3.3 How Introduced Species Affect Ecosystems - Mr. Huang's ......3-3A Graphing Loosestrife Growth Find Out ACTIVITY Chapter 3 Ecosystems continually change over time.• MHR 139 Biologists

Native species are organisms that naturally inhabit an area. Introduced species are

introduced into an ecosystem and are usually beneficial or harmless. Some introduced

species are invasive and can destroy ecosystems. These species reproduce rapidly and

are often aggressive. Lacking natural predators, they easily outcompete native species

and alter habitats.

On the Sunshine Coast, a European leaf-feeding beetle (Figure 3.36A) isslowly restoring the damaged wetland ecosystem at Lily Lake. Nativespecies such as cattails are growing again, and the habitat is able tosupport a diversity of wildlife. Native species are plants and animals thatnaturally inhabit an area. The beetles have accomplished this feat byeating their way through stands of purple loosestrife, their sole food.Purple loosestrife (Figure 3.36B) destroys wetlands and quicklyreproduces, as each plant can produce more than 300 000 seeds. Itchokes out other plants and is too dense to shelter wildlife. It wasbrought to North America from Europe in the early 1800s, likely as seedsin ships’ ballast (heavy materials used to stabilize ships), and is now wellestablished in many water habitats. In Europe, leaf-feeding beetles keeppurple loosestrife under control, but here, native wildlife avoids it.Scientists have tested the European beetles to make sure they can safelybe introduced into local wetlands. The beetles are providing a cost-effective biological control of the loosestrife scourge.

As this story shows, ecosystems can be disturbed when people,intentionally or by accident, transport plants, animals, or micro-organismsinto regions where they did not exist previously. These species are calledintroduced species or foreign species. (You may also see them referred

How Introduced Species AffectEcosystems

3.3

Words to Knowintroduced speciesinvasive speciesnative species

138 MHR • Unit 1 Sustaining Earth’s Ecosystems

Did You Know?

Invasive zebra mussels, whichwere introduced to the GreatLakes, grow so close togetherthat they block off waterpipelines. Blocked pipes canaffect water supplies to citiesand to hydroelectriccompanies, which depend on water for powergeneration.

Figure 3.36 The European leaf-feeding beetle eating purple loosestrife leaves (A). Purple loosestrife has destroyed many wetlands in North America (B).

A B

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Graphing Loosestrife Growth3-3A Find Out ACTIVITY

Chapter 3 Ecosystems continually change over time. • MHR 139

Biologists frequently measure the rate of reproduction ofintroduced species in a particular area. The data biologistsgather from these measurements can help them determineways to control introduced species that are invasive. In thisactivity, you will graph the results of a study on loosestrifegrowth in a wetland area.

What to Do1. Study the table below. The data in this table were

collected from five areas within a wetland ecosystem.

2. Construct a line graph to illustrate the relationshipbetween the dependent and independent variables.

3. Draw a line of best fit.

What Did You Find Out?1. Does there appear to be a relationship between the

growth of loosestrife plants and the amount of lightthe plants receive? If so, then state the relationship.

2. The five areas where the data were collected wereclose together. What abiotic factors in these areaswould be the same?

3. Why is it important to the study that these abioticfactors are the same in each of the five areas?

to as non-native species, exotic species, or alien species.) Most introducedspecies are harmless or beneficial in their new environments, such as theloosestrife-eating beetle. But some, such as purple loosestrife, are invasivespecies. Invasive species are organisms that can take over the habitat ofnative species or invade their bodies, thus weakening their immunesystems. With climate change and the expansion of international trade andtravel, invasive species are entering new ecosystems at an increasing rate.Scientists believe this rapid spread of introduced invasive species is a majorcause of global biodiversity loss.

Number of Percentage of Loosestrife Plants Shade in Area

2 90

45 2

26 40

36 15

10 70

Go to Science Skill 5 for information on selectingand graphing dependent and independent variables.

Science Skills

The Impact of Introduced Invasive SpeciesInvasive species often have high reproduction rates, are aggressivecompetitors, and lack natural predators in new habitats. Exploiting thenew niche, an introduced invasive species has the potential todramatically change the ecosystem. Such introduced species can affectnative species through competition, predation, disease, parasitism, andhabitat alteration.

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Competition

Introduced invasive species compete against native species for essentialresources such as food and habitat. While the original community hasadapted to sharing resources, invaders disturb this balance. In SaltspringIsland’s Ruckle Provincial Park, for example, the invasive carpet burweedhas spread dramatically since it was discovered there in 1997 (Figure3.37). Originally from South America, the burweed competes with fourrare native plants for habitat. Its spiny tips also easily pierce the skin ofanimals and campers. Since the burweed was found early, however, itmight be possible to remove it from this ecosystem.

Predation

Introduced predators can have more impact on a prey population thannative predators, as prey may not have adaptations to escape or fightthem. Yellow crazy ants that escaped from cargo from West Africa havedevastated the population of red crabs of Christmas Island, Australia.These ants can build supercolonies the size of 500 football fields and arevoracious eaters. They will devour all plants and also prey on the young ofreptiles, birds, and mammals. Swarms of ants mount violent attacks,squirting formic acid at their prey. It is estimated that they have killed 20 million land crabs on the island (Figure 3.38). The red crabs are akeystone species of the island, as they reduce leaf litter and recyclenutrients for rainforest tree seedlings.

Disease and parasites

An invasion of parasites or disease-causing viruses and bacteria can weakenthe immune responses of an ecosystem’s native plants and animals,including humans. This weakening provides opportunities for less dominantspecies to outcompete other species, severely altering the ecosystem. Forexample, in the 1880s, parasitic sea lampreys made their way intofreshwater systems through canals built between the Great Lakes ineastern Canada. Figure 3.39 shows how they affect fish in thisenvironment.

Figure 3.38 Yellow crazy antsattacking a crab

Figure 3.37 Carpet burweed

Figure 3.39 The sucker-like “mouth” of the sea lamprey (A) allows the lamprey to attach to this fish (B). Lampreys suck the body fluids fromtheir prey.

