Eutrophication: Practice Questions

During the process of eutrophication, what causes the eventual reduction in dissolved oxygen levels, leading to the death of marine organisms?

Which human activity is a direct cause of eutrophication through the release of untreated organic waste into coastal waters?

The diagram shows the stages of eutrophication in a marine ecosystem. Which sequence correctly identifies the transition from nutrient entry to the death of larger organisms?
1. Algal bloom occurs
2. Decomposers respire aerobically
3. Nutrient runoff enters the sea
4. Death of organisms requiring dissolved oxygen
5. Producers die and sink

When agricultural fertilisers wash into the ocean, they often trigger a rapid growth of algae known as an algal bloom. What is the most immediate negative impact of this bloom on seagrasses growing on the seabed?

In coastal marine environments, which specific substances found in agricultural runoff are the primary triggers for the process of eutrophication?

In terms of their physical properties, why are modern agricultural fertilisers particularly prone to causing eutrophication in coastal waters?

Explain the biological mechanism that connects the death of producers during an algal bloom to the mass mortality of fish in a marine ecosystem.

Eutrophication is an environmental process often triggered by human activities on land, which can have significant impacts on marine ecosystems near the coast.

(a) Explain how the application of fertilisers to farmland helps to increase the yield of food crops.

(b) Define the term algal bloom.

(c) Identify the group of organisms that increases in population to break down dead organic matter, such as dead algae, during the process of eutrophication.

(d) Name one specific coastal marine ecosystem that is highly susceptible to the impacts of nutrient runoff from the land.