ECOLOGY Syllabus links What is ecology Ecology is

ECOLOGY

Syllabus links

What is ecology? • Ecology is the interaction between living things (organisms) and between organisms and their environment

What is the biosphere? • The biosphere is the part of the planet containing living things • Extends 8 km into the atmosphere and 8 km deep in the oceans

Ecosystems What is an ecosystem? “An ecosystem is a group of clearly distinguished organisms that interact with their environment as a unit”

Can you think of any examples of sample ecosystems? • • • Hedgerow Woodland Lake Desert Tropical rain forest Grassland

Habitat, population and community • A habitat is the place where a plant or animal lives • A population is all the members of the same species living in the same area • A community is all the different populations in an area

Environmental factors affecting organisms • Abiotic factors are non – living factors • Biotic factors are living factors • Climatic factors refer to weather over a long period of time • Edaphic factors relate to soil: soil p. H, soil type, and the moisture, air and mineral content of soil

What environmental factors are important in aquatic environments? • In land based ecosystems the most important environmental factors are temperature and rainfall, with light being relatively abundant • In aquatic environments temperature is less important? ? ? • It does not vary so rapidly, and while water is plentiful, lack of light might be a problem • Examples of aquatic ecosystems include ponds, lakes, oceans, river an streams

5 Factors to consider in aquatic environments • • • Light Currents Wave action Salt content Oxygen concentration

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Energy flow • Every ecosystem requires a constant input of energy from an external source to function properly • The sun is the primary source of energy on this planet • Feeding allows energy to flow from one organism to another in an ecosystem

Producers and consumers • • Producers Organisms that carry out photosynthesis are called producers Consumers are organisms that take in food from another organism. All animals are consumers - Primary consumers feed on producers - Secondary consumers feed on primary consumers - Tertiary consumers feed on secondary consumers. If no other organism feeds on them they are called top consumers

Food chains • A grazing food chain is a sequence of organisms in which one organism is eaten by the next member in the chain • The arrows between the organisms in the adjacent food chains signifies a flow of energy

Trophic levels • Each feeding stage in a food chain is called a trophic level • Producers form the first trophic level, primary consumers the second and so forth… • Scavengers, decomposers or detritus feeders ( which feed on small pieces of dead or decomposing plants and animals) can take food from each trophic level

Length of food chains • 10% of the energy in each trophic level is passed on to the next • The other 90% is used by the organisms or is lost as heat, waste or detritus • The amount of energy passing from along a food chain decreases from 1 trophic level to the next and this limits the length of the food chain

Food webs • A food web consists of two or more interlinked food chains • Food chains and food webs attempt to show the feeding inter – relationships in an ecosystem • They also show the flow of energy through the ecosystem

Pyramid of numbers • A pyramid of numbers represents the number of organisms at each stage in the food chain • Now draw a pyramid of numbers for the below food chain grasses → rabbits →fox

Niche • The ecological niche of an organism is the functional role it plays in the community • The organisms niche includes what it eats, what it is eaten by, and how it interacts with other organisms and with its abiotic environment • A food niche refers to the feeding role of the organism in the habitat, e. g. what it eats, how it eats and what it feeds on • 2 species that have identical niches cannot survive in the same habitat for long and this results in organisms occupying different niches

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Nutrient recycling • Nutrient recycling is the way in which elements (such as carbon and nitrogen) are exchanged between the living and the non – living components of an ecosystem • Whereas energy coming from the sun flows in 1 direction, the nutrients that make up the bodies of living things are recycled and used time and time again

The Carbon Cycle • Carbon is exchanged between living things and the environment in the form of CO 2 • Three groups of organisms have roles to play in the carbon cycle: 1. Plants 2. Animals 3. Microorganisms

Global warming • In recent years there has been concerns that the concentration of CO 2 has risen from 0. 028% to 0. 036% as it is a ‘greenhouse gas’ • This is caused by the burning of fossil fuels and deforestation • These increased levels of CO 2 may contribute to global warming • If predictions are correct the effect for us will be devastating Greenhouse Effect - animated diagram

Flash Tutorial The Nitrogen Cycle • Living things need the element nitrogen • Nitrogen fixation is the conversion of nitrogen gas into ammonia (NH 3), ammonium (NH 4+), or nitrate (NO 3 -) – is carried out by volcanic action, lightning, industrial processes and some bacteria

Flash Tutorial The Nitrogen Cycle • Decomposition of dead organisms is carried out by bacteria and fungi – these organisms release nitrogenous compounds such as ammonia (NH 3) into the soil

Flash Tutorial The Nitrogen Cycle • Nitrification is the conversion of ammonia and ammonium to nitrite then nitrate is carried out by bacteria in the soil • Some of the nitrate formed in the soil is absorbed and assimilated by plants • Denitrification is the conversion of nitrates to nitrogen gas

Roles of organisms in the Flash Tutorial Nitrogen Cycle • Bacteria: 1. Nitrogen fixing bacteria 2. Bacteria of decay 3. Nitrifying bacteria 4. Denitrifying bacteria • Fungi • Plants • Animals

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Human impact on ecosystems Pollution – is any undesirable change in, or harmful addition to, the environment • Domestic pollution • Agricultural pollution • Industrial pollution

Ozone depletion – an example of air pollution • Ozone O 3 is a gas that forms in the upper atmosphere between 10 and 45 km above the Earth’s surface • It helps to absorb and shield the earth from incoming ultraviolet radiation Total Ozone Mapping Spectrometer ozone images

What causes ozone depletion? • CFC’s (chlorofluorocarbons) • Freon gas refrigerators • Insulating foams (styrofoam) • Some fire extinguishers (halons) • High flying jets

Effects of ozone depletion

Control of ozone depletion • Reduce CFC emission • Don’t use sprays or foams that contain CFC’s • Fridges should be disposed of in an environmentally friendly way

Conservation – The wise management of our natural resources Why is it important?

Fisheries in Ireland • Over fishing has reduced fish stocks at sea. • The use of small-mesh nets can result in too many young fish being caught Conservation in fisheries in Ireland • Fish quotas have been assigned to different countries to ensure that enough fish are left to replenish the stock • Using larger meshed nets to allow the young to reproduce

Waste management • • 1. 2. 3. This involves preventing pollution and conserving the environment and where possible it involves recycling Example of waste management are: In agriculture slurry is stored and is spread on dry land In the fishing industry the waste parts of fish are neutralised, pulped, dried and recycled as fertiliser or pig feed In forestry any parts of trees not removed from the forest are allowed to decay and return nutrients to the soil

Problems in waste disposal • Wastes may cause disease • Poisonous chemicals from wastes can enter drinking water supplies or plants • Waste nutrients can result in EUTROPHICATION and the death of aquatic plants and animals • Landfill sites can be smelly, and attract undesirable wildlife • Dumping at sea may lead to the pollution of the sea • Incinerators may release toxic fumes

Options For Waste Disposal Minimisation • Use less materials and packaging, Reduce, Reuse Recycling • Bottles, cans, paper, cardboard and plastic Use of Micro organisms • • 1/3 of household rubbish can go into a compost heap and allow bacteria and fungi to decompose it Our sewage can be decomposed by micro organisms in fermenters and the methane gas produced can be used to generate electricity Scientists have developed biodegradable plastic Use Bacteria to digest oil spills rather than detergent

The process of sewage treatment