The fish that ate everything (and other true tales); ravenous fish, noxious weeds, wild hogs, and deadly germs: Can anyone stop invader species? (Life science: food chains/invaders species).Biologists slip on yellow protective suits and ease into aluminum skiffs, which rock in the murky water. It's just after daybreak in Crofton, a quiet Maryland town of 20,000 not far from the nation's capital. Scientists usually come to rural ponds like this to study the aquatic life. Not this time. Today, September 4, 2002, they have come to kill it. "We're going to see a lot of dead fish here," says Eric Schwaab of the state's Department of Natural Resources Many sub-national governments have a Department of Natural Resources or similarly-named organization:
Prowling prowl v. prowled, prowl·ing, prowls v.tr. To roam through stealthily, as in search of prey or plunder: prowled the alleys of the city after dark. v.intr. beneath a thick carpet of lily pads and pond scum are Channa Channa is a genus of the Channidae family of snakehead fishes. It contains about 29 species. Fish in the genus (called cá lóc in Vietnamese) are prized in Vietnamese cuisine, and are sometimes used as a main ingredient in the sour soup called argus, freaky-looking fish better known as northern snakeheads (see above). The fish, as one government official puts it, are "like something from a bad horror movie." Originally from China, these torpedo-shape terrors grow to 1.2 meters (4 feet) and gobble up nearly everything in sight. They're also one of the few species of fish that can wriggle short distances over land. Ever since a local fisherman reeled in the first snakehead here last May, this four-acre pond tucked behind a donut shop has become ground zero for the global fight against invasive species--alien organisms like the snakehead, which threaten to overrun native habitats. If the snakehead flip-flopped from the murky Maryland pond into the Little Patuxent River just 69 meters (75 yards) away, "the consequences could be disastrous," says Michael Slattery, a biologist with the U.S. Fish and Wildlife Service. He and others fear the snakehead could wipe out the darters, sunfish sunfish, common name for members of the family Centrachidae, comprising numerous species of spiny-finned, freshwater fishes with deep, laterally flattened bodies found in temperate North America. , and other indigenous (native) species that call the river home. MASS INVASION The snakehead is one of approximately 50,000 alien, or nonindigenous, species of plants, animals, and microorganisms now thriving in the U.S., according to Cornell University scientist David Pimentel. Not all are bad, he notes: Wheat, rice, and other staple foods were originally transported to the U.S. from other countries by early settlers. So were dogs, cats, horses, cows, sheep, pigs, goats, and most animals that we eat, ride, or keep as pets. It's only when new arrivals overpower-native life that scientists worry. In the U.S., invasive species cause an estimated $137 billion worth of damage each year. Purple loosestrife loosestrife, common name for the Lythraceae, a widely distributed family of plants most abundant as woody shrubs in the American tropics but including also herbaceous species (chiefly of temperate zones) and some trees. , for example, a flowering-herb turned noxious weed that arrived from Europe in the 19th century, now chokes waterways in 48 states and cost $45 million per year to control, to a Cornell study. The Maryland snakehead cleanup--a relatively small invasive-species skirmish--is to cost $50,000. But to biologists, it's money well spent. "You never know what a new species is gong to do to an area," says Roy Van Driesche, a scientist who studies invasives at the University of Massachusetts The system includes UMass Amherst, UMass Boston, UMass Dartmouth (affiliated with Cape Cod Community College), UMass Lowell, and the UMass Medical School. It also has an online school called UMassOnline. in Amherst. "You can get some nasty surprises." Take the brown tree snake--an accidental invasive species. This native of Southeast Asia stowed away on military aircraft after World War II--winding up on the formerly snake-free island of Guam. With no natural predators to stop it, the snake population exploded and began gobbling up the island's native wildlife. Today, some of Guam's native birds, such as the Guam flycatcher and bridled white-eye, and reptiles such as the Micronesian gecko gecko (gĕk`ō), small or medium-sized lizard of the family Gekkonidae. The more than 300 species are distributed throughout the warm regions