ECOLOGY

Dominican College, Griffith ave.

Section 1 – Factors affecting Organisms

Environmental Factors Affecting Organisms

Environmental Factors Abiotic Factors Biotic Factors

Climatic Factors Edaphic Factors Aquatic Factors

Abiotic Factors

These are non-living factors and include:Currents: Plants and animals get washed away. There is a need for attachments. eg Limpets have a muscular foot: Seaweeds have holdfastsSteepness: Steep slopes lose water quickly. Fewer organisms will grow higher up the shore where it is very steep

Abiotic Factors

Exposure: Plants and animals lose water when the tide is out. To prevent dessication, plants and animals have shells or mucilage.Aspect: This is the direction a surface faces. South facing slopes have more plant growth.

Biotic Factors

These are living Factors:Food: The more available food, the more organisms that will survive. eg More plankton…more limpets…more dog whelksPredation: These reduce the number of prey. eg More dog whelks…less limpets

Biotic Factors

Humans: May have a negative effect on the environment. eg PollutionCompetition: Competition for scarce resources (food/space/light/mates).

eg Limpets and barnacles compete for space on a rock. Seaweeds compete for light

Climatic Factors

Refers to weather over a period of timeTemperature: Determines the rate of reactions. eg the amount of growth in a plantSalinity: Organisms need to be specialised to live in such a harsh environment like saltwater (Crabs have osmoregulators)

Climatic Factors

Light Intensity: This affects the rate of photosynthesis. eg Plankton grows best in the upper layers of water due to the higher rate of light intensity.

Humidity: The more the humidity, the less the evaporation.

Edaphic Factors

Pertaining to soil.Soil Type: Sandy soil loses water while clay soil retainsSoil pH: Plants are adapted to specific soil pH’s.Humus: Vital to plant life. Binds soil particles…retains water and minerals… provides food for worms.

Edaphic Factors

Air Content: Oxygen is essential for life.

Water content: Essential for life. Mineral content: Necessary for

healthy growth.

Aquatic Factors

Light: May not penetrate too far down into the water.Currents: May wash away organisms.Wave Action: May physically damage organisms.O2 Conc: Not as plentiful in water as Air.

Section 2 – Energy flow

Trophic Levels

This refers to the feeding level/stage to which an organism belongs

Trophic Level 1 ProducerTrophic Level 2 Primary ConsumerTrophic Level 3 Secondary ConsumerTrophic Level 4 Tertiary Consumers

(PROBABLY the top carnivore)

Energy Flow

All food is ‘grass’. ‘Grass’ absorb only 1% of the suns energy.

Producers only pass 10% of their energy to the next trophic level.

For this reason food chains are limited. In general should only have a max of 4 trophic levels.

Food Chain

The simplest way to represent the flow of energy in an ecosystem.

Plankton Limpet WhelkProducer Primary Secondary

Consumer Consumer

Food Web

Two or more interlinked food chains.

Food Web

Two or more interlinked food chains.

Section 3 – Definitions

Ecology

The study of the interactions between living things (organisms) and between organisms and their environment.

Biosphere

That part of the planet containing living organisms.

The biosphere is the living world. It extends high into the atmosphere, to the bottom of the ocean, and deep down into caves.

Ecosystem

This is a group of clearly distinguished organisms that interact with their environment as a unit.

Habitat

A habitat is a place in which you find animals and plants.

The kind of animals and plants which can live in a habitat depend upon what the habitat is like. Is it very hot or cold? Is it very wet or dry?

Producers & Photosynthesis

Green plants are producers: this means that they use the sun's energy in photosynthesis to produce new living material.

All food chains start with a producer.

Carnivores & Herbivores

Animals, fungi and bacteria are all consumers. They get their energy by eating other living things. Primary consumers eat plants, we also call them herbivores. Some herbivores, like limpets, graze on plants.

Carnivores are secondary consumers, they eat other animals.

Carnivores

Omnivores

Some animals can choose between being a herbivore and being a carnivore: they eat both animals and plants and they are called omnivores.

They are either primary or secondary consumers.

Scavengers

Scavengers are also consumers, but they wait for their prey to die first.

eg. Sandhoppers and bacteria

Niche*****

This is the functional role of an organism in an ecosystem or habitat (The feeding role of the organism).

What it eats What it is eaten by How it interacts with others and

with its abiotic environment.

Pyramid of Numbers

Represents the number of organisms at each stage (trophic Level) in a food chain. (Makes it easy to compare numbers at a glance).

