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ECOSYSTEMS, BIODIVERSITY, BIOACCUMULATION, BIOMAGNIFICATIONS Biosphere The area of earth that can support life is called the Biosphere. The biosphere is composed of Lithosphere: solid part - km’s below the earth’s surface Atmosphere: gaseous part 1-2km above the earth (spores/bacteria) surviving here Hydrosphere: liquid part 7-10 km deep (includes all fresh and saltwater on earth) Biomes Within the Biosphere, smaller areas known as Biomes exist. Biome Examples: Desert, Arctic, Grassland, Scrub Forest, Rainforest, Arid Rainforest, Taiga, Savannah, Ocean, Fresh Water Ecosystems Going even smaller, we have what are known as Ecosystems. This level is where the study of ecology begins to become manageable. An ecosystem can be various sizes, but is generally somewhat distinct from the Biome proper. Possible ecosystems: Fresh water lake, swamp, coniferous forest, rotting log, forest floor, a single cedar tree - Within an ecosystem, there are both living and non-living parts. Living. The living organisms Biotic part ants, trees, snakes, bush pigs, sloth etc. Non Living. water, sunlight, oxygen, soil, nutrients, temperature Abiotic Part Habitats and Niches Each organism has a place in which it physically lives. This is known as the organism’s Habitat. e.g. centipedes inhabit: Undersides of fallen leaves - The combination of the job an organism does (what it eats/what benefits it provides) and where it lives is known as the organism’s Niche. e.g. centipede’s niche: Living under leaves, eating dead plant matter and insects. Generally there is only one organism per niche. Organism Niches: Squirrel: Live in tree, harvest acorns Sloth: Live in tree, eat leaves, feed tigers Biodiversity: When one species of organism becomes dominant, it reduces the amount of other types of species in an ecosystem. This is bad for the ecosystem Reasons: Every organism in an ecosystem fills an important niche. The loss of even the most seemingly insignificant organism can have unpredictable effects farther up the food chain. Ecosystems become more fragile if they have less species in them. Think disease epidemic, pollution, flooding etc. Bioaccumulation & Biomagnifications There are two basic terms we are discussing here. Bioaccumulation: The absorption of synthetic chemicals into a food chain. Biomagnification: The increase in concentration of that chemical as you go up a food chain. E.g. the amount of mercury in parts per million (concentration) in minnows will be dwarfed by the amount in full grown trout. Bioaccumulation We are concerned about these phenomena because together they mean that even small concentrations of chemicals in the environment can find their way into organisms in high enough dosages to cause problems. For Bioaccumulation to occur pollutant must be: 1. Long Lived - If a pollutant is short-lived, it will be broken down before it can become dangerous. 2. Mobile – Must be able to get into an organisms tissues - If it is not mobile, it will stay in one place and is unlikely to be taken up by organisms. 3. Fat soluble – water soluble chemicals would pass out of the body in the urine. Fat soluble chemicals stay put in the body’s fat. - If the pollutant is soluble in water it will be excreted by the organism. Pollutants that dissolve in fats, however, may be retained for a long time. 4. Biologically Active – Causes harm to the organism that eats it. E.g gold is not biologically active and will not harm an organism if ingested in small amounts. Mercury is biologically active and will cause the brain of the organism harm.