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BIODIVERSITY: Alien Species Eroding Ecosystems and Livelihoods

By Stephen Leahy

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 experts.

"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 hours. 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 animals.

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," he added.

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.

Comment: The largest impact to our planet is the out-of-control human population. This is a global issue that needs to be addressed.  NOW!

Invasive Species Lie in Wait, Strike After Decades

December 20, 2010

OSLO (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.

Species that 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.

The study, which is likely to hold true for other continents too, means that the seeds of future, perhaps bigger, problems have literally already been sown. 

The study 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.

Birds and insects were quickest to get established in new habitats, helped by their mobility. Others took far longer to reach the critical numbers to become invasive. 

Introductions 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. 

Increasing 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 world. 

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.

Comment: 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 offensive.  

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