Nature Out of Balance: How Invasive Species Are Changing the Planet
Chapter One Here There and Everywhere Depending on where you live you’ve probably heard about invasive species that spell Big Trouble They’re in the news They might be in your school grounds or even your backyard Experts might have visited your class to tell you about them And you might even have been part of a group of volunteers volunteers helping in the battle against them You’ll see a few of these invasion all-stars throughout the pages of this book The white fuzz on this little brown bat’s face means it has white-nose syndrome Caused by a fungus that likely came to North America from Europe white-nose syndrome is killing millions of bats PETE PATTVINA USFWS CC BY 2.0 Eco-Fact A native species is one that occurs naturally in a place having evolved there over a long period of time without any help from humans 88 But first What IsIs an Invasive Species Anyway What an Invasive Species Anyway Any type of organism a living thing such as a plant animal insect fish fungus virus or bacteria can be an invasive species It usually doesn’t misbehave in its home habitat where it has evolved as a native species But once it has been moved to a new area where it is a non-native species it begins to spread and become a bully causing problems for the native species there and often for humans as well That’s when we call it a non-native invasive species Although these organisms are blamed for everything from extinctions of native species to billions of dollars in damage to
crops and to nature they aren’t bad in themselves The real villains are us humans since we moved them to the new place whether by accident or on purpose Movers and Shakers Movers and Shakers Species can travel naturally sometimes thousands of miles to new regions and even to different continents In fact these invasions are an essential part of the history of life on Planet Earth If the first plants hadn’t invaded land from the ancient ocean about 500 million years ago Earth certainly wouldn’t be the amazing place it is now And if species of all kinds hadn’t traveled when the ice sheets melted after the Ice Age things would look very different from the way they do today Every species must have been invasive at some point or it wouldn’t have continued to exist Very small organisms like bacteria can be carried huge distances across oceans and continents by wind and air currents Larger organisms expand their ranges the areas in which they occur naturally by following the food and other conditions that they need But humans have also been moving species around by accident since they first left Africa more than 100,000 years ago and on purpose since they became farmers more than 10,000 years ago In fact most of the species that have spread to new places in the last several centuries were moved there by us We’re the all-star vector for non-native species Eco-Fact Not all invasive species are non-native Native species can also become invasive although they usually cause fewer problems Eco-Fact WeedWeed is simply a label we give to plants that grow where we don’t want them usually in our gardens and in farmers fields A weed typically grows or spreads rapidly and it can be a native species or a non-native species This modern liverwort’s ancestors were likely among the first land plants They managed to change the earth’s climate alter its soils and allow other life to evolve ED Reshike getty images
Accidental Hitchhikers Accidental Hitchhikers We move species accidentally in lots of different ways For example early humans probably had seeds from plants in their hair and clothes or on their tools dropping them as they traveled to new regions But the main source of accidental movement of species today is international trade The globalization of our economies economies and culture has also caused the globalization of many species Insects can hitchhike on the fruits and vegetables grain and wood that we get from and send all over the world Snails slugs and bugs can also be hidden on plants traveling from faraway places to our gardens Reptiles and amphibians can travel to new homes in cargo containers Scientists esti mate that more than 10,000 species a day are being carried in ships ballast water taken onboard in one place to balance the ship and its load and then dumped in another part of the world when it unloads including fish shellfish algae fungi viruses and bacteria The more stuff we buy and sell the more non native species move around Even the stuff we throw away including all the plastic that ends up in the oceans carries countless creatures from one continent to another Scientists say that our trash could be responsible for a new wave of invasive species on our coasts Mussels barnacles and sea squirts can survive for years attached to plastic and eventually wash up on distant shores ready to take up residence The massive 2011 earthquake and tsunami in Japan pulled five million tons of debris into the Pacific Ocean Currents and storms carried some of it all the way to the west coast of North America Everything from small pieces of plastic to docks and entire fishing boats served as rafts for a mass migration of marine creatures Researchers have found almost 300 species that survived the trip Ballast water emptied from ships moves species around the world every day PHIL AUGUSTAVO Getty Images Debris from the 2011 Japanese earthquake and tsunami like this boat that washed up on an Oregon beach two years later carried hundreds of species to North America STEVEN RUMRILL SHELLFISH PROGRAM leader OREGON department of FISH and wildlife 10
Lake Lake St St ClairClair non-contaminated provinces states status unknown provinces states contaminated provinces states This map shows how far zebra mussels right and the closely related quagga mussel have spread since they were first identified in Lake St Clair in the mid-1980s Map COURTESY of central KOOTENAY invasive SPECIES Society DATA COURTESY OF THE US GEOLOGICAL Society Freevectormaps COM INVASIVE ALL-STARS Zebra Mussels In the mid-1980s a European ship released some zebra mussels likely from its ballast water into Lake St Clair a small lake between Ontario and Michigan that connects Lakes Huron and Erie Originally from the Caspian Sea in Asia the mussels spread rapidly throughout the Great Lakes and the waterways linked to them Zebra mussels attach to hard surfaces in huge numbers tens of thousands of them to a bob Nichols US DEPARTMENT OF AGRICULTURE 20120106 OC AMW 0189 square yard square meter They clog pipes screens and other equipment costing businesses and communities money They cling to native mussels and clams smothering them And when they filter water through their bodies toxins get concentrated in them which can then harm the birds and other wildlife that eat them 11