of the world, mostly in the Old World. Despite folklore to the contrary, their bite is not poisonous. , are extinct. Other alien species have been introduced deliberately. In the 1930s, the U.S. government paid Southern farmers to plant an Asian vine called kudzu kudzu (k  d`z ), plant of the family Leguminosae (pulse family), native to Japan. , which they hoped would stop soil erosion. It did--and then some. Today, kudzu is dubbed the "vine that ate the South"--it grows up to 31 centimeters (1 foot) per day and suffocates everything in its path. The roots of a single vine can weigh up to 400 pounds! CHAIN GANG Scientists now think twice about dragging an organism from its native home. When an alien species kills off a native species, it can seriously disrupt the food chain, the intricate web in which energy or nutrients pass from one organism to another. For example: Energy from the Sun makes grass grow; grasshoppers Grasshoppers may refer to one of the following:
v. re·fu·eled also re·fu·elled, re·fu·el·ing also re·fu·el·ling, re·fu·els also re·fu·els v.tr. To supply again with fuel. v.intr. on grasshoppers; hawks prey on snakes, and so on. In short, every life form serves as food for another, creating an interdependent link between all plants and animals Plants and Animals are a Canadian indie-rock band from Montreal, comprised of guitarist-vocalists Warren Spicer and Nic Basque, and drummer-vocalist Matthew Woodley.[1] They are signed to Secret City Records. . When an invasive species disrupts and dominates a food chain, it can siphon siphon (sī`fən, –fŏn), tube through which a liquid is lifted over an elevation by the pressure of the atmosphere and is then emptied at a lower level. food energy away from other organisms in the chain. For example, the Texas horned lizard has all but disappeared from Texas, due mostly to invasive fire ants. Fire ants are an aggressive South American species known for their sizzling sting and ornery or·ner·y adj. or·ner·i·er, or·ner·i·est Mean-spirited, disagreeable, and contrary in disposition; cantankerous. [Alteration of ordinary. behavior. They arrived in Texas in the 1920s, and decimated the state's native harvester-ant population, which horned lizards feed on. Without its staple food, the horned lizard starves. In the Great Lakes, a similar situation is ravaging tiny plantlike water organisms called plankton plankton: see marine biology. plankton Marine and freshwater organisms that, because they are unable to move or are too small or too weak to swim against water currents, exist in a drifting, floating state. . Hailing from Europe's Caspian Sea, the fingernail-size zebra mussel, a mollusk mollusk: see Mollusca. mollusk or mollusc Any of some 75,000 species of soft-bodied invertebrate animals (phylum Mollusca), many of which are wholly or partly enclosed in a calcium carbonate shell secreted by the mantle, a soft with a razor-sharp black-striped shell, hit North America in 1988--via a transoceanic tanker. Since then, it has spawned like wildfire: A single female can produce up to 1 million offspring a year. The pests inhale a quart of water a day to feed on plankton, their primary food source. The problem: Indigenous fish and shellfish also rely heavily on plankton and must compete with mobs of zebra mussels for dinner. Without plankton they die, and so do the larger fish that prey on them. Zebra mussels also clog intake systems at water treatment and power plants and smother boat engines. ALIEN BUSTERS Solving the invasive-species problem won't be easy. U.S. legislators are considering tougher restrictions on transoceanic tankers to prevent them from dumping water--and biological stowaways--in U.S ports. But laws can only go so far. The snakehead didn't wriggle 7,000 miles from its native China to rural Maryland on a ship. A local man bought a live male and female in New York's Chinatown to make snakehead soup--in Asia the fish are considered a delicacy. Eventually he changed his mind and dumped them in the Crofton pond. Scientists are working on ways to predict whether an organism will be a nuisance by compiling an invasive-species "profile"--just as police do with potential criminals. But other scientists argue that it's impossible to predict what an alien species will do on foreign turf. So, for the moment, scientists must resort to warfare. Bullets, explosives, and electric shock are some of the weapons scientists have wielded against invasive organisms. In Maryland the weapon was poison. Biologists sprayed the pond waters with 18 gallons of rotenine, a chemical that reeks of mothballs. Made from the