Science 1206/2200

Unit 1 - Chapter 2Change and diversity in Ecosystems

What are some examples of pests?DEFINITION: Pg.52Living organisms that fall into one of three categories:

1.Humans believe it to be UNDESIRABLE (ahem, gross).2.It has a NEGATIVE impact on the human environment.3.It is in COMPETITION with a HUMAN USE for a resource.

DEFINITION:•Chemicals used to kill various pests.

Pesticides

Two main categories based on ORIGIN:

•FIRST GENERATION PESTICIDES•SECOND GENERATION PESTICIDES

FIRST-GENERATION pesticides• ORIGIN:NATURAL• Examples: Arsenic, lead, mercury, nicotineSECOND-GENERATION pesticides• ORIGIN: HUMAN-MADE/SYNTHETIC• Examples:DDT, penicillin

4 SUBCATEGORIES:• INSECTICIDE:kills INSECTS• HERBICIDE:kills plants• FUNGICIDE:kills mould/fungi• BACTERICIDE:kills bacteria

Pesticides Over TimePesticide types have changed over time.Older pesticides• FAT-SOLUBLE

• When ingested by an organism, these pesticides attach to fat cells. • This was highly effective as they PERMANENTLY remain in the organism.

Newer pesticides•WATER-SOLUBLE

•When ingested, they are effective in the target pest, but do not accumulate in fat cells.

•This type dissolves in water and can be flushed out of an organism’s system.

Bioaccumulation

Also known asBIOAMPLIFICATION or BIOMAGNIFICATION

A phenomenon in food chains whereby FAT-SOLUBLE PESTICIDES build up in the fat cells of consumers at higher trophic levels.

Bioaccumulation and DDTDDT stands for:•Dichlorodiphenyltrichloroethane• second generation: human-made.

Introduced as a FAT-SOLUBLE insecticide to control insects that:

•Feed on agricultural crops•Damage forests (ex: spruce budworm)•Carry diseases (ex: malaria)

• It was VERY EFFECTIVE at killing pests•But there was an unknown effect ,it stayed in

the bodies of other organisms . . .

FIRST NOTICED EFFECTS:• Egg shell thinning in top carnivore birds, such as Bald Eagle• Thin shells meant HIGH RATES of chick mortality

It takes about 15years for DDT to break down in the environment.

What do we do?• Ban DDT and other fat-soluble pesticides.

It is now banned in CANADA (1977) and many parts of the world, BUT SOME COUNTRIES are still using it.

• Use water-soluble pesticides instead.

• Use sustainable alternatives to pesticides.

DDT Continues to be a Problem to Us Even Though We Have Banned It

•Third - world countries south of the U.S. border such as Mexico and Central America, continue to use DDT.

• Migratory birds go there in winter and bioamplify the DDT in their bodies

•The migratory birds Retur and are fed upon by predators in our country

IPM for short

A sustainable approach to managing pests that involves:

• PREVENTION• AVOIDANCE• MONITORING• SUPPRESSION

•CHEMICAL CONTROL•BIOLOGICAL CONTROL

2 MAIN TYPES OF PEST MANAGEMENT

Although chemicals are highly effective, there are several DISADVANTAGES to using them, including:

Chemical Control

•BIOACCUMULATION•Not TARGET-SPECIFIC•Not 100 % EFFECTIVE (some pests will not be killed)•Could lead to PESTICIDE RESISTANCE

Biological ControlsAlthough they are more TARGET-SPECIFIC, there are several DISADVANTAGES including:• Expensive• Short-Term Effectiveness• Organisms simply move to another area

Methods include using:• NATURAL PREDATORS• DISEASE ORGANISMS• COMPETITORS• PHEROMONES

Pesticide ResistanceSome pests are naturally immune to pesticides.Once non-immune pests are killed off, the immune PESTS are left to reproduce a new generation of PESTICIDE RESISTANT PESTS.

