7. Resources and Eutrophication D4.2

What is required for stability in ecosystems?

Supply of energy, recycling of nutrients, genetic diversity, and climatic variables remaining within tolerance levels.

What is an example of a possible tipping point in ecosystem stability?

Deforestation of the Amazon rainforest.

What role do keystone species play in ecosystems?

They have a disproportionate impact on community structure and their removal can lead to ecosystem collapse.

How does sustainability of resource harvesting depend on the rate of harvesting?

The rate of harvesting must be lower than the rate of replacement.

What are some factors affecting the sustainability of agriculture?

Soil erosion, leaching of nutrients, supply of fertilizers, pollution due to agrochemicals, and carbon footprint.

What is eutrophication?

Eutrophication is the excessive nutrient enrichment of water, often caused by leaching of fertilizers.

What are the consequences of algae bloom?

Algae blooms block sunlight, deplete oxygen, and can kill photosynthesizing plants.

What is meant by Biomagnification?

It refers to the increasing levels of toxins that accumulate in the tissues of consumers at higher trophic levels.

What is the major environmental issue caused by plastics?

Plastics persist in the natural environment and can cause harm to marine life.

What is biological oxygen demand (BOD)?

BOD measures the amount of dissolved oxygen needed to break down organic material in water.

How does deforestation impact rainforest processes?

It reduces the area needed for transpiration which affects atmospheric water vapor generation, cooling, and rainfall.

What are mesocosms and their purpose?

Mesocosms are experimental systems that allow investigation of the effect of variables on ecosystem stability.

What farming practice can lead to increased pest problems?

Monocultures, or repeated growth of the same crop.

What human activities can cause eutrophication?

Leaking excess nitrogen and phosphate containing chemicals (fertilizers) used in agriculture.

What is the significance of apex predators in ecosystems?

Their reintroduction can help restore natural processes and connectivity in ecosystems.

What factors contribute to soil erosion?

Tillage practices such as plowing and harrowing reduce soil quality.

What is the potential impact of overfishing on fish populations?

Many fish, such as cod, are on the verge of extinction due to overfishing.

How can the sustainability of fish harvesting be assessed?

By ensuring the rate of harvesting does not exceed the rate of fish population recovery.

What ecological role does nutrient cycling play in ecosystems?

It maintains ecosystem health and stability by recycling essential nutrients necessary for growing organisms.

What are the effects of eutrophication on aquatic and marine ecosystems?

Eutrophication can lead to hypoxia (low oxygen levels), loss of biodiversity, fish kills, and shifts in species composition, disrupting the balance of aquatic food webs.