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Ecology Environmental Science Mr. Vickers Ecology • The study of living organisms in the natural environment, how they interact with one another and how the interact with their nonliving environment Levels of organization atoms molecules species population organelles cells community tissues organs systems organism ecosystem biosphere ECOLOGY Species • A group of organisms that can reproduce and produce fully fertile offspring Great White Pelican Pelecanus onocrotalus Population • A group of organism of the same species which live in the same habitat at the same time where they can freely interbreed • Habitat: the environment in which a species normally lives or the location of a living organism The black-veined white butterfly (Aporia crataegi) mating Community • All the populations of the different species living and interacting in the same ecosystem 7-spotted lady bug (Adephagia septempunctata) Bean aphids (Aphis fabae) Red ant (Myrmica rubra) Broom plant (Cytisus scoparius) Ecosystem • Community (Biotic) interacting with environment (Abiotic ) Components of an Ecosystem • Biotic Factors: living or once living organisms • Abiotic Factors: nonliving factors that have an effect on living things Examples: - Water: organisms have water in their bodies (50-95%) and chemical reactions need water to happen. - Soil: type of soil determines which plants and other organisms live in that location - Light and Temperature: affect photosynthesis (plant growth is limited to amount of sunlight) Energy + CO2 + H2O → C6H12O6 + O2 Energy and Organisms • Autotrophs: organisms which can synthesize their own complex, energy rich, organic molecules from simple inorganic molecules (e.g. green plants synthesis sugars from CO2 and H2O; bacteria in deep sea vents doing chemosynthesis) - PRODUCERS • Heterotrophs: organisms who must obtain complex, energy rich, organic compounds form the bodies of other organisms (dead or alive). – Ex: consumers and decomposers (saprotrophs and detritivores) Decomposers • Detritivores: heterotrophic organisms who ingest dead organic matter. (e.g. earthworms, woodlice, large scavengers). Ingest first, then digest. Earthworm (Lumbricus terrestris) • Saprotrophs: heterotrophic organisms who secrete digestive enzymes onto dead organism matter and absorb the digested material. (e.g. fungi, bacteria). Digest first, then absorb. Chanterelle (Cantherellus cibarius) Consumers • Omnivore: eats both plants and animals • Carnivore: meat eater • Herbivore: plant eater Food Chains • Sequence of relationships between trophic levels. • Show the flow of energy from the SUN to the heterotrophs • Trophic level: an organism’s feeding position in a food chain • Producers: essential to every single food chain Food Web • Shows the feeding relationships in a community. Arrows show the flow of energy. Read the article and generate a food web: http://ehp.niehs.nih.gov/members/2004/112-8/focus.html How much is available to the caterpillar’s predator? Plant material eaten by caterpillar 200 J 67 J Feces 100 J 33 J Growth (new biomass) Cellular respiration Energy and Nutrients • Energy enters ecosystems as light and usually leaves as heat. • Nutrients do not usually enter an ecosystem and must be RECYCLED. Nutrients include: carbon, nitrogen, phosphorus, magnesium... The Carbon Cycle The Nitrogen Cycle Pyramids of Energy Biomass • Amount of dry matter in one organism • Each bar represents: dry weight of all organisms in one trophic level Trophic level Dry weight (g/m2) Tertiary consumers 1.5 Secondary consumers 11 Primary consumers 37 Primary producers 809 Populations • Characteristics: – – – – Size: number of individuals at a certain time Density: number of individuals in a certain space at a particular time Spacing: clumped, uniform, random Age Structure • Pop. Change = (birth + immigration) – (death + emigration) • Limiting factor: prevents the continuing growth of a population in an ecosystem – Can be: - water, air, light, food - diseases, competitors, predators, parasites Population Growth • Exponential Phase: population increases exponentially because the natality rate is higher than the mortality rate. • Transitional phase: difference between natality and mortality rates are not as great, but natality is still higher so population continues to grow, but at a slower rate. • Plateau phase: natality and mortality are equal so the population size stays constant. • Carrying Capacity: the maximum population size that can be supported by the environment The Greenhouse Effect • • • Light from the sun has short wavelengths and can pass through most of the atmosphere. This sunlight warms the earth which in turn emits long wave radiation. This long wave radiation is bounced back by the greenhouse gases, such as carbon dioxide, methane, water vapor, oxides of nitrogen and sulphur dioxide The Greenhouse Effect • Natural and essential to life • Human pollution is making it worse = causing global warming – Oxides of nitrogen: industrial processes, burning fossil fuels, fertilizers – Methane: cattle, waste disposal, natural gas leaks – CO2: burning fossil fuels • Consequences: – – – – Changes in climate = effects on the ecosystem Extinction Melting glaciers = rise in sea level Increase in photosynthetic rates Changes in atmospheric CO2 Precautionary Principle • Action should be taken to prevent harm even if there is not sufficient data to prove that the activity will have severe consequences • If people want to do activities that may cause a change in the environment they must prove first it won’t do harm • We should take action now: reduce carbon emissions before it’s too late • Should people invest money to reduce carbon emissions if we are not 100% sure about the consequences of global warming? • More expensive to be eco-friendly • What should consumers do? Arctic Ecosystems - North America, Greenland, Iceland, Norway, Russia Example: polar bears/seals/algae affected Loss of ice habitat Increased success of pests/pathogens/mosquitoes Increased decomposition Expansion of temperate species/reduced range for arctic species Rise in sea levels Climate change Disturbance of food chains Melting of permafrost