8. Biomagnification, Microplastics, Rewilding D4.2

What are the requirements for stability in ecosystems?

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

What is a possible tipping point in ecosystem stability mentioned in the notes?

Deforestation of the Amazon rainforest.

Why is a large area of rainforest necessary for ecosystem stability?

It generates atmospheric water vapor through transpiration, which contributes to cooling, air flows, and rainfall.

What model is used to investigate the effect of variables on ecosystem stability?

Mesocosms.

What role do keystone species play in ecosystems?

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

What is the definition of sustainability in resource harvesting from ecosystems?

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

What are two examples of renewable resources from ecosystems?

One terrestrial plant species and one species of marine fish.

What factors affect the sustainability of agriculture?

Soil erosion, leaching of nutrients, pollution from agrochemicals, and carbon footprint.

What is eutrophication and its primary cause in aquatic ecosystems?

Eutrophication is caused by the leaching of nitrogen and phosphate fertilizers.

What is biomagnification?

The increase in concentration of toxins in the tissues of organisms at higher trophic levels.

Provide examples of toxins that undergo biomagnification.

DDT and mercury.

Why are larger fish more problematic in terms of mercury concentrations?

They accumulate higher concentrations due to consuming larger quantities of prey.

What is a significant environmental issue caused by plastics in oceans?

They are non-biodegradable and can be ingested by marine animals, leading to suffocation and entanglement.

What are the two main groups of plastics mentioned?

Macroplastics (larger than 5mm) and microplastics (less than 5mm).

How do microplastics affect marine food chains?

They can bioaccumulate and increase the concentration of toxins in higher trophic levels.

What is rewilding in the context of ecosystem restoration?

Returning land and oceans to a more natural state, often by doing nothing.

Give an example of a rewilding project mentioned in the notes.

Hinewai Reserve in New Zealand.

What invasive species management strategy is employed in rewilding?

Removal of alien mammals like goats and control of invasive plants.

What interventions can speed up the rewilding process?

Reintroduction of apex predators, control of invasive species, and removal of livestock.

What is one major consequence of ecosystem degradation by human actions?

Loss of biodiversity and ecosystem services.

What are some human activities that threaten the stability of ecosystems?

Deforestation, pollution, climate change, urbanization, and overfishing are significant human activities that threaten the stability of ecosystems.