BIODIVERSITY: Alien Species Eroding Ecosystems and Livelihoods
UXBRIDGE, Canada, May 21 2009 (IPS) - Continent-hopping alien species are worsening
poverty and threaten the agriculture, forestry, fisheries and natural systems
that underpin millions of livelihoods in developing countries, warn biodiversity
"The livelihoods for 90 percent of people in Africa directly rely on natural
resources such as marine coastal biodiversity," said Ahmed Djoghlaf, executive
secretary of the Convention on Biological Diversity (CBD).
"Around the world more than 1.6 billion people depend directly on forests for
their survival," he told IPS from Montreal.
Biodiversity is not just fuzzy animals and pretty birds. It is the diversity of
life on Earth that comprises ecosystems which in turn provide vital ecosystem
services including food, fibre, clean water and air.
"Biodiversity is poor countries' most precious asset," Djoghlaf stressed.
Alien species are plant, animal, insect and other species that have been
introduced outside of their natural habitats. They have become one of the two or
three major drivers behind the current extinction crisis.
Today, one in four mammals is on the verge of extinction. Of the 44,838 species
catalogued by the International Union for Conservation of Nature (IUCN), 38
percent are on their way out. Currently, one species goes extinct every three
And at least 40 percent of all animal extinctions, for which the cause is known,
are the result of invasive species.
The scope of this global biological invasion is stunning. New Zealand has more
than 20,000 introduced plant species competing with the 2,000 or so endemic
plant species. Many of the aliens can't survive outside gardens or farm fields
but at least 2,000 aliens have become 'naturalised' and are indeed competing
with the locals, causing several documented extinctions of native New Zealand
flora that do not exist anywhere else.
"The scale and speed of this is unprecedented in Earth's history," said Anthony
Ricciardi, an invasive species biologist at Montreal's McGill University.
"Walk into the Canadian woods and one in five species growing wild will be a
non-native," Ricciardi said in an interview.
But doesn't this global shuffling of species produce more biodiversity, or at
least keep it the same? "At the local scale, it can look like there are more
species and sometimes there are," he acknowledged.
However. this mass movement of species is reducing overall biodiversity. When
the Nile Perch was introduced into Africa's Lake Victoria, 100 to 150 endemic
fish species were wiped out.
There are many similar instances but most often the invaders do not directly
cause extinctions. Instead they compete for food, habitat and other resources,
reducing local species numbers to low levels. And then a bad weather event,
disease or some other stress comes along and suddenly the native species is
gone, Ricciardi said.
"Every invasive species has an impact but most go undocumented. They are
insidious and often subtle in terms of impacts," he said.
Unnoticed, some invaders spread far and wide, adapt to local conditions and then
years afterwards become a major problem by degrading or dramatically altering
the ecosystems they are in.
"Invasives are a form of biological pollution, but one that can change and
adapt," Ricciardi said.
Local species are vulnerable to these invaders because they do not have any
evolutionary experience to cope with them. There many examples of large numbers
of species on isolated islands decimated by goats, cats and rats simply because
those species never lived there until someone introduced them. And that is the
key - invasions are tightly connected to human behaviour.
Keeping all aliens out is impossible. The best hope for biodiversity is to know
which species are the potential troublemakers and figure out how they are or
could be moved around. That is the containment strategy of most countries, where
anyone crossing the border is asked if they are carrying plants, seeds or
Australia, with a long history of bad-news invaders like rabbits and cane toads,
insists that visitors surrender all fresh food, animal and plant products.
Climate change is also making it easier for some species to shift their
traditional ranges and move into new regions where it had been too cold
previously. While the initial jump by the West Nile virus from North Africa to
New York City in 1999 wasn't climate related, its continued survival and spread
ever northwards into central Canada is related to warmer winters in the region.
And that virus has reduced populations of a number of bird species and has
killed dozens of people.
Invasive species affect all aspects of society just as the loss of biodiversity
does, said Ricciardi. "We simply don't know all the impacts of losing species,"
There are major studies underway to take a stab at figuring that out, said the
CBD's Djoghlaf. "In 2010, we hope to release a Stern-like report on the economic
value of the loss of biodiversity."
The Stern Review on the Economics of Climate Change released in 2006 examined
the impacts of climate change on the world economy.
"Biodiversity needs to be seen and understood as not just a 'green issue' but an
important economic asset in need of protection," Djoghlaf said.
The largest impact to our planet is the out-of-control human population. This is a global issue that needs to be addressed. NOW!
Species Lie in Wait, Strike After Decades
(Reuters) - Animals and plants introduced from foreign habitats may not reveal
themselves to be harmful 'invasive' species for decades, according to a European
study published on Monday.
are moved away from their natural predators back home can displace native
species in their new habitats, and scientists say the problem already costs
Europe 12 billion euros ($16 billion) a year.
which is likely to hold true for other continents too, means that the seeds of
future, perhaps bigger, problems have literally already been sown.
compared the effects of "alien species" such as American ragweed, Canada geese
or Japanese deer in 28 European countries. The study's findings indicated
that it can take decades to figure out which alien species will be disruptive,
and looking at those that arrived in 1900 was a better indicator of current
problems than looking at those from 2000.
"This lag in
the cause-and-effect relationship would mean that ... the seeds of future
invasion problems have already been sown," said the study, published in the U.S.
Proceedings of the National Academy of Sciences.
insects were quickest to get established in new habitats, helped by their
mobility. Others took far longer to reach the critical numbers to become
to Europe from the 19th century included ragweed, whose pollen is blamed for
some hay fever, and the black locust tree, also from North America, which can
damage European grassland with its ability to store nitrogen.
trade and travel during the 20th and 21st centuries means that the problems are
likely to worsen unless checks on everything from the ballast tanks of ships to
coffee or grain imports are tightened.
"We should do
more about this problem now," said Stefan Dullinger, of the University of
Vienna, Austria, who was among authors of the study from institutes in New
Zealand, the Czech Republic, Germany, Switzerland, Spain, Italy and France.
"Otherwise, things can become even much worse than they are in a few decades,"
he said. The findings for Europe were likely to be mirrored elsewhere in the
The study also
recommended that Europe should target controls at animal and plant species that
were so far causing no damage but were known to be invasive in other habitats.
Climate change could also add to the spread. "Warmer temperatures could trigger
the spread of invasive species that are limited by climate now," Dullinger said.
How convenient that we rant and rave about all this, yet ignore the massive
destruction caused daily by our own species worldwide. About 2 billion more
people are projected to be on this planet by 2050, the result of our reckless
breeding. We’ve plundered and destroyed the lives and homes of millions of
non-human species without a second thought, and keep right on going. Sadly,
consumption and greed are the norms of all society, with human selfishness most
Sir David Attenborough speaking on climate change (2015)
See Population Matters
June 24, 2013
Invasive species threaten natural
habitat across Canada
Humans changing the environment
more than ever