Pyramid of Numbers Cntd

Normal Pyramid of Numbers:

Plankton

Mussels

Starfish

Gull

Pyramid of Numbers Cntd

Inverted Pyramid of Numbers:

Hawk

Oak Tree

Blackbirds

Spiders

GreenFly

Pyramid of Numbers Cntd

Inverted Pyramid of Numbers:

Pyramid of Numbers Cntd

Parasitic Pyramid of Numbers:

Rose Bush

Mites

GreenFly

Section 4 – Recycling

Nutrient Recycling

This is the way in which elements or minerals are:

Absorbed by organisms Released when organisms die Absorbed by other organisms

Elements are exchanged between the living and non-living components

The Carbon Cycle

Carbon is normally exchanged in the form of CO2.

The carbon cycle is the way in which CO2 is taken from and added to the environment

The Carbon Cycle

The Carbon Cycle

The Carbon Cycle

The Carbon Cycle

3 groups of organisms have roles to play. Plants – Remove Carbon by Photosynthesis

and release it by Respiration Animals obtain Carbon by eating plants and

release it by Respiration Microbes decompose dead materials and

return Carbon to the environment

The Nitrogen Cycle

The Nitrogen Cycle

The Nitrogen Cycle

Human Impact on ecosystems

A. PollutionB. ConservationC. Waste Management

A) Pollution

Any undesirable change to the environment.

Domestic – household waste Agricultural – disposal of slurry

sileage effluent as well as overuse of fertilisers

Industrial – smoke causing acid rain

Case Study 1: Air Pollution and the Depletion of the Ozone Layer

Ozone is a gas that surrounds the earth and protects the earth from the harmful UV rays.

The Cause:It is being depleted by the use of: CFC’s in aerosols Freon gas in fridges Industrial detergents

Case Study 1

The Effects: Increased numbers of skin cancers Serious damage to crops Concern that Plankton numbers will

be depleted……less food……less organisms

Case Study 1

The Control: Reduction of use of CFC’s Replacement of CFC’s with HFC’s

which break down more quickly Don’t dump fridges into landfill

which will release the freon gas.

Case Study 2 – Excessive Fertiliser or Animal Waste on Grassland

The Cause: Excessive fertiliser or animal wastes

may wash into streams.

Case Study 2

The Effect: The minerals in the fertiliser cause

algae to grow in the water. The oxygen in the water gets used

up. All living things die(Process is called eutrophication)

Case Study 2

Case Study 2

The Control: Limit the use of fertilisers so that

excess is not washed away. Slurry (animal waste) should only be

spread on grassland when the weather is dry

B) Conservation

The wise management of our existing natural resources in order to allow as many species as possible to survive.

B) Conservation – One Practice

Don’t destroy hedges (food for birds)

Reduce fishing quotas Use of larger mesh size when net-

fishing

C) Waste Management

The basic principle here is that the waste produced is recycled in a safe manner.

eg Animal waste in the form of slurry is stored in concrete pits (no leakage), only spread in dry conditions and never near lakes or streams

Waste Management Cntd.

Minimised: Reduce

Re-use

Recycle

Waste Management Cntd.

Problems with waste disposal:Waste may contain disease causing microbesLandfills are smelly and rodent infectedToxic chemicals may leak into the water table

Waste Management Cntd.

Role of Microbes:Break down the biodegradable matterSmall amounts of sewerage released into rivers/sea are broken down by the bacteria and fungi that live naturally there

Waste Management Cntd.

Role of Microbes:Bacteria and fungi are used in secondary sewerage treatment. Primary treatment involves screening (getting rid of plastic containers etc. )and sedimentation (separating solids sludge from water!)

Waste Management Cntd.

Role of Microbes Cntd:Secondary treatment is where the sludge is placed into an enclosed tank and broken down by bacteria.

Methane is produced in the process and may be collected and used as a fuel source

Waste Management Cntd.

Role of Microbes Cntd:The liquid portion is passed into larger open shallow tanks, where 98% of the organic material is broken down by microbes.

At the end waste waters are treated with chlorine

Section 5 – Symbiosis

Symbiosis

Symbiosis occurs when two organisms from different species live, in close association, where at least one of them benefit.Parasitism: One species gains at the expense of the otherMutualism: Both organisms benefit

Parasitism

eg Lice living on a dog/human

Mutualism

eg Lichens Structurally, lichens are among the

most bizarre of all forms of life. That's because every lichen species is actually composed of two, possibly even three,  distinct species of  organisms.

Mutualism Cntd.

One species is a kind of fungus. Usually the other  species is an alga, but sometimes it can be a photosynthesizing bacterium known as a cyanobacterium.

Mutualism Cntd

Fungus: Absorbs water and minerals Algae: Carries out photosynthesis