monde
--> attention aux invasions biologiques…
3
Chasse pour les trophées ou pour le sport
Les plus gros spécimens sont tués
préférentiellement
Ce sont en général les
meilleurs reproducteurs
L’impact est disproportionné par
rapport aux nombres prélevés
Commercial
exploitation
• Produits dérivés de la
récolte sont vendus sur
le marché (noir)
Chute importante de
populations dues au commerce
international:
• Alligators, crocodiles
• Tigers, Rhinos, Elephants
• Fur-bearing animals: cheetahs,
cats, otters, chinchilla, vicuna,
some monkeys
• Mahogany, cedar
• Orchids, other plants
• Tropical fish, birds
3
Médecine traditionnelle
Est souvent d’autant plus efficace que l’espèce est rare Cause importante de mortalité pour certains grands mammifères
3
Parties du tigre utilisées pour la
médecine traditionnelle Chinoise
Tiger Subspecies: 5,000-7,400 total
3
(down from ~150, 000)
Siberian
Caspian
Wild
0 (1950s)
Captive
150-200
490
South China
Wild
30-80
Captive
48
Indochinese
Bengal
Wild
Captive
Wild
3,250-4,700 1,050-1,750 Captive
30
333
Sumatran
Wild
Captive
400–500 235
Java
Bali
0 (1972)
0 (1937)
3
Le rhinocéros noir Les éléphants d’Afrique
et le commerce de l’ivoire
Population Africaine:
1979: ~ 1,3 millions
1989: 625 000
Afrique du Sud:
19ème siècle: 200,000
1920: 120
3
Surpopulation dans certaines zones
Grand primates (tous menacés)
Chimpanzés (2 espèces) & Gorilles (3 sousespèces) en Afrique de l’Ouest
Nombres réduits par 50% ces 20 dernières
années :
• Perte d’habitat
• Commercialisation de la viande
• Virus Ebola virus - Seront vraisemblablement éteintes
dans la nature dans 30 ans
Orang-Outans à Borneo et Sumatra (2 espèces)
Nombres réduits par 91% depuis un siècle :
• Perte d’habitat
• Commercialisation de la viande
- Seront vraisemblablement éteintes dans la
nature dans 20 ans
3
La crise du gibier vide les forêts Africaines
Concerne à peu près toutes les espèces de vertébrés,
à hauteur de 1-5 millions de tonnes
La situation est la plus
préoccupante pour les primates
tels que les gorilles et les
chimpanzés
La population Africaine a été
multipliée par 8 au 20ème siècle
60% de la viande qui y est
consommée est du gibier
La viande de brousse ‘bushmeat’ représente un marché
de plusieurs millions de dollars dans les pays tropicaux
d’Afrique, d’Asie et d’Amérique du Sud
Il ne s’agit pas seulement d’un problème
écologique ou même éthique, mais bien
d’un problème socio-économique complexe
3
Intensive commercial
exploitation
• L’histoire montre que ce
type d’exploitation n’est
pas bien géré et mène
souvent à la destruction
complète de la ressource
Grand Pingouin (Pinguinus impennis)
Chassé pour ses plumes à partir
de 1785. Éteint en 1844
3
La Tourte voyageuse ou pigeon migrateur
Ils étaient probablement entre 3 et 5 milliards lors de la colonisation de
l’Amérique par les Européens
«passenger pigeons» : leur passage pouvait obscurcir le ciel pendant des heures.
Tellement nombreux, qu’ils servirent à nourrir les nouvelles villes de la côte Est.
Et également de tir par loisir (1er à tirer 30000 oiseaux remporte la compétition)
3
Le 1er septembre 1914, à 13h00, Martha le dernier spécimen de
l’espèce est morte à l’age de 29 ans, 25 ans après l’extinction de
l’espèce dans la nature
C’est peut être l’unique fois dans
l’histoire où on connaît l’instant
exact de l’extinction d’une espèce.