A B

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Certain regions of the Rocky Mountains are alsounder threat. Whitebark pine is a keystone species thatgrows in these areas. This species is at risk because of atree fungus called blister rust, which was introduced inthe early 1900s. Whitebark pine grows in very windy areaswhere no other tree can grow (Figure 3.40A). Whitebarkpine branches create a snow fence to capture snow athigher elevations and control the snow melt by graduallyreleasing water in the spring. The tree also provides coverand shelter for many species, and its seeds provide foodfor squirrels and Clark’s nutcrackers (a type of bird). Therust weakens the tree’s natural defences, making it morevulnerable to insect infestations (Figure 3.40B).

To help the whitebark pine, prescribed burns areoccurring. Burning will create more forest openings inwhich new pines can develop. The burning of lodgepolepine in the area will decrease mountain pine beetles,which also attack whitebark pines. A long-term goal ofplant geneticists is to create rust-resistant seedlings.

Habitat alteration

Introduced invasive species can make a natural habitatunsuitable for native species by changing its structure orcomposition. They may change the light levels, decreasedissolved oxygen in water, change soil chemistry, orincrease soil erosion. They can upset the balance ofnutrient cycling, pollination, and energy flow. Wild boarsare one of the world’s worst invasive species, damagingthe environment by rooting, wallowing, and spreadingweeds that interfere with natural succession (Figure 3.41). They are alsoomnivores that will eat native birds, reptiles, frogs, soil organisms, fruit,seeds, and bulbs.


Did You Know?

The West Nile virus, which istransmitted to humans andanimals by mosquitoes that havefed on an infected bird, was firstidentified on this continent inNew York in 1999. Its most likelymeans of transport was aninfected bird or a person

returning from a country wherethe virus is common.

Figure 3.40 Whitebark pines (A) do not produce conesuntil they are 50 to 80 years old. Such slow reproductionmeans the population is not likely to develop resistanceto blister rust (B) before severe damage is done.

A

B

Figure 3.41 This wild boar has just raided the nest of an albatross.

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In British Columbia, many introduced invasive species are having animpact on ecosystems. Table 3.3 presents some of the most destructive ofthese species.

Eurasian milfoil

Eurasian milfoil was likely brought to North America in the late 1800s and was firstidentified in British Columbia in 1970 in Okanagan Lake. It is highly adaptable and thrivesin disturbed and contaminated waters. It forms wide, dense mats at lake surfaces, cuttingoff sunlight to organisms below and interfering with recreational activities. It can growfrom plant fragments, which are often spread by boats. In the Okanagan, the plant iscontrolled by rototilling to cut out roots from lake bottoms. A native weevil that eatsmilfoil shows promise as a biological control. The weevils must be cultivated and broughtinto infested areas in large numbers to be effective.

Norway rat

These invaders may have escaped from early European explorer and fur-trading ships. Theyare extremely well adapted to almost every environment and feed on almost any foodsource, including meat, grain, seeds, fungi, land and marine invertebrates, fish, and birds.A female rat can produce up to 72 young per year. On Queen Charlotte Islands (HaidaGwaii), they have caused a decline in ground-nesting sea birds, such as ancient murreletsand puffins, by eating their eggs and young. Efforts are currently under way to control ratpopulations by using poisons in affected areas.

American bullfrog

Bullfrogs were brought to British Columbia in the 1930s as a source of frogs’ legs forrestaurants. Released into the wild when the industry failed, bullfrogs caused no problemsuntil about 1990, when they began to breed rapidly. They have since taken over habitats inthe southwest and have eaten so many native frogs that they have made the red-leggedfrog an endangered species. Bullfrogs can grow as big as dinner plates and will evenattack ducks and small mammals. On southern Vancouver Island, bullfrogs and theirtadpoles are removed as quickly as possible from an area. It is hoped that this action willblock further spread into a sensitive watershed.

European starling

The starling has caused the decline of several bird species including the yellow-billedcuckoo, western bluebird, and band-tailed pigeon. In the late 1800s, 50 breeding pairswere brought to North America, and their ability to outcompete native birds for nestingsites has led to their spread across North America, including tundra biomes. Starlings are afast-growing species that exploits many types of nesting sites as well as types of food in awide variety of ecosystems. In British Columbia, starlings outcompete western bluebirds fornesting habitat. They also can devastate fruit crops and grain crops. In some agriculturalareas, the introduction of barn owls has helped control starling populations.

Table 3.3 Some Introduced Invasive Species in British Columbia

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Reading Check1. What is a native species?2. What is an introduced species?3. What is an invasive species?4. Using examples, describe four ways in which introduced species can

affect ecosystems.


Saving an Ecosystem Under Siege The Garry Oak Ecosystem Recovery Team (GOERT) is on a mission—tosave one of British Columbia’s most precious ecosystems from invaders.These beautiful forests of southeastern Vancouver Island, the GulfIslands, and pockets of the Fraser Valley are one of the most biologicallyrich ecosystems in the province and also one of the most threatened(Figure 3.42). Because of habitat loss as a result of land development,less than 5 percent of the original ecosystem remains relativelyundisturbed, with the major threat now coming from introduced invasivespecies. Introduced invasive species such as Scotch broom, English ivy,and invasive grasses make up more than 80 percent of the plant cover.Garry oak trees are considered to be a keystone species because they arethe main support for the food web of this ecosystem.

Figure 3.42 The Garry oak ecosystem (A). Historically, natural wildfires from lightning and fires set by local First Nationspeoples promoted the growth of the camas lily, an important food source (B).

A B

One of the toughest species to control is Scotch broom (Figure 3.43Aon the next page), which was introduced in the mid-1800s as a decorativegarden plant. The bushy shrub produces up to 18 000 seeds per plant. Itsnumerous yellow flowers attract bees for pollination, and it is well adaptedfor surviving drought. By replacing native shrubs, it ruins the habitat fornative birds and butterflies that are adapted for open meadows. Scotchbroom also fixes nitrogen in the soil, creating an overload of nitrogen that interferes with the growth of some native species.