leaves and roots of tropical plants, rotenine is absorbed through a fish's gills and prevents it from breathing oxygen. It didn't take long for the fish to die. By lunchtime, fish bobbed belly-up all across the scum-covered water. Swapping spray guns for nylon nets, biologists skimmed up the dead. In all, they collected more than 120 snakeheads that day--as well as 60 pounds of sunfish, catfish, and other native species. few weeks after all the fish were dead and the rotenine had dissolved, scientists restocked the pond with native fish. Eric Schwaab, head of the Maryland snakehead strike force, stood with his back to the poisoned pond. "Hopefully this will be the last installment in the snakehead saga," he says. Resources Everything you ever wanted to know about invasive species: www.invasivespecies.gov Biological Invasions: Economic and Environmental Cost of Alien Plant, Animal, and Microbe microbe /mi·crobe/ (mi´krob) a microorganism, especially a pathogenic one such as a bacterium, protozoan, or fungus.micro´bialmicro´bic mi·crobe n. Species, by David Pimentel, CRC (Cyclical Redundancy Checking) An error checking technique used to ensure the accuracy of transmitting digital data. The transmitted messages are divided into predetermined lengths which, used as dividends, are divided by a fixed divisor. Press, 2002 "Aliens Invade America," by Sharon Begley, Newsweek, August 10, 1998 Did You Know? * More than 4,000 non-native plants and 2,300 non-native animals populate the U.S. * Scientists estimate that up to 49 percent of all endangered species endangered species, any plant or animal species whose ability to survive and reproduce has been jeopardized by human activities. In 1999 the U.S. government, in accordance with the U.S. are directly threatened by invader species. * Invasive species cost the U.S. an estimated $122 billion per year. Cross-Curricular Connection History: Cats and dogs Cats and Dogs A slang term referring to speculative stocks that have short or suspicious histories for sales, earnings, dividends, etc. Notes: In a bull market analysts will often mention that everything is going up, even the cats and dogs. are not indigenous to North America. Trace their roots and write an essay comparing them to more notorious invasive species, like the northern snakehead fish. How are their circumstances similar? How are they different? Critical Thinking: Imagine the food chain and where you fit in. What would happen if it were disrupted by an invasive species? Describe a chain of events. VITAL STATS BIG FISH, SMALL POND SPECIES Northern snakehead (Channa argus) NATIVE LAND China AREA OF INVASION Maryland waters HOW IT GOT THERE At least 17,000 have been imparted to the U.S. for food since 1997. THE DAMAGE It devours smeller fish and disrupts local ecosystems; survives outside water far several days. Grows up to 1.2 meters (4 feet) and weighs up to 7 kilograms (15 pounds). VITAL STATS HOG WILD SPECIES Feral pig (Sus scrofa) NATIVE LAND Europe, Asia, North Africa AREA OF INVASION Virtually everywhere there is food; mountains, farms, marshlands, deserts. HOW IT GOT THERE Domesticated do·mes·ti·cate tr.v. do·mes·ti·cat·ed, do·mes·ti·cat·ing, do·mes·ti·cates 1. To cause to feel comfortable at home; make domestic. 2. To adopt or make fit for domestic use or life. 3. a. as farm animals nearly 5,000 years ago. THE DAMAGE The wild hog is an omnivore omnivore: see carnivore. omnivore Animal that eats both plant and animal matter. Most omnivorous species do not have highly specialized food-processing structures or food-gathering behaviour. . It devours everything in its path--weeds, rodents, bird eggs, even manure. It tramples crops, kills native vegetation, and spreads illness, such as foot-and-mouth disease foot-and-mouth disease, highly contagious disease almost exclusive to cattle, sheep, swine, goats, and other cloven-hoofed animals. It is caused by a virus that was identified in 1897. . Some weigh up to 450 kilograms (992 pounds)! VITAL STATS THE VINE THAT ATE THE SOUTH SPECIES Kudzu (Pueraria lobata Pueraria lobata, n See kudzu. Pueraria lobata a coarse, perennial leguminous vine. Has woody stems but very palatable and nutritious foliage equal in value to alfalfa. Called also kudzu. ) NATIVE LAND Japan AREA OF INVASION Southeastern U.S. HOW IT GOT THERE Introduced in the 1930s to help farmers stop soil erosion. THE DAMAGE This weedy vine can grow 0.3 meters (1 foot) a day. Tens of thousands of plants can smother e single acre of land. Kudzu out-competes native plants far food end shade, and blankets valuable farmland. VITAL STATS TERROR ISLAND