Backyard Ecology

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other vocabulary lists:
http://www-bioc.rice.edu/pblclass/6th%20grade/Biology/ecosystems/Ecosystem%20Notes.pdf

Algael Bloom For a more in-depth definition try http://www.whoi.edu/redtide/

Basic Defintions

  • Food Chain - A food chain is the series of organisms showing feeding relationships. A food chain almost always begins with a green plant (producer) which is eaten by an animal (consumer). The arrow means 'is eaten by', and shows the flow of matter and energy along the food chain. There are no decomposers in a food chain.
        EG: Grass(Producer)-->  Grasshopper(1st order Consumer)--> Kookaburra(2nd order Consumer)
  • Producer - usually a green plant that produces its own food by photosynthesis
  • First-order Consumer - the organism that eats the producer
  • Second-order Consumer - the organism that eats or derives nutrients from the first-order consumer
  • Herbivore - a plant eater
  • Carnivore - an organism that obtains nutrients from the blood or flesh of an animal
  • Omnivore - an organism which eats both plant and animal matter
  • Scavenger - an consumer that eats dead animals (e.g. crab)
  • Detritivore - a consumer that obtains its nutrients from detritus
  • Decomposer - an organism such as bacteria and fungi that breaks down dead organisms and their wastes
  • Trophic Level - A trophic level is each level in a food chain. Matter is always 'lost' as heat energy at each trophic level.
  • Basal Energy Requirement (B.E.R.) - the amount of energy used by an organism's body just to keep alive, when no food is being digested and no muscular work is being done
  • Food Web - a network of interrelated food chains in a given area
  • Loss of Matter and Energy - At each trophic level along a food chain, there is always a 'loss' of matter and energy in the forms of waste (e.g. carbon dioxide, faeces), and heat and kinetic energy (e.g. constant body temperature of mammals, the energy used to move). Up to 90% of matter and energy can be 'lost' at each level.
  • Biomass - the total dry weight of the organisms in a trophic level
  • Biomass Pyramid - a diagram showing the biomass at each trophic level of a food chain

BIOLOGICAL MAGNIFICATION
  • Some chemicals that are taken in from the environment by plants, or consumed by animals, cannot be excreted by organisms. They accumulate in the body by the organisms, sometimes up to toxic levels. The more organisms there are in a food chain, the greater is the accumulation in the higher order consumers. Such chemicals include the pesticide DDT, and heavy metals such as mercury.

BIOLOGICAL CONTROL
  • Pests - Pests may be plant or animal. They usually are introduced from overseas. Because of both their ability to survive and reproduce successfully in the Australian habitat, and their lack of predators or parasites, they reach pest population numbers, competing with the native flora and fauna.
  • Biological Control of the populations of pest plants and animals is accomplished by non- chemical means involving predation, parasitism, or interruption to reproduction. Biological control is usually specific to a particular pest organism.
  • Successful Biological Control Experiment Examples
  1. Prickly Pear Cactus - This introduced species was a pest throughout cattle farms in Queensland. The introduction of the Cactoblastis Moth reduced its numbers through consumption.
  2. European Rabbit - Rabbits arrived in Australia in 1788 and reproduced rapidly. The Myxoma Virus was developed in the 1900's to spread by direct contact and cause death.
  • Unsuccessful Biological Control Experiment Examples
Cane Toad - Cane toads were originally introduced to sugar cane fields to reduce the numbers of cane beetles destroying sugar cane. However, cane toads did not eat cane beetles, instead reproducing rapidly themselves and causing death to native wildlife which ate them. No successful predators exist in Australia.

CYCLES
  • Law of Conservation of Matter
Matter cannot be created nor destroyed in any chemical reaction. It can only be transformed from one form to another.
  • Cycle - A cycle shows the reusing of certain elements and compounds (e.g. water, carbon, oxygen, nitrogen, phosphorus) in different forms in ecosystems.

WATER CYCLE
  • The sun provides the heat energy required for the cycle to continue.
  • The oceans and rivers are the main reservoirs of water.
  • Evaporation - Water evaporates into the atmosphere.
  • Condensation - Water condenses into droplets in the clouds.
  • Precipitation - As the water droplets in clouds enlarge, water falls to earth in the form of rain, snow or hail.
  • Transpiration - Water is lost through the leaves of plants ('trees perspiring').