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The grey squirrel (Figure 3.43B) and the gypsy moth (Figure 3.43C)are examples of animal invaders. Grey squirrels outcompete the native redsquirrels for acorns, as they tend to be larger and stronger and can storemore fat. The grey squirrel is also better adapted to survive habitatdestruction. Gypsy moth larvae can completely strip the oak trees of theirleaves. A severely damaged tree is more vulnerable to infections, and,without leaves for photosynthesis, the tree eventually dies.

Camas plants aresometimes referred to ascultural keystone speciesbecause they played asignificant role in the dietof First Nations such asthe Coast Salish andinfluenced how Garry oakmeadows were sustained.Find out more aboutcultural keystone species.Start your search atwww.bcscience10.ca.

Reading Check1. What is the major threat to the Garry oak ecosystem today?2. How does Scotch broom harm this ecosystem?3. Name two at-risk species in the Garry oak ecosystem.

Restoring this ecosystem will be a huge undertaking, but GOERT’spartnership of governments, First Nations, conservationists, scientists, andbusinesses believes the work is critical. Some scientists believe that climatechange will make Garry oak ecosystems the forests of the future. They arebetter adapted to summer droughts than Douglas fir forests, which maybe forced farther north and into alpine regions. The GOERT team has astrategy that includes long-range planning and information gatheringright down to local weed pulls. One hands-on project through ParksCanada is the restoration of eight small islands in the Gulf IslandsNational Park Reserve. Invasive shrubs are being removed and nativespecies planted from seeds collected at the site.

Figure 3.43 Three invaders of the Garry oak ecosystem: Scotch broom (A), grey squirrel (B), and gypsy moth larva (C)

A B C

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In this activity, you will use what you have learned about invasive species to help you interpret the informationin the following news article.

What to Do1. Read the following news article and then answer the questions below.

Can Island Invaders Be Stopped?3-3B Think About It

What Did You Find Out? 1. Why are rats such successful island invaders?

2. Why are rats considered to be one of the worstinvasive species in ecosystems?

3. How do you think 1 pair of rats can add 5000 ratsto a population in 1 year?

4. What factors allowed rats to become so numerousin the Aleutian Islands?

5. Why do you think scientists placed bait stations soclose together on Langara Island?

6. Suggest reasons why scientists will monitor theresults of the bait drop on Rat Island beforeproceeding further.

Rats have invaded islands worldwide forcenturies. They are to blame for 90 percentof island seabird and reptile extinctionsaround the world. Many ecologists believerats are one of the world’s worst invasivespecies because they damage theenvironment by burrowing and leavingbehind huge amounts of droppings. Moredevastating is the fact that rats areomnivores that eat large numbers of eggsand birds. They also compete with nativewildlife for seeds, young plants, andinsects. Norway rats, in particular, are aterrible threat to island ecosystems.

In the late 1700s, Norway rats escapedfrom the ships of early European explorersand fur traders. Since rats are such strongswimmers, they made it to the AleutianIslands in Alaska. Without predators, ratpopulations on these islands grew quickly.In the 1940s, hundreds of military shipsvisited the Aleutian Islands during WorldWar II and the rat population increaseddramatically. In the 1980s, Norway ratswere found on Queen Charlotte Islands(Haida Gwaii) in British Columbia.

Norway rats usually have 4 to 6 litters ayear, with each litter containing 6 to 12babies. One pair of rats can produce apopulation of more than 5000 rats in anarea in 1 year. In the Aleutian Islands ofAlaska, Norway rats have almost wipedout sea birds, such as puffins, auklets,and storm petrels, on about 12 of thelarger islands. On Langara Island inHaida Gwaii, rats had, until recently,drastically reduced one of the largest andmost successful colonies of ancientmurrelets in the world. Ecologists areworking to restore the sea bird nestingsites in these island ecosystems. Forexample, Norway rats have beensuccessfully eliminated on Langara Islandby placing rat bait stations close together.On Langara Island, sea bird coloniesappear to be bouncing back. A helicopterdrop of rat bait is planned for Rat Islandin the Aleutians. Scientists are waiting seehow successful this project will be beforedeciding whether to try to exterminatethe rats on other islands.

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Career Connect

Ecotour OperatorWatching grizzly bears feed on salmon and seeing akermode bear and her cubs walk down a river areeveryday experiences for ecotour operator DouglasNeasloss. Douglas Neasloss lives in Klemtu on the centralcoast of British Columbia. Working with wildlife andcreating jobs without resource extraction are two of thereasons Douglas Neasloss loves his job.

Q. What do you do as the lead guide for an ecotourismbusiness?

A. We lead cultural and wildlife ecotours from earlyspring to late fall. The tours usually last from four toseven days. We teach about wildlife such as grizzlyand kermode bears (also known as Spirit Bears) andthe changes in their diet from berries to salmon. Wevisit many cultural sites, such as old totem poles,petroglyphs, and burial boxes, and explain theirsignificance to the tourists.

Q. What is a typical day like for you?

A. I wake up very early, make sure the clients eat a goodbreakfast, and then we leave Klemtu by about 7:30A.M. in the boat. We travel for just over an hour to getto the different bear-watching sites. We give a speechon how to safely observe bears and then set up agood place to watch from. We focus on groupmanagement to minimize the effects on theenvironment from the tour and to reduce the chanceof a bear encounter. We carry only red-pepper sprayand a radio. We often see grizzly bears, kermodebears, wolves, and wolverines in the area. We headback to the boat for lunch and out again after lunchfor more viewing. We are developing a protocol forthe Spirit Bear habitat. Our tours limit the impact onthe environment, and we promote leaving a placebetter than when we go in.

Q. What training do you need to be an ecotourismoperator?

A. I have completed a lot of courses to prepare myself. Forexample, I have certificates in advanced wilderness andmarine first aid, navigation, and kayak and bear guiding.I also have a small-vessel licence, and I am a certifieddiver, national heritage interpreter, and First Host.

Q. What sparked your interest in ecotourism?

A. There were a lot of things. I wanted to learn more aboutmy culture and to learn about the past from my elders.I wanted to have a job that was not linked to resourceextraction and one where we could create opportunitiesfor others. It is also my passion—I love being outsideand with the bears—you can’t get bored in this job.