Forest Insect Pests in Newfoundland.•1. Eastern Hemlock Looper: Most

damaging pest to our forestry. Causes complete defoliation (loss of leaves/needles) of balsam fir in one year.

•2. Spruce Budworm: Defoliator in the caterpillar stage. It can kill a tree over a number of years. It’s considered one of the most destructive forest pests in North America

Forest Insect Pests in Newfoundland.

Biogeochemical Cycles and Human Impacts

Introduction

Biogeochemical cyclesThe recycling of material s though living organisms and the physical environment.

BiochemistScientists who study how life works at a chemical level.

The work of biochemists has lead to the understanding

that living organisms are composed of some of the same

elements that are found in air, water, and soil.

Biogeochemical Cycles

•Although there are 92 elements known to occur naturally on Earth, fewer than 20 elements are presently known to occur in the tissues of living things.

•For example, only elements make up 99.2% of human tissue.

Biogeochemical Cycles

•The four elements that make up the majority of living tissue are:

▫Oxygen▫Carbon▫Hydrogen▫Nitrogen

The Cycling Process•The 4 elements (O,C,N, and H) are cycled constantly between 2 parts of nature▫Living Organisms▫Physical Enviroment

The cycling of these elements is dependent on two

of processes in order to work:▫Biological Processes▫Geological Processes

Biological Processes•The cycling of these elements require living organisms, which make up the biosphere of Earth.

•What are some examples of Biological Processes?▫Respiration▫Photosynthesis▫Decomposition▫Assimilation▫Excretion

Geological Processes•The cycling of these elements require the

physical environment which includes▫Air – Atmosphere▫Land – Geosphere▫Water – Hydrosphere

•Examples of geological processes▫Fossilization▫Erosion▫Combustion/Burning▫Weathering▫Sedimentation

3 Types of Cycles

•Carbon Cycle

•Nitrogen Cycle

•Oxygen Cycle

The Carbon Cycle Pg. 62-65•The cycling of carbon though the atmosphere , the physical environment, and ecosystems

http://www.youtube.com/watch?v=dDBU0lg-HYE

Carbon and the Biosphere•How important is Carbon for life?

▫Carbon is the element that is the backbone for all life on Earth. In other words, we are carbon-based life forms.

•How does carbon move though living organisms?▫The two main processes that help cycle

carbon though the biosphere are photosynthesis and cellular respiration

Carbon and Nonliving systems•Where is carbon stored in the non-living

environment?▫Two types of carbon storage:

1.Organic reservoirs: stored as the result of decomposition of living organisms. The processes are specific and years to complete

•When detritus gets trapped under peat, it forms coal.

•When detritus gets trapped under oceans, it forms oil and natural gas

Carbon and Nonliving systems2. Inorganic reservoirs•3 main areas•Air - .03% of air is carbon•Oceans – both dissolved (carbon gas) and in shells

•Land – in sedimentary rocks, which can be released during violent volcanic eruptions.

Carbon and Living Systems

•Reservoirs: Bodies of living things.•Carbon returns in an inorganic form when

living things die.•Some ecosystems such as bogs store huge

quantities of carbon in organic form. Decomposition is slow and can lock away. Sediments can form over this and creates coal.

The Nitrogen Cycle pg. 66-67

DEFINITION:

• The movement of nitrogen through the atmosphere, physical environment and ecosystems.

Nitrogen and the Biosphere WHAT IS NITROGEN USED FOR IN LIVING

ORGANISMS?• Nitrogen is used to make DNA and PROTEINS. • DNA is the GENETIC MATERIAL found in every

living cell.WHERE IS MOST NITROGEN FOUND ON

EARTH?• Most nitrogen on Earth is found in the air. • The air is 79% NITROGEN.• This atmospheric nitrogen is in the form N2, a gas.• Although nitrogen is plentiful in the air, it is

UNUSABLE to most living organisms (we cannot simply “breathe in” nitrogen).

