1DBIOL - PP10 (Humans & Biodiversity)

8/6/2014

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SNC1DBIOLOGY

SUSTAINABLE ECOSYSTEMS

L Humans & Biodiversity

(P.54-60)

Biodiversity

So far, we have referred to biodiversityas the variety of species on Earth. Butthe term also refers to other levels ofbiodiversity. Differences amongindividuals of the same species arecalled genetic differences or geneticdiversity. For example, in a wolfpack some wolves may be better ableto resist certain diseases than othermembers, and some may be betterthan others at tolerating a lack ofwater.

August 6, 2014 1DBIOL - Humans & Biodiversity 1

Biodiversity

NOTE!

The lack of genetic diversity in apopulation can be a real threat to itssurvival and can even lead toextinction.

GENETIC DIVERSITY

� differences among individuals ofthe same species


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Biodiversity

As was explained earlier, biodiversity also refers to the variety ofecosystems found on Earth. This includes human-made ecosystems, suchas farms, as well as the variety of naturally occurring ecosystems. Becausedifferent ecosystems provide different services, it is vital that we maintainas many types of ecosystems as possible.


Biodiversity

Human activity has caused all levels of biodiversity to decrease at anunprecedented rate. The five major causes are habitat change,overexploitation, pollution, invasive species, and climate change.


Biodiversity

HUMANS & BIODIVERSITY

� humans have caused all levels of biodiversity to decrease

� five major causes are:

• habitat change

• overexploitation

• pollution

• invasive species

• climate change


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Habitat Change

Habitat change is the process bywhich humans alter a habitat enoughso that the native species can nolonger live there. Throughout thebiosphere, habitat change is the mostcommon cause of declines in thepopulations of many species.


Habitat Change

HABITAT CHANGE

� process by which humans alter ahabitat so that the native speciescan no longer live there (i.e.shoreline development)

� most common cause of thedecline in a population


Habitat Change

PRACTICE

1. How can digging out and removingmaterial from the bottom of a harbourto make water deeper impact theecosystem?

habitat change


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Overexploitation

Overexploitation of a resource meansusing a resource faster than it can bereplaced which often leads to extinction.

NOTE!

Overexploitation of the seas is one of thegreatest environmental catastrophes inhuman history. Consider Atlantic Canadawhere cod used to be abundant but by the1990s the cod populations were so low thatthe cod fishery had to be closed.


Overexploitation

OVEREXPLOITATION

� the use of a resource faster than it canbe replaced (i.e. fish, trees, water, ...)

� often leads to extinction


Overexploitation – DYK?

Around the world, theoverexploitation of fresh water isa major concern. For example,the Aral Sea was once the fourthlargest freshwater lake in theworld. However, to irrigate crops,water was diverted from the tworivers that flowed into the lake.Dropping water levels split thelake in two, creating the North andSouth Aral Sea. And as the waterlevel dropped, the fishdisappeared (and so too did thecommercial fishing industry).


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Overexploitation

PRACTICE

2. Give two examples ofhow overexploitation ofa resource has harmedecosystems.

East coast cod fisheries

Aral sea


Pollution

Pollution is any substance added tothe environment that produces acondition that is harmful to organisms.This includes:

• solid wastes (i.e. garbage) thatcannot be recycled

• air pollution that causes globalwarming and acid rain

• run-off and sewage that containsnutrients leads to eutrophication(i.e. algae blooms)


Pollution

Pollution is any substance added tothe environment that produces acondition that is harmful to organisms.This includes:

• human wastes that containchemicals interfere with theendocrine system of the fish (i.e.hormones)

• thermal pollution (i.e. warm water)that reduces the oxygen levels inthe water


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Pollution

NOTE!

Water is critical to life and pollutedwater can actually promote the growthof some micro-organisms, which feedoff the pollution. However, theseorganisms use up oxygen, whichmeans oxygen is removed from thewater at a higher rate. So, in additionto the possible toxic effects thepollution can have on an aquaticecosystem, its presence results in lowoxygen levels in the water. This cancause organisms to die.


Pollution

POLLUTION

� any substance added to the environment that is harmful to organisms

� includes:

• solid wastes (i.e. garbage) that cannot be recycled

• air pollution which causes global warming and acid rain

• run-off/sewage that contains nutrients causes eutrophication

• human wastes that contain chemicals

• thermal pollution (i.e. warm water) that reduces O2 levels


Pollution

PRACTICE

3. Why do people in today’s society createmore pollution than people who livedlong ago? (2 reasons)

• our population has increased

• we use lots of synthetic & toxicsubstances


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Pollution

Not only can water become polluted very easily, the pollution can enter thewater sources in different ways. Point source pollution is pollution thatenters a body of water at a specific place from an identifiable source (i.e.an oil spill, waste water from pulp and paper mills, ...).


Pollution

Non-point source pollution is pollution that enters bodies of waterindirectly when water from rain or snow travels over land and picks uppollutants from many different sources (such as agriculture, industry,urban, forest, ...) before entering a stream or a lake.


Invasive Species

An invasive (or exotic) species is anon-native species that causes harmto the ecosystem into which it hasbeen introduced. Invasive speciestend to out-compete native species,often because they have no naturalpredators in the new ecosystem orthey reproduce faster than nativespecies.


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Invasive Species

INVASIVE (EXOTIC) SPECIES

� non-native species

� typically out-compete the nativespecies because:

• they have no natural predatorsor

• they reproduce faster


Invasive Species

PRACTICE

4. Female emerald ash borers produce about50 to 100 eggs, which are laid individuallyon the bark surface or within bark cracksand crevices. As larvae hatch, they tunnelinto the tree, where they feed and spendthe winter. Why do you think areas nearwhere the insect has been found haverestricted the sale and movement offirewood?

prevent spread of eggs/insects


Climate Change

Climate change is the cause of aloss of biodiversity around the worldand is being driven by a processcalled global warming. And globalwarming, which is an increase inEarth’s average temperature, iscaused partly by an increase incarbon dioxide in the atmosphere. Inthe Arctic, for example, the ice packsare shrinking and so seals and polarbears are losing their habitat.


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Climate Change

CLIMATE CHANGE

� has caused a loss of biodiversityaround the world

� is driven by global warmingwhich is caused by an increase inthe carbon dioxide in theatmosphere


Climate Change

NOTE!

According to an ongoing temperature analysis conducted by scientists atNASA’s Goddard Institute for Space Studies (GISS), the average globaltemperature on Earth has increased by about 0.8 °C (1.4 °F) since 1880,with about two-thirds of the warming occurring since 1975. And recentestimates speculate that during the next century the global surfacetemperature is expected to rise a further 1 to 6 °C (1.8 to 10.9 °F).


U Check Your Learning

1. What are the five major ways that humans have caused all levels ofbiodiversity to decrease?

• habitat change

• overexploitation

• pollution

• invasive species

• climate change


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2. Identify the misconception in each of the following statements.

(a) If an ecosystem appears to have a lot of one particular species,then it must be healthy.

(a) a lot of one species indicates that there is a problem andsustainability is unlikely




(b) Biodiversity is unimportant to humans.

(b) biodiversity is very important to humans because it means theecosystem is healthy and sustainable




(c) A large, smelly swamp is a nuisance to humans and notecologically valuable.

(c) swamps are very valuable because they play an important role inthe water cycle by filtering water (and they are rich in nutrientsand support many species)


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WIKI (BIOLOGY)

O.... 1DBIOL - WS4 (The Zebra Mussel)


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1DBIOL - PP10 (Humans & Biodiversity)