Q. How is biology connected to ecotourism?

A. As a guide, you need to know a lot about a lot ofthings. You need a very broad knowledge about all ofthe terrestrial and marine species we see and howthey are connected. We are passing this knowledge onto our clients. We spend a lot of time working withbiologists studying everything from the marineenvironment to the grizzly and kermode bears. We areconstantly learning more from them as well, which wecan then pass on to our clients.

Q. How do traditional knowledge and scientificknowledge come together in your tour?

A. We often use the stories from our elders to show thelinks between land and water. We follow up with thescientific facts in a way that helps people see theimportance of trying to protect the environment.Salmon is a keystone species, which helps us see thelink between the health of the water and the land. Wetalk a lot about the sustainability of ecosystems. Theelders say that everything in nature is connected, andI think that scientists are now starting to realize thatas well.

Questions

1. What are some of the courses needed to be anecotour operator?

2. What are two ways in which this ecotour operatorpromotes protection of the environment?

3. How does Douglas Neasloss combine the traditionalknowledge of his culture with scientific knowledge?

Douglas Neasloss

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Checking Concepts1. (a) Give an example of a native species.

(b) Give an example of an invasive species.2. Why are some introduced species a threat to

native species?3. Explain why the threat of introduced invasive

species in ecosystems has increased in the pastfew decades.

4. List three characteristics common to manyintroduced invasive species.

5. List three ways in which introduced invasivespecies have an impact on native species.

6. Explain why introduced predators can bemore dangerous than native predators.

7. How can introduced species alter habitats? 8. Copy and complete the following chart to

summarize the activity of some introducedinvasive species in British Columbia.

9. (a) List three introduced species in the Garryoak ecosystem.

(b) Describe the effect on the Garry oakecosystem of each of these introducedspecies.

10. Give an example of an introduced speciesthat: (a) is a competitor(b) is a predator(c) causes disease(e) alters habitat

Understanding Key Ideas11. How do introduced parasites affect

ecosystems? 12. What effect does the introduced species

shown in the photograph below have on atropical rainforest ecosystem?

13. How does blister rust indirectly affectsquirrels and nutcrackers in the whitebarkpine ecosystem?

14. Why do scientists think that if the Garry oakecosystem survives it may replace Douglas firforests in the future?


A new field of science called invasive ecology isstudying the effects of introduced species.Based on the knowledge you have gained inthis section, write a brief explanation for eachof the following findings.

(a) Next to habitat destruction, introducedinvasive species cause the greatest numberof extinctions worldwide.

(b) Introduced species tend to be moredestructive if they are from a completelydifferent group of organisms than thenative plants and animals in an ecosystem.

Pause and Reflect

Introduced Method of Negative Invasive Introduction Effect on Species into Ecosystem Ecosystem

Eurasian milfoil

Norway rat

American bullfrog

European starling

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Prepare Your Own SummaryIn this chapter, you have investigated how naturaland human-influenced changes affect ecosystems.Create your own summary of the key ideas fromthis chapter. You may include graphic organizersor illustrations with your notes. (See Science Skill11 for help with using graphic organizers.) Usethe following headings to organize your notes:1. How Changes Occur Naturally in Ecosystems2. How Natural Events Affect Ecosystems3. How Humans Influence Ecosystems 4. How Introduced Species Affect Ecosystems

Checking Concepts1. Describe the process that makes change

possible in living things.2. Explain how the diagram of the sticklebacks

below illustrates the concept of adaptiveradiation.

3. Describe ecological succession in terms ofchanges in the abiotic parts of an ecosystem.

4. What role do micro-organisms play inecological succession?

5. In ecological succession, how do pioneerspecies change the biotic and abioticenvironment?

6. Which of the following are mature (climax)communities? (a) tundra(b) sand dune(c) temperate rainforest(d) wetland

7. Use two examples to explain how floodingaffects an ecosystem.

8. List three effects of prolonged drought.9. What is the importance of sustainability?

10. Give three examples of sustainable practicesdescribed in this chapter.

11. How do human activities cause habitatfragmentation?

12. Provide an example of resourceoverexploitation.

13. How can water contamination result fromresource exploitation?

14. Using examples, explain the effect of invasivespecies on ecosystems.

15. Give two examples of populations ofkeystone species that have been negativelyaffected by an invasive species.

Understanding Key Ideas16. Using the example of the Galapagos finches

shown in the illustration below, explain hownatural selection resulted in the variety offinches on the Galapagos Islands.

C h a p t e r

3

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17. What can cause a living species to becomeextinct?

18. Identify the two main causes of soildegradation and how they occur.

19. (a) Describe the importance of land use andresource use.

(b) How do you think land use and resourceuse have changed over the past century?

20. Describe a soil management practice thatimproves plant growth.

21. How can overexploitation affect a food web?22. How can traditional ecological knowledge be

applied to resource management? 23. What factors have caused an increase in

invasive introduced species and losses inglobal biodiversity?

24. How might the introduction of an invasiveplant species alter a habitat for the following? (a) other plants (b) animals

Applying Your Understanding25. White sturgeon are prehistoric-looking fish

that can reach a length of 8 m and a mass of850 kg. White sturgeon are called livingfossils because they have not changed muchduring their 175 million years on Earth.Having survived volcanic eruptions, ice ages,and the extinction of dinosaurs, whitesturgeon are now threatened because ofhuman alteration of their environment. For example, the Nechako white sturgeonpopulation has dropped from over 5000 fishto fewer than 600 in the past 50 years. Mostof these fish are more than 30 years old, butin the past, sturgeon as old as 160 years have been found. The lack of younger fish means that either white sturgeon are notreproducing successfully or the young arenot surviving to adulthood. (a) Explain what will happen to white

sturgeon if young fish are unable tosurvive.

(b) Make a list of possible human-causedchanges in the environment of whitesturgeon that may have caused theirdecline.

(c) Make a list of some sustainable practicesthat might prevent their decline.

