Overview
This lecture covers human impacts on ecosystems, focusing on pollution (water, land, air), conservation of resources, endangered species, and strategies to maintain biodiversity.
Human-Caused Pollution
- Pollution is the addition of harmful substances to the environment, making it unsafe for living things.
- Water pollution sources include untreated sewage, pesticides, and excess fertilizers.
- Eutrophication is caused by nutrient overload, leading to algal blooms and reduced oxygen, harming aquatic life.
- Plastics are non-biodegradable, persisting in the environment and harming aquatic and land ecosystems.
- Plastic pollution in water causes habitat destruction, animal deaths, and releases toxins into the food chain.
- On land, plastics pollute soil, harm wildlife, and break down into microplastics that further contaminate ecosystems.
- Air pollution is mainly caused by methane (from livestock and landfills) and carbon dioxide (from burning fossil fuels).
- Greenhouse gases trap heat, causing global warming, climate change, rising sea levels, and extreme weather.
Conservation and Sustainable Use of Resources
- Conservation is the careful management of natural resources for current and future use.
- A sustainable resource is produced as quickly as it is removed, preventing depletion.
- Forests can be conserved through education, protected areas, quotas, and replanting.
- Fish stocks are conserved by education, closed fishing seasons, catch quotas, and using proper nets.
Endangered and Extinct Species
- An endangered species has very few individuals and is at risk of extinction; extinct means none remain.
- Causes include climate change, habitat destruction, over-hunting, over-harvesting, pollution, and introduced species.
- Conservation methods include habitat protection, education, captive breeding, and seed banks.
Importance of Conservation Programs
- Conservation maintains biodiversity, reduces extinction, protects ecosystems, and supports essential functions.
- Captive breeding uses artificial insemination and in vitro fertilization to help endangered animals reproduce and maintain genetic diversity.
Risks of Small Population Sizes
- Small populations have reduced genetic diversity, making them more vulnerable to disease and environmental changes, increasing extinction risk.
Key Terms & Definitions
- Eutrophication — Process where nutrient overload causes oxygen depletion in water, harming aquatic life.
- Non-biodegradable — A material that does not break down naturally in the environment.
- Greenhouse effect — The trapping of heat in Earth's atmosphere by greenhouse gases, causing global warming.
- Sustainable resource — A resource produced as quickly as it is consumed, preventing depletion.
- Endangered species — Species at risk of extinction with very few individuals remaining.
- Extinct species — Species that no longer exist anywhere in the world.
- Captive breeding — Breeding endangered species in controlled environments to boost their populations.
Action Items / Next Steps
- Review chapter 20 notes on human impacts, pollution, and conservation strategies.
- Learn key definitions and examples for possible exam questions.