2 3 Effect of Bioaccumulation on Ecosystems Amphibians

2. 3 Effect of Bioaccumulation on Ecosystems • Amphibians are valuable indicators of environmental health w live both on land in the water w are sensitive to chemical changes to their environment • Amphibian observations w Since 1980 s, many amphibian species have suffered declines in population w Alarming increases in amphibian birth deformities w Theories to explain these changes include drought, increased UV rays, pollution, habitat loss, parasites, pesticides and Amphibians, like this frog, have diseases. exhibited drastic changes since the 1980 s. See pages 92 - 93 (c) Mc. Graw Hill Ryerson 2007

Bioaccumulation • Bioaccumulation = the gradual buildup of chemicals in living organisms w Chemicals are taken up and stored faster than they Organisms are sometimes are broken down and excreted exposed to toxic chemicals. w Many harmful chemicals can bioaccumulate • Keystone species = species that can greatly affect population numbers and the health of an ecosystem w E. g. , salmon, in BC ocean ecosystems • Biomagnification = suffers a chemical w If a keystone species bioaccumulation, when chemicals become more concentrated at each it can affect every other organism in the ecosystem trophic level • Occurs when pollutants are stored in plant tissue and in animal fat tissue (c) Mc. Graw Hill Ryerson 2007

(c) Mc. Graw Hill Ryerson 2007

Bioaccumulation Examples 1. Red Tide and Humans w Red tide = when certain algae bloom (become very numerous), turning coastal water reddish w algae produce toxic chemicals à bioaccumulate in clams, mussels & oysters à if humans consume these shellfish, can cause serious illness and even death See page 94 (c) Mc. Graw Hill Ryerson 2007

Bioaccumulation Examples 2. PCBs and Orcas w PCBs = chemicals that were used in the mid-1900 s in many applications (in paint, fluorescent lights, motors, electronics, sealing & finishing products, etc. ) w PCBs were banned in 1977 because of their environmental impact § PCBs bioaccumulate and have a long half-life (break down very slowly and stay in organisms a long time) § Probably cause cancer in humans § Will affect the reproductive success of orcas until at least The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae. 2030

https: //vimeo. com/43516716 When you watch this video, note: 1) The Salish Sea is the water off our BC coast 2) The person who describes bioaccumulation is really describing biomagnification (c) Mc. Graw Hill Ryerson 2007

POPs • Persistent organic pollutants (POPs) = carbon-containing compounds that remain in water and soil for many years w Examples: PCBs and DDT w 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 § Now banned in many countries because it has a long half-life and biomagnifies § Even at low levels (5 ppm), DDT in animals can cause nervous, immune, and reproductive system disorders. See page 96 Spraying DDT, 1958 • ppm = parts per million (c) Mc. Graw Hill Ryerson 2007

https: //www. youtube. com/watch? v=w_Zo. LKrxn_M LAST VIDEO BREAK… (c) Mc. Graw Hill Ryerson 2007

Heavy Metals • Heavy metals = metallic elements that are toxic to organisms w The worst: lead, cadmium & mercury 1. Lead (Pb) w Is extremely toxic – not considered safe at any level w Can be taken in by: eating, absorption through skin, inhaling w Can cause in humans: anemia, nervous system damage, kidney failure, sterility & low fertiliity, impaired mental development w Levels of lead in the soil have increased due to human activities w Lead is no longer used in many products it was Electronics once Waste Contains Lead. used in w Nearly all lead batteries are now recycled w Many electronics contain lead but few are recycled – most end up in See page 97 landfill (c) Mc. Graw Hill Ryerson 2007

Heavy Metals, cont’d. 2. Cadmium (Cd) w in the environment in low levels naturally w used in the manufacture of plastics and nickelcadmium batteries w toxic to earthworms and causes many health problems in fish. w In humans, can cause lung disease, cancer, immune system damage, and infertility § the main source of cadmium is smoking See page 97 -98 (c) Mc. Graw Hill Ryerson 2007

Heavy Metals, cont’d. 3. Mercury (Hg) w Some mercury enters the environment naturally § By volcanoes, hot springs & rock weathering w Humans have doubled the amount of mercury present § By burning fossil fuels, waste incineration, mining, and the manufacture of items like batteries. § Coal burning is responsible for 40% of the mercury sent into the atmosphere w Mercury bioaccumulates in the brain, heart and kidneys of many animals, including fish and humans See page 97 -98 (c) Mc. Graw Hill Ryerson 2007

Reducing Chemical Pollution • Reducing the effects of chemical pollution w Use of chemicals § Example: Add a chemical to the soil to react and change lead to a form that organisms aren’t likely to take in w Bioremediation = the use of micro-organisms or plants to help clean up toxic chemicals. • Some microorganisms naturally feed on chemicals and reduce them to non-toxic compounds • Example: the oil industry uses bacteria to “eat” oil spills. See pages 99 (c) Mc. Graw Hill Ryerson 2007

To Do Now • Bioaccumulation Worksheet (c) Mc. Graw Hill Ryerson 2007