If everyone on Earth consumed as much as wedo in North America, we would need threemore Earths to sustain us. Study the followingtable comparing Canadian and globalconsumption averages per person.

(a) Make a list of how each item in the tableharms the environment.

(b) Make a list of sustainable practices thatmight reduce the impact Canadians arehaving on the environment.

Pause and Reflect

Global Average

4.1 tonnes of CO2produced per personper year from theconsumption of fossilfuels and farmproducts and as aresult of land clearing(2003)

9 vehicles driven per100 people (2002)

52 kg paper used perperson per year (2002)

174 L of gasoline usedper person per year(2001)

633 m3 fresh waterused per person peryear (2000)

Canadian Average

17.0 tonnes of CO2produced per personper year from theconsumption of fossilfuels and farmproducts and as aresult of land clearing(2003)

47 vehicles driven per100 people (2002)

281 kg paper used perperson per year (2002)

1389 L of gasolineused per person peryear (2001)

1494 m3 fresh waterused per person peryear (2000)

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U N I T

1


1 Biomes and ecosystems are divisions of the biosphere.

• The large regions within biomes have similarbiotic and abiotic components. (1.1)

• Abiotic factors influence the characteristicsand distribution of biomes. (1.1)

• Biomes with similar characteristics can exist indifferent geological locations. (1.1)

• Adaptations are characteristics that enableorganisms to better survive and reproduce.(1.1)

• Abiotic components in ecosystems includeoxygen, water, nutrients, light, and soil. (1.2)

• Biotic interactions in ecosystems includesymbiosis, competition, and predation. (1.2)

2 Energy flow and nutrient cycles support life in ecosystems.

• Food chains and food webs are models thatshow how energy flows from producers toconsumers in an ecosystem. (2.1)

• Food pyramids are models that show the lossof energy from one trophic level to another.(2.1)

• The nutrients carbon, nitrogen, andphosphorus move in and out of the abioticand biotic components of terrestrial andaquatic ecosystems. (2.2)

• Human activities affect nutrient cycles andcause harm to ecosystems. (2.2)

• Contaminants such as persistent organicpollutants and heavy metals canbioaccumulate in organisms and negativelyaffect species in ecosystems. (2.3)

3 Ecosystems continually change over time.

• Natural selection is the process that enablesorganisms to change in response to changesin the abiotic and biotic components of anecosystem. (3.1)

• Adaptive radiation is the change from acommon ancestor into a number of differentspecies that can inhabit different niches. (3.1)

• Ecological succession refers to changes in theabiotic and biotic components of anecosystem over time. (3.1)

• Natural events such as flooding, tsunamis,drought, and insect infestations can changethe abiotic and biotic conditions of anecosystem. (3.1)

• Human activities such as agriculture, resourceexploitation, and the introduction of invasivespecies can change ecosystems and result inhabitat loss. (3.2)

• Introduced invasive species can affect nativespecies through competition, predation,disease, parasitism, and habitat destruction.(3.3)

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Key Terms• abiotic• biome• biotic• commensalism• ecosystem• mutualism• parasitism• predation• symbiosis

Key Terms• adaptive radiation• ecological succession• introduced species (foreign species)• natural selection

Key Terms• bioaccumulation• biodegradation• carbonate• cellular respiration• decomposers• denitrification• food chains• food pyramids• food webs• heavy metals• keystone species

• nitrification• nutrients• PCBs• pesticides• photosynthesis• trophic levels

Unit 1 Summary • MHR 151

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Reducing Your Ecological Footprint

In 1992, William Rees, a Canadian ecologist, andSwiss-born Mathis Wackernagel, working togetherat the University of British Columbia, introduceda concept called the ecological footprint. Anecological footprint is an estimate of how muchland is needed to support each person on Earth.Calculating the size of our “footprint” helps us tounderstand the impact we have on Earth’sresources. Calculating an ecological footprintinvolves estimating the amount of land requiredfor such uses as housing, agriculture,transportation, resource extraction, waste disposal,fossil fuels, and other land uses.

The actions you take every day can increase ordecrease the size of your personal ecologicalfootprint. In this project, you will compare yourecological footprint to those of others and createa plan to reduce its size.

ProblemHow can you create a plan to reduce the size ofyour ecological footprint?

Criteria• Your plan must include a calculation of your

own ecological footprint and present acomparison of your ecological footprint tothose of others.

• Your plan must identify actions that currentlyincrease the size of your ecological footprint.

• Your plan must identify actions that wouldreduce the size of your ecological footprint.

Procedure1. Find an ecological footprint calculator on the

Internet. Begin your research atwww.bcscience10.ca.

2. Follow the instructions on the appropriatewebsite, and calculate your ecologicalfootprint in hectares.

3. Study the table below. • Compare your ecological footprint to the

average ecological footprint for a personliving in Canada.

• Think about why the size of yourecological footprint is similar to ordifferent from that of other Canadians.

• Compare your ecological footprint tothose of people living in other countries.

• Think about why the size of thesefootprints might differ from your own.

• Research ways you could reduce yourecological footprint.

Report Out 1. Create your plan to reduce the size of your

ecological footprint. Develop a format thatmeets the criteria and will be informative andinteresting to others. Challenge yourself totake actions that will reduce the size of yourecological footprint. At the end of one week,write a short report on the actions you took,the obstacles you encountered, and the stepsyou plan to take in the future.


Global Ecological Footprints

Country Ecological Footprint (hectares per person)

United States 9.57

Canada 8.56

France 5.74

United Kingdom 4.72

El Salvador 1.72

Ghana 1.23

Vietnam 0.76

Ethiopia 0.67

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Unit 1 Integrated Research Investigation • MHR 153

Each product we create and use has an ecologicalimpact. Raw material extraction, manufacturing,distribution, product use, and product disposal canall damage the environment. For example, theincrease in the use and replacement of electronicproducts such as televisions, computer equipment,cellphones, and iPods® has resulted in mountains ofelectronic waste piling up in landfills across Canada.This vast amount of waste contains toxins that canleach into ground water and cause contamination.Increasingly, governments are requiring businessesand individuals to become more aware of theenvironmental costs of electronic products. Oneway to assess these costs is to use a method called“cradle-to-grave” analysis. Cradle-to-grave analysisassesses all the environmental impacts that canoccur during the life cycle of a product, from rawmaterial extraction to disposal. In this investigation,you will conduct a cradle-to-grave analysis on oneelectronic product.

