Bioaccumulation and Biomagnification

What is bioaccumulation?

bioaccumulation refers to how pollutants enter a food chain or food web.

How does bioaccumulation occur?

involves an increase of concentration in pollutants from the environment to the tissue of an organism. Smaller, simpler organisms towards the bottom of a food chain will often absorb these pollutants more easily.

What is biomagnification?

biomagnification refers to a pollutant's ability to increase in concentration as it moves from one trophic level to the next.

How does biomagnification occur?

involves an increase in concentration from one link in a food chain to another due to the relative amount each organism consumes.

In order for biomagnification to occur, what are the conditions that pollutants must be?

in order for it to occur, the pollutants must be:

Long-lived - does not break down easily

Mobile - air, water, etc.

Soluble in fats - does not readily dissolve and be excreted, which means it can accumulate in fat tissue and be retained for long periods of time.

Biologically active - can affect living matter

What is DDT and what is/was it used for?

DDT, an abbreviation for dichlorodiphenyltrichloroethane is an insecticide used in agriculture. It has now been banned in many countries.

What impact does biomagnification of DDT have on birds?

The high concentration of DDT interferes with the calcium metabolism of birds and induces eggshell thinning. This causes the population to decrease.

What impact does DDT have on humans?

Following exposure to high doses of DDT, human symptoms include nausea, vomiting, tremors, shaking and seizures. It is considered a possible human carcinogen (cause of cancer).

Evaluate the pros and cons of DDT use

Pros

- great and cheap toxin for insects, helping plants grow without the risk of being eaten

- used to cure malaria and typhus during WWII

Cons

- high exposure leads to problems with the nervous system and liver

What are macroplastics and microplastics?

Macro plastics are plastic items with a diameter of >5mm.

Microplastics are plastic items with a diameter of <5mm.

How is microplastic and macroplastic formed?

They are formed in oceans when sunlight, chemical reactions, waves and water currents break down large plastic products, called macroplastics. The plastic pieces become smaller in diameter and are called microplastics once they reach a diameter of <5mm.

Why is microplastics and macroplastics a problem?

Because plastics do not decompose, the only way they are broken down is into smaller pieces. Due to their small size, they go unnoticed. They are easily mistaken for food by birds and marine life. Over the years the amount of microplastics just increases.

Impact of plastic on Laysan albatross

It injures or kills the birds by cutting their stomachs or taking up space, making them feel 'full' when they are starving.

Impact of plastic on sea turtles

Plastic can cause blockage in their intestines and pierce the intestinal wall causing internal bleeding.