Nitrogen and the Biosphere HOW DO LIVING ORGANISMS GET

NITROGEN?•Plants and animals cannot use N2 gas.

We can use nitrogen in TWO FORMS:•AMMONIA, NH3•NITRATES, NO3-WHAT ARE THE KEY NITROGEN CYCLE

PROCESSES?•NITROGEN FIXATION•DENITRIFICATION

Nitrogen CyclesNITROGEN FIXATION•Also known as NITRIFICATION•Gaseous nitrogen, N2, is converted to usable

forms in TWO WAYS:

•By LIGHTNING•By NITROGEN-FIXINGBACTERIA•These bacteria are found in the ROOT

NODULES of LEGUMES such as ALFALFA and CLOVER.

Nitrogen CyclesDENITRIFICATION•DENITRIFYING BACTERIA convert

usable forms of nitrogen back into gaseous nitrogen, N2.

•These bacteria are found in the soil. These bacteria do not require oxygen.

•Denitrification ensures balance among soil nitrates, nitrites, and atmospheric nitrogen, and completes the nitrogen cycle.

•Lawns/Bogs Pg. 67

Oxygen Cycle•Oxygen is used in the process of cellular

respiration by both plants and animals. •Carbon is released in the form of CO2 as a

waste product of this reaction. •Plants take in the inorganic gas CO2 and use

it in the process of photosynthesis to make organic sugars such as glucose

•Oxygen is released as a waste product of the photosynthesis reaction.

•The reactions of cellular respiration and photosynthesis are reciprocals of each other

Oxygen Cycle

Human ImpactsCARBON CYCLE

GLOBAL WARMING and the GREENHOUSE EFFECT

NITROGEN CYCLE

AQUATIC EUTROPHICATION

Deforestation - Increased CO2 levels add to global warming

OXYGEN CYCLE

GLOBAL WARMING and the GREENHOUSE EFFECT

Humans have DISRUPTED the CARBON CYCLE

in TWO MAIN WAYS:Burning FOSSIL FUELS:Increased CO2

DEFORESTATION:Decreased O2 production by plantsIncreased CO2

The increase in CO2 levels have led to an ENHANCED GREENHOUSE EFFECT.

WHAT ARE GREENHOUSE GASES?

Gases that have the ability to HOLD HEAT INthe atmosphere.These gases are important to keep the Earth warmenough to sustain life.

3 Main Greenhouse Gases1) CARBON DIOXIDE CO2

Sources:•Cellular Respiration•Combustion (burning)

2) METHANE CH4

Sources:•Fossil fuel production and transportation•Decomposition•Livestock

3) NITROUS OXIDESSources:•Combustion•Agricultural Fertilizers•Industrial Emissions

Global Warming 101Humans have DRAMATICALLY INCREASED

the amount of greenhouse gases in the atmosphere, leading to the ENHANCED GREENHOUSE EFFECT, or GLOBAL WARMING.

Possible Effects•Increased spread of disease•Rising sea levels and loss of polar ice

capsFigure below is 1979 versus 2005

•Loss of freshwater sources•More extreme weather•Accelerated species extinction

Aquatic EutropicationHumans have impacted the nitrogen cycle by releasing 2 substances into AQUATIC ECOSYSTEMS:

•FERTILIZERS•UNTREATED HUMAN SEWAGE

Fertilizers, and untreated human sewage, contain NITRATES and PHOSPHATES.These chemicals LEACH into water ways through groundwater, road runoff, etc.

Lakes that have HIGH LEVELS of phosphates and nitrates can undergo EUTROPHICATIONA transformation from an

OLIGOTROPHIC LAKE to a EUTROPHIC LAKE.

Lakes that have HIGH LEVELS of phosphates and nitrates can undergo EUTROPHICATIONA transformation from an

OLIGOTROPHIC LAKE to a EUTROPHIC LAKE.

THINK ABOUT IT!!!!!!!!!!!!!