BackgroundBritish Columbia currently has electronic wasteregulations that are making industries, businesses,and individuals responsible for collecting andrecycling electronic waste. As a result, televisions,computer monitors, computer processing units,and printers have not gone to landfills. Thegovernment and organizations such as theElectronics Stewardship Association of BritishColumbia are requiring both producers andconsumers to be more responsible for the life cycleof the products they produce and use.

Find Out MoreAs a group, choose one electronic product toconduct a cradle-to-grave analysis on. You willneed to become an expert on this product tosuggest new ways to produce, transport, use, ordispose of the product. Begin your research atwww.bcscience10.ca. Follow these guidelines foryour assessment.

1. Design: Research the technology used todesign the product and the impact it has onthe environment.

2. Manufacturing: Research the raw materials usedto create the product and the impact of themanufacturing processes used. Few products aremade from only one material or involve onlyone process. You may want to assign a differentmaterial and process to each group member.

3. Transportation: Research how a product istransported and how far it travels to reach thestore where it will be sold. (Considertransportation to both warehouses and stores.)

4. Consumer: Research the approximate distancea consumer travels to purchase the product.What type of transportation is used? Analyzethe environmental impact of driving a car,riding a bike, taking a bus, or walking.

5. Useful life: Research how long the productshould last. Does it degrade over time orbecome outdated by newer technology?Compare the environmental impact of productsthat must be replaced frequently with productsthat have longer life cycles. Consider the factorsthat influence consumers to replace a productbefore the product’s useful life is over.

6. Disposal: Research how the product isdiscarded. Does it end up in a landfill? Is toxicwaste produced from its disposal? Researchexisting and new ways in which the productcould be recycled.

Report Out1. Create a poster or multimedia presentation to

display the results of your research. 2. Your company is striving to become a better

environmental citizen. From knowledge gainedthrough your research and that of yourclassmates, brainstorm a list ofrecommendations for new ways to produce,transport, use, or dispose of the products yourcompany produces.

Assessing Electronic Products from Cradle to Grave

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Visualizing Key Ideas1. Copy the following concept map into your notebook. Fill in as many terms as you can without looking

in your textbook. After you have completed the map, go back through the unit to check your work.Fill in any missing terms using a different colour of pen.

Ecosystemcontinual

changes overtime

biodiversity

sustainabilityadaptations

interactionsnutrients

energy flow

sustainable practices in

and use

protection and

(from bare rock to forest)

(following a forest fireor flood)

naturalchanges canresult in

human-causedchanges canresult in

interactions

(physical and chemical)

are and

exchanged

is necessary for

ecosystems

is threatened by

loss caused by

can occur

if species fail to adapt to

in their

environment

in species result from a process

called

nutrient move

carbon, , and

through ecosystems

food chains and

levels and pyramids

and consumers

interactions

(species, populations, community)

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Using Key Terms2. In your notebook, state whether each of the

following statements is true or false. If thestatement is false, rewrite it to make it true. (a) A biome is the largest division of the

biosphere.(b) A population refers to all the members of

a particular species within an ecosystem.(c) In commensalism, one species is harmed

and the other species benefits.(d) The top carnivores in a food chain have

the most energy because the amount ofenergy available to organisms increasesfrom trophic level to trophic level.

(e) The amount of available energy decreasesat each higher trophic level.

(f) Nutrients and energy can be recycled inan ecosystem.

(g) Plants make their own food mainly from agas.

(h) Respiration is the opposite ofphotosynthesis.

(i) Phosphorus cycles between theatmosphere, the land, and the bioticcomponents in ecosystems.

(j) Decomposers release some energy that iscycled back to plants.

(k) In an ecosystem, a mature communitynaturally changes over time.

Checking Concepts

3. Identify the biome described in eachstatement below.(a) This biome has permafrost, a short

growing season, and no trees.(b) This biome has a dry climate, and its daily

and seasonal temperatures fluctuategreatly.

(c) This biome is generally found in theinteriors of continents.

(d) The dominant vegetation in this biomeincludes lichens, mosses, and small shrubs.

(e) This biome has the least seasonal variationin climate.

(f) The main vegetation in this biome isconiferous trees.

4. Give an example of a structural adaptation, abehavioural adaptation, and a physiologicaladaptation for animals that live in the tundrabiome.

5. Match the following terms to the descriptionsin parts (a) to (e). (i) community(ii) species(iii) organism(iv) ecosystem(v) population(a) a division of the biosphere in which

abiotic components interact with bioticcomponents

(b) groups of individuals that belong to thesame species and live in the same area

(c) a single living thing(d) different populations that interact within

an ecosystem(e) a group of organisms so similar to one

another that they can mate and produceoffspring that can reproduce

6. Arrange the terms listed in question 5 inorder from the smallest component to thelargest component.

7. Identify each of the following bioticinteractions. (a) An ant species feeds on the sweet-tasting

chemicals produced by a caterpillarspecies. The ants vigorously protect thecaterpillars and carry them to their nestsat night for safety.

(b) An agouti (a type of rodent) feeds on theseed pods of the Brazil nut tree by pryingthe grapefruit-sized pods open with itsextremely strong teeth. The agouti alsoburies some seeds far away from theparent tree, which then germinate andform the next generation of trees.

(c) A whip worm lives in the large intestine ofa dog and causes the dog to lose mass.

Unit 1 Review • MHR 155

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(d) A salamander uses its sticky tongue tocapture an insect.

(e) A fungus provides moisture from the soilto a tree’s root system, which preventsthe roots from drying out. The treeprovides sugars and starches to thefungus, which the fungus uses for food.