SPECIES Brown tree snake brown tree snake see boigairregularis. (Boiga irregularis) NATIVE LAND Australia, Indonesia, Papua New Guinea Papua New Guinea (păp` ə, –y , Solomon Islands AREA OF INVASION Island of Guam HOW IT GOT THERE Stowed away on military aircraft during the 1940s. THE DAMAGE With no natural predators, its population has exploded--up to 13,000 snakes per square mile! It has made extinct nine of Guam's 11 land birds; also climbs on and damages electrical wires, sometimes causing island-wide power outages. It's mildly poisonous to humans. RELATED ARTICLE: Invisible menace. SPECIES West Nile virus West Nile virus, microorganism and the infection resulting from it, which typically produces no symptoms or a flulike condition. The virus is a flavivirus and is related to a number of viruses that cause encephalitis. (Flavivirus). A virus is microscopic disease-causing particle. The West Nile virus commonly infects birds end mosquitoes. A human can contract the virus if bitten by an infected mosquito. NATIVE LAND Africa, western Asia, the Middle East AREA OF INVASION Midwest and eastern U.S. HOW IT GOT THERE The virus first appeared in the U.S. in 1999. Scientists are still unsure haw it traveled here. THE DAMAGE As of October 2002, an estimated 2,796 people have been infected in the U.S.; 148 have died. Less than 20 percent of those infected develop symptoms, which can include fever, headache, and skin rash. RELATED ARTICLE: Minds On Science. TOAD TROUBLES Cane toads (Bufo marinus) may be Australia's most bothersome invader species. The warty wart n. 1. a. A hard rough lump growing on the skin, caused by infection with certain viruses and occurring typically on the hands or feet. b. A similar growth or protuberance, as on a plant. 2. amphibians amphibians members of the animal class Amphibia. Includes frogs, toads, newts, salamanders and cecilians all capable of living on land or in water. devour everything they can fit in their mouths: lizards, mice, dog food, even other cane toads. And because they're poisonous to eat, they have no natural predators. Imagine you're part of a scientific team whose mission is to determine if the number of cane toads populating a 4,047 square meter (1 acre) area of land is increasing over time. Your best method to estimate changes in the toad population is a "capture-recapture" experiment over a three-week period. The first week, you capture 750 cane toads, tag them, and release them back into the wild. Week two, you catch 50 toads, observe that 40 have tags, and then release the toads. During week three, you again capture 50 toads; this time 20 have tags. Use the equation below to calculate the total population of toads for each week. # OF TOADS TAGGED / TOTAL POPULATION = # TAGGED TOADS CAPTURED / TOTAL # TOADS CAPTURED * Think: 1 How did the population of cane toads change between weeks 2 and 3? 2 What is another way you might figure out the number of toads living in the area? VITAL STATS MUSSEL mussel, edible freshwater or marine bivalve mollusk. Mussels are able to move slowly by means of the muscular foot. They feed and breathe by filtering water through extensible tubes called siphons; a large mussel filters 10 gal (38 liters) of water per day. MOBS SPECIES Zebra mussel (Dreissena polymorpha) NATIVE LAND Western Russia AREA OF INVASION Great Lakes HOW IT GOT THERE In ballast water from transoceanic boats. THE DAMAGE One female produces up to 1 million eggs a year! The mussels clog water-treatment facilities, encrust en·crust also in·crust tr.v. en·crust·ed, en·crust·ing, en·crusts 1. To cover or coat with or as if with a crust: boat engines, end kill off native species. Directions: Answer the following in complete sentences. 1. What are invasive species? And what is the opposite of invasive species? 2. The snakehead fish is native to China. How did it wind up invading a pond in Maryland? 3. What is the biggest disruption caused by invasive species? 4. Choose one invasive species from the story. Describe how it arrived and caused havoc. ANSWERS The Fish That Ate Everything 1. Invasive species are alien organisms threatening to overrun local habitats. Indigenous, or native, species is the opposite of invasive species. 2. A man purchased a pair of live male and female snakeheads from New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of City's Chinatown to make soup. He changed his mind and dumped the fish into the Crofton, Maryland pond. 3. The most basic yet biggest disruption by invasive species is on the food chain. 4. Answers will vary. |
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