Il n’aura fallut que 50 ans pour que
l’homme extermine cette espèce
Ref: http://www.ulala.org/P_Pigeon/George.html
3
Loutre de mer
(commerce de fourrures)
1750-1790: 250 000 peaux
Populations en 1965 :
Russie: 6 000
Alaska: 25 000
Washington: éteinte
Oregon: éteinte
Californie: 600
Mexique: éteinte
Columbie Britannique: éteinte
3
Bison d’Amérique
Année
1860
1889
1900
1905
1908
1913
1967
1972
1994 - 2002
Nombre
60,000,000
1,100
500
1,697
2,047
3,000
20,000
30,000
~200,000
3
Great Whale Populations
Group
Species
Past
Rights
Right whale
200,000
8,000
Bowhead whale
120,000
7,500
Blue whale
200,000
2,000
Fin whale
470,000
111,000
Sei whale
200,000
25,000
Minke
140,000
940,000
Humpbacks
Humpback whale
125,000
10,000
Grays
Atlantic Gray whale
?
extinct
10,000
26,000
Rorquals
Pacific Gray whale
From "State of the World, 1994"
1993
3
Etat actuel des populations de baleines
Extinct
Atlantic Gray
Atlantic Bowhead
Struggling
Western Pacific Gray
North Atlantic Right
Southern Blue
Recovering
Minke: 900,000
Gray (Pacific): 26,000
Bowhead (Pacific):
– 1500 (1976) to 7,500
North Atlantic humpbacks:
– 5,505 (1980’s) to 11,000 (2000)
Humpback whales, California coast:
– 88 (1979) to 607 (1991)
Blue whales, California coast:
– 500 (1979) to 2049 (1991)
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Surexploitation des
stocks de poissons
Accroissement des prises au niveau mondial
3
Effondrements…
Anchois du Pérou
Prises, en millions de tonnes
Rendement maximum supportable
Accroissement de
l’exploitation
Effondrement du stock
3
Stocks de la Nouvelle-Angleterre
Abondance
Exploitation
3
Stocks de sardine Californienne
Date
Prises (tonnes)
1936-37
3/4 million
1957-58
17
3
Déclin des stocks
Million tons
4,5
4
3,5
3
Prises des années 60
Prises de 1992
2,5
2
1,5
1
0,5
0
Source: Food and Agriculture Organization
3
Déclin des poissons prédateurs
90 % de tous les gros poissons y inclus Thons, Marlins, Espadons,
Requins, Morues, et Flétans ont déjà disparu
Ref: http://ram.biology.dal.ca/~myers/depletion/
3
Thon rouge
Le thon rouge, oscille entre 6 et 12%
de son niveau de susbistance, restant
au seuil de l’extinction
Date
Catch
1970
300,000
1990
30,000
Marlin blanc, marlin bleu
Evolution de la biomasse
du marlin blanc Les experts prédisent une extinction imminente (sinon déjà passée) pour
ces deux espèces, exploitées à 8 et 4 fois le niveau maximum supportable
3
Esturgeons
27 espèces: toutes menacées
3
Effondrement des stocks
d’invertébrés aux Etats-Unis
• Californie:
• Homards
• Calamars
• Abalones
• Oursins
• Chesapeake Bay:
• Crabes bleus
• Huitres
• Autres:
• Crevettes
• Crabes dormeur
• Crabes royaux
• Limules
Stocks de calamars en Californie
Prises de 1996 : 80 000 tonnes, pour une
valeur de 33.5 millions de dollars US
Prises de 1998 : 0 tonne
Etc…
5th part
Biodiversity protection
Etc…
The first rule of any clever tinkerer is to keep all the pieces
Aldo Leopold, fondateur américain de l’écologie
Species protection
« flag » species
« umbrella » species
« keystone » species
« engineer » species
We manage increasingly better to save species,
sometimes from the very brink of extinction
Space protection
Protected areas
Preservation of a larger group of species
Space protection
Protected areas
Also allows to protect biodiveristy at the global level, in a
fully functionning ecosystem
Here also progresses are encouraging, with
more, larger and better designed reserves
Progresses in Conservation Biologie are enormous
- We are increasingly
efficient, we understand
better decline causes and
how to reverse them
- there are increasingly more
professions related to nature
protection
- The interest from the publis is also increasing
There are reasons to be optimistic!!
For scientists
- The solution?
- Fundamental research
For the others
= understanding of decline causes
- Applied research
= optimization of biodiversity protection
- Biodiversity management
= restauration, reintroductions, conservation ex-situ,
design and management of protected areas, …
More and more successes in conservation programs
For scientists
- The solution?
- Act fast
For the others
- Who?
- Everyone
- Priority?
- Information
Compared to scientific progresses,
public awareness is really progressing slowly
During this seminar, I used the photos of around 50 species.
Given the current rate of extinction, this is about the same
number of species than those who disappeared today
And those who will disappear tomorrow
And the day after tomorrow Etc…
Extinction is forever…
Thanks