The Story of Stuff highlights how we are all organisms intimately connected with the ecosystem and toxins in our consumer products have an effect on us.
Homework: Read and do homework questions on section 2.2 of the Study Guide, pages 47 to 53 of the pdf document
Class Notes:
How do
toxins move through the trophic
Levels? Toxins
concentrate up the trophic levels.
(notice that this is the opposite of what energy does). Toxins may effect all the organisms in ecosystems. If they harm KEYSTONE SPECIES, then the entire ecosystem may unravel.
Keystone species a keystone species is the most important member of the ecosystem, without which, the entire ecosystem would collapse. The keystone of a bog is sphagnum moss. the keystone of a pacific west coast rainforest is salmon.
Bioaccumulation bioaccumulation is when
toxin levels increase in organisms on the same trophic
level
Biomagnification toxins
magnify going up the food pyramid. An example is the pesticide DDT. DDT is sprayed on crops. These crops (corn) are eaten by rodents. Each individual rodent has a higher
dose of DDT compared to the individual corn plant. The rodents are eaten by snakes, Each snake receives a
higher dose than the individual rodent.
The snakes and rodents are consumed by a predator like a hawk or
eagle. This type of top predator
receives the highest dose of all.
Similarly, in an aquatic ecosystem, the phytoplankton (producers)
consume toxins that move to the zooplankton, small fish, bigger fish, sharks
and whales. The higher the trophic
level, the greater concentration of toxins.
Examples of toxins
PCB – industrial residue, interferes with reproduction
HEAVY METALS
Lead – naturally occurring in soil, in manufacturing of paints, batteries,
electronics, soldering.
Neurotoxin, reproductive toxin, kidney failure
Mercury – released through mining, burning fossil fuel, coal
burning, a neurotoxin
Cadmium, manufacture of plastics and batteries. Reproductive toxin
Flame retardant: found in new clothing
PPCPs : drugs, cosmetics, vitamins,
antibiotics, sources: pharmaceutical companies (controlled), hospitals,
residences (uncontrolled), agribusiness.
Examples of endocrine disrupters estrogen mimics or estrogen, these reduce sperm
count, cause fertility problems, and, in some amphibians: change sex.
Phthalates: lining in canned food, plastic
drink containers, some plastic food containers, plastic wrap, deodorant,
cosmetic additive
Avoiding toxins eat
low on the food pyramid. Plants and primary
consumers have the lowest toxic load.
Eat
organic
Protect
water sources: ground water in Ontario was found to be
contaminated with personal care products and pharmaceuticals Use
safe, natural personal care products: olive oil as conditioner, vitamin e for
lip balm.