CARBON AND OXYGEN CYCLES
  • Carbon occurs in all living organisms in the forms of carbon dioxide, carbohydrates (sugars and starches), proteins and fats.
  • Oxygen occurs in all living organisms in the forms of oxygen gas, water, carbon dioxide, carbohydrates, proteins and fats.
  • Photosynthesis - Photosynthesis is the process used by plants containing chlorophyll to utilise sunlight, carbon dioxide and water to form sugar (as glucose) and oxygen.
                Carbon Dioxide + Water Glucose Sugar + Oxygen
                CO2                 + H2O C6H12O6           + O2

  • Respiration - Respiration is the process that most living organisms (including animals, plants, fungi and micro-organisms) use to obtain energy from glucose sugar and oxygen. The wastes formed are carbon dioxide and water.
        Glucose        + Oxygen Carbon Dioxide + Water + Energy
        C6H12O6     + O2 CO2 + H2O                           + Energy

ENVIRONMENTAL ISSUES
  • Climate Change / Global Warming and Greenhouse Effect - The earth's atmosphere allows a lot of sunlight to reach the earth's surface, but reflects much of that light back into space. Some gases trap more sunlight, so that less light reflects back into space. These gases are called Greenhouse Gases, because the effect is like being in a plant glasshouse, or in a car with the windows wound up. The result is a gradual increase in earth's temperature or Global Warming. The major greenhouse gases are water, carbon dioxide, methane, nitrous oxide, ozone and chlorofluorocarbons (CFC's). Possibly, the main man-made causes are thought to be carbon dioxide and methane from factory, power station and car emissions, the waste products of respiration,logging, the mining of fossil fuels and the breakdown of plant matter in swamps. The long-term effects may include melting of ice-caps and a rise in sea level, and a global change in climate and type of vegetation.
  • 'Hole' in the Ozone Layer - Ozone is a gas in the earth's upper atmosphere whose chemical formula is O3. Ozone acts to block out much of the sun's ultraviolet radiation which causes skin cancer and contributes to the fluctuations of global climatic conditions that affect the environment. Above Antarctica is a thinner layer of ozone caused by the destruction of ozone gas by emissions of chlorofluorocarbons and hydrochlorofluorocarbons that are propellents in pressure-pak spray cans and refrigerants in refrigerators and air-conditioning units. In 1987, a treaty called the Montreal Protocol was introduced to reduce usage of ozone-destroying gases. Australia has banned CFC's, but many nations such as China still use them.
  • Acid Rain - When gases such as sulphur dioxide and nitrogen oxides react with water in the atmosphere to form sulphuric acid and nitric acid, they form an acidic 'rain' which can destroy vegetation. Some of these gases are from natural sources such as lightning, decomposing plants and volcanoes. However, much of these gases are the result of emissions from cars, power stations, smelters and factories.
  • Air Pollution - Air pollution is the release into the atmosphere of excessive amounts of harmful gases (e.g. methane, carbon dioxide, sulphur dioxide, nitrogen oxides) as well as particles (e.g. dust, tyre rubber, lead from car exhausts). To reduce emissions, the Australian government has legislated that all new cars use unleaded petrol and have catalytic converters fitted to the exhausts.
  • Water Pollution
  1. Sewage is all household waste water. Many detergents contain phosphates which act as plant fertilisers. When these phosphates and the sewerage reach rivers, they help water plants to grow in abundance, reducing the dissolved oxygen in the river water. The result is death of aquatic animals due to suffocation by the algal blooms. This harmful effect is called eutrophication.
  2. Biodegradable detergents are more environmentally friendly because they are readily broken down to harmless substances by decomposing bacteria.
  3. Suspended solids in water such as silt reduce the amount of light that reaches the depths of the water in lakes and rivers. This reduces the ability of aquatic plants to photosynthesise and the result is less plant and animal life. Turbidity is the measure of 'cloudiness' or the depth to which light can reach in water.
  • Introduced Species are species of plants or animals that have migrated or been brought to Australia. Many fit into the natural ecosystems and are kept in control by natural predators and parasites. However, some become pests as they are well-adapted to our environment, readily obtain nutrients, and lack natural predators or parasites. Examples include rabbits, foxes, carp, and prickly pear cactus plant.
  • Biological Control is an environmentally-friendly method to control these pests by the introduction of species-specific, living organisms to control their numbers. Successful examples include the myxoma virus and the calici virus for rabbits, and the cactoblastis moth feeding on the prickly pear. Unsuccessful examples include the introduction of the cane toad to reduce the numbers of natural cane beetles.
  • Biological Magnification is the accumulation in body tissues of certain chemicals such as DDT pesticide and mercury. The higher along the food chain, the greater is the accumulation, sometimes to toxic levels, causing birth defects and death.
  • Soil Salinity has increased greatly since the widespread logging of trees by farmers. Deep tree roots normally draw water from the underground water table. However, when logging of trees occurs, the water table rises close to the surface bringing with it salt from rocks. This creates soil that is so salty that vegetation cannot grow effectively. The result is loss of vegetation and erosion.
  • Population Explosion is the rapid increase in population in developing countries causing famine, and also in developed countries causing more demand for energy and with that, increased pollution and destruction of the environment.

Source: Queensland Science Teachers

Complex Definitions


Biodiversity
  • The Gould League's definitions compare biodiversity to other types of diversity such as species diversity and ecosystem diversity. http://www.gould.org.au/wildlifecams/habitat_view.asp?id=8018