2.3 - Effect of Bioaccumulation on Ecosystems Amphibians (ie. frogs) live both on land and in water. They are sensitive to chemicals changes in the environment, therefore are valuable indicators of environmental health. Since the 1980s…  many of the world’s amphibian species (there are 5700 known!) have suffered declines in population  there have been alarming increases in amphibian birth deformities Many theories attempt to explain these changes, including drought, increased UV rays, pollution, habitat loss, exposure to pesticides, parasites and diseases. YIKE S!

Parasites or Chemicals? Methoprene is considered a biochemical pesticide because, rather than controlling target pests through direct toxicity, it interferes with an insect’s life cycle and prevents the insect from reaching maturity / reproducing. Chemicals can change into another form when they get exposed to light, heat, or other chemicals in the environment. Because chemicals can change like this when they are in the environment, it is possible that methoprene changes into a new form after it is sprayed. The new form of methoprene may cause deformities in frogs, even if the original form of the chemical does not.

Synthetic Chemicals …are human-made chemicals. enter the environment in air, water, soil become biomagnified in food pyramids  harm organisms when decomposers cannot biodegrade these chemicals, they build up in the environment…

Bioaccumulation Bioaccumulation refers to an organism slowly building up the amount of chemicals in their bodies.  These chemicals can be eaten or absorbed, and sometimes cannot be effectively removed from the body of the organism.  rate of intake and storage > rate of breakdown (metabolism) & excretion

Bioaccumulation chemicals can enter organisms via:  food intake  skin contact  respiration chemicals may be stored in fat tissue, but are released when fat is burned chemicals can:  affect nervous system  affect reproductive system  affect immune system  cause birth defects

Keystone Species A keystone species is one that can greatly affect population numbers. It exerts great influence on the structure & the health of an ecosystem (ie. salmon). If a keystone species suffers chemical bioaccumulation, it can affect every other organism in its far-reaching niches.

Biomagnification Biomagnification is the process in which chemicals not only accumulate, but become more concentrated at each trophic level.  chemicals that do not get broken down build up in organisms at each level of the food pyramid  chemicals trapped in tissues are released when tissues are broken down for energy

Biomagnification - Example When shellfish eat the algae that cause red tide, they accumulate toxins. The toxic shellfish can cause paralytic shellfish poisoning when consumed by humans.

Bioaccumulation in BC An example of bioaccumulation in BC is the effect of PCBs (polychlorinated biphenyls) on the Orca. PCBs are chemicals that were used for many industrial and electrical applications between the 1930s and ‘70s. PCBs were banned in 1977 because of fears of their environmental & health impacts. PCBs…  have a long half-life  suppress the immune system  likely cause cancer in humans  will affect the reproductive success of Orcas until at least 2030 Alison!! BBC Controlling our food monsanto 5:30 Anniston, Alabama

Bioaccumulation in BC

Bioaccumulation - POPs Chemicals like PCBs and DDT are called persistent organic pollutants (POPs). POPs (like all organic compounds) contain carbon, and remain in water & soil for many years. many POPs are insecticides  DDT was introduced in 1941 to control mosquito populations, and is still used in some places in the world.  Like PCBs, DDT bioaccumulates, biomagnifies, & has a long half-life.  At even low levels (5 ppm), DDT is toxic / harmful & can cause nervous, immune & reproductive system disorders in animals.

Bioaccumulation – Heavy Metals Heavy metals  are high-density, metallic elements  are toxic to organisms at low concentrations  also bioaccumulate  do not degrade & cannot be destroyed within the biosphere Lead, mercury and cadmium are some of the most polluting heavy metals.

Bioaccumulation – Lead Lead is found naturally at low levels, but levels have increased. Pb is considered unsafe at any level many electronics contain Pb, and must be recycled carefully Pb can…  be ingested  be inhaled  be absorbed through skin  cause anemia, kidney failure  cause nervous & reproductive system damage

Bioaccumulation – Cadmium Cadmium is also found naturally at low levels  Cd is used in the manufacture of plastics and Ni-Cad batteries  Cd is strongly attracted to organic matter in soil  taken up by plants  eaten by animals  Cd is toxic to earthworms, and causes many health problems in fish  the main source of Cd exposure in humans is cigarette smoke (tobacco plants absorb Cd)  Cd can cause lung diseases, cancer, infertility damage to DNA, nervous & immune systems

Bioaccumulation – Mercury Mercury is also found naturally. Much more Hg has entered ecosystems through…  the burning of fossil fuels (coal burning accounts for 40% of the Hg released into the atmosphere)  waste incineration  mining  the manufacture of items like batteries methylmercury bioaccumulates in the brain, heart and kidneys of many animals  Hg compounds bioaccumulate in fish, adding risk for any fish-eating organisms.

Reducing the effects of chemical pollution By trapping chemicals in the soil, they cannot enter food chains as easily. Bioremediation is the use of living organisms (ie. micro-organisms / plants) to help clean up through biodegradation the organisms are then removed from the ecosystem  the oil industry often uses bacteria to “eat” oil spills

Plants & Bioremediation Certain natural species (ie. alfalfa, juniper, poplar trees) are also excellent at bioremediation. concentrate heavy metals in their tissues root systems hold contaminated soil in place, preventing spread of contaminants via water & wind