2 3 Effect of Bioaccumulation on Ecosystems Amphibians
2. 3 Effect of Bioaccumulation on Ecosystems • Amphibians live on both ______ and in the _____. w Amphibians are sensitive to ______________in the environment. w They are therefore valuable indicators of environmental _______. w Since the 1980 s, many of the world’s amphibian species have suffered __________in population. w There also have been alarming increases in amphibian ___________. w Many theories attempt to explain these changes, including Amphibians, like this frog, have drought, increased UV rays, _______, habitat loss, exhibited drastic changes since parasites, and ________. the 1980 s. See pages 92 - 93 (c) Mc. Graw Hill Ryerson 2007
Bioaccumulation • Bioaccumulation refers to the gradual buildup of _________ in ____________. w Many harmful chemicals cannot be ________ naturally. w These chemicals can be_____or absorbed and sometimes cannot be removed from the body of the organism effectively. w If a keystone species suffers a chemical bioaccumulation, it can affect ____________in its far-reaching niches. § A keystone species is a ________of an ecosystem. Organisms are sometimes • Biomagnification is the process by which exposed to toxic chemicals become more __________ at each ___________. w At each level of the food pyramid, chemicals that do not get broken down _________ in organisms. w When a consumer in the next trophic level eats organisms with a chemical accumulation, it receives a ___________of the See page 94 chemical(s). (c) Mc. Graw Hill Ryerson 2007
Bioaccumulation (continued) • An example of bioaccumulation in British Columbia is the effect of PCBs on the ______. w PCBs are chemicals that were used for many ________ and __________applications in the mid-20 th century. w PCBs were banned in 1977 because of their _____________. § PCBs __________ and have a long ______ (they break down very slowly). § PCBs will affect the _____________ of orcas until at least 2030. The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae. See page 95 (c) Mc. Graw Hill Ryerson 2007
Bioaccumulation (continued) • Chemicals like PCBs and DDT are called _______________________(P OPs). w POPs contain carbon, like all organic compounds, and remain in _____ and_________for many years. w Many POPs are ___________, used to control pest populations. § DDT was introduced in 1941 to control mosquito populations, and is still used in some places in the world. § Like PCBs, DDT also bioaccumulates and has a long half-life. § Even at _________(5 ppm), DDT in animals can cause nervous, immune, and reproductive system ___________. See page 96 Spraying DDT, 1958 • ppm = parts per million (c) Mc. Graw Hill Ryerson 2007
Bioaccumulation (continued) • Heavy metals are ___________that are toxic to organisms. w Levels of ______ in the soil have increased due to human activities. § Lead is not considered safe at _______level. § Many electronics contain lead and must be ________________. § Lead can cause ______ and nervous and reproductive system _______. w Cadmium is also found in low levels naturally. § Cadmium is used in the manufacture of plastics and _____________ batteries. Electronics Waste Contains Lead. § It is toxic to ________ and causes many health problems in________. § In humans, the main source of cadmium is See page 97 exposure to _________________. (c) Mc. Graw Hill Ryerson 2007
Bioaccumulation (continued) w __________ also is found naturally. w Mercury has entered ecosystems through the burning of ___________, waste incineration, mining, and the manufacture of items like _________. § Coal burning accounts for ______of the mercury released into the atmosphere. w Mercury bioaccumulates in the______, heart and kidneys of many animals. § Mercury compounds bioaccumulate in fish, adding risk for any organisms ____________. • Reducing the effects of chemical pollution w ____________ is the use of micro-organisms or plants to help clean up toxic chemicals. § Example: the oil industry uses bacteria to “______” See pages 98 - 99 oil spills. (c) Mc. Graw Hill Ryerson 2007
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