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12 THE NEW TANNER Invaders threaten ecosystem Over millennia, the makeup of species within an ecosys- tem reaches a balance. Whether it's rabbits in Aus- tralia, zebra mussels in the Great Lakes, or freshwater shrimp in British Columbia, one of the greatest threats to this balance and diversity of life on earth is from foreign plants, insects and other ani- mals that are introduced to new areas. The spread of introduced or invasive species has been one of many damaging envi- ronmental side-effects of the push towards a globalized economy. As worldwide trade has increased, species have been given free rides to virtu- ally every corner of the planet, and that's meant big trouble to indigenous creatures, some of which have been pushed to the brink of extinction by invaders. Invasive species reach foreign ecosystems in a vari- ety of ways. The ballast wa- ter of freighters, for example, is a virtual aquarium of exotic species and its routinely dumped in the harbours of port cities. Grain, lumber, fruit and millions of other goods are shipped around the world every day. These can carry insects, small mammals, plant spores or other organisms that are then released into new areas. Combined with an ex- plosion of global travel, it's easy to see how species can move from place to place. Usually imported species, having evolved elsewhere, are unable to gain a foothold in their new habitats and eventually die out. However. ¢ V6 Engine « AM/FM Science Matters by David Suzuki humans have altered the planet so much that naturally occurring species are often weakened so that invaders can more readily take hold. What's more, as our climate changes, new regions be- come habitable for species that were previously limited by temperature or precipita- tion levels. Today the United States alone spends more than $500 million annually on combat- ing invasive species. These are estimated to be costing the country billions in lost crops and damage to infra- structure, not to mention add- ing to the loss of indigenous species and their habitats. Worldwide, the problem has become so large that there is now an entire scientific jour- nal devoted to the subject. Not all invasive species are introduced by accident. Sometimes they are released intentionally, which can have disastrous consequences. In British Columbia, for example, the introduction of a tiny freshwater shrimp as a food source to help boost fish populations in lakes had ex- actly the opposite effect. The fast-reproducing shrimp ended up out-competing na- tive Kokanee (a freshwater salmon) and trout for food. In just 30 years, Kokanee num- bers have dropped 99 per cent. An introduction of mos- quito fish- one of the oldest methods of biological control ~has also had unintended side effects. These fish were re- leased in areas of Canada, the U.S., New Zealand and Aus- tralia to reduce mosquito populations. Unfortunately, studies from some areas show that the fish actually prefer tadpoles to mosquito larvae. Some researchers suggest that mosquito fish may be linked to declining aebiiae populations in California. Given the known impact of invasive species, the tens of thousands of Atlantic salmon that continue to escape from open cage fish farms along the B.C. coast should be a big concern, especially consider- ing the weakened state of wild stocks. Every species on this planet has a role to play in the functioning of the biosphere as a whole. When introduced species run rampant and dis- place indigenous species, the result is a loss of biodiversity. In turn, this reduces the ca- pacity of the earth to fulfil the biological cycles that maintain all life. Ecologists are con- cerned that the spread of invasives could result in a few successful species dominat- ing the planet, resulting in what some have dubbed a global McEcosystem. As economic powers push towards greater globalization, greatly increased diligence to prevent invasive species from spreading is required, A bio- logically poor McEarth would be an unhealthy and lonely place to live. 2000 Mazda 626 bh CD Player * Swing Vent Feature ° 16" Alloy Wheels « Air Conditioning « Remote Entry » Power a "eo ™ ~ x " é THURSDAY. OCTOBER 21, 1999 For better grades this fall, better Sylvan Learning Centre® can help your child make the In our positive, stress-free environment, children actually become excited about learning. You can see it on their faces -- and on their report cards. Sylvan® offers help in reading, writing, math, algebra, study skills, homework support and time management. To learn how Sylvan can benefit your child, call today. 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