Presentation on theme: "Effects of Bioaccumulation on Ecosystems"— Presentation transcript:
1 Effects of Bioaccumulation on Ecosystems Chapter 2.3
2 What do you know? Bioaccumulation Bio-magnification Orcas and pollutionPesticides and the environmentPersistent organic pollutantHeavy metal
3 BackgroundSome organic compounds as well as some heavy metals remain in the environment for a long timeAs lower orders on the food chain consume plant or animal materials containing these chemicals, the chemicals can accumulate in tissuesThe chemicals become biomagnified, moving up the food chainSome chemicals are toxic at very low levels, causing reproductive failure, organ malfunction, and death.
4 Bio-indicators help monitor the health of the environment
5 Amphibians are bio-indicators Life cycle includes aquatic phaseShell-less eggs are susceptible to environmental effects of run-off and other pollutantsHighly permeable skin, which they use to breathe, also makes them more sensitive to toxic substancesScientists believe that the factors that are negatively affecting amphibians today are also harming other speciesIf the frogs are showing negative effects, what does that say about the environment and other species?
6 Some chemicals are toxic at very low levels! Parts perppm = Parts per Million1cent in $10,000ppb = Parts per Billion1 cent in $10,000,000ppt = Parts per Trillion1 cent in $10,000,000,000Some chemicals are toxic at very low levels!
8 BioaccumulationBioaccumulation refers to the gradual buildup of chemicals in living organisms.Many harmful chemicalscannot be decomposed naturallycan be eaten or absorbed and sometimes cannot be removed from the body of the organism effectively.A keystone species is a vital part of an ecosystemIf a keystone species suffers a chemical bioaccumulation,it can affect every other organism in its far-reaching niches.Organisms are sometimes exposed to toxic chemicals.See page 94
9 BioaccumulationBiomagnification is the process by which chemicals become more concentrated at each trophic level.At each level of the food pyramid, chemicalsthat do not get broken down build up in organisms.When a consumer in the next trophic level eatsorganisms with a chemical accumulation,it receives a huge dose of the chemical(s).Organisms are sometimes exposed to toxic chemicals.See page 94
10 Bioaccumulation (continued) An example of bioaccumulation in British Columbia is the effect of PCBs on the Orca.PCBs are chemicals that were used for many industrial and electrical applications in the mid-20th century.Because PCBs do not degrade,The whale actually consumes4550 kg worth of accumulatedPCBs.See page 95The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae.
11 Bioaccumulation (continued) PCBs were banned in 1977 because of their environmental impact.PCBs bioaccumulate andhave a long half-life(they break down very slowly).PCBs will affect thereproductive cycles of orcasuntil at least 2030.The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae.See page 95
12 Bioaccumulation (continued) Chemicals like PCBs and DDT are called persistent organic pollutants (POPs)POPs contain carbon, like all organic compounds, and remain in water and soil for many years.Spraying DDT, 1958See page 96
13 Bioaccumulation (continued) Many POPs are insecticides, 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 bioaccumulatesand has a long half-life.Even at low levels (5 ppm), DDT inanimals can cause nervous, immune,and reproductive system disorders.ppm = parts per millionSpraying DDT, 1958See page 96
14 Bioaccumulation (continued) Heavy metals are metallic elements that are toxic to organisms.Levels of lead in the soil have increased due to human activities.not considered safe at any level.Many electronics contain lead and mustbe recycled carefully.can cause anemia and nervous andreproductive system damage.Electronics Waste Contains Lead.See page 97
15 Bioaccumulation (continued) Cadmium is also found in low levels naturally.used in the manufacture of plasticsand nickel-cadmium batteries.toxic to earthworms and causes many health problems in fish.In humans, the main source of cadmium is exposure to cigarette smoke.Cadmium causes lung diseases, cancer,and nervous and immune system damage.Electronics Waste Contains Lead.See page 97
16 Bioaccumulation (continued) Mercuryalso is found naturallyhas entered ecosystems through the burning of fossil fuels, waste incineration, mining, and the manufacture of items like batteries.Coal burning accounts for 40 percent of the mercury released into the atmosphere.bioaccumulates in the brain, heart and kidneys of many animals.bioaccumulate in fish, adding risk for any organisms eating fish.Take the Section 2.3 QuizSee pages
17 Bioaccumulation (continued) Reducing the effects of chemical pollution = Bioremediationthe use of micro-organisms or plants to help clean up toxic chemicals.Example: the oil industry uses bacteria to “eat” oil spills.Also: trapping chemicals in the soil where they cannot enter the food chains as easily.Take the Section 2.3 QuizSee pages
21 Reading check and Reflection Read Page 94-99Make some notes about what you learnDo reading check questions P.96 and P.99Write a half page reflection about:The impact of bioaccumulation on ecosystemsMethods of reducing chemical pollution
22 Find out activity 2-3A - Page 93 Do not eat the Candies!Tap the prey on the elbow only.Answers to What Did You Find Out?The pesticide affected all or almost all of the animals in the ecosystemThe pesticide would continue to affect animals in the ecosystem for the next 50 years. This would make the ecosystem unhealthy.