Energy flows in food chains from:
- producers – the plants – to
- 1st consumers – plant-eaters to
- 2nd and 3rd etc consumers – the meat-eaters and parasites- to
- Decomposers: worms, snails, bacteria, fungi
Pollution and accumulation of persistent chemicals
When certain chemicals enters the food chains, they may accumulate in the fatty tissues or bones and increase in amount for every step in the food chain. Persistent Organic Pollutants (POPs) are regarded as particularly dangerous accumulating chemicals.
- Food chains (Short video)
- Producers, consumers, decomposers (Short video)
- Ecological pyramids and bioaccumulation or bio-magnification
Ecosystems can be disrupted
Eosystems may change suddenly or over time. If the change happens over a long period of time, most species can adapt to the new conditions.
Ecosystems may be disrupted through natural causes, such as a natural change in climate, or natural disasters like earthquakes, volcanic eruptions and tsunamies. Human activities may also disrupt ecosystems, locally as well as globally. Human activities may enhance existing natural processes or cycles, such as the greenhouse effect, or create completely new conditions, such as depleting the ozone layer with ozone depleting chemicals, or add POPs to the energy flow in the food chains.
Pollution through high concentrations of waste and secreta may affect water bodies and cause eutrophication.
Ecosystem services are the benefits people obtain from ecosystems. These include provisioning services such as food, water, timber, and fiber; regulating services that affect climate, floods, disease, wastes, and water quality; cultural services that provide recreational, aesthetic, and spiritual benefits; and supporting services such as soil formation, photosynthesis, and nutrient cycling
Millennium Ecosystem Assessment – Synthesis
More comprehensive information
- “Home”: Movie
- Story of stuff. Video and Interactive website on ecology, consumption and pollution
- UNEP, Dead planet – living planet
- Climate and distribution of life. Taped Lecture
- Pesticides Cause ‘Catastrophic’ Harm to People and Planet, UN Report Says (March 2017)
|Chapter 3||3. Impacts|
|Chapter 4||4. Ecosystems|
|4.1 Ecosystems and energy flow|
|4.3 Agricultural land|
|Chapter 5||5. Green economy|