8. Biomagnification, Microplastics, Rewilding D4.2

Page 1: Introduction

  • Guiding Question: "What changes caused by humans threaten the stability of ecosystems?"

Page 2: Stability as a Property of Natural Ecosystems

D4.2.1 Evidence of Ecosystem Stability

  • Ecosystems, such as forests and deserts, demonstrate continuity over long periods, persisting for millions of years.

D4.2.2 Requirements for Stability

  • Stability requires:

    • Supply of energy

    • Recycling of nutrients

    • Genetic diversity

    • Climatic variables within tolerance levels

D4.2.3 Deforestation of the Amazon Rainforest

  • The Amazon rainforest's large area generates atmospheric water vapor through transpiration, influencing cooling, air flows, and rainfall.

  • There is uncertainty about the minimum area necessary to maintain these processes.

D4.2.4 Models for Investigating Ecosystem Stability

  • Mesocosms can be set up in:

    • Open tanks

    • Sealed glass vessels (preferred for preventing matter exchange while allowing energy transfer)

  • Aquatic or microbial ecosystems are usually more successful than terrestrial ones.

  • Ensure care and maintenance of mesocosms follows IB experimental guidelines.

D4.2.5 Role of Keystone Species

  • Keystone species have a disproportionate impact on community structure. Their removal poses a risk of ecosystem collapse.

D4.2.6 Assessing Resource Harvesting Sustainability

  • Sustainability depends on harvesting rates being less than replacement rates, illustrated with:

    • One terrestrial plant species

    • One marine fish species

D4.2.7 Factors Affecting Agricultural Sustainability

  • Considerations include:

    • Soil erosion

    • Nutrient leaching

    • Fertilizer supply

    • Pollution from agrochemicals

    • Agricultural carbon footprint

D4.2.8 Eutrophication Effects

  • Eutrophication arises from leaching nitrogen and phosphate fertilizers, increasing biochemical oxygen demand (BOD).

D4.2.9 Biomagnification of Pollutants

  • Understanding accumulation of toxins in higher trophic levels (e.g., DDT, mercury).

D4.2.10 Microplastic and Macroplastic Pollution

  • Plastics are persistent due to non-biodegradability and impact marine life.

D4.2.11 Restoration via Rewilding

  • Methods include:

    • Reintroduction of apex predators

    • Connectivity between habitats

    • Minimizing human impacts (e.g., ecological management)

  • Example: Hinewai Reserve in New Zealand.

Page 3: Biomagnification of Pollutants

  • Pollutants from human activities enter food chains, accumulating in higher concentrations at top food chain levels.

  • Toxins tend to accumulate in fat tissues (e.g., mercury).

Page 4: Concentrations of Toxicities in Fish

  • Large fish species contain higher mercury concentrations; thus, they should be avoided (especially during pregnancy).

Page 5: DDT and Its Impact

  • DDT, an insecticide, accumulates in animal fat; banned in many countries but still used in some for malaria control.

Page 6: Biomagnification and Food Webs

  • Biomagnification varies across aquatic and terrestrial food webs; examples include PCB-153 and B-HCH concentrations observed at different trophic levels.

Page 7: Plastics in Marine Environments

  • Plastic waste represents a major threat, with marine animals often mistaking it for food, leading to suffocation and entanglement.

Page 8: Plastic Pollution Impact on Turtles

  • Articles detail how loggerhead turtles struggle with plastic pollution affecting their survival.

Page 9: Categories of Plastics

  • Plastics are categorized into:

    • Macroplastics: Large, visible (>5mm)

    • Microplastics: Tiny pieces (<5mm)

Page 10: Microplastics and Their Accumulation

  • Microplastics can bioaccumulate in food chains, increasing in higher trophic levels; their abundance is rising in marine environments.

Page 11: Sources of Microplastic Pollution

  • Various origins of microplastics include:

    • Laundering synthetic textiles

    • Manufacturing processes

    • Stormwater runoff

    • Erosion and littering

Page 12: Laysan Albatross and Plastic Ingestion

  • Laysan albatrosses ingest indigestible plastics; graphs show the mass of materials in their boluses at different locations.

Page 13: Ecosystem Degradation Consequences

  • Human actions lead to biodiversity loss, species extinction, and diminishing ecosystem services; efforts are underway to encourage natural ecosystem restoration through rewilding.

Page 14: Concept of Rewilding

  • Rewilding focuses on restoring land and oceans to natural states, often by minimizing human interference.

  • Example: Hinewai Reserve in New Zealand.

Page 15: Invasive Species Removal

  • Removal of invasive species (e.g., goats, gorse) can help in native species recovery and ecosystem balance.

Page 16: Enhancing Rewilding Efforts

  • Strategies include reintroducing apex predators, managing invasive species, and removing livestock to promote natural restoration.

Page 17: Rewilding Projects in Europe

  • Examples of European rewilding projects focuses on how to achieve ecosystem restoration, exploring principles and case studies like the Iberian Highlands and Danube Delta.