Bioaccumulation BioAMplification

Definition Bioaccumulation is the concentration of a substance such as a pesticide in the body of an organism ( 1 organism) Bioamplification is the increase in the concentration of a substance as it moves higher up the food web (Food chain)

Bioaccumulation

Bioamplification

Which has the most mercury build-up?

The Issue Some chemicals don’t break down or get eliminated easily As harmful chemicals increase in concentration through bioaccumulation within in an organism levels can climb to greater than levels in the environment Through bioamplification levels can become toxic as it moves up the food chain Pesticides, pollution, toxins and other chemical enter into animals and even us!! This is dangerous because we are consuming toxins and these toxins also limit environments CARRYING CAPACITY.

DDT A pesticide that does not break down quickly. Bioaccumulated in birds like osprey, peregrine falcons, and bald eagles The number of these birds declined rapidly because DDT interfered with calcium metabolism and a females ability to make strong eggs.

Arctic ecosystems are especially vulnerable PCB’s and Mercury Fat-soluble chemicals such as mercury and polychlorinated biphenyl’s bioamplify in food webs Arctic ecosystems are especially vulnerable High levels of the toxins are found in long-lived consumers like whales, walrus, and fish (canned albacore tuna)

Pests Organisms that people consider harmful or inconvenient Damage crops, or reduce yields Can be weeds, animals such as mice, insects such as aphids or fungus

Pesticides A substance used to kill a pest Reduce competition, increase yield, plants therefore grow faster Types include: herbicide- kill plants, insecticide-kill insects, rodenticide- rodents, fungicide- fungi, molluscicide-snails and piscicide-fish

Modern synthetic pesticides are more short-lived than pesticides from the past like DDT Broad spectrum: toxic to a wide range of species Narrow spectrum: toxic to a limited number of species Work by causing physical or biological harm to the pest

Pesticide Issues Non-target species Bioamplification Can kill beneficial organisms (predatory insects, kill bees needed for pollination, create food chain collapse) Bioamplification Pesticide resistance When a pesticide is no longer effective in killing the target species. Becomes increasingly difficult to control pests Pesticide Dependence As we kill off non-target species, and resistance increases we enter into a cycle of dependence on pesticides. Alternatives include organic farming and integrated pest management

Organic Farming Techniques Biological control- using predatory insects like parasitic wasps, ladybugs Altered timing- plant/harvest at times to avoid peak insect times Crop rotation and mixed planting- Prevent pests from establishing to maximum levels Baiting pests Pheromone baits Integrated Pest Management uses all organic techniques but uses pesticides and fertilizers when necessary