Impact of Humans on Ecosystems

Question 1

What are ‘alien species’?

Answer 1

Species arrives in a non native habitat. Often is not well adapted and will not survive. Sometimes species are successful and become invasive.

Question 2

What is ‘competitive exclusion principle’?

Answer 2

Two species cannot occupy the same niche or there will be competition for the same resources.

When one species has the slightest advantage, that species will dominate.
Advantages include higher reproductive rate, larger/more agressive, faster/more efficient forager and absence of predator.

Question 3

Define ‘biomagnification’

Answer 3

A process by which chemical substances become more concentrated at each trophic level.

Bioaccumlation occurs within one trophic level, and is when an individual eats contaminated food or drinks contaminated water, building up chemical substances.

Question 4

What are the effects of micro and macroplastics? (4)

Answer 4

• Suffocation: if inhaled or wrapped around throat.
• Blocks the intestine/stomach (animal ceases feeding, leading to starvation).
• Both macro and microplastic debris are ingested by many marine organisms, which mistake debris for food.
• Accumulates in cells—enters the food chain (biomagnification)—poisons (some plastics contain toxic chemicals).