8. Use an example to explain how energy flowsthrough an ecosystem.

9. Using an example of each, compare andcontrast the diets of detrivores, omnivores,and herbivores.

10. Explain why a plant requires each of thefollowing nutrients.(a) carbon(b) nitrogen(c) phosphorus

11. How do some marine organisms contributeto carbon stores?

12. Describe how a carbon atom moves throughthe carbon cycle. In your answer, use thefollowing terms: atmosphere, producers,calcium carbonate, cellular respiration,decomposers, dissolved organic matter,consumers, bacteria, green plants, marinesediments, sedimentary rock.

13. Explain the role of bacteria in the followingprocesses.(a) nitrogen fixation(b) nitrification(c) uptake of nutrients(d) denitrification

14. How do persistent organic pollutants suchas DDT affect living organisms?

15. Using the example of an aquatic food chain,explain how PCBs bioaccumulate andbiomagnify.

16. Describe the harmful effects on humans ofbioaccumulations of the following.(a) lead(b) cadmium(c) mercury

17. Identify the process that makes change inliving things possible.

18. List two abiotic factors that influenceecological succession.

19. Explain how primary succession differs fromsecondary succession.

20. The retreat of a glacier leaves barren rockand little soil. Describe the changes thatmight occur over a long period of timefollowing the retreat of the glacier. Includethe following in your description: physicaland chemical changes, changes in plant life,and changes in animal life.

21. Explain why ecologists now think thatclimax communities are continuallychanging.

22. How do natural disturbances such as forestfires affect mature communities?

23. Describe the ways in which introducedinvasive species alter habitats and change thebiodiversity in an ecosystem.

Understanding Key Ideas24. Explain why each of the following

statements is true.(a) The temperate rainforest biome is wetter

and cooler than the temperatedeciduous biome.

(b) The tropical rainforest biome is muchwetter and warmer than the borealforest biome.

(c) The permanent ice biome is much drierand colder than the temperate grasslandbiome.

25. Give two examples of how animal speciescan avoid predators or defend themselvesagainst attacks.

26. Using the example of a squirrel, explain thedifference between a habitat and a niche.

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2

3

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27. Make a flowchart to show how food energyis produced and used by organisms in aterrestrial food chain. Use the followingterms in your chart: animals, plants,decomposers, cellular respiration,photosynthesis, producers, primaryconsumers, secondary consumers.

28. Explain how herds of large mammals cansurvive in grassland biomes. Use the term“available energy” in your answer.

29. Explain how each of the following processescycles carbon through an ecosystem. (a) photosynthesis (b) respiration (c) decomposition (d) ocean mixing

30. How does carbon return to theenvironment when fossil fuels are burned?

31. Although growing soybeans and peasreplenishes nutrients in the soil, growinglarge, single crops of these plants could havea negative effect on an ecosystem. Explainhow this might happen.

32. How might increased river temperaturesaffect bear populations?

33. What would be more concentrated in anorganism: 1 ppm (part per million) or 1 ppb(part per billion) of a chemical? Explain.

34. DDT is toxic at 5 ppm. Study the diagrambelow showing how DDT biomagnifies. Fromthe data given in this diagram, determine atwhich trophic level DDT is toxic.

35. A woodpecker’s feet, tail, beak, and tongueallow the bird to catch insects under thebark of trees. Explain how the process youidentified in question 17 may have resultedin these adaptations.

36. Explain why it might be easier to walkthrough a mature old-growth forest thanthrough a young forest undergoingsuccession.

37. How can water contamination from humanactivities such as mining affect biodiversity?

Thinking Critically38. The diagram below shows a food web in the

Antarctic Ocean.(a) Explain why a decline in the population

of baleen whales might lead to anincrease in the populations of seals,penguins, and krill-eating fish.

(b) What might happen to the other speciesif the population of baleen whalesincreased but the population of krillstayed the same? Explain.

39. Some plants have adaptations that protectthem from predation by herbivores. Give anexample that would best illustrate such anadaptation.

40. What happens to the energy in topcarnivores when they die?


tertiary consumers

13.8 ppm

2.07 ppm

0.23 ppm

0.04 ppm

secondary consumers

primaryconsumers

primaryproducers

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41. Large carnivores have a greater chance ofbecoming extinct than smaller organisms.What factors make this statement true? Useexamples in your answer.

42. The impact of human activities on nutrientcycles is detrimental to biotic communities.Explain.

43. How would an ecosystem be affected iflethal levels of a heavy metal bioaccumulatedin a keystone species?

Developing Skills44. Use the following data to construct a

climatograph, then answer the questionsthat follow.

(a) In what biome would you find thislocation? Explain.

(b) In what zone is this biome located?45. Plants, such as tomatoes, require adequate

amounts of phosphorus for energy transferbetween their cells and for healthy plantdevelopment. If the amount of phosphorusin the soil is limited, the growth of tomatoplants can be reduced. Design anexperiment to determine the minimumamount of phosphorus required foroptimum tomato plant growth.

(a) What would be your hypothesis? (b) What would be your independent

variable?(c) What type of data would you collect?(d) List at least five abiotic factors you

would control in your experiment.(e) What biotic factors would you control in

your experiment?

Applying Your Understanding46. There is a relationship between a soil fungus

called mycorrhiza (plural: mycorrhizae) andthe roots of plants. The fungus obtainssugars from the plant and absorbs mineralsand water from the soil, which then enterplant roots. If the mycorrhizae are removedfrom the plant’s roots, the plant’s rate ofgrowth and reproduction is reduced. What is this relationship an example of?A. parasitismB. mutualismC. commensalismD. predation

47. High school students conducting anecological study of a pond in a public parkwere surprised to discover dead fish floatingon the water. The park was located next to apublic golf course. The students noted thatCanada geese were residents of the park.Which of the following is a possibleexplanation for the dead fish?A. The dead fish were the result of biotic

and abiotic factors.B. The pond was experiencing

eutrophication.C. The Canada geese were upsetting the

nitrogen balance in the pond.D. All of the above are factors.

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Month Average AveragePrecipitation (mm) Temperature (ºC)

J 115 21

F 110 22

M 86 19

A 38 17

M 24 14

J 5 11

J 2 12

A 6 14

S 22 17

O 24 19

N 105 20

D 123 20

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48. On the island of Oahu, Hawaii, lives a groupof tree snails found nowhere else in theworld. These small snails once covered thelowlands and the volcanic ridges of theisland but are now confined to themountaintops. Forty-two species hadevolved from one original species, but onlyseven or eight species remain today. Therosy wolf snail was brought to Oahu to killthe giant East African snail, which wasbecoming a road hazard and destroyinggardens, but the rosy wolf snail preferred toeat the tree snail. Rats and habitat loss in thelowland areas are also threatening thesurvival of the remaining tree snail species.Forty-two species of snail arose on what wasonce a barren volcanic island. What is this anexample of?A. successionB. pioneer speciesC. adaptive radiationD. biomagnification

49. Which of the following is true of the rosywolf snail described in question 48?

A. I onlyB. I and II onlyC. I, II, and III onlyD. I, II, III, and IV

50. A previously unidentified survivalmechanism has been found in the tropicalrainforests of Central and South America.Roundworm eggs are eaten by black ants asthe ants feed on bird feces. The yellowishroundworms cause the abdomens of theblack ants to change from black to amber.When sunlight shines on the ants’abdomens, they appear red. The infectedants change their behaviour, now holdingtheir swollen bellies higher in the air. To abird, the ants look like juicy red berriesready to be picked. Normally, birds wouldavoid the bad-tasting black ants, but nowthey become lunch.

The roundworm has what type ofrelationship to the ant?A. parasiticB. predatoryC. mutualisticD. commensal

51. Which organism benefits from therelationship identified in question 50?A. the roundworm because it infects the antB. the roundworm because it is carried

away by birdsC. the roundworm because the ants change

colourD. the bird because it now eats the ants


I The rosy wolf snail is an example of anintroduced invasive species.

II The rosy wolf snail is a carnivore.

III The rosy wolf snail is at the same trophic levelas the rat.

IV The rosy wolf snail is in a commensalrelationship with the giant East African snail.

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52. A long prairie drought has killed the wasps,robber flies, and other predators thatnormally feed on grasshopper eggs. A moistwinter protected the eggs from drying out,and a warm spring produced plenty ofvegetation. The result was a dramaticincrease in the number of grasshoppers,which destroyed most of the plant life in thearea. What would be the effect of thegrasshopper infestation on this ecosystem?A. Only the antelopes would die of

starvation.B. The wolves and coyotes would die of

starvation.C. The antelopes, wolves, and coyotes

would die of starvation.D. Only the grass species would be

affected.53. The shipworm is a type of marine clam that

destroys the wood of ships and marine piers.Scientists were recently surprised to discoverthat bacteria found on these clams’ gills canchange atmospheric nitrogen into nitrates,which the clams can use to make protein.Why would scientists be surprised by thisdiscovery?A. Bacteria are not known to change

atmospheric nitrogen into nitrates.B. Only plants are known to fix nitrogen

through symbiosis.C. Scientists believed that clams changed

atmospheric nitrogen. D. Clams were not known to make protein.

54. What is the process in the nitrogen cycledescribed in question 53 called?A. nitrificationB. denitrificationC. decompositionD. nitrogen fixation

55. A common species of phytoplankton knownas Phaeocystis globosa is able to chemicallysense which type of predator is in theneighbourhood and change its shapeaccordingly. If the predator is a herbivoresuch as a paramecium, which eats a morerefined, small-particle diet, the algae willform a dense colony. If the grazers are smallcrustaceans such as copepods, which eat achunkier diet, the algae will detach from thecolony into single cells. What is theadaptation shown by this phytoplanktonbest described as?A. a structural adaptationB. a physiological adaptationC. a behavioural adaptationD. a survival strategy

56. Phaeocystis phytoplankton blooms play a keyrole in the carbon cycles of cold oceans and sometimes account for as much as 85 percent of an ocean’s carbon producers.Fecal waste from the copepods that eat thephytoplankton falls to the deep ocean floor.An increase in ocean temperature due toglobal climate change could affect thesephytoplankton and ocean carbon stores.How could climate change affect thePhaeocystis phytoplankton blooms and thecarbon cycle?

A. I and II onlyB. I, II, and III onlyC. I, II, and IV onlyD. II and IV only

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I Less phytoplankton may be produced.

II Less carbon would be held in deep oceansediment.

III Atmospheric carbon would be increased.

IV Atmospheric carbon would be decreased.

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57. Several years ago, toxaphene, an agriculturalpesticide, was found in trout and theirpredators osprey in Bow Lake high in themountains of Banff National Park. Thischemical was also found in freshly fallensnow. What is the most logical explanationfor these findings?

A. I and II onlyB. II and IV onlyC. III and IV onlyD. II, III, and IV only

58. Some scientists think that Earth is currentlyexperiencing the sixth great period of massextinction. Geological records show that,during the past five mass extinctions, 50 to90 percent of species estimated to existduring those times became extinct.Although the previous mass extinctions hadnatural causes, the current steep rise inspecies extinction is the result of humanactivities. Which of the following activities isresponsible for this extinction?

A. I and II onlyB. I, II, and II onlyC. I, III, and V onlyD. I, II, III, IV, and V


In this unit, you have learned about biotic andabiotic interactions in ecosystems and howenergy flow and nutrient cycles support life inecosystems. You have also learned howorganisms are adapted to live in specifichabitats and how human activities can threatenthese habitats. Prepare a short speech onsaving a particular habitat in your community.Use examples from this unit to help you write aconvincing speech.

Pause and Reflect

I degradation and destruction of habitats

II deforestation

III resource exploitation

IV introduction of invasive species

V pollution

I Osprey carried the fish to the lake.

II Agricultural run-off washed the pesticide intothe lake.

III Toxaphene was carried in the atmosphere andfell on cold mountaintops.

IV Toxaphene was biomagnified in the lakeecosystem.

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3.3 How Introduced Species Affect Ecosystems - Mr. Huang's ......3-3A Graphing Loosestrife Growth Find Out ACTIVITY Chapter 3 Ecosystems continually change over time.• MHR